• TABLE OF CONTENTS
HIDE
 Cover
 Acknowledgement
 Table of Contents
 Preface
 Magnitude of the industrial waste...
 Florida industrial waste probl...
 The equitable utilization of stream...
 Title Page
 Developments in the disposal of...
 Reduction of organic matter in...
 The removal of oils, fats and grease...
 Investigation of Alafia and Peace...
 The challenge of industrial waste...
 Kraft mill effluent control...
 Kraft mill effluent control practice:...
 Theory and practice in stream pollution...














Industrial wastes practices
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 Material Information
Title: Industrial wastes practices proceedings of the Fifth National Public Health Engineering Conference, May 20 and 21, 1952
Series Title: Bulletin series ;
Physical Description: 60 p. : ill., map ; 28 cm.
Language: English
Creator: University of Florida -- Dept. of Civil Engineering
University of Florida -- Engineering and Industrial Experiment Station
Conference: Public Health Engineering Conference, 1952
Publisher: Florida Engineering and Industrial Experiment Station, College of Engineering, University of Florida
Place of Publication: Gainesville
Publication Date: 1952
 Subjects
Subjects / Keywords: Factory and trade waste -- Congresses   ( lcsh )
Water -- Pollution -- Congresses   ( lcsh )
Genre: government publication (state, provincial, terriorial, dependent)   ( marcgt )
bibliography   ( marcgt )
conference publication   ( marcgt )
non-fiction   ( marcgt )
 Notes
Bibliography: Includes bibliographical references.
Statement of Responsibility: sponsored by the Department of Civil Engineering.
General Note: "October, 1952."
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Source Institution: University of Florida
Holding Location: University of Florida
Rights Management: All rights reserved by the source institution and holding location.
Resource Identifier: ltqf - AAA6455
ltuf - ANY9293
oclc - 27125682
alephbibnum - 002858178
System ID: UF00005137:00001

Table of Contents
    Cover
        Cover
    Acknowledgement
        Page 2
    Table of Contents
        Page 3
    Preface
        Page 4
    Magnitude of the industrial waste problem in the southeast
        Page 5
        Page 6
        Page 7
        Page 8
        Page 9
    Florida industrial waste problems
        Page 10
        Page 11
        Page 12
        Page 13
        Page 14
        Page 15
        Page 16
        Page 17
    The equitable utilization of stream resources by industries
        Page 18
        Page 19
        Page 20
    Title Page
        Page 1
    Developments in the disposal of citrus processing wastes
        Page 21
        Page 22
        Page 23
    Reduction of organic matter in citrus press liquor by aerated yeast propagation
        Page 24
        Page 25
        Page 26
    The removal of oils, fats and grease from wastes
        Page 27
        Page 28
        Page 29
    Investigation of Alafia and Peace Rivers
        Page 30
        Page 31
        Page 32
    The challenge of industrial waste to the engineer
        Page 33
        Page 34
    Kraft mill effluent control practice
        Page 35
        Page 36
        Page 37
        Page 38
        Page 39
    Kraft mill effluent control practice: Discussion
        Page 40
        Page 41
        Page 42
        Page 43
    Theory and practice in stream pollution control
        Page 44
        Page 45
        Page 46
        Page 47
        Page 48
Full Text



ENGINEERING PROGRESS


at the
University of Florida


Vol. VI. No. 10


INDUSTRIAL WASTES PRACTICES


(Proceedings of the Fifth National Public Health Engineering Conference)


May 20 and 21, 1952


DEPARTMENT OF CIVIL ENGINEERING


Bulletin Series No. 57


Published monthly by the
FLORIDA ENGINEERING AND INDUSTRIAL EXPERIMENT STATION
College of Engineering S University of Florida 6 Gainesvlle

Entered as second-class matter a, the Post Office at Gainesville, Florida







ACKNOWLEDGMENTS



The program for the Fifth Public Health Engineering Conference was worked out by the State
Coordinating Committee on Surface and Underground Water Pollution Prevention and Abatement
representing the groups listed below:


Mr. David B. Lee
Mr. Ralph G. Cooksey
Mr. R. B. Fuller
Mr. W. T. Edwards
Dr. A. P. Black
Mr. Wylie W. Gillespie
Mr. W. W. Giddings
Mr. James Massey
Mr. W. T. Mcliwain
Mr. Joseph W. Davin
Mr. Robert Hoy
Mr. J. F. DeQuine
Prof. John E. Kiker
Dr. David B. Smith


Florida State Board of Health
Florida wildlife Federation
Florida Phosphate Industry
Florida Pulp and Paper Industry
Florida Section, American Water Works Association
Florida Engineering Society
Florida Citrus Industry
Florida Newspapers
Florida Municipalities
Florida Realtors
Florida Sewage Works Association
Florida Fish and Game Commission
University of Florida, Chairman
Florida Engineering & Industrial Experiment Station,
Vice-Chairman


The Conference was conducted by the Sanitary Engineering Section of the Civil Engineering
Department. It was made possible through the cooperation of Dean Joseph Weil, College of Engi-
neering; Ralph W. Kluge, Head Professor of Civil Engineering; and David B. Lee, Director, Bureau
of Sanitary Engineering, Florida State Board of Health. The papers included in these Proceedings
were edited by Dr. Ellwood R. Hendrickson.

A ladies program was arranged by a special committee consisting of Mrs. David B. Smith,
Chairman, Mrs. Ralph W. Kluge, Mrs. Thomas Furman, and Mrs. John Kiker.

A major portiun of the credit for the success of the conference is, of course, due to those who
took part in the presentation of papers. The discussions were presented enthusiastically, and it
is believed that the papers herein published will speak for themselves.










TABLE OF CONTENTS

Page
Acknowledgment ............ ...... . ................................ 2

Preface ............. .... ............ ......... ......... ......... 4

Magnitude of the Industrial Waste Problem in the Southeast, by Lewis A. Young .. ..... 5

Florida Industrial Waste Problems, by John W. Wakefield ......................... 10

The Equitable Utilization of Stream Resources by Industries, by Earle B. Phelps ..... .. .18

Developments in the Disposal of Citrus Processing Wastes, by F. W. Wenzel ........... 21

Reduction of Organic Matter in Citrus Press Liquor by Aerated Yeast Propagation,
by M. K. Veldhuis ..............................................24

The Removal of Oils, Fots and Grease from Wastes, by F. S. Gibbs ................. 27

Investigation of Alafle and Peace Rivers, by William R. Clary .......... ...........30

The Challenge of Industrial Waste to the Engineer, by Malcolm Pirnie ................ 33

Kraft Mill Effluent Control Practice, by Harry W. Gehm ........................ 35

Kraft Mill Effluent Control Practice, Discussion by Anthony W. Pesch ............... 40

Theory and Practice in Stream Pollution Control, by Richard D. Hoak ................ 44

Disposal of Oil Brine Wastes, by Harry P. Kramer ......................... ..50

Influence of Industrial Wastes on Sewage Treatment, by A. A. Kalinske .............. 54









The papers in this Bulletin were presented by various
speakers at the Fifth National Public Health Engineering
Conference, sponsored by the Civil Engineering Department,
College of Engineering, as a public service function of the
Engineering and Industrial Experiment Station, University
of Florida. The opinions of the speakers are their own.
They do not necessarily reflect the opinions of staff mem-
bers or the policies of the University of Florida.







PREFACE


In 1948, The Department of Civil Engineering sponsored the first of a series of annual Public
Health Engineering Conferences. These conferences have placed emphasis upon the specific
topics of Stream Sanitation, The Economics of Sewage Treatment, Suburban Sanitary Services,
and Radiological Health and Civil Defense. In each of these conferences an attempt was made to
investigate and answer problems of current interest in the public health engineering field.

In recent years, there has been a tremendous surge in the industrialization programs of the
southern states. This, however, is not an unmixed blessing, for one need only survey the degrad-
ation of streams in the older industrial areas to realize what can happen to natural water resources
subjected to industrial usage. Consequently, the regulatory agencies, and others, are directing
attention to the possible effects which wastes from industries can have upon natural waterways
as well as the means for minimizing these effects. With this thought in mind the fifth and present
conference was designed about the theme of industrial wastes.

In formulating a program for the fifth conference, an attempt was made to include a detailed
discussion of the characteristics and methods of treatment of specific wastes which constitute
existing or potential problems in the South. Among those which might be mentioned are the wastes
of citrus products, oil, fat and grease wastes, phosphate- mining wastes, pulp and paper mill
wastes, and oil brine wastes. In addition, the effect of these and other wastes on municipal treat-
ment plants and the receiving streams was emphasized.

One hundred and sixty-three persons from ten states were registered at the conference, which
was held May 20-21, 1952, on the campus of the University of Florida.


David B. Smith
Assistant Director, Engineering and Industrial Experiment Station







MAGNITUDE OF THE INDUSTRIAL WASTE
PROBLEM IN THE SOUTHEAST

by

Lewis A. Young
Officer in Charge
Southeast Drainage Basins
Public Health Service


The water resources of the Southeast have played
an important part in its industrialization. Industry is
becoming more and more aware of the fact that a clear,
clean water supply is one of its most important raw
materials. Its water requirements are great, both as to
quantity and as to quality. To quote from a statement
by the National Association of Manufacturers:

t"A shortage of water for industrial purposes just
as surely as a shortage of manpower, of raw mate-
rials, or of capital- could defeat our hopes for fu-
ture growth and prosperity, and even imperil our
National safety. No industry or business can long
survive where water is unavailable or inadequate
as to quantity or quality."

Most of the streams of the Southeast are still relatively
unspoiled. Water is abundant in all parts of the area
and for the most part is of good chemical quality, well
suited to industrial use. The high turbidities common
in the streams that originate in the Piedmont Plateau
do not present a water treatment problem.

Industries have been and are being attracted to the
area. The textile, paper and chemical industries require
not only large quantities of water, but a water which
is soft that is, low in chemical hardness.

It is fortunate that the public is generally aware of
the need for water-pollution control. The pollution
which now exists can be checked and controlled and
comprehensive plans can be developed to protect this
most vital natural resource before great damage is done.
There are instances where pollution, both industrial
and municipal, has already destroyed the full useful-
ness of the water for miles below the point of waste
discharge. The damage is not as great not the situation
as critical as it is in other areas of the country. Some
of the streams in those areas have become so polluted
that the development of new industrial water supplies
is too costly and further expansion of industry is pre-
vented until the water of the streams can be returned
to a more satisfactory condition.


We should nor be lulled, however, into a state of
false security because such serious pollution does not
exist in the streams of the Southeast at the present
time. The localized pollution conditions which exist
throughout the area could easily spread and damage
entire water courses if pollution is not controlled and
future planning does not take into consideration the
safe-guarding of the water resources. We have rather
complete data regarding the pollution that exists in
some of the rivers and underground waters.

You are probably familiar with the old practice of
discharging industrial wastes, particularly those from
the citrus industry into the limestone caverns in Central
Florida. Fortunately, this unsatisfactory means of dis-
posal has been stopped. Before it was stopped, how-
ever, many ground water supplies in the area were dam-
aged. The decomposition of these organic wastes pro-
duced quantities of methane gas, building up gas
pressures in the water-bearing formation. The quantity
of gas produced was sufficient to force the abandon-
ment of expensive water supply wells causing appre-
ciable financial loss. Flash explosions of the methane
have occurred on at least four occasions near Orlando,
resulting in several cases of severe burns. One such
instance attracted considerable attention as the water-
supply well burned vigorously for several days. It has
been reported that in some instances the gas produced
was actually used,

The discharge of untreated municipal and industrial
wastes in the Jacksonville area and in the lower
reaches of the St. Johns River have polluted that stream
for a distance of about 33 miles, limiting the use of
its water. Shell-fishing is prohibited because of the
pollution that exists.

In the vicinity of Palatka, Rice Creek, a tributary
of the St. Johns River, and a large area of the St.
Johns Rivet are badly polluted by the effluent from the
Hudson Pulp.and Paper Corp., a sulfate pulp mill.
It is reported that recently improved operation of the
plant has reduced the amount of the putrescible mate-





rial discharged to the stream. Lagoons currently being The discharge of naval-stores wastes and other


planned for construction by the company will, when
completed, further reduce or eliminate the damage now
being done.

The effects of the discharge of wastes from the
phosphate-mining industry and cirrus-canning plants
are being studied in a survey of the Peace and Alafia
Rivers. Industrial discharges from the Container Corp.
of America, Rayonier Inc., and other industrial plants
in the Fernandina area have polluted the estuaries in
that region.

Industrial pollution is not limited to Florida. In
Georgia, near Savannah, the Savannah River is polluted
by the discharges from two paper mills. The extent of
of the pollution is being studied at the present time.

The Macon Kraft (paper mill) at Macon, Georgia is
directed by an act of the State legislature to operate
so as not to overload the stream. The City of Macon,
which is located above the paper plant, discharges its
wastes to the river untreated, and does considerable
polluting of the stream before it reaches the paper plant.

Alabama streams receive their share of pollution
from the industrialized areas which have developed in
that State. Three tributaries to the Warrior River, in
the Birmingham area, are exempt from the Alabama Water
Pollution Control Act,- and are used as industrial sew-
ers. The City of Birmingham is constructing new sew-
age treatment works.

Chemical plants at Tuscaloosa pollute the Warrior
River for a considerable distance downstream.

The Coosa River below the Anniston-Gadsden area,
where there are a number of large industrial plants, is
polluted and there have been reported fish kills in this
river. The Coosa News Print -- Paper and Pulp Plant,
and Beaunit Mills near Childersburg are new plants
which included pollution controls in the original con-
struction, and do not-seriously pollute the river at this
point.

The Pepperell Mills on one of the tributaries of the
Tallapoosa River in Alabama have recently placed in
operation a new complete waste treatment plant which
should greatly improve the conditions of this stream in
the Opelika area.

Municipal and industrial pollution in Mobile Bay
has forced the closing of the shell-fish areas in the
lower part of the bay.


industrial wastes into Bayou Bernard near Gulfport,
Mississippi, has caused serious pollution in thae area.
Naval-stores wastes from the Hercules Company near
Hattiesburg are also a source of pollution.

The Gaylord Container Corporation, a paper plant
at Bogalusa, La., has polluted the Pearl River for a
considerable distance downstream.

The headwaters of the Holston River in Virginia
receive discharges of inorganic industrial waste which
contribute excessive amounts of hardness chlorides
and sulfates to the receiving waters. The detrimental
effects of these wastes result in an increase in cost of
treating of the public water supplies of Bristol, Kings-
port, and Knoxville, Tenn. Waters so polluted are also
unsuitable for many industrial uses.

Pulp and paper mill wastes emptying into the upper
reaches of the French Broad and Pigeon Rivers in North
Carolina limit the use of their waters in Tennessee,
The effect of this pollution is felt throughout the down-
stream reaches of the river.

Domestic and industrial pollution from the Knoxville
and Chattanooga areas have damaged other water uses
on the main stem of the Tennessee River. For over 40
miles below Knoxville this stream is not suitable for
use as a public water supply. Industrial development
has been limited because of existing pollution. Density
currents in Emery River, armofthe Watts Bar Reservoir,
have carried pollution upstream a distance of over a
mile to the Harriman water intake, damaging the public
water supply.

Prior to the time that voluntary corrective action
was taken by the Camp Manufacturing Co. (paper mill)
at Frankfurt, Va., fish kills were reported in the Black
Water River below the plant's waste outfall.

Municipal and industrial pollution in the Neuse
River in North Carolina prevents its use for needed
additional water supply for the City of Raleigh.

It is not possible to itemize all the damage result-
ing from pollution. The discharge of spent chemicals
-such as sizing wastes and dyes from textile plants -
has overloaded municipal sewage treatment works
reducing their effectiveness. The volume of industrial
wastes is increasing as the South changes from agri-
culture to industry. The tasks of water-pollution con-
trol become more complex and difficult as other indus-
tries such as wool-scouring and synthetic-pharmaceu-







ticals plants select industrial sites in the area. New is closing the gaps that divided it industrially from the


industrial water supplies are being developed such as
the 10 billion gallon a day supply at Charleston, South
Carolina, attracting still more industries.

There is a technological revolution of the highest
order sweeping the Southeast in the 10 States, south
of Kentucky and Virginia and east of Mississippi. In-
dustry is moving to the area because of the availability
of raw materials, power, labor and good industrial water
supplies.

The Sears Roebuck Company in planning future
development carefully analyzed their sales records for
the past 45 years. These sales records covered the
entire United Stares, and the data obtained from them
indicated that the New England area had passed its
peak and was in a decline. The Midwest remained more
or less static. The Far West was developing, but they
decided that its industrial development would be limit-
ed, because of the lack of adequate water supplies.
According to their findings the portion of the country
that had the best chances for continued development
was the Southeast area. It is hard to say how much
their thinking was influenced by the availability of
water. The same conclusions, however, would probably
have been reached based entirely on the availability
of industrial water supplies. Some areas have badly
used their screams and the water now is polluted to such
an extent that it is not satisfactory for further indus-
trial development. The Midwest has rather limited water
supplies in most of the areas and until comprehensive
action programs have been adopted to assure adequate
continuous water supplies, industrial development will
be limited to certain areas where water is available.

In the West the water supplies are very definitely
limited and until basin developments provide additional
water supplies, the industrial development will be
limited. Here in the Southeast there is an abundance of
water of such quality that industrial development will
continue.

The first industries to come south were the textile
plants. One of the most striking phenomena in the post-
war industrial scene has been the movement of the
country's woolen and worsted mills from New England
to the South. Other industries have come too, with
improved processes permitting the production of such
things as paper from southern pine. Two decades or
more ago Southern industry included only the naval
stores, the phosphates, and masonite hardboard plants.
The industrialization of the South is no longer limited
to a ifw major industries. For the first time, the South


rest of the country.


There were other outside forces which prevented
industrialization of the South. Chiefly, the freight rate
differential that imposed a heavy penalty on shipping
of any manufactured goods from the South. The early
starts of industrialization were mostly wiped our, and
the South depended almost entirely upon agricultural
pursuits for its livelihood. This held the South to a
colonial raw material status permitting the North in-
dustrialist to "buy cheap and sell dear."

The stumbling blocks have been removed and the
South is doing a phenomenal job of catching up. Indus-
trial research laboratories have been established and
are showing industries the way to improve their prod-
ucts and utilize more fully the natural resources of the
Southeast area. This is resulting in the industrial de-
velopment, as is indicated by statistics furnished by
the Alabama State Chamber of Commerce, where from
1940 to 1950 the number of industrial establishments
increased 145.6 per cent. The number of industrial
employees increased 86 per cent during the 10 year
period, and their salaries increased 709 per cent. The
value of manufactured products in 1950 was more than
21/ billion dollars, an increase of 340 per cent over
the 1940 figure. Alabama has gained another 58 new
industries in 1951. What has occurred and is occurring
in Alabama is common to the other Scares of the area,
Industry is abandoning its old time industrial plants
in the North and replacing them with streamlined air-
conditioned southern plants. These new plants can be
built on sites where there is plenty of space for expan-
sion and for construction of waste-treatment facilities.


The availability of electric power permits the plant
to be designed as a one story structure, which for some
industries is a definite advantage. The network of sur-
faced roads and the availability of transportation facil-
ities permit the location of the plant at a distance from
urban areas. With this development comes a mounting
pollution load on the streams. It is a problem that must
be solved if healthy industrial growth is to result. We
engineers are the ones who will have to solve this prob-
lem. Fortunately, for the most part industry has shown
a cooperative attitude and in many instances has taken
the lead in developing methods of properly handling
its wastes. It must be a cooperative effort on every-
one's part. The public should be informed so that they
will understand what the limitations are, and what can
be done to prevent unnecessary pollution of the water-
ways.






The need for water-pollution control should be ob- elimination. Many of the existing sources of pollution


vious to everyone. The streams have limited ability to
assimilate the waste discharged into them. If we are
to prevent conditions such as those that have already
developed in other parts of the country, gross pollution
of the streams must be prevented. Nor does anyone
want a repetition of what happened in the highly indus-
trialized area of the Raritan Valley in New Jersey. The
river was so over-burdened with the tremendous waste
loads dumped into it by its cities and industries that
it was found necessary to bar new industry and to pro-
hibit expansion of existing plants. That area has em-
barked upon an enormously costly project of cleaning
up the Raritan River. It will take years, at the very
least, to undo the damage that has been building up
over the past decades.

There are other regions of the country much closer
than New England and New Jersey where rapid indus-
trialization, without the corresponding measures for
maintaining water quality, has resulted in greatly de-
creasing the usefulness of this priceless resource for
many years to come.

We must plan so as to abate the pollution which
exists and to prevent further polluting of our streams.
At the same time we must provide for equitable utiliza-
tion of the streams for all water uses. The day has
long passed for taking care of pollution problems after
they occur. We must plan in advance for a logical de-
velopment of the water resources and not permit critical
conditions to develop because of unwise use of the
streams. Industry, always alert and responsive to the
value of public good will, is beginning to recognize the
capital worth of an active program of industrial pollu-
tion control. This is paying dividends in many instances
by the recovery of valuable by-products which hereto-
fore have been lost to the stream. Industrial represent-
atives have formed a National Technical Task Commit-
tee on industrial waste. This committee's 53 members
from 36 types of industries represent a total of about
10,000 individual plants across the nation. Through this
committee, industry is becoming increasingly aware of
the advantages of pooling information and resources
to find solutions to their industrial-waste problems.

The first step in water-pollution control planning is
to obtain factual data regarding existing pollution and
determine the ability of the streams to assimilate
wastes discharged to them. Our judgment in developing
such plans can be no better than the basic data on
which the judgment is based. Most of the States in the
area have started the first task that of pin-pointing
the present pollution sources and taking steps for their


have already been listed by the Water Pollution Con-
trol Agencies in connection with their work in assem-
bling the material for the cooperative state-federal
reports on water pollution in the Southeast Drainage
Basins. A Summary Report for the area containing this
information was released on April 27 and copies can
be obtained from your State Water Pollution Control
Agency or by writing to the Southeast Drainage Basins
Office in Atlanta.

Tennessee, in accordance with its water-pollution
control law, has held public hearings throughout the
State and has presented to the public the conditions
which exist in the streams and recommendations as to
what should be done to correct existing and prevent
future pollution. These hearings were well attended.
The minutes of the hearings were adopted by the Ten-
nessee Stream Pollution Control Board establishing
the stream conditions which must be maintained to pro-
tect the quality of the water.

After learning the present stream conditions, estab-
lishing desired water uses and applying standards for
quality of those uses based on the best scientific
knowledge, it is then possible to determine the degree
of treatment required in order to maintain those condi-
tions. Ordinarily it is not the responsibility of the State
to specify the particular type of treatment. The State
sets the standards and it is then the responsibility of
the industry or the city concerned to provide adequate
treatment. However, in many cases the state agency
can help in determining in advance whether the proposed
type of treatment will be adequate to safeguard the
established water uses.

Another important phase of the State Water Pollu-
tion Control Agency's work is keeping all segments
of the public informed as to its activities -- what they
are doing -- and why what they are planning -
and their progress. Obviously it is understandable that
those who will pay for the construction should have an
interest in knowing why it is needed.

We do not work directly with local communities in
the field. We feel this is a function of the state agency.
We do believe, however, that we can give assistance
in a number of ways one in the development of mate-
rial which presents general information on water pol-
lution to stimulate interest in the problem as a whole.
Examples of such material already available include the
bulletins, "Clean Water is Everybody's Business,"
"Excerpts from the President's Water Resources Policy
Commission Report," "Water Pollution in the United








States" (a National Summary), and "The Fight to Save
America's Waters," the Mark Trail booklet on water
pollution.

The 10 River Basin Offices established under the
Federal Water Pollution Control Act work with the
states in the comprehensive planning to abate and pre-
vent pollution of the streams. The first phase in the
national program has been completed. All the available
data on each of approximately 226 subbasins in the
in the country, have been assembled into summary te-
ports on each of the 15 major drainage basins. The
second phase is now underway with the development
of individual river basin reports, such as the St. Johns,
which was recently completed in cooperation with the
Florida State Board of Health. The facts in these re-
ports have been assembled at considerable expense
of time and effort on the part of the State. These facts
which were gathered are basic to the development of
water-pollution control programs. In addition we hope
they will be given wide distribution as a part of a
planned informational program. The importance of a


carefully developed and executed informational program
cannot be over-emphasized. The public must be inform-
ed regarding the damages caused by pollution, the
methods of abatement, the cost involved and the bene-
fits resulting from water-pollution control.

A program of this kind calls for whole-hearted team-
work, every one with any interest in water use must
do his part in the development of over-all plans which
will assure maximum utilization of the water resources.
In most instances such cooperation has been forthcom-
ing from the states, local governments, industry, or-
ganized groups, and individuals.


If this type of teamwork in the fight against pollu-
tion can continue, we can look forward with real op-
timism to the development of sound comprehensive pro-
grams for the protection and development of the water
resources. Through wise planning and cooperation by
all concerned the industrial development of the area
can continue without damage to the water resources.






FLORIDA INDUSTRIAL WASTE PROBLEMS

by

John W. Wakefield
Chief, Sewage and Industrial Waste Section
Bureau of Sanitary Engineering
Florida State Board of Health


From a water pollution standpoint, Florida today,
in my opinion, stands at- a cross-roads. In population
and industrial development it has reached a size where
wastes are beginning to tax the resources of receiving
streams. The choice now is between limiting water
pollution to reasonable levels, thus allowing full de-
velopment of the industrial potential while stillprotect-
ing the State's greatest natural resource against damag-
ing degradation and uncontrolled water pollution, with
eventual degradation, of streams to the point where in-
dustry itself will be stifled and recovery of lost assets
will be well-nigh impossible of attainment.

The experience through which the Commonwealth
of Pennsylvania is now passing should be ample evi-
dence of dangers to which this latter policy can lead.
Industries, cities and the State itself are spending many
millions of dollars in an attempt to recover even a small
part of their lost stream resources and the success of
the venture is made quite doubtful by the degree to
which they had allowed their streams to become pol-
luted before initiating this campaign. No longer is
Pennsylvania concerned primarily with protection of
fish and wildlife. On many of her streams the very
cities and industries, which are themselves responsi-
ble for degradation of waters at downstream points, are
endangered by other cities and industries at upstream
points. No small part of the goal they struggle to
achieve is to safeguard industrial water supplies for
industries which have been guilty of faulty waste
practices themselves.

We in Florida have not reached such a level. Only
at a few isolated points have the oxygen resources of
the streams become depleted sufficiently to become a
problem. Recent advances in the provision of adequate
sewage-treatment plants for our cities has about held
the line with bacterial pollution of our surface waters,
and decided progress has been made in eliminating
underground pollution. Relatively simple steps taken
now by existing industries and municipalities, coupled
with a vigorous and determined policy of pollution con-
trol for future industrial or municipal developments,
can prevent further degradation, and also recover some


of the lost ground. On the other hand, a continuation
of the ruinous road which some cities and many indus-
tries have been following can lead only to a total loss
of much of our water resources; and to the eventual
expenditure of many millions of dollars more than is
now necessary, without assurance of success.

Let us look now at a few of Florida's major indus-
trial-waste problems. Number I industry is, was, and
we hope will continue to be that of serving tourists.
With a gross take of something over $400 million it
demands careful consideration from all. The waste
from the industry is, of course, domestic sewage; and
thanks to a very healthy post-war sewerage expansion
program, facilities to care for wastes from this indus-
try are far more advanced than for most other industries
in Florida.

The significance of the tourist industry, however,
goes far beyond the added population of cities during
the winter months. The tourist industry is dependent
to no small extent on clean waters. Tourists are at-
tracted by beautiful streams and lakes, by good fish-
ing, boating and swimming, by cooling offshore breezes
flavored with the tang of the sea or perfumed with the
odor of flowers. Conversely, tourists have been repelled
by unsightly debris-laden streams, and one whiff of dis-
agreeable odor will send them on their way. Even more
important let word get out of even a small water-
borne disease epidemic in Florida and the economic
loss will make the fruit-fly era look like a bonanza.

Florida's Number 2 industry, and probably first in
the production of truly industrial waste, is the citrus-
processing industry. Great strides have already been
made in waste elimination in this industry. Through the
development of cowfeed production and molasses pro-
duction from cowfeed press liquor, the industry has
corrected or can correct its solids and strong liquid-
waste problems. There remain, however, exceedingly
voluminous wastes which, while in no sense rivaling
the strength of press liquor at 100,000 parts per million
B.O.D., nevertheless are in many cases considerably
stronger than domestic sewage and in the course of a








TABLE I


CITRUS PROCESSING WASTE DATA*


Grapefrult Combination Conmlnaian
Single Strength Sectonlizng Orange Juice Cow Feed Single Strength Single Strength
Juice Plant Ploan Concentrate and and Cow Feod and
(2 Plants) (2 Plants) Avg. (4 Plants) Molosses Mill Sectlonlxing Molass..
Production 18,850 Cases 4,420 Cases 20.042 gal. 103.6t 8. S. 11.247 S.S. 7148 Cases
Per tay 28,744 Cases 3.718 Cases Concentrate Tons Cases Feed, 47 Tons:
Sections-4,58 Molauses, 5490 gal.
Cases

Wast. Flow 15B,610 211,700
(gpd) 813,200 420,260 2,396,500 2,308,770 853,000 1,459,300
5-day-20oC. 182 873
B.O.D. (p.p.m.) 182 945 82 495 460 395
Lb.B.O.D./1000 12.7 384 57.1 tb./1000 113 lb./Ton+
Case 43.1 887 got. Cont.
Pop. Equiv. 1408 9070
B.O.D. 7280 19,400 6,675 68,350 19,160 28,200
Suspended 25 140
Solids (p.p.m.) 85 124 27 30 96 56 to 144
Settleablo 30
Solids mI./1 -- 4.1 0.1 10 0.05
Tat I Solids 532 2,498
(p.p.m.) 1,030 1,793 296 442 895 430 to 1605

*Data from the files of the Florida State Board of Health Stream S.nilatioa Laboratory. All caSs are for No. 2 canE.
+Dry Feed only. Does not include liquid molasses sold as feed.


day will discharge many pounds of organic matter into
streams or lakes. Analyses of wastes from certain
citrus plants which have recently been studied are
shown in Table I. These ate based on a very limited
number of samples from the number of plants indicated
and the results may not be typical.


Please note the volume and strength of wastes from
the orange juice concentrate plants. The rapid growth
of this phase of the industry from its start in 1945 to a
production of 31,218,000 gallons of frozen concentrate
in 1950-51 makes this a most important source of or-
ganic pollution. If the values given in Table I are at
all typical, it seems apparent that these plants are
discharging organic wastes equivalent co a domestic
population of slightly less than 10.5 million persons.
That is several times the total population of Florida.
Note also this is from concentrate plants only and
does not include single strength or sectionizing plants,
nor cowfeed and molasses plants. To say the least it
constitutes a problem. Also note in Table I that the
greatest single source of organic waste is from a cow-


feed and molasses plant. So far as we know this waste
is made up entirely of water from the barometric leg,
used in evaporating the molasses, and stack gas wash-
er waters, used to prevent air pollution from the cow-
feed drying plant. It is true that this planthas eliminated
the solids and subsequently the liquids which formerly
caused serious pollution problems; but now, obviously,
it is creating a pollution problem of its own. The B.O.D.
here is probably largely entrained press liquor from the
barometric evaporators and fly-ash from the dryer stacks.

I would like to call attention to the solids content
of these wastes. Note chat excepting the grapefruit-
sectionizing plants, the suspended solids are compar-
atively low and the total solids quite high while settle-
able solids are almost nil. This means that convention-
al settling tanks with or without chemical precipitation
can have little value. To be successful the method of
treatment must be biological in nature, since something
must extract the carbonaceous material-mostly sugar-
from solution and must use that material to build a
solid particle large enough to be settled, floated or
filtered from the liquid. The only method of achieving






this that I know of is to feed that material to living and breaking this tar down into its several components.


organisms which will then grow and multiply to form
the solids required.

Several attempts have been made to find a satisfac-
tory method to treat these wastes. In 1941 von Lossecke
and associates.i) reported that a standard rate trickling
filter could be used successfullyand suggested a formu-
lafor deriving the size of the filter. If his formula is ap-
plied to the average results for the concentrace-plant
waste shown in Table I, the required filter for 75 per
cent B.O.D. removal would be 4875 sq. ft. in area by
6 ft. deep or 29,200 cu. ft. of stone. We do not consider
this at all impossible of attainment, but we will admit
some resistance on the part of management to expendi-
tures of the size necessary for such a treatment plant.

More recently McNary and associates have studied
the production of methane by means of anaerobic fer-
mentation. Laboratory studies indicate that good methane
production can be secured and the B.O.D. of the waste
can be reduced by as much as 90 per cent in 24 hours
digestion. However, they found it necessary to pre-
aerate the waste to remove peel oil which they found
to be toxic to the methane-producing bacteria. Their
studies are continuing on a pilot plant scale.

At the present time the Florida State Board of
Health is, with the cooperation of the Florida Canners
Association and the U. S. Public Health Service, carry-
ing on a research project to study citrus-waste treat-
ment by means of high-rate trickling filters, activated
sludge and spray irrigation. Only the trickling filter
studies have been started to date, and it is too early
to make any predictions about these.
Disposal by spray irrigation mentioned above has
been successfully practiced for other canning plant
wastes and looks very promising for those plants
where suitable land is available. Sanborn of the Nation-
al Canners Association states(2) that the best results
can be achieved by spraying the waste either on a
field with a good cover crop or on a forested area with
a heavy mulch of leaves. He states that this should be
preceded by fine screening, that the remaining solids
are not a serious problem if a good cover is available,
but does tend to clog the soil when sprayed on bare
ground.

Let us now look at Industry Number 3 ranked only
by tourists and citrus both in value and in organic
waste volume. I refer to the wood-products processing
industry and its wastes. This includes: paper and pulp
manufacturing plants; certain turpentine distilling
plants; several plants extracting tar from pine stumps


and at least one palmetto fiber plant. Florida has pulp
and paper mills of the sulfate type at the following
locations: Fernandina, Jacksonville, Palatka, Port St.
Joe, Panama City and Cantonment near Pensacola. One
sulfite mill is located also at Fernandina. In addition
one mill at East Port, on the St. Johns River just east
of Jacksonville, is nearing completion and a second,
which is to be a bleached pulp plant, is projected on
the Fenholloway River near Perry. Another sulfate mill
is also about to be placed under construction in Georgia
just south of Valdosta, the waste from which will dis-
charge into the Withlacoochee River near the point
where it crosses the Florida border. No accurate deter-
mination is available at this time on the pounds of
B.O.D. discharged by each of these mills, but surveys
have been conducted on the condition of the receiving
waters. It can be stated quite definitely on the basis
of this survey that the Amelia River and its tributaries
in Nassau County, Rice Creek and its tributaries in
Putnam County and Six-Mile Creek in Escambia County
are damaged to a considerable extent, and it can be
predicted that the Fenholloway River will be added
to this list when the plant in Taylor County is placed
in operation. It should be stated, however, that in these
latter three cases, namely Rice Creek, Six-Mile Creek
and Fenholloway River, the great majority of the land
adjacent to the streams is owned by the paper company
involved and comparatively little damage is suffered
by other individuals.

The survey mentioned above indicated that the other
three operating plants were discharging wastes in such
quantity and strength as not seriously to deplete the
receiving waters available to them. However, since
that survey a fish kill has been reported in St. Andrews
Bay and all of the mills have increased production.
Therefore, it is quite possible that the information
given in the report of the survey mentioned is no longer
up to date.

The U. S. Public Health Service, through its Cin-
cinnati Experiment Station, has cooperated with the
Florida State Board of Health and the industries con-
cerned in making a study of two of the plants listed
above, but the data could not be released in time to
be included in this paper.

Another branch of the wood products industry is
that of processing pine to obtain turpentine and rosin.
There are many small turpentine "stills" in Florida
which, so far as we know, have no waste problems.
There has been developed, however, a process of clean-
ing the gum prior to distilling in order to produce a








TABLE II


NAVAL STORES WASTES*


PINE GUM PROCESSING WASTES
Wash Tonk Combined
Discharge Effluent*


PINE WOOD PROCESSING WASTES


Extraction
Pluon


Destructive
Distlflation
plurlt


D. O. (p.p.m.) 0 5.8 2.48 0
I.O.D. (p.p.m.) 617 19 3.400
B.O.D. (p.p.m.) 7,450 510 69.3 26,200
02 Consumed (p.p.m.) 360 45,000

pH 3.2 7.1 4.5 3.0
M.O. Alk, (p.p.m.) 94 0 to27 0
Acidity (p.p.m.) 1,164 47 8,207
Tnral Suspended Solids (p.p.m.) 1,234 34 242 248
Vol. Suspended Solids (p.p.m.) 1,214 32 214 233
Phenol (p.p.m.) -- 470
appearance Heavy Gum Light Gum Clear Umber
Emulsion Emulsion Color
Flow (gpd.) 3,000 150,000 4,300,000 31,600
Population Equiv. (B.O.D.) 1,120 1,580 13,500 40.700
Lbs. B.O.D. per Unit Production 1.00/lb. gum 2.95/lb. gum 4.60/Ton wood 69.2/Ton wood

*Frorn the file of ihe Florida State Board of Health.
tlncludes c.ondnser water, wash water and separator condensaie.
1Acid water discharge. Does not include condenser water.


better grade of rosin. In this process the gum is washed
with oxalic acid which reduces the ferric compounds
in the gum to ferrous, thus making them soluble and
amenable to removal by further washing. The waste
from the plant includes this wash water, still conden-
sate containing low concentrations of turpentine, and
cooling water for the condenser. The character of the
wash water and the combined effluent are given in
Table UI. This waste is being lagooned at the present
time, but is amenable to treatment by chemical precipi-
tation if it becomes necessary.

Also shown in Table II are data from two plants
obtaining tar from pine stumps and roots. The extraction
plant achieves this by extraction with napcha and sep-
aration of fractions with other solvents. In the other
case the tar is obtained by destructive distillation and
the fractions are recovered by partial distillation. The
extraction-plant waste discharges into a large tidal
lagoon and, while biological hfe in that vicinity seems
to be very limited, the only comments we have had from
residents are words of praise from boatmen who like


to anchor their boats in the waste to rid them of crus-
tacea and worms.

Such is not the case with the other plant, however.
Destruction of fish life, sludge and floating tar have
all been matters of complaint and the industry is now
studying the problem in an attempt to find a method of
treatment. In that connection two papers presented at
Purdue suggest possible treatment methods for this
waste. The firstr) was an oxidation process for pheno-
lic wastes utilizing chlorine dioxide. It was stated that
sodium chlorite when added to an acid waste will form
chlorine dioxide, a very powerful oxidizing agent. Since
this waste has a pH of 3.0 and considerable phenol,
among other things, this may be a possible answer. The
other paper(4) was on a waste treatment plant for a
tank car cleaning plant which treated a very strong and
highly variable waste. Coal dust was mixed with the
waste to remove phenols and oils by adsorption, and
the sludge separated by flotation. The effluent was
clarified by chemical precipitation and oxidized on a
trickling filter. It is doubtful if anything so complicated







s TAT E


FLORID


Location Map

PEBBLE PHOSPHATE MINING INDUSTRY
Producing 69% of the World's
Supply of Phosphate Rock
(Diameter of Circle 50 miles)


0-

. S .


I


FLORIDA








would be required by tar extraction plants, but since
charcoal is a by-product, the flotation process might
bear investigation.

The fourth ranking industry in Florida is the phos-
phate mining and processing industry. Few Floridians
outside of the industry appreciate the importance of
the Florida-produced phosphate rock not only to the
State and the Nation, but also to the rest of the world.
Practically all of the present production in Florida
takes place in an area within 25 miles of Barrow where
69 per cent of the world's supply of phosphate rock is
produced (see map).

It should be mentioned that the phosphate wastes
may have side effects on the receiving waters not readi-
ly apparent and not necessarily detrimental. For in-
stance, this waste contains considerable soluble phos-
phate. This undoubtedly stimulates the growth of
aquatic plants in the streams and lakes receiving this
waste. Such growth may be beneficial by supplying
food for fishes, hiding places for young fish, and by
supplying oxygen to the water through photosynthesis.
On the other hand, plants can also be detrimental. Lake
Hancock in Polk County for example is almost com-
pletely covered with water hyacinths while the bottom
is a mass of dead and decaying hyacinths. Water flow-
ing from Lake Hancock is practically devoid of oxygen,
nor from domestic or industrial waste, but simply from
the decay of plants and the fact that the living water
hyacinths blanket the water to such an extent as to
prevent reaeration. For these reasons and also the
turbidities encountered, the biological aspects of phos-
phate wastes may be more important than the measur-
able chemical or biochemical effects.

The meat-processing industry is probably the next
in importance from an industrial waste standpoint. This
includes slaughterhouses, sausage plants, meat-curing
plants, etc. Table IIl shows the waste characteristics
of two large meat-processing plants which we have
studied. Fortunately in many cases the wastes from
this industry are discharged to a city sewer and except
for increasing the load on the city sewage treatment
plant, they cease to be a problem. This is apt to become
an increasingly important waste, however, due to the
growth of beef-cattle production in Florida. We ranked
12th in the nation in 1951 and production is steadily
increasing.

The metal-working industry occasionally gives us
some difficulties and Table IV shows the characteris-
tics of wastes from two such plants. The first is from
a plant manufacturing metal louvers and consists of


TABLE Ill


MEAT PACKING WASTES*

Plant No. I Plant Ho. 2
Composite Wastes R.nd.ing Killing ProessIng
Plant Floor Rooms
B.a.D. (p.p.m.) 936 2,125 104 240

Toal Susp.
Solids (p.p.m.) 1,910 5,873 68 100

PH 7.1 7.2 7.5 8.2

Trcal
Alk. (p.p.m.) 258 363 201 315

Chlorides (p.p.m.) 1,740 141 154 463

Flow (gpd.) 500,000 18,000 242,0003 57,600

Pop. Equiv.
(B.O.D.)1 23,000 3,780

Pop. Equiv. (SS)2 39,750 5,327

B.O.D. P.E./hog
Unit4 52 17

SS P.E./hog 24
Unit 90

IBaead on Average B.O.D. load of 0.17 lb. per capital per day.
2Baaed on average Supended Solids load of 0.2 Ib. per capital
per day.
Include cooling water.
4One hog unit is equivalent to 0.4 cattle.
*From the files of the Florida State Bourd of Health.

metal cleaning solutions and effluent from the paint
spray booth where a water spray is used to remove
droplets of paint from the air. The other is a plating
plant using cyanide. The waste is, of course, highly
toxic to animals and to aquatic life, but is quite amen-
able to treatment by oxidation with chlorine(5).

Milk wastes constitute some problems and we have
one somewhat unique milk waste treatment plant. A
large dairy in Miami utilizes an Infilco accelator as
a chemical precipitation plant.

Laundry waste is another that presents some prob-
lems and we have quite a number of small chemical
precipitation plants serving "Help yourself" laundries
in suburban areas.







TABLE IV


METAL PROCESSING WASTE*


PLANT NO. 7 ELECTRO-PLATING WASTE
Sampling Source
Plant of Quantify pH Cyanide
Tank No. Waste ppm

I Mineral 50 gal./week 8.5
Spirits
Decreasing

II Water 1400 gal./doy 7.8
Rinse

III Alkaline 50 goI./week 12.8
Cleaning

IV Water 1900 gal./day 9.1
Rinse

V Muratic 50 gal./mo. 0.2
Acid
Pickling

VI Water 1900 gal./day 5.3
Rinse

VII Sodium Nona Dis- 12.5
Cyanide charged
Plating

VIII Water 600 gl./doy 10.9 200
Rinse

IX Wetr 1400 gnl./day 8.6 4
Rinse

X Chromic 50 gal./day 4.3
Acid
Rinse

Xl Nitric 50 gal./week 1.3 6
Acid
Rinse

Comrbinod
XII Wastes 6700 gal./day 7.5


*From the files of the Florida State Board of Health.

In conclusion, I would like to express the concept
on which the policy of the State Board of Health is
based. We believe that it is the responsibility of every


PLANT NO. 2 METAL CLEANING AND PAINTING WASTE

Sampling Source
Point of Quantity pHI Appearence
Tank No. Waste

I Detrgent 3400 gal./yr. 11.9 Turbid
Cleaning

II Rinse 4000 gal./day 9.4 Clear
Water

III Acid 1700 gal./yr. 2.03 Greenish
Cleaning

IV Rinse 750 gal./day 3.53 Medium
Water Turbid

V Chromic 5100 gal./week 4.57 Yellow
Acid

VI Point 1600 gal./wmek 10.26 Turbid
Booth Emulsion
Spray

VI Treated 1600 gol./week 11.75 Clear
1400 ppm
Hydrated
Lime

II,IV,V,VI Combined 5800gal./doy 8.0~ Very
(Treated) Waste To Slightly
Drainage Turbid



individual or company to care for its wastes so that
they will not damage or interfere with the rights of
others. This responsibility may be delegated by the
individual to a governmental agency and in this case
it is incumbent upon the agency, such as a city, to
handle wastes in such a manner as to protect the in-
dividual. In the case of industrial waste we believe
the waste to be a product of production and the cost
of proper disposal of that waste should be charged to
the cost of production. Finally, we believe that streams
and other surface waters should be utilized to the
greatest benefit for all concerned, including service as
receivers of waste products from our cities and indus-
tries. In each case sufficient treatment should be given
to the waste prior to discharge into streams so that the







stream may continue to be used for all legitimate pur- (2) Sanborn. N. H., "The Disposal of Food Processing


poses by the public. A reasonable portion of the re-
sources of the stream are available for waste disposal
and the natural self-purification of the stream must be
considered in delineating that portion. Municipal author-
ities, industrial management and the general public
must all be educated to the concept of full utilization
of stream resources for the benefit of all. Only by using
our resources wisely may the full industrial and commer-
cial potential of Florida be reached.


References

(1) Pulley, G. N., Nolte, A. J.. Goresllne, H. E. and
Von Loeacke, 1I. W., "Experimental Treatment of
Citrus Canning Effluent in Florida" Sewage
Works journal, 13. 115, (1941).


Wastes by Spray Irrigation," 7th Annual Industrial
Waste Conference, Purdue Univ. 1952.

(3) Aston. R. N., "Chlorine Dioxide in Waste Treat-
ment." 7th Annual Industrial Waste Conference,
Purdue Univ. 1952.

(4) G.tzelt, o., "Performance of General American's
Newest Tank Car Waste Treatment Plant (Salger-
town, Pennsylvania)." 7th Annual Industrial Waste
Conference, Purdue Univ. 1952.

(5) Dobson. John G., "The Treatment of Cyanide Waste
by Chlorination." Proc. 3rd Industrial Waste Con-
ference, Purdue Universtiy, 1947, Extension Series
No. 64, The Engineering Extension Dept., Purdue
University.







THE EQUITABLE UTILIZATION OF STREAM RESOURCES BY INDUSTRIES


by

Earle B. Phelps
Professor of Sanitary Science
University of Florida


In order that we may approach our subject from an
area of common understanding and mutual agreement
let me preface this discussion with a simple proposi-
tion which should be self-evident. Unlike such natural
resources as iron ore or timber land, stream resources
are in the public domain, held in trust and administered
by the state in the public interest.

This distinction is inherent in the very nature of
water. It performs many tasks in its long journey from
the clouds to the sea as a free agent, serving many
masters but slave to none. Even such temporary owner
ship as may be found in the storage of well water in a
factory supply tank may become a matter of public con-
cern as a waste water disposal problem. As a logical
corollary to this proposition of community ownership
and control, it would seem that the only suitable crite-
rion of equitable apportionment of water resources
among various claimants is the principle of maximum
beneficial use.

The old common-law conception of riparian rights
to the reasonable use of a stream, subject always to
the exercise of similar rights by lower riparian pro-
prietors, has long vexed the courts in their attempts
to clarify the meaning of the word reasonable. Que ex-
treme definition has been "without material change
in either quantity or quality." At the other extreme it
has been held in certain jurisdictions that the unavoid-
able discharge of the waste waters from a dominant
regional industry (coal mining) is reasonable in equity
regardless of any resultant damage to the stream. These
seemingly harsh interpretations of the common law are in
fact no more extreme than is the legislative exercise
of eminent domain under which, with due compensation
provided, water may be stored, diverted or otherwise
pre-empted, for public use. It is merely necessary to
extend the meaning of "public use" to the needs of an
industry which supports a large segment of the pop-
ulation.


A strictly parallel situation appears in legislative


action prohibiting or limiting stream pollution or, in the
opposite direction, in the exemption of specified streams
from a general anti-pollution measure.

In each of these situations the controlling principle
is clearly that to which attention has been drawn-the
principle of maximum benefits, the application of which,
according to the circumstances, may lead to either the
justification or the prohibition of pollution or even to
the diversion of the stream itself. The benefits to be
derived from the utilization of streams may be express-
ed in such general terms as public health and public
welfare and may include such specific community inter-
ests as public water supply, industrial development in
the public interest, fisheries, recreation, wild life con-
servation, and others. Certain of these uses, notably
water supply and many industrial uses, require the re-
turn of the water to the stream in a more or less pol-
luted condition. Facilities for waste disposal, there-
fore, must be noted among the legitimate beneficial
uses of streams.

Thus the problem of overall conservation of water
resources, so simply stated as utilization for maximum
benefits, is actually rather complex. It is characterized
by overlapping and competitive demands, many of them
mutually conflicting or incompatible. It is quite true,
however, as has been pointed out by Mark Hollis (),
that this conflict among uses of streams is not basical-
ly a conflict of interests; that the "total use" concept
resolves the several legitimate uses of natural waters
into an "allied interest" in which each specific use
is properly emphasized.

The proposition that the use of water constitutes
a loan to be returned unchanged and undiminished is
obviously self-defeating. This has been made quite
evident by the failure of many of the earlier state regu-
lations. Equally untenable is the presumption that
ownership of stream assets resides in the riparian pro-
prietor who assumes no accountability for their con-
servation or misuse. A rational adjustment should lead
to some middle ground between these two positions








neither of which can be justified under the maximum
benefit rule.

Florida is much more fortunate than many of the
more highly industrialized states in that, in the formu-
lation of a master plan for the utilization of her streams,
the major problem is in planning for future development
rather than the restoration of grossly polluted streams.
The time is ripe, however, for the application of the
"ounce of prevention." Here again we are fortunate in
being able to study situations and remedies in other
jurisdictions.

One approach to the problem of allocation of stream
resources is a system, currently adopted by several
states, of stream classification for best use. An excel-
lent example of what may be termed this modern ap-
proach to stream sanitation is the enactment in 1949
by the Legislature of the State of New York of a new
section of the Public Health Law setting up a State
Water Pollution Control Board and making the following
Declaration of Policy. "It is declared to be the public
policy of the State of New York to maintain reasonable
standards of purity of the waters of the State consistent
with the public health and public enjoyments thereof,
the propagation and protection of fish and wild life, in-
cluding birds, mammals and other terrestrial and aquatic
life, and the industrial development of the Stare, and
to that end require the use of all known available and
reasonable methods to prevent and control the pollution
of waters of the State of New York."

The first action of this Board was the adoption of a
system of stream classification upon the basis of "best
usage" and the establishment of quality specifications
for each class. The specifications adopted and promul-
gated by the Board represent a consensus opinion of
their own experts and of a number of volunteer con-
sultants.
Water quality standards are established for seven
classes of fresh water streams each defined by its
"best use." These classes range from:

Class AA, best use, Water supply source; to be
chlorinated only,
and
Class A, best use, Water supply source; to be
subjected to standard treatment, coagulation,
sedimentation, filtration and chlorination,
through successive classes designated as appropriate
for bathing, fishing, agricultural and industrial, waste
disposal and transportation, and finally to
Class F, best use, waste disposal alone.


Similar classifications are set up for salt waters and
for ground waters.

Prior to the assignment of a class designation and
corresponding quality standards to a specific stream or
tributary the Board is required to make an adequate
study of the stream in question, to distribute copies
of the report of such a study to city and town officials
and to other interested persons, and to advertise ard
hold public hearings. The Board then legally assigns
to each stream, even down to minor tributaries, its best
use and corresponding class designation, after which
it proceeds to the development of an adequate program
of pollution abatement which may be the subject of
further public hearings.

Such a system of classification for best use would
appear to simplify our approach to the problem of stream
conservation. It does so to the extent that it leads us
directly to two major considerations of the problem-
method and cost of waste treatment. It is safe to pre-
sume that both these essentials have already been
evaluated to some extent in the classification pioce-
dures. These, as has been pointed out, include sub-
mission of the published results of a detailed survey
on each individual stream or minor system to public
officials and private interests involved; and a public
hearing on the proposed classification, at which indus-
trial interests have full opportunity to explore the
economic consequences of the proposals. Remedial
treatment, however, especially of the industrial wastes,
involves further expert consideration of currently avail-
able means or methods, and of the possibility of the
development of economic solutions through research.

In the support of research programs of this son the
industries have taken the leading role. Following an
early example set by the tanning interests in Pennsyl-
vania in jointly sponsoring studies by the Pennsylvania
State Department of Health, many of the large industrial
groups have supported research dealing with their
specific problems.

The activities of the National Council for Stream
Improvement of the pulp and paper industries are too
well-known to require more than passing mention. Simi-
lar activities of the Petroleum Institute and of other
industrial groups all point up the fact that industry is
becoming increasingly aware of its own self interests
and of its responsibilities for good public relations.

On a still larger scale is the program of the National
Task Committee on Industrial Wastes, supported by a
large number of industrial groups and acting with the






U. S. Public Health Service under Public Law 845. He believes it would simplify matters if the neces-


Several subcommittees, each in its special industrial
field, are already engaged in active research.


These activities relate to only one segment of the
problem of stream conservation. They deal with the
important phase of remedial procedures. The comple-
mentary segment, the receiving stream, is equally im-
portant in the total program. The stream survey should
in fact and in any specific instance take precedence.
Detailed and somewhat prolonged studies are required
in order to evaluate the stream's capacity to receive
and dispose of pollution, whether by diluiion, self puri-
fication or otherwise, within the limits of any specified
quality requirements. Not only in its present condition
but its total capacity for future development must be
known, as well as its chemical, biological and hydro-
logic characteristics.


In Florida, both segments of the stream sanitation
problem are under investigation by the State Board of
Health, in cooperation with industry. Extensive stream
examinations are currently under way in the evaluation
of stream quality as affected by industrial waste waters
of the phosphate mining industry and the citrus canning
industry. Regulatory and remedial procedures are also
under investigation. Similar studies have been made, in
cooperation with the National Council for Stream Im-
provement, of the influence of pulp mill wastes dis-
charged into Florida streams.


Finally the subject of equitable distribution of
stream resources involves the subordinate question
of costs and their distribution. This is particularly
pertinent along those highly industrialized streams in
which the stream resources have been destroyed through
overloading and misuse and where the recovery of these
lost assets calls for radical measures. Under these
circumstances Camp(2) has suggested a program involv-
ing an industry-wide survey to the end that the total
remedial requirements be first established. This situa-
tion would then be examined with reference to the most
economical treatment of the total load without reference
to individual sources. This treatment would then be
applied and its cost apportioned, on some equitable
basis, among the contributors.


sary works were constructed and operated by some
public authority, financed through long term bonds and
the total costs assessed against the contributors on
some agreeable basis of apportionment and as yearly
operating charges. This would automatically reduce
the entire cost of treatment to an operating cost de-
ductible from gross income and with no added capital
investment.

It is obvious that, under any plan of waste treat-
ment, costs will be charged to production and will be
borne by the consumer. In competitive fields, industry
will naturally seek new locations favorable to waste
disposal at minimum costs. To this extent, that area
is most favored for industrial development which has
protected its streams for maximum industrial use and
against misuse. In this respect Florida again is in a
focrunate position. For the most part her problems are
preventive rather than curative.

Before setting up a policy, however, let some thought
be given to what may be termed the esthetic viewpoint.
To the mill owner the cost of waste treatment is merely
asingle-entry item onthe books, possibly set off against
an intangible public relations benefit. To the public,
upon whom, as consumer, the cost ultimately falls, it
becomes a payment for clean streams. Our oft vaunted
"scale of living" merely means provision of those
finer and nicer comforts and enjoyments of life, of the
luxuries of yesterday which will become the necessi-
ties of tomorrow. This scale of living has become the
measure of a prosperous people and of prosperous times.
Many of our problems in stream sanitation would be
solved in a way representing true economy if we put
into the balance sheet the values conserved to the
public; the luxury, if we will, of clean streams which
we can usually well afford to enjoy.


References

(1) Hollis, Mark D.. "Aims and Objectives in Environ-
mental Health," American Journal of Public Health,
41:263 (March 1951).

(2) Camp, Thomas B., "Pollution Abatement Policy,"
Proceedings A.S.C.E.,Separate No. 10, March 1950.















(Proceedings of the Fifth National Public Health Engineering Conference)

May 20 and 21, 1952



INDUSTRIAL WASTES PRACTICES




SPONSORED BY THE

DEPARTMENT OF CIVIL ENGINEERING


FLORIDA ENGINEERING AND INDUSTRIAL EXPERIMENT STATION

College of Engmeering University of Florida Gainesville



Bulletin Series No. 57

October, 1952








DEVELOPMENTS IN THE DISPOSAL OF CITRUS PROCESSING WASTES


by

F. W. Wenzel
University of Florida Citrus Experiment Station
Lake Alfred, Florida


With an ever increasing amount of citrus fruit going
each year to the citrus-processing industry in Florida,
the handling and disposal of the citrus wastes from
processing plants continues to be a problem, the mag-
nitude of which depends upon many factors including
the size and location of the plants, the types of pro-
ducts processed, and the availability of facilities for
the manufacture of citrus by-products. Publications
by von Loesecke et a(8), Ingols(2, Heid(), and
McNary"4'5) adequately described conditions existing
in the past and the various methods used for disposal
of citrus wastes. A summary of the present situation
by von Loesecke(9) was recently presented at a sym-
posium on liquid industrial wastes.

At the present time the disposal of the solid and
most of the concentrated liquid citrus wastes is accom-
plished chiefly through their conversion into citrus
molasses and dried citrus pulp for cattle feed. During
the last several years a definite effort has been made
by many processors to segregate concentrated liquid
wastes from the diluted liquid wastes for special treat-
ment or conversion into molasses or feed. The disposal
of diluted citrus wastes in an economical and complete-
ly satisfactory manner has not yet been accomplished.

A conference on citrus waste disposal, planned by
the waste-disposal committee of the Florida Canners
Association, was held on March 14, 1952, at the Florida
Citrus Experiment Station, Lake Alfred. The purpose
was to review existing experimental citrus waste dis-
posal projects and to discuss and formulate a program
for future citrus-waste research. Representatives of
the Florida Canners Association, Florida Citrus Com-
mission, Florida State Board of Health, Florida Citrus
Experiment Station, U. S. Public Health Service, Uni-
versity of Florida, and the National Canners Associa-
tion were present. A brief discussion of some of the
proposals and suggestions made at this meeting that
were considered to be applicable to the disposal of
citrus wastes, and therefore worthy of future consider-
ation, will now be presented.

The following methods for the treatment and disposal
of citrus wastes were suggested and discussed: (1)


aeration with the addition of nutrients in order to sus-
tain optimum B.O.D. reduction, (2) spray irrigation,
(3) use of trickling filters, (4) use of activated sludge,
and (5) anaerobic methane fermentation following aero-
bic treatment.

Mr. Sanborn of the National Canners Association
reported that a simulated grapefruit waste, prepared by
diluting canned unsweetened grapefruit juice with tap
water, lacked sufficient nitrogen to sustain optimum
B.O.D. reduction. Diluted juice with an average B.O.D.
of 1725 p.p.m. was continuously fed to a three-compart-
ment aeration system over a period of 16 hours. The
feeding rate provided a detention period of 12 hours per
aerator (total 36 hours). When nitrogen and phosphorus
nutrients were added, the effluent had an average B.O.D.
of 55 p.p.m. on a settled sample and 35 p.p.m. on a
centrifuged sample. Without these nutrients and under
the same conditions except that the raw waste had a
B.O.D. of 1,877 p.p.m., Sanborn reported that the cor-
responding settled and centrifuged composites were
283 and 221 p.p.m. respectively. Similar results were
also obtained using a total detention period of 18 hours.
The nutrients used were sodium nitrate and trisodium
phosphate to supply 3 p.p.m. nitrogen and I p.p.m.
phosphorus per 100 p.p.m. of B.O.D. in the raw waste.
It appeared from limited data that supplementary phos-
phorus is not necessary. For large usage, liquid ammo-
nia would be the cheapest source of nitrogen. It is
understood thatthis aeration method with added nutrients
will be cried in the near future at the plant of Juice In-
dustries Division of Clinton Foods, Dunedin, Florida,
where the necessary facilities are available.

The use of spray irrigation as a means of cannery
waste disposal, as applied by various vegetable and
fruit canning plants throughout the United States during
1951, is described by Sanborn7). The irrigation of
citrus groves with citrus-waste water has been report-
ed(2) r, cause tree damage, and this, as well as other
reasons, would indicate that such practice should not
be used in the future. However, the application of
spray irrigation to help produce pasture for cattle graz-
ing or green crops for chlorophyll production may war-
rant future investigation.






Von Loesecke et al8 used experimental standard
rate trickling filters for treatment of citrus wastes and
obtained results indicating that large and expensive
installations wouldbe needed because oflow efficiency.
Two experimental high-rate triclding filters were in-
stalled at two processing plants in Florida in 1951, and
investigations are now being carried on by Mr. O'Neal
of the Florida State Board of Health in cooperation
with the Florida Canners Association and the U. S.
Public Health Service. Mr. O'Neal also indicated plans
for future investigations pertaining to spray irriga-
nion and the use of activated sludge." McKinney and
Horwood'31 recently reported the isolation from acrivat-
ed sludge of organisms other than Zooglea ramigera
and gave the B.O.D. removals by these organisms over
a 24 hour aeration period using a synthetic sewage
substrate.

McNary et al reported the following information
concerning the anaerobic methane fermentation of citrus
wastes, a cooperative research project of the Florida
Citrus Commission and the Florida Citrus Experiment
Station. When this project was started in 1946, consid-
erable quantities of citrus press liquor were being
thrown away because its concentration and sale as
citrus molasses was unprofitable. Devising a means of
treating this material as a waste seemed to be the most
urgent problem at that time. Digestion with methane
bacteria appeared to be the most practical way to treat
a concentrated waste of this nature. Repeated attempts
to digest citrus liquids were unsuccessful. The cause
of the difficulty was found (6) to be the presence of
citrus peel oil which is toxic to methane-producing
bacteria even in trace amounts. Trace amounts are
toxic because the peel oil is cumulative in the digester
sludge.

Peel oil can be reduced below harmful levels in
citrus liquids when the latter are aerated in the presence
of organic solvents such as alcohol and acetone. These
solvents can be produced in situ by allowing micro-


organisms to grow in the liquid during aeration. The
addition of an aeration stage prior to the anaerobic
treatment system reduced the yield of methane, since
the yeasts and bacteria in the aeration chamber rapidly
used up the sugars and released carbon dioxide. The
process was made more complicated and the initial
investment was increased. The reduction in total solids
and B.O.D. were not drastically affected.

When we had arrived at this point in citrus waste
technology, the citrus wastes themselves had changed.
No longer were appreciable quantities of relatively
concentrated citrus liquors being thrown away. Instead
they were evaporated to citrus molasses which could
now be profitably marketed. Since we had acquired
considerable experience with methane fermentation by
this time, it was thought to be desirable and sensible
to continue to experiment with the weaker citrus wastes
to see if this type of treatment has a proper place in
the citrus industry. If not, then our attention could be
turned to other procedures.

A laboratory scale, two-stage procedure was worked
out and was in operation for almost a year. Two con-
centrations in the raw waste were dealt with, 4000 to
5000 and 1800 to 2000 p.p.m. B.O.D. Excellent reduc-
tions in B.O.D. and organic solids were obtained. The
process was sensitive to changes in conditions and
required expert operation, however. The same procedure
is now being studied on a pilot-plant scale. An evalu-
ation of its potentialities as a means of treating citrus
wastes should be available soon.

Before citrus waste disposal problems will be com-
pletely solved, much further work will have to be done.
Lack of experimental data concerning some of the
various methods of treatment discussedis quite evident.
Such data, however, can be obtained through the activi-
ties of various industrial, governmental and other agen-
cies, and it is hoped that these activities will be con-
tinned until a satisfactory solution is found.







Literature Cited


(1) Held. J. S.. "Drying citrus cannery wastes and
disposing of effluents." Food Inds., 17. 1479-
83 (1945).

(2) Ingols, R. S., "The citrus canning disposal problem
in Florida." Sewage Works./., 17. 320-329 (1945)

(3) McKtnney, Ross E. and lorwood, Murray P., "Fund-
amental approach to the activated sludge process.
1. Floc-producing bacteria." Sewage and Industrial
Wastes, 24. 117-123 (1952).

(4) McNary, R. R., "Industrial wastes citrus canning
industry." Ind. Eng. Chem., 39. 625-627 (1947).

(5) McNary, R. ., "Disposal of citrus cannery wastes."
Bull. 26, 93-95 (1949). Engineering and Industrial
Experiment Station, University of Florida.


(6) McNary, B. R.. WoHord, R. W.. and Patton, V. D..
"Experimental treatment of citrus waste water."
Food Tedhnol., 5. 319-323 (1951).


(7) Sanborn, N. H., "Spray irrigation as a means of
cannery waste disposal." Proceedings National
Canners Association Technical Sessions, 45th An-
nual Convention, January 20, 1952.


(8) Von Loesecke. Harry W.. Pulley. George N., Nolte,
Arthur J., and Goreallne, Harry E., "Experimental
treatment of citrus cannery effluent in Florida."
Sewage Works 1., 13, 115-131 (1941).


(9) Von Loesecke. Harry W., "Liquid industrial wastes
citrus fruit industry." Ind. Eng. Chem., 44, 476-
482 (1952).







REDUCTION OF ORGANIC MATTER IN CITRUS PRESS LIQUOR BY AERATED YEAST PROPAGATION


by

M. K. Veldhuis
U. S. Citrus Products Station*
Winter Haven, Florida


The production of feed yeast (Torulopsis uilis) from
certain waste liquors has interested many investigators
because it offers a means of disposing of the wastes
and at the same time obtaining a product which would
pay at least part of the cost of operation and, under
favorable conditions, return a profit. The yeast produced
is high in protein, rich in the B-complex vitamins, and
valuable for use in feeds.

These investigations were undertaken at the U. S.
Citrus Products Station on the production of citrus
waste materials in an effort to provide an additional
outlet for citrus press liquor. Usually this liquor has
been made into a molasses at some expense and sold
for use as feed, but at times this operation has not
been profitable. A batch system of yeast propagation
was investigated and reported upon in 1942 (1). A sum-
mary of later work in cooperation with theDr.P.Phillips
Canning Company, Orlando, Florida, using a continuous
method and equipment developed at the Southern Re-
gional Research Laboratory was published in 1948 (2).
Additional work was done with the continuous system
of yeast propagation and the results on the utilization
of the organic matter during these studies are to be
summarized here.

Experimental

The large propagator had a total capacity of 800
gal. and was capable of holding about 500 gal. of fer-
menting liquid during active aeration. Airas fine bubbles
was admitted through porous aloxite tubes fitted in the
bottom of the propagator. After the initial build-up of
culture in the propagator, the nutrient medium, prepared
from citrus press juice, was added continuously at a
predetermined rate. At the same time, an equal volume
of yeast slurry was drawn continuously from the propa-
gator. Yeast was recovered by centrifuging and drying
the concentrated slurry on a drum drier.

In some of the experimental work, a smaller propa-
gator of 6 gal. capacity was used. The air was distrib-

*One of the laboratories of the Bureau of Agricultual and
Industrial Chemistry, Agricultural Research Administration,
U. S. Department of Agricultue.


uted by means of a tube with 1/16 inch holes instead
of with aloxite tubes.

The press liquor used in the yeast propagation was
obtained during the commercial manufacture of citrus
feed from waste citrus canning peel. It had a soluble
solids content of 8 to 10 per cent (Brix), of which
about two-tairds consisted of sugars. The press liquor
was diluted with water in some cases to obtain the
desired strength. In order to obtain efficient yeast pro-
duction, ammonium sulfate was added to Irovide an
ample supply of nitrogen in available form and trisodium
phosphate was added to furnish phosphorus. The pH
during propagation was about 4.0 and could be varied
within limits was varying the ratios of the two nutrients.

Analyses were made to determine the amounts of
sugar utilized and amounts of yeast produced. In some
cases, the reduction in the Oxygen Consumed value
was estimated. In still other cases, the reduction in
non-volatile organic matter and the production of vola-
tile organic matter were determined. Yeast yield was
determined by separating the yeast, drying, and weigh-
ing. Non-volatile organic matter (soluble) was estimated
by removing any yeast or other suspended matter, dry-
ing under vacuum at 700F., weighing, washing, weighing
again, and noting the loss in weight. Volatile organic
matter was estimated with an Ebulliometer and express-
ed as ethyl alcohol. Conventional methods were other-
wise employed.

In the first series of experiments, the small propa-
gator was used and the strength of the feed was varied
from 1.50 Brix to 6.60 Brix and the effect on utilization
of sugars, reduction in non-volatile organic matter,
Oxygen Consumed value, and yeast yield noted.

In the second series of experiments, the large prop-
agator was used, the feed rate varied from 92 gal. per
hour to 234 gal. per hour, and the effect noted on utiliz-
ation of sugars and yield of yeast.

In the third series of experiments, the large propa-
gator was again used and some results have been
selected, showing the effect of yeast growth under







favorable conditions on sugar utilization, non-volatile and seventh runs indicated a eturn to normal with re-


organic matter, Oxygen Consumed values, yield of vola-
tile organic matter, and yeast yield.

Results

In Table 1, the results of the first series of experi-
ments are given. Varying the concentration of the feed
to the small propagator from 1.50 Brix to 6.6 Brix, in
intervals of approximately 10 Brix, had no significant
effect on the percentage of sugar utilized. Utilization
of the sugars was 94 per cent or more in all cases. The
values for non-volatile organic matter show no material
differences with increase in strength of feed. There
were some variations, but these are normal for this type
of work. The yield of yeast was highest with the more
dilute feed to the unit and decreased rapidly with higher
concentrations. From the standpoint of efficient yeast
production, it would appear advisable to keep the con-
centration at 2.5 Brix or below, but if the main purpose
was to decrease the sugars or organic matter, and yield
of yeast was secondary, higher concentrations might be
preferable.
TABLE I

EFFECTS OF VARYING THE CONCENTRATION
OF FEED TO THE YEAST PROPAGATOR.*


Sugars


Non-Volatrle
organic
matter
decrease


Oxygen
Consumed

decrease


eBrix Per cent Per cent Pe er cent er cent r cent

1.5 0.6 94 65 71 70
2.5 1.3 96 63 73 65
3.6 2.0 94 51 60 44
4.6 2.0 95 49 66 32
5.5 2.1 95 51 74 23
6.6 3.8 97 50 62 26

*Detention time in propagator 3 bours; Aeration rate 0.27
cu. ft./gal./mvn.
**Based on sugars in feed.
Data from the second series of experiments are
given in Table II, showing the effect of varying the
rate of feed. In the first four runs where the feed rate
was increased from 92 to 184 gal. per hour, no marked
difference in the percentage utilization of sugars was
observed, but with a feed rate of 234 gal. per hour, the
dilution with feed exceeded the growth rate, the culture
became diluted, and substantial quantities of sugar
appeared in the effluent. The results with the sixth


duced feed rate. These results indicate that a detention
time of at least 2% hours in the propagator is necessary
to maintain satisfactory yeast propagation. In the eighth
run, the strength of the feed was decreased by dilution
with an equal amount of water. This illustrated again
the increased yield with dilution and destruction of
about the same percentage of sugars.
TABLE II

EFFECTS OF FEED RATE ON UTILIZATION
OF SUGARS AND YIELD OF YEAST

Fe.d Aeration Sugars Sugars in Yeast
rate rae In feed effluent yield*

Cu. ft./
Gal./hr. gal./min. Pr cent Per cent Per cent

92 0.56 5.8 0.62 33
139 0.36 5.3 0.43 34
131 0.27 5.7 0.63 36
184 0.27 5.9 0.31 35
234 0.27 6.0 2.44 12
184 0.29 5.4 0.53 23
129 0.25 5.8 0.25 34
139 0.24 3.1 0.11 49

*Based on m ar. in feed.

TABLE IIl

UTILIZATION OF ORGANIC MATTER UNDER
FAVORABLE CONDITIONS FOR YEAST GROWTH

Feed Aeration Sugar Non- Oxygen Volatile Yeast
rate rate utlfiz- volcafll consumed organic yield
atfon organic value matter
matter decrease
decreoas

Gal./hr. Cu.ft./ Per Pa Per Per Per
gol./min. cent cent cent cent cent

139 0.27 68 0.26
147 0.28 66 79
142 0.34 100 0.17 49
138 0.19 100 65 81 0.18 63
140 0.44 69 0.27
161 0.30 100 79 0.35 50

*Based on sugars in feed.







In Table M, some results are given for the large
propagator with yeast propagation under favorable con-
ditions. In these experiments, the utilization of the
sugar was complete and abom two-thirds of the organic
matter destroyed as illustrated by the oxygen consumed
value and noa-volatile organic matter values. A small
amount of volatile organic matter was obtained in all
cases.



Since some volatile materials were obtained with
quite efficient yeast production, it was thought that
the values might be even higher with high concentra-
tions of feed and low yields of yeast. All the product
was collected over a 72-hour period and the volatile
organic matter distilled. The yield of volatile organic
materials collected in this manner represented 30 per
cent of the sugars originally present and consisted of
over 90 per cent ethyl alcohol. Thus even with aerated
yeast fermentation, considerable quantities of alcohol
may be expected under certain conditions.


Application has been made of the yeast propagation
as a preliminary step to a methane fermentation in
citrus wastes of about 1 per cent total solids by McNary
and co-workers (3). Rapid continuous propagation of
yeast has possibilities in reducing the sugar contents
of other citrus effluents as a preliminary step to other
methods of disposal.


Summary


Some typical results showing the effectiveness in
decreasing the amounts of sugar in citrus press liquor
of a continuous method of yeast propagation with
Torulopsis uilis have been given. The action is rapid
and can be completed with a detention time of 2.5 to
3 hours. The depletion of sugars is virtually complete
under a wide range of conditions. However, under some
conditions, in addition to yeast, which is removed with
a centrifuge, substantial quantities of volatile materials
(alcohol and esters) may be formed. The yeast propa-
gation rapidly utilizes the sugars which constitute
about two-thirds of the soluble solids in citrus press
liquor. The remaining organic materials ae likely to
consist of pectin, pectic degradation products, glyco-
sides (naringin and besperidin), and salts of citric acid.

Refernces

(1) Nolte, H. J. on Loesecke, H. W., and Pulley. e.
N.. "Feed Yeast and Industrial Alcohol from Citrus
Juice." Ind. Eng. Chem. 34, 670-73 (1942).

(2) Veldhals, M. K., and Gordon, W. O.. "Experiments
on the Production of Feed Yeast from Citrus Press
Juice." Proc. Fla. State Hort. Soc. 61, 32-36, (1948).

(3) McNary, Robert R.,Wolford, Richard W., and Patton,
Vincent D.. "Experimental Treatment of Citrus
Waste Water." Food Technol, 5, 319-323 (1951).







THE REMOVAL OF OILS, FATS AND GREASE FROM WASTES


by

F. S. Gibbs
President, F. S. Gibbs, Incorporated


The requirement to remove oils, fats and greases
from industrial wastes is encountered in an extremely
broad field of waste problems. Mineral oils and greases,
vegetable oils and fats, animal oils and fats, with their
innumerable derivatives, are major pollution factors in
many different industries. Furthermore, the presence of
oils, fats, and greases in a waste water complicates
the treatment problems, interfering with most clarifica-
tion and purification methods.

The solution of these problems is economically and
often profitably possible with the utilization of the one
characteristic which is common to practically all of
the oils, fats and greases. It is the utilization of the
basic fact that the specific gravity of oils, fats and
greases is, with rare exception, less than the waste
waters in which they are contained. The obvious, yet
sadly neglected, method for the removal of these low
specific gravity suspensions is to float them. Simple
flotation, depending solely on the lower specific gravity
of the suspension to cause it to float, is not enough.
Usually there is not enough difference in the specific
gravities of the suspensions and the water to give a
clean separation and a stable floating sludge. The low
specific gravity suspensions can be readily induced
to rise speedily to the liquid surface and there form a
stable compact sludge by the attachment of volumes
of tiny air bubbles to the suspensions. The attachment
of tiny air bubbles to the suspension particles increases
their buoyancy, giving the particle a determination to
move directly to the liquid surface even under condi-
tions of counter-current, i.e., downward liquid flow.
With flotation equipment providing continuous and de-
pendable introduction of volumes of tiny air bubbles,
automatic concentration and removal of the surface
sludge, and full control of all ranges of wastes flow,
the inherent capabilities of flotation are made into a
simple, economical, practical and exceptionally effi-
cient unit of waste-treatment equipment.

In making the case forair-inducedflotation removal
of oils, fats and greases from waste waters, the con-
tending thought arises, what about the other suspen-
sions present in the waste water, suspensions that
have a specific gravity greater than the waste water?"
It is true that industrial wastes rarely, if ever, will


contain a simple suspension or emulsion of an oil, fat
or grease without any other suspension being present.
The presence of the heavier suspensions in combination
with oils, fats and greases does not prevent the air-
induced flotation process from producing excellent re-
moval efficiencies onthe total suspensions. Air-induced
flotation, aided when necessary with chemical coagula-
tion, will provide far better removal efficiencies under
the widely varying conditions of an industrial waste
containing oils, fats, greases and other suspensions
than will any other type of clarification equipment.
Obviously, to obtain satisfactory removal efficiencies
with settling clarification, the suspension particles
must all have a specific gravity greater than 1.0. The
oil, far or grease particles will have a specific gravity
of from 0.85 to 1.0. We are dealing with a mixture of
suspensions which results in conditions wherein the
heavier suspensions are made buoyant by the lighter
suspensions, some to the point of floating and many
more to the point of having a resultant specific gravity
so near that of the water vehicle, it is impossible to
obtain settling of the suspensions. These conglomerate
particles remain in suspension and carry through the
clarification plant and into the effluent.

Another characteristic of wastes containing oils,
fats and greases (and this characteristic is applicable
to practically all industrial wastes) is the fact -that
the wastes are not homogeneous. An industrial plant
making a single product, and continuously in production,
will not have a homogeneous waste water. The mixed-up
characteristics of the subject wastes cause little
concern in the operation of air-induced flotation clari-
fication equipment but it can sand does thoroughly upset
settling clarification. The varying quantities of oils,
fats or greases in the wastes make it impossible to
achieve dependable efficiencies in settling clarification.
With flotation equipment providing efficient removalE
from waste water containing a minimum of oil, fat or
grease, any increase over the minimum actually is
beneficial. It is not necessary that the heavier suspen-
sions be in the minority for achieving efficient clarifi-
cation with flotation equipment. The suspensions usual-
ly encountered either will accept the 'attachment of
numbers of tiny air bubbles directly or will, with chemi-
cal coagulation, precipitation or neutralization, entrap





the air bubbles in the agglomerating particles. In either times the suspensions float. The flotation unit under


case the result is the same. The air bubble attach-
ment is sufficient to reduce the specific gravity to less
than 1.0.

An illustration of direct attachment of air bubbles
to heavy suspensions without chemical application
is in the flotation clarification of the wastes of a vege-
table-oils refinery. This plant has a number of sewers
which unite in a sump ahead of the flotation equipment.
One of the sewers at times contains, highly caustic
centrifugal refining wastes. This water combines in
the sump with barometric-condenser waters and other
cooling waters which contain a high magnesium sal
concentration. The effect of the canstic waters is im-
mediate in the precipitation of large quantities of mag-
nesium hydroride, which has a specific gravity of 2.4.
In the flotation unit the flocculent characteristic of the
magnesium hydroxide entraps the tiny air bubbles and
the particles are buoyed to the surface where they are
continuously removed. It is interesting to note that
during the periods of the caustic refining waste flow,
influent samples settle readily to a clear supernatant
unless some other sewer discharge happens to contain
some vegetable oil or fatty acids. In the latter case
the large volume of suspensions remains suspended
throughout the volume of the sample.

An illustration of chemical neutralization causing
heavy suspensions is in the flotation clarification of
soap-acidulation wastes. The pH of this waste varies
between 1.0 and 4.0, the low pH being caused by spent
sulfuric acid. Lime slurry is applied ahead of the flota-
tion unit to neutralize the waste to a pH of over 7.0.
The neutralization forms large quantities of calcium
sulfate which is relatively insoluble and has a spe-
cific gravity of 2.96. The tiny air bubbles attach to
the heavy suspensions and achieve an excellent re-
moval efficiency.

In some cases it is necessary to add a coagulating
chemical to crack an emulsion or to agglomerate colloi-
dal suspensions. An illustration is a case wherein
chemical coagulation of a pigskin washing water bear-
ing grease, emulsions and other suspensions is em-
ployed prior to flotation clarification. The pH of this
waste water varies from 1.0 to 7.0. The grease content
varies from practically nothing to 6000 p.p.m. Lime
slurry is added first to a controlled pH of 8.0. Then
alum is added for coagulation, to a pH of 7.0 to 7.5.
The aluminum hydroxide, with a specific gravity of
2.42 is removed along with the grease and other suspen-
sions. An influent sample will at times settle readily
at other times the solids stay in suspension, and some-


all conditions, provides greater than 99 per cent removal
efficiencies, the effluent being of sparkling clarity.

Another case is of particular interest because it is
only desired to remove petroleum oils from a waste
water with no concern for other suspensions in the
waste. The industry washes and refines used crankcase
oil. The waste-water discharge is into a municipal
sewer. The water carries varying contents of inert sus-
pensions and oils. The sewerage authorities ordered
the industry to eliminate the oil from the plant's sewer
discharge. The refinery installed a gravity separator
as designed by the American Petroleum Institute. When
placed in operation, the separator removed considerable
quantities of the oil and other suspensions but the
effluent to the sewer still carried oil, and all samples
showed an oil slick. Again an order was issued to the
refinery to eliminate the oil from the sewer discharge.
The refinery, believing that a second A.P.I. separator
would provide the same percentage removal that the first
separator achieved, built a completely separate and
additional A.P.I. separator to operate in series with
the first. When the second unit was placed in operation
it provided practically no additional oil removal. Ap-
parently, the oil carrying through the first separator
was either in an emulsified state or the oil particles
were adhering to other suspension particles so that
the combination remained in suspension, neither settl-
ing nor floating. The sewerage authorities then issued
an order which in effect stated that the refinery must
eliminate all oil from the sewer discharge or go out of
business. The refinery investigated all types of oil
removal waste treatment equipment and found nothing
that would promise anything better than they had al-
ready achieved. In desperation, and as a last resort,
the refinery came to us.

The problem was interesting. It didn't come within
the limits of our previous experience but it was des-
perate enough to warrant a good try. We agreed to see
what could be done with air flotation, and went to work
on the problem.

The physical layout at the refinery was such that,
in the limited time set by the sewerage authorities, it
would be impossible to ty air flotation on the final
effluent of the two A.P.I. separators. It was possible
only to try air flotation on the influent to the first sep-
arator. An existing oil-storage tank was converted into
a flotation unit. The waste-water flow was pumped to
the flotation unit ahead of the A.P.I. units. When placed
in operation, the flotation unit effluent carried an oil
slick for the first 48 hours, and air flotation was con-








sidered to be a failure. Then, the flotation unit effluent
cleared. No oil slicks appeared in numerous effluent
samples even though the samples were heated. The
flotation unit effluent samples did contain inert suspen-
sions in varying quantities. It was evident that the
volumes of tiny air bubbles were scouring the minute
oil particles off the other suspension particles and
moving the oil to the surface for subsequent removal.
The oil slicks that did appear during the initial 48
hours were evidently from the residual oil remaining
on the sidewalls of the converted oil storage tank. This
flotation unit, born in desperation and built in haste,
has continued to operate with complete satisfaction in
the elimination of oils from the refinery waste waters.

Air-bubble-induced flotation is rapidly proving it-
self to be a valuable tool for engineers in their efforts
to eliminate pollution and recover values lose in indus-
trial wastes containing fats, oils and greases. The
phrase, "recover values lost," deserves more than a
passing mention. While most flotation units have been
installed because of a pressing need to eliminate a
specific pollution problem, the value of the recovered
fats, oils or greases has often proved the flotation
unit to be a profitable investment. Because the flotation
unit operates with a short retention period, and because
the oil, fat or grease is continuously removed under
conditions which prevent rancidity, the recovered mate-
rial is not downgraded. Acidulation and/or rendering
of the recovered material is readily accomplished with
minimum cost. One case has been encountered in which
the animal fat being discharged in a 500 g.p.m. waste
flow has a net value of several hundred dollars per day.

Air-induced flotation, in addition to its exceptional
abilities on removal efficiencies, has many advantages
over other types of clarification equipment. A correctly


designed flotation unit is not upset by abrupt changes
in rates of waste flow or temperature changes. The
surface sludge (or skimmings) is removed continuously
and the per cent of solids is considerably greater than
in the sludge obtained in settling clarification. The
sludge usually is self-draining or readily filterable
without chemical treatment. The unit effluent is sata-
rated with dissolved oxygen. The effluent, the sludge,
and the operating unit are completely free from disagree-
able odors. Of possibly the greatest importance is the
fact that the flotation unit performs its work within
only 10 to 20 minutes retention, which results in mini-
mum space requirements and low capital expenditure.

While this paper concerns itself with the removal
of oils, fats, greases and their derivatives from indus-
trial wastes, it is interesting to note that air-induced
flotation is performing admirably on other wastes. In
the paper industry, fiber and filler are being recovered
for re-use from waste water and the water itself is
being recovered. Many colloidal suspensions, which
cannot be clarified economically by other methods,
can be handled with air-induced flotation. Air-induced
flotation is not a panacea for all industrial waste ills,
but it definitely does provide removals which cannot
be achieved with other types of clarification equipment.
The full potentialities of flotation methods have not
been explored. Today's sewage treatment plants are
prohibitively expensive in capital costs for most med-
ium-sized municipalities. The operation and mainte-
nance costs of the treatment plants are excessive.
Air-induced flotation clarification and purification
methods are ideally suited for sewage treatment. Work
done to date has shown some startling results. It is
indicated, and most strongly so, that air-induced flota-
tion will be the solution to the present high-cost bar-
rier to achieving sewage pollution elimination.






INVESTIGATION OF ALAFI AND PEACE RIVERS


by

William R. Clary, Director
Strem Sanitation Laboratory
Florida State Board of Health
Lake Alfred Florida


In July, 1949, a project to investigate the reported
pollution of the Alafia and Peace Rivers was establish-
ed by the State Board of Health with the cooperation
of the operating members of the phosphate industry.
The project covers a territory extending from Lakeland
and Haines City on the north to Punta Gorda on the
south, and from Lake Wales on the east to Gibsonton
or East Tampa on the west.

The first step was to locate rivet sampling stations
above and below all known sewage outfalls and indus-
trial waste systems. To date, 98 such stations on the
Peace River and 29 stations on the Alafia River have
been established. Until this year monthly samples
were collected; presently they are on a quarterly basis.
In addition, hundreds of samples have been collected
under emergency conditions. There have been present-
ly collected and analyzed 4,500 chemical samples,
967 bacterial samples for examination in Jacksonville
and 934 observations of river conditions usually at the
time of collecting bacterial samples. In addition, 101
river gagings have been made and data collected from
some 30 rainfall stations. These activities largely
concerned routine work.

In addition to routine work, 15 active mining opera-
tions were examined at least one time and some several
times. As you might suspect, citrus processing opera-
tions have taken up much time. Since citrus is a sub-
ject to be discussed thoroughly elsewhere at this con-
ference, it will simply be noted that operational studies
have been made at 57 citrus plants of 31 companies
in 15 municipalities. Detailed studies of the effluents
at about one-half of these plants are complete insofar
as they may affect this study.

Relative to sewage disposal, new plants have been
installed, since the study started-at Lakeland, Barrow,
Winter Haven and Brewster. Lake Wales has a new
plant under construction. Of special interest is the
question of sewage disposal in the lower Peace Riv-
er Valley since, as a result of the present work and
that of the Regional Engineer of the Florida State
Board of Health, those cities above Arcadia have been


warned to take the initial steps to provide adequate
sewage-disposal systems. The purpose is to protect
the water supply of Arcadia which is taken from the
Peace River and treated in a rapid filter plant. There
has been an increasing bacterial load. While auxiliary
treatment was recommended for this water supply, it
was felt necessary that the upper cities should reduce
the pollutional load reaching the water plant. In addi-
tion, Arcadia was advised that steps should be taken
to provide treatment for its sewage now entering the
Peace River without treatment of any kind below its
water system.

This investigation is principally concerned with
the pebble-phosphate industry largely located in Polk
and Hillsbrough Counties. There is elsewhere in
Florida a small amount of activity inthe rock-phosphate
field. That this industry is of great importance to Hills-
"-borough and Polk Counties and to the State of Florida
may be gained from the following:

1. Of the world's phosphate supply, more than
three-fifths is mined in this country and most
of it in the above two Florida counties.

2. Whereas before World War II a 4,000,000-ton
Florida production was thought enormous, last
year saw a production of over 8,000,000 tons.
Furthermore, it is estimated that by 1954 Florida
would produce 10 to 12 million tons and that
there would be a yearly increase for 15 to 20
years.

The pebble phosphate is located in the ground beneath
a sand overburden from a few feet to 60 feet in depth,
which depth represents the economical recovery limit
and only then when two measures are employed. The
pebble phosphate is embedded in quartz sand and fine
clays which, with the phosphate, comprise the matrix.
The matrix may have a depth of a few feet to as much
as 50 feet. The matrix may contain 20 per cent sand,
20 per cent clays and 60 per cent phosphate, but there
can be many variances from these percentages. For
instance, the clays (phosphatic slimes) may be as








much as 45 per cent which makes a very difficult dis-
posal problem.

In present day mining of the phosphate, huge drag-
lines are used to remove the overburden which is used
to form dikes and dams. However, when the depth of
overbrden exceeds 40 feet, the first layers of over-
burden are removed hydraulically by the equipment
used to get the matrix to the washer. That is to say,
hydraulic guns are used to form a slurry which is pump-
ed to a disposal area. At times, the upper layers of
earth contain organic materials which prevent the liquid
waste from completely clarifying.

After the overburden is removed from a section of
the matrix, a well, so-called, is either formed on the
surface ofthe ground by the dragline bucket or by blast-
ing. The dragline then proceeds to dump matrix into
this well where a slurry is formed by means of hydraulic
guns. The slurry is pumped by stage pumps as much as
several miles to the washer and flotation plant.

At the washer, the matrix is passed through a series
of screens where the larger particles of phosphate are
separated from the smaller sizes and stored in hoppers.
Years ago this was the end of the process. The remain-
ing phosphate in the sand and clay mixture was wasted.
While much of this mixture undoubtedly found its way
to the nearest watercourse, large amounts were stored
in old pits which were later remained for the so-called
flotation feed.

Next, the flotation feed finds its way to the flota-
tion plant where, in a very complicated procedure, most
of the finer particles of phosphate are recovered to a
size as small as will be retained on a 200-mesh screen
and, experimentally at least, on a 300-mesh screen.
After treatment with such chemicals as caustic, kero-
sene, fuel oil and tall oil, the phosphate is floated
from the sand in cells or on moving belts or on shaker
tables. In one step, the phosphate may be further re-
fined by treatment with sulfuric acid and amines where-
by sand is floated from the phosphate. It is in this
process that fresh well water is used. This water usu-
ally comprises the make-up water lost in the slime-
settling system by evaporation and by percolation into
the ground and through dams. Any surplus is wasted
into the nearest receiving body of water. The slime is
separated from the phosphate and sand in hydrosep-
aracors-circular tanks with a peripheral weir. When
you realize that a large plant and mine may be circulat-
ing water at a rate of 72,0000000 gallons per day,
(50,000 g.p.m.), you can visualize the enormous prob-
lem of sedimentation. This is important, for much of


the circulating water is sent to the slime-settling areas
for clarification, for efficient re-use, and to prevent
stream pollution.

Phosphate slimes which may comprise 45 per cent
of the matrix have the unhappy facility of expanding
when wet. It has been reported in the field that the
slime in one acre-foot of matrix will occupy 1% acre-
feet of space when returned to a settling area. Hence,
the settling areas fill rapidly with this presently un-
wanted material. The sand can be used to form hills
and the industry longs to discover a method to dispose
of slime in the same way. At all of the present mining
areas except three, the slimes readily clarify and the
wastes discharged to the receiving streams do not
cause complaint. At the three mines the slimes are
semi-colloidal and do not clarify easily. The managers
of these three mines make every effort to store these
slimes and as much rain water as possible; however
when, in the interest of dam safety, water is discharged,
there is apt to be complaint. As mentioned previously
detailed inspections have been made of the active
mines. The first such inspection followed the dis-
covery of highly turbid water in the Peace River near
and below Ft. Meade early in January, 1950. Investi-
gations disclosed that this turbid condition of the water
was largely due to the operations of one company which
was found to have inadequate slime settling facilities.
Conferences were held with company officials and a
program of improvement was recommended. While the
company was found to be working on the problem at
the time of the first inspection, three months were to
elapse before the company solved its problem. Inaddi-
tion, six dam slides were witnessed which did not re-
lease slimes to any watercourse, five dam breaks which
released large volumes of slimes to either the Peace
River or the Alafia River and one dam breakwhich re-
leased slimes to a neighboring mining operation. Since
the mine was of sufficient size no unsettled slimes
reached a watercourse. In this connection, the receiv-
ing management should be commended for making every
effort to prevent river pollution. Relative to the dam
failures, it is of interest to note that 14 months elapsed
before the first one occurred, but that in a period of
less than a year there were a total of six such failures.
Maximum observed turbidities in river water following
or during major disturbances follow


1950 disturbance
Dam Break No. 1
Dam Break No. 2
Dam Break No. 3
Dam Break No. 4


3,000 ppm
8,000 ppm
3,200 ppm
800 ppm
15,000 ppm Creek
620 ppm River







Dam Break No. 5 20,000 ppm 8. Vibration caused by using heavy equipment on


Dam Break No. 6


No slimes reached river


While the above comprise the major mishaps, too
many minor disturbances occur whereby improperly
treated phosphate wastes have been discharged to our
streams. These could usually have been avoided by
arrention to detail of operation and at times by long-
range planning.


These matters have not gone by without further con-
sideration by the Florida State Board of Health. Cor-
rective recommendations either have been made direct-
ly to the company concerned or to the industry as a
whole through Progress Reports prepared by the writer
for dissemination throughout the phosphate industry and
the health departments concerned. In addition, these
matters are discussed thoroughly with the three mem-
bers of a Phosphate Managers' Committee which meets
with members of the Bureau of Sanitary Engineering
on a quarterly basis. As you might suspect, the matter
of dam breaks has been of increasing concern to the
Florida State Board of Health. Recently, a letter was
directed to the seven phosphate companies through
their committee chairman which summarizes the various
dam breaks and gives suggested reasons for their
failure. The companies were urged to review the cir-
cumstances noted and determine if failures could be
minimized in the future. It was the opinion of the Flor-
ida State Board of Health that these failures could be
prevented bycarefulengineering planning and operation.
You may be interested to know why these dams failed.
Actually this is not easily determined. There may be
one factor or many factors, but among the suggested
reasons for the dam failures referred to above were:

1. Improper base preparation-logs, sticks and
roots left in dam-water may have finally seeped
by and weakened dam.
2. Old pipes left in dam-water may have finally
seeped by and weakened dam.
3. Seepage through base section may have caused
base to soften and give way.
4. Possible effects of rainfall prior to failure.
5. Improper distribution of "mass" of dam-that is
to say, a huge pile of earth without proper pro-
portion for the job at hand.
6. Seepage through dam may have caused outer
face of dam to slide and pressure of confined
water caused remaining portion to overturn.
7. Overtaxing of dams beyond originally designed
use.


or near dam in re-enforcing weak point may have
caused one structure to let go.
9. Insufficient protective strip at toe of dam.
10. Use of explosives near dam.
11. Clear water against inner face of dam so deep
that line of seepage falls above toe of dam.

We are told that the phosphate waste kills fish or
otherwise affects fishing. At no time during a dam
break have any dead fish been found, except those
which were stranded in the affected areas by lowering
of the water. Once dead fish were found in a ditch
which had received turbid water from a slime settling
area. The fish were reported dead when washed out of
the settling area. There was ample dissolved oxygen
at the time of the examination. On another occasion,
when early in 1950 the Peace River was found to be
so highly turbid, dead or dying fish were found at the
mouth of Charlie Creek near Gardner. While the river
water had a turbidity of 1000 ppm, there was ample
dissolved oxygen to sustain fish life.*

No conclusions are offered at this time. This in-
formation is presently being supplemented by studies
conducted bythe Department of Biology, which is study-
ing the biological life of the two rivers, including fish
life. All of us have much work to do in our search to
determine the effects of improperly created phosphate
waste upon the waters of the two rivers. That the dis-
charge of large quantities of improperly treated phos-
phate waste into the two rivers is aesthetically objec-
tionable, there can be no argument. These are beauti-
ful bodies of water, especially in their lower reaches,
and should afford beneficial recreation to many people.

In discussing a subject of this nature, we cannot
ignore the public opinion which has been expressed
from time to time both through complaints reaching
this office and the office of the Governor of Florida
and through the newspapers. The phosphate industry is
not without deficiencies; neither is the industry with-
out responsibility. However, progress has been made
in spite of the major disturbances noted above. That
the industry can and will do a better job there is no
doubt.

*Since preparing this report, the seventh dam bceak has oc-
eunred. Three dead fish wer observed in the receiving
waters and about 30 dead fish were reported by a game
warden. It is understood that a number of these fish were
retrieved by the game warden for examination by interested
biologists. Careful examination of these fish should reveal
the cause of their death.







THE CHALLENGE OF INDUSTRIAL WASTE TO THE ENGINEER


by

Molcom Pirmi
Consulting Engineer
New York


Unprecedented attempts to supply the urgent needs
of the world have accelerated industrial expansion to
transform increasing numbers of clear, sparkling rapids
into surging brown turbid masses of colored froth-covet-
ed water. Often the distinctive odor announces the
manufacturing process which created such pollution.
For the chemist,bacteriologist, engineer and industrial-
ist therecreational adventure was ended before the anti-
ticipated peaceful luncheon. Now, there are many real
jobs for them to do before the true vacation, carefree
spirit can be revived. Let us hope in the meantime that
not all of the trout, bass, shad and salmon will dis-
appear.

The shad industry in the Delaware River was smoth-
ered by sewage and industrial wastes discharged in
the estuary from Philadelphia to Delaware Bay. Prom-
ise of recovery of commercial shad fishing worth several
million dollars a year is given in the Incodel plan to
increase greatly the dry weather flow of the River and
the sewage disposal works being built by the city of
Philadelphia. The shad fry in their mid and late summer
migration to the ocean will then find oxygen sufficient
to sustain life in this recently fatal stretch of the
journey between breeding grounds and the ocean.

Industrial wastes polluting our natural waters and
invigorating atmosphere are a rapidly mounting chal-
lenge to all technologists and industrial managers with
vision. Wastes so concentrated as to destroy Nature's
self purification processes in rivers, lakes and armos-
phere are profligate spending of natural resources.
Their existence spurs the creative mind to action. Out
of the laborious trial and error come reclamation pro-
cedures which ultimately may approach complete use
of the raw materials processed by the manufacturer.

Any new development in waste treatment must ans-
wer in the affirmative that most important question:
"Will it be worth what it costs?" Twenty-five years
ago, when the relatively easy recovery of solids lost
in processing raw materials saved more than its cost,
the president of a company operating mills located in
several eastern states said to me, "Whenever I have
been forced to reduce pollution of a stream passing a


mill, new income from salable by-products kicked me
upstairs." Later, sale of valuable by-products paid
the greater costs of more difficult recoveries from in-
dustrial wastes.

Today there are methods developed to cultivate
Nature'smicro-organisms which oxidize andprecipitate,
or those which partly gasify and concentrate various
organic pollutions in water. The first method makes
use of a World War II machine for producing oxygen at
low cost for immediate use. We expect this recent de-
velopment to permit the engineer to design sewage-
disposal facilities for primary treatment that can later
be converted into complete treatment. Thus, the engi-
neer continues to receive new tools with which he can
reduce space requirements and cost of treatment of in-
dustrial wastes.

In our enthusiasm to recapture "clear, cool water"
in the natural drainage systems of areas containing in-
creasing populations and industrial activity, engineers
must temper enthusiasm with hard-headed inquiry into
impact of cost upon the economic structure of the area
to determine if benefits in fact are worth their cost.
Otherwise the financial burden of works built now to
produce the ultimate in collection and purification of
wastes may greatly reduce the established rate of pop-
ulation and industrial development.

The engineer must set his sights on the ultimate
development and plan immediate steps within the abil-
ity of the community to pay. These preliminaries taken
together with future steps will provide the best approach
to perfect solution of the problem.

One of our largest cities, right here in Florida, is
struggling today with the financing of a project design-
ed almost beyond the financial means of the city. It
is a real challenge to design within our ability to pay.
When we do, substantial good may be realized at once
and enjoyed as our finances build upto permit comple-
tion of the final steps in the practically perfect dis-
posal system.

During the second quarter of this century research






has developed processes which now permit economical
conversion of much of the two and one-half billion
poundsof wastes annually derived from Florida's citrus-
processing industries into valuable cattlefeed. Other by-
products have also been developed to add profits from
waste treatment which will urge the processor to al-
low only the most dilute liquid wastes to reach the
recreational waters enjoyed by millions of tourists in
Florida.

At present there are four general methods by which
industrial pollution can be reduced:

1. Modification of the industrial process to reduce,
concentrate, netralize or eliminate the waste.
As an example, the widespread use of save-alls
for permitting re-use of white water in paper
mills has resulted in considerable reduction in


waste discharges from these plants.

2. Recovery of useful by-products from the wastes,
such as cattle feed or activated carbon in the
citrs, ati-biotics and paper industries.

3. Treatment of wastes. In many cases this must
be the important method of reducing wastes,
particularly where small concentrations of phenol
cause objectionable tastes in down current water
supplies.

4. Discharge of industrial organic wastes for treat-
ment in municipal sewage treatment plants. This
is often an economical and effective method.
Care must be exercised, however, to avoid injury
to the sewage-treatment process by toxic or too
greatly concentrated industrial wastes.








KRAFT MILL EFFLUENT CONTROL PRACTICE

by

Harry W. Gehm
National Council for Stream Improvement, Inc.
New York, N. Y.


Wood pulp is produced in the South almost exclu-
sively the by craft process. Some groundwood and sul-
fite pulp are manufactured, but these represent only a
small percentage of the total pulp tonnage. Thirty-two
units, ranging in size from 200 to 2000 tons daily, now
produce over seven million tons annually. Two others
are under construction at present; a number of others
are in the planning stage, and expansion of many of
the existing mills is either underway or planned for
the immediate future. The size and rapid growth of
this industry are remarkable, particularly since it is
only about twenty-five years old. Responsibility for
this expansion outside of resources, general economics
and markets, can be attributed to the process itself
which can handle the available species of wood abun-
daat in the South. The kraft process has been improved
to such a degree that the pulp uses have been greatly
extended beyond the coarse papers and board products
which were originally its only uses. Now even dissolv-
ing pulp, which contains over 95 per cent alpha-cellu-
lose, is produced by this process followed by bleach-
ing treatment. Hardwoods as well as pine can be pulped
by modifications of the kraft process. This has further
increased the scope of its application.

Since the chemical requirement for kraft pulping
greatly exceeds most other processes, its application
has always depended upon chemical recovery and sal-
vage of the heat value from the lignins and other sub-
stances cooked from the wood. Early recovery methods
were rather crude andthe recovery plant was considered
a stepchild of the manufacturing units. Today, how-
ever, such is not the case. Engineering developments
have brought the kraft mill to a point where it is the
ultimate, of all industrial processes using natural raw
materials, with respect to recovery and utilization. In
fact, gross wastes have been almost entirely elimi-
nated and heat, as well as chemical, recovery extended
to the point where further conservation does not appear
possible. Recovery values well in excess of 95 per
cent are not uncommon in modern mills.

A tabulation of mill waste materials and their pres-
ent disposition is presented in Table I. It is obvious
upon inspection of this table that but three wastes of


any consequence remain to be disposed of. The dregs
and grits are inorganic insolubles which dewater read-
ily and are produced only in small quantity; hence, are
generally easily disposed of on adjacent land as fill.
TABLE I

DISPOSITION OF KRAFT MILL WASTES
WASTES NOW RECOVERED DISPOSITION

Spent Cooking Chomicols ...... Recovere
Dissolved Wood Substances . Burned
Bork ................. Burred
Knots ............... .. Burd or Recooked
R.jicts & Scrrnings ......Recookd or Sold
Tupentine ............. .Recovered or Sold
Toll Oil .............. Sold Crude or Refined
Lime Mud ............. Raclimed
Fine Fibr ............. .Recapturd and incorporated
in Product


WASTES

Cousticizing Dregs . .... .. Fill
Lim Slakr Grts . . . . .Fill
Effluent Water . . . . Discharged Directly or After
Equalization or Trotment

The only remaining material requiring disposal is
the used water or effluent. These effluents contain
traces of residual chemicals and wood substances
which prohibit their further reuse in the mill. They
contain in general, the major individual effluents shown
in the process diagrams presented in the following
figures. Figure 1 outlines the pulping process itself.
Examination of this diagram reveals that the major
waste from the pulping operation is overflow from the
decker seal pit. This effluent contains traces of chem-
icals and wood substances remaining in the pulp after
the washing operation. The greatest improvement in
this part of the process has come through the elimina-
tion of wash water effluent. Development of closed
countercurrent vacuum washing systems has been re-
sponsible for this advance which has led to both high-
er recovery efficiency as well as a reduction of the
BOD load in the effluent of between 50 and 75 per cent.







CONDENSER


B.L.
BROWN STOCK
, WASHERS


WW or


BARKING CHIPPER' I --
DRUM CHIP RECHIPPER CHP DIESTER
SCREEN STORAGE
Bark to
waste


LEGEND
Chlp. or pulp
White Water or Fresh Water (W.W.or FW.)
Black Liquor (B.L.)
White Liquor (W.L.)
Waste lines


SCREENED STOCK
CHEST
To Bleach Plant


Scu /m
o waste


-I
BL Lfor
dilution


BLACK LIQUOR
To STORAGE
recovery.._ _
process


WW
DECKERS SCREENS KNOTTER SED


To Paper Mill


I Knots to
waste


reuse or waste


FIGURE I


PULP MILL FLOWSHEET
Stock Preparation


Decker seal pit discharge varies between 200 and 500
ppm. of 5-day oxygen demand. Other pulp-mill dis-
charges are digester relief and blow-down condensates,
together with log wash water, turpentine decanter water
and floor washings. These are low in volume as com-
pared to the decker seal pit overflow and generally
have a lower oxygen demand. They are significant,
however, in that the condensates, decanter water and
floor washings contain substances such as sulfides,
resin acids and mercaptans that are potentially toxic to
aquatic life. When danger of reaching toxic levels in
the receivingwaters exists, the condensates are stripped
of objectionable substances in packed towers by power
plant stack gases. This development has eliminated
any danger of toxic damage to aquatic life by normally-
operating pulp mills located on streams having low ren-
off.

In Figure 2, the heat and chemical recovery system
of the kraft process is outlined. The major effluent
from this section of a mill is the condensate from the
evaporators. There surface evaporators are employed


the volume of this discharge is low and the BOD value
relatively high. Barometric condensers produce an
effluent very low in oxygen demand, but voluminous
due to the quantity of water required by the jets. Ap-
plication of long-tube evaporators in as many as seven
effects has greatly reduced carry-overwith the resulting
high losses formerly occurring in this operation. Im-
proved foam control and trapping devices have further
reduced carry-over of liquor into the condensers. A
better appreciation of evaporator capacity requirements
in relation to losses has also done much to reduce the
concentration of organic matter and salts in this dis-
charge. Other waste waters emanating from this divi-
sion of the process are minor in both volume and pollu-
tional load.

The paper machine section shown in Figure 3 is
the third division of the mill producing waste water
in considerable volume. Water removed from the pulp,
together with that discharged by showers used to clean
wires and felts, makes up the machine water. It is low
in oxygen demand but higher than other mill waste









CONDENSER EVAPORATORS






B.L BL I

L-BSTORAGE J STORAGE





GL -Gr- Iquar-- *
Condensate -
to waste .

LEGEND refties SOAIMER
S- Steam SOAP M
BL Black liquor--- STORAGE W
GL -Green liquor--- -
Wt- White liquor---
FW Fresh water-
Gases


B.L STORAGE


CAUSTICIZERS GREEN LIQUOR
STORAGE


FIGURE 2


PULP MILL FLOWSHEET
Recovery & Cooking Liquor Preparation


PAPER MACHINE
PRESSES


SCREENED
STOCK JORDAN
CHEST


Water Water
t I FOURDRINIER


DRYERS CALENDAR
- -A Q WINDER


CONSISTENCY
REGULATOR
*To waste
or reuse


PAPER MILL FLOWSHEET


waters in suspended solids content. This effluent is
normally recycled to some degree in the machine sys-
tem. Overflow is clarified by means of save-alls or
thickeners to recover all usable fiber and a large pro-
portion of it reused in the pulp mill for dilution pur-
poses, or in the condensers. This water contains a
small amount of spent cooking liquor solids, together
with some fine fiber, wood debris, and papermaking
chemicals. The problem in respect to further reuse of
such waters is mainly foaming.


The engineering problems involved in improving
this effluent, hence increasing fiber recovery, have
been of three types. One has been direct removal of sus-
pended fiber for return to the system. Improved clarifica-
tion and filtration techniques have provided very effec-
tive means of accomplishing this end. This is reflected
bythe fact that less than half of one per cent of the pulp
is lost in processing; the bulk of this being extreme
fines. Secondly, the reuse of machine water, rather


CASCADE
EVAPORATOR


RECOVERY
FURNACE


FIGURE 3






than fresh water, in diluting pulp for processing prior stream power stations can have a profound bearing .


to rethickening has improved fiber reclamation, as
much of the fiber present-in the machine water is re-
captured in the thickening process. Thirdly, bulk fiber
losses which often occurred during machine breaks
and other operating irregularities have been curtailed
through in-mill improvements.

Realization that the first most effective step, and
the least costly method, of reducing pollution loads is
through internal improvement has made the southern
kraft industry an example of effective waste control.
It has also put it in a much better position with regard
to waste treatment in cases where this procedure may
be necessary. This is most important for the following
reasons:

(1) Volume of waste to be created.
(2) Concentration of waste.
(3) Quantity of final residue to be disposed of.
(4) Expansion of production.

All these revolve around capital, cost and operation
of treatment facilities which must be kept within rea-
sonable bounds. Effluent volume decreases of as much
as 50 'per cent and waste strength reductions of as
great as 75 per cent based on oxygen demand have
been realized. Under these conditions, it would be
expected that stream-pollution problems would be non-
existent. However, three circumstances mitigate against
this. These are: 1) the hydrology of southern streams;
2) the large size of the manufacturing units, and 3)
flow control and water temperature rise at power sta-
tions utilizing some streams.

In regard to the hydrologic conditions, extremes in
flow variations can be appreciated from examination
of one stream which has a normal discharge of 20,000
cfs. during the cold months and 200 cfs. throughout
the dry hot season. Operational difficulties under these
conditions can readily be appreciated.

As previously stated, the size of the kraft mills
varies from 200 to 2000 tons of product daily. Process-
ing differences, plant equipment, and production all
affect the volume of effluent discharged; but a fair
average range would be between 20,000 and 40,000 gal-
lons per ton. Hence, effluent volumes range from about
4 to 80 million gallons daily. From these figures it is
readily apparent that during the dry season mill effluent
can constitute a considerable proportion of the receiv-
ing stream.

Impoundment and control of water discharge at up-


upon the effect of mill effluent on a stream. In some
cases, control can be advantageous in that higher than
normal dry weather flowage can be assured. In others,
particularly where operation of the power station is
intermittent or where condensers raise the water tem-
perature appreciably, the result can be just the op-
posite.

The major detrimental effect of kraft-mill effluent
on streams providing insufficient dilution is dissolved-
oxygen depletion. The low saturation value observed
for many southern streams resulting from the high water
temperature provides a very limited oxygen reserve.
This, coupled with the fact that oxidation rates are
close to the peak at existing temperatures, accentuates
the problem. Since fish require dissolved oxygen for
their respiration, the entire oxygen reserve of a stream
is not available for oxidizing the waste, because an
appreciable residual must be maintained if fish are to
thrive.

Kraft-mill waste imparts color to receiving waters
due to the lignin and other dark-colored wood residues
dissolved in the mill effluent. In both nature and appear-
ance, the color is similar to that imparted by decaying
vegetation. The color in itself is not harmful to the
stream and does not prevent its use for most purposes.
It can, however, change the appearance of a stream,
thus arousing objections from the public. Instances of
this difficulty are not as common in the South as it
may appear, largely because of the fact that many mills
discharge into streams that are high in natural color
content, turbid or, in the case of coastal mills, the
effluent is discharged into salt or brackish waters.

Fish toxicity of kraft effluents was once an impor-
tant factor. The presence of dangerous quantities of
caustic soda, sulfides, mercaptans and resin acids in
the discharge of the mills was not uncommon. At pres-
ent, toxicity problems due to normal effluent are non-
existent due to recovery system improvements, by-
product separation and other in-mill changes (such as
condensate stripping). Even at very low dilution ratios
such changes have reduced the concentration of po-
tentially toxic substances in the effluent well below
the minimum lethal concentration in receiving waters.
The provision of waste equalizing facilities, as well
as segregation of abnormal sewer losses for discharge
to lagoons, has also played an important part in the
virtual elimination of this problem.

Research efforts by the pulp and paper industry
have in recent years been directed toward finding suit-







able methods whereby kraft effluents can be reduced velopment stage in a flexible and fully instrumented


in oxygen demand and color. Laboratory observations
revealed that after removal of most of the suspended
matter, storage for a period of from 20 to 30 days at
warm-weather temperatures would be accompanied by a
reduction in oxygen demand of from 50 to 75 per cent.
In accordance with these findings several mills, having
large areas of adjacent suitable land,built and operated
lagoons employing this discovery.

Further experimentation revealed that the oxidation
obtainedon storage was almost entirelydue to microbial
activity. In order that the process might be made more
widely applicable, the industry set up a project at
Louisiana State University for the purpose of deter-
mininghow this oxidation process might be accelerated.
It had previously been found that sewage-oxidation
methods were relatively ineffective, hence it appeared
that either something was lacking which was required
by the organisms, or toxic materials were present which
prohibited satisfactory rates.


Careful research covering a period of five years
indicated that high-oxidation rates could be achieved
if nutritive deficiencies of ammonia and phosphate in
the waste were rectified, initial anaerobiasis was elim-
inated and an acclimated seeding maintained. Labora-
tory trial indicated that, after a short preconditioning
treatment, storage for three to five days would produce
oxygen-demand reductions of greater than 90 per cent.
This research has been carried into the pilot-plant de-


unit. The best means of applying the laboratory find-
ings, as well as the over-all economics of the process,
are being worked out.

Simultaneously, investigation of a chemical-treat-
ment process has been carried on at the same institu-
tion. This process involves time precipitation and re-
carbonation and is capable of removing most of the
color as well as a substantial portion of the BOD of
the spent process waters. In order to bring this process
within economic reason, it must be integrated with the
lime recovery system of the mill. This requirement
necessitates the solution of several difficult problems.
One is control of lime feed and recarbonation in the
proper ratio under fluctuations in waste requirements.
A second is the production of a dewaterable sludge of
reasonable density, and the third, the effect of this
material on returning of the causticizing mud under
continuous operating conditions. This process is also
undergoing pilot-plant development at two southern
mills.

Of future interest is the possibility of reclaiming,
through use of these processes, substantial quantities
of process water. If this can be accomplished it may
prove of great importance in future development of the
industry in the South. Water is as necessary as wood
and all other raw materials topulp and paper production,
and the rapidly increasing interest of industry in this
once apparently boundless resource is indicative of
the fact that it is by no means unlimited in quantity.







KRAFT MILL EFFLUENT CONTROL PRACTICE

Discussion by

Anthony W. Pesch
Manufacturing and Engineering Department
International Paper Company


As Dr. Gehm has pointed our so clearly in his paper.
a great deal has been accomplished by the U. S. kraft
pulp and paper industry in reducing the losses to the
streams. The growth in the kraft industry and the devel-
opments in kraft pulp and paper mill efficiency that
have taken place during the past thirty years are as-
tounding. The kraft pulping process was discovered
by accident in Europe in 1879 as an offshoot of the
soda process, but it was not until 1907 that the process
came to North America commercially (Brompton Pulp
and Paper Company, East Angus, Quebec). Kraft pulp
production started commercially in the United States
during the following year and by 1910 a pulp mill was
operating on southern pine at Orange, Texas in a mill
that first operated on the soda process but which was
converted to kraft a year or two later. Why did it take
so long fdr the kraft process to become established in
the United States and Canada when we consider that
groundwood and soda and sulfite pulps were already
being produced here in relatively large quantities dur-
ing the 1880's and earlier? After all, the groundwood
and soda and sulfite processes are not much older than
the kraft process. And why was it that the growth of
the kraft industry in the South did not become a major
factor until after about 1920?

The reasons for this slow start of the kraft industry
have become obscured during the passage of time.
People only realized very gradually the economic and
other advantages of wrapping paper, grocer bags, kraft
multi-wall sacks and kraft and other boxes and shipping
containers made from paper pulp. Some of us recall the
time when small wooden box plants were to be found
all over the country. Today, we seldom see a wooden
box and very few people now realize that it takes much
less wood to make a paper shipping container than the
wood that is required for a wooden box to do the same
job; and that the paper shipping container normally
carries its contents to destination in better condition,
in most instances, than the wooden box. Usually the
wooden box is superior only for certain very heavy com-
modities. Furthermore, wooden boxes cannot practicably
be salvaged for reuse whereas many paper boxes are
made into new paper over and over again. Everybody
knows that paper boxes weigh much less than wooden


boxes (and therefore involve less freight on tare weight)
but few people stop to realize that the drain upon our
forests would be much greater than it now is if kraft
shipping containers had not replaced wooden boxes;
and unfortunately very few people know, even today,,
that pulpwood is only one of the minor drains upon the
forest; that fires, for example, annually destroy sev-
eral times as much timber than is consumed annually
by the entire wood-pulp industry of the United States.

Some of us have seen the further growth of the paper
industry stunted in certain sections of this country
by lack of pulpwood and I cannot refrain at this point
from stressing the need for the general public to inter-
est itself in the program for conserving our timber sup-
plies, even in the South. Fire is still the greatest single
bugbear, and the need for controlling forest fires and
other timber enemies is going to become more and more
apparent as time goes on if one of the South's greatest
assets, namely pine timber, is to continue to be in
adequate supply.

As recently as 15 years ago the opinion of well in-
formed people in the paper industry still was that there
was an inexhaustible supply of pine pulpwood in the
South. Due, principally, to the tremendous growth of
pulp production since about 1935, we now know that
this simply is not true. And we now realize that better
control of fire, the elimination of the practice of burn-
ing grass in the woods during the winter and early
spring, generally improved practices in the management
of forest lands and an intensified program of reforesta-
tion are essential to the maintenance of the pulp and
paper industry in the South, even on its present scale.

Entirely aside from the basic use and economic
factors influencing the tremendous growth of the kraft
industry in North America, and particularly in the South,
there has been another factor which has accounted for
much of this growth; this same factor accounts to a
very large extent also for the very marked decrease in
the amount of waste reaching the receiving waters per
ton of kraft pulp and paper production. I refer here to
the marked developments and improvements in kraft
pulp mill machinery particularly in the case of mul-







tiple-effect evaporators for concentrating the spent ing equipment have been at least as great as those in


cooking liquor (black liquor); equipment for separating
and washing the black liquor from the pulp; chemical
recovery furnaces, including electrostatic precipicators;
and caustic room, woodyard, woodroom and save-all
equipment for the reduction of wood, bark and fiber
losses.

The improvements are particularly significant in
the case of the multiple-effect evaporator. Until the
forced circulation evaporator was introduced into the
kraft industry (about 1930 by Swanson Evaporator Co.)
and until the old Kestner evaporator was resuscitated,
so to speak, and developed by several of the U. S.
evaporator manufacturers into the present long-tube,
vertical-film type evaporator, the loss of black liquor
to the sewer during evaporation was a major factor in
the losses leaving a kraft pulp mill. The older types of
multiple-effect evaporators suffered badly from carry-
over and entrainment, principally caused by the marked
foaming tendencies of black liquor from southern pine.
Furthermore, it was impossible, physically and econom-
ically, to build the older types of evaporators in very
large capacities with the result that the older kraft pulp
mills were almost always short of the desired evapora-
tion capacities. With modern LTV film-type evaporators
the condenser water is normally so nearly free from
black liquor carry-over and entrainment that it is water-
white in color. This improvement stems largely from
the advantages inherent in the LTV type, insofar as
black liquor is concerned, and partly from improvements
in the design of the vapor heads and catch-alls. Un-
fortunately, some improvement is still desirable for
carry-over and entrainment from the "last effect" of
the LTV evaporator. By last effect I mean, of course,
the effect at the vacuum end. Due to the low absolute
pressure which it is necessary to carry in the vapor
head of the last effect, the vapor densities at that point
and in the corresponding catch-all are naturally very
low and therefore the problem of preventing carry-over
and entrainment from the last effect involves the design
and construction of this vapor head and catch-all for
the high vapor velocities involved, so that added costs
do not become prohibitive. It is my own presonal opin-
ion that studies by the evaporator manufacturers (and
by chemical and mechanical engineers in this and other
industries) of these remaining liquor-loss difficulties
will gradually result in a marked reduction in the amount
of carry-over and entrainment.

Improvements to recovery furnaces, to disc and sim-
ilar direct contact evaporators, to electrostatic pre-
cipitators on the flue gases from the recovery units, to
caustic room equipment and to lime recovery and reburn-


the case of the multiple-effect evaporators. Improve-
ments to woodyard and woodroom equipment and prac-
tices have eliminated, or greatly reduced, the problem
of pulpwood bark getting into the screams- At one time
the woodyard and woodroom bark and other wood waste
was often burned up in order to get rid of it and, as Dr.
Gehm pointed out, relatively little use was made of the
hearing value content of the black liquor. Today the
amount of steam generated from woodyard and wood-
room refuse and from black liquor is sufficient to fur-
nish all, or nearly all, of the steam and electric power
requirements of an unbleached kraft pulp mill.

In the case of equipment for separating the black
liquor from the pulp there have also been very signifi-
cant improvements. Until recent years this job was
done in so-called open pans or, and somewhat more
efficiently, in diffusers. In most cases, however, the
job is done better today with rotary vacuum filters, or
with screw presses, or with a combination of rotary
vacuum filters and screw presses. Experience with
screw presses on this job is, however, still very limit-
ed. Sofar as diffusers are concerned, they can do an
effective and efficient job of pulp washing and black
liquor recovery without excessive dilution with wash
water. But, under present economic conditions, the in-
vestment and operating costs of an adequate diffuser
room have become relatively so very high that, for a
new installation, diffusers can no longer compete with
rotary vacuum filters and screw presses. Unfortunately,
in the case of rotary vacuum filters as of this date, the
consumption of electric power for pumping liquor is
excessive.

Dilution of the black liquor with wash water is also
usually excessive whenthe filters are operated towhere
the pulp is washed so clean that there is relatively
little subsequent loss of residual black liquor to the
sewer from the Wet Machine Room. It happens to be my
own personal opinion that material improvements in
equipment and process are possible insofar as the sep-
aration of black liquor from pulp is concerned; that
perhaps the right way of doing this job has not even
been conceived and that probably we will see marked
progress in both the process and the machinery during
the next five or ten years.

The kraft pulp industry has long been conscious of
kraft mill odors and it certainly has made considerable
progress in reducing the losses of sulfur compounds
going to the atmosphere. The chief problem in prevent-
ing sulfur compounds from reaching the atmosphere
stems from the fact that some of the sulfur contained in






the black liquor is so unstable, when it reaches the kraft mill more than 95 per cent of the black liquor is


disc evaporators and recovery furnaces, that pan of it
is volatilized at these two points and carried into the
flue gases and up the recovery room chimney. From
laboratory and pilot plant experiments in Europe and
in North America, and on the basis of some commercial
experience in Scandinavia and in Canada, we know that
the sulfur compounds in the black liquor can be stabi-
lized to a marked degree by oxidizing these sulfur com-
pounds with atmospheric oxygen by bringing the black
liquor into adequate, intimate contact with air. Unfor-
runazely, all of our efforts in the South to utilize these
known facts have failed because of the relatively ex-
cessive foaming tendency of the black liquor from pine.
This foam problem on black liquor from southern pine
is so serious that nobody has been able thus far to
devise any practicable equipment for oxidizing kraft
black liquor, even on a pilot-plant scale.

Consider the following equation:


2000-lb. Salt Cake 200-lb. Makeup
Equv. to Disesaersl Salr Cake
m2000x Salt Cke Equiv.
to Digesters


90% Overall Sodium
-Recovery Efficiency


The amount of soda chemicals, nor including sodium
chloride, contained in the white liquor which must be
charged into the digesters as cooking liquor is chemi-
cally equivalent to about 2,000 lb. of salt cake (con-
taining 95% Na2SO4) per ton of air-dry pulp. The exact
amount of digester cooking chemicals required varies
somewhat with the type of pulp, e.g. whether "raw"' or
"medium" or "easy bleaching" type, bur 2,000 Ib.of
salt cake equivalent per ton is about normal for a me-
dium-soft unbleached pulp cooked from pine.


In the average modern kraft mill it requires around
200 lb. of salt cake per ton of air-dry pulp to replace
all of the soda losses from the mill. On that basis, as
you can see from the above formula, the recovery of
chemicals in such a mill amounts to 1,800 lb. of 95%
Na2SO4 equivalent per con of pulp which is equivalent
to 90 per cent over-all soda recovery efficiency based
on the white liquor to the digesters. Insofar as an ap-
preciable portion of the lost digester chemicals still
escape as "fume" from the recovery units, even when
electrostatic precipitators are used, and because some
of the total salt cake added as make-up represents
losses of green liquor and white liquor ahead of the
digesters, it follows that the per cent recovery of the
total black liquor produced must be appreciably greater
than the recovery efficiency shown by the above formu-
la. What this all means is that in a good average modern


recovered and substantially less than 5 per cent of the
black liquor reaches the effluent receiving waters.

When I became associated with the kraft industry
in 1924, one mill in the South stilt required from 600
to 800 lb, of salt cake make-up per ton of pulp; and
during the six years that I spent at a Wisconsin kraft
mill (1924 to 1930) the latter mill averaged 525 lb. of
salt make-up per ton of pulp without any material im-
provement during those six years with the exception
of about 50 per cent increase in the kraft pulp production
rate per day. Losses of black liquor from the multiple-
effect evaporator were the most significant ofthe losses
ar that mill by modern standards.

It is perhaps superfluous for me to point out that
the developments and refinements which have taken
place in the kraft industry during the last 25 years
have required a great deal of capital outlay as well as
a great deal of hard work and serious study, both by
the equipment builders and inside of the kraft industry
itself. It is only natural that the main driving force be-
hind this astounding development has been economic in
nature because everything that is lost during pulp and
paper manufacture, either into the receiving waters or
to the atmosphere, represents losses of purchased raw
materials.

But, at the same time, there has also been a growing
realization by the management of the kraft industry of
the need of reducing these losses in order to eliminate
stream pollution. Responsible people in the kraft indus-
try in the South ae fully aware of the need for conserv-
ing our available pine-timber supply and that conscious-
ness has also made them more conscious of the need
for conserving other raw materials particularly those
described above in order to guard the supply of non-
replaceable natural resources such as purchased fuel
or sulfur. For example, adequate suitable water is not
only an essential ingredient in the final making of paper
but it is also an extremely important essential tool be-
cause it is the medium in which all of the chemical and
mechanical operations of pulp and paper making are
carried out. That is one reason why the kraft paper
industry is today very conscious of the need for con-
serving fresh water resources, both ground water and
surface water. It is now universally recognized that
the addition of any surplus fresh water during pulp and
paper manufacture increases the waste of raw materials
from both the pulp and paper mill, including pulp fiber
itself. From the standpoint of enlightened self-interest,
the kraft industry has every reason to reduce its wastes
and to prevent and eliminate stream pollution.








As stated above, foam is the most important obstacle
encountered in the battle for waste elimination from the
kraft pulping industry in the South and it is the problem
of excessive foaming which makes further progress dif-
ficult at the moment. The old saying is, "You cannot
make a silk purse from a sow's ear," and perhaps it
will never be possible and practicable to make black
liquor which will be non-foaming. Palliatives in the
way of foam killers may help at certain points but, per-
sonally, I believe that learning how to reduce foam gen-
eration, and how to combat foam by improving machinery
so that foam will be less of a problem, is the more ef-
fective approach. Unfortunately, the theoretical and
technical aspects of foam and foam stability are not
known as well as they should be, but I am convinced
that we will learn a great deal more about how to handle
foam as time goes on.

Many of us in industry see the dire need for more
men with a thorough understanding of engineering and
other scientific fundamentals a crying need not only
for men with initiative and the ability to think straight
and clearly but also men to realize the need for serious
application and hard work after they have acquired ade-
quate training and knowledge of the fundamentals.


With reference to the lagooning or impounding of
kraft mill effluent mentioned by Dr. Gehm, it happens
to be true that my company has found this method very
effective for preventing undesirable stream conditions
at certain of its plants. In one Louisiana plant at least,
it has been the only way out thus far.


At our Panama City, Florida plant, the conditions
in St. Andrews Bay, including the appearance and clean-
liness of the beaches in the neighborhood of the mill,
have improved markedly as the combined result of recent
reductions in mill losses, temporary impounding of cer-
tain of the mill effluents in order to remove settleable
solids, and the installation of a long underwater pipe-
line resting on the bottom of the bay. This long under-
water pipeline is so arranged that thorough, quick and
complete mixing of the final effluent with the receiving
waters takes place so that stratification of the effluent
at the surface, due to the somewhat higher effluent tem-
perature as compared to the bay water, is prevented.
Removal of all but a minor portion of the settleable


solids has eliminated unsightly deposits on the beaches
within the past year.

With regard to the biochemical and chemical methods
of treating kraft mill effluents described by Dr. Gehm
and now being studied by the National Council, we in
the kraft pulp and paper industry naturally hope that an
adequate and economical treatment system will finally
be found. The laboratory and pilot plant studies made
and sponsored by the National Council do look promis-
ing but further development work and the test of time
are required for determining whether or not our hopes
are based on a sound foundation. We agree with Prof.
Earle B. Phelps, and other eminent authorities in the
field of stream sanitation, that the controlled utilization
of streams and other surface waters for waste disposal
purposes is logical and in line with a sound and sensible
policy of utilizing and conserving our natural resources.
On that basis it is our conviction that even the impound-
ing of kraft mill effluent, followed by periodic discharge
to the receiving waters, represents a waste of capital
and operating costs whenever such impounding meas-
ures are not the most economically effective method
for preventing undesirable stream conditions. I feel the
same way about any after-treatment method of kraft pulp
and paper mill effluent disposal and, therefore, believe
that it is only sensible first of all to reduce to the prac-
ticable economic point, the amount of waste going into
the receiving waters before submitting a given kraft
operation to the added burden of the capital and operat-
ing costs involved in any after-treatment method. Any
reduction in waste, this side of the law of diminishing
returns, represents lowered manufacturing costs and
conservation of our natural resources; whereas the
after-treatment of any wastes which could be economi-
cally prevented means increased manufacturing costs
and a waste of natural resources.

Referring to the possible chemical and biochemical
methods of treating kraft mill wastes that were mention-
ed in Dr. Gehm's paper, I would like to conclude by
stressing that the kraft industry in the South is anxious
to continue and to develop these studies. The need
should be emphasized for making baste carefully in
order to avoid wasting capital, labor and natural re-
sources on treatment plant costsandoperating expenses;
treatment plants which might not even do the job ade-
quately and which might soon become obsolete-






THEORY AND PRACTICE IN STREAM POLLUTION CONTROL


by

Richard D. Hoak
Mellon Institate
Pittsburgh, Pa.


Every good citizen favors sound measures for abat-
ing stream pollution. The visual effects of uncontrolled
discharge of sewage and industrial wastes cannot be
avoided by the observant, and certain less obvious
results of pollution are fairly easy to recognize. Actu-
ally, relatively few persons have seen streams of any
size which were completely free of pan-made pollution.
But although the desirability and necessity of pollution
control is widely accepted, agreement on the methods
and extent of control is considerably less universal.

There are two principal reasons for the difficulty
often experienced in gaining full agreement on pollution
control measures. The first, and more important, is our
meager knowledge of the specific effects of most pollu-
tants on scream ecology and water usage. It is true that
scientific research is steadily yielding detailed infor-
mation on many aspects of the problem, but its funda-
mental complexity, and the enormous variability of con-
ditions encountered, combine to prevent very rapid prog-
gress. Organized attack on the broad questions involved
in pollution control has been relatively recent, and new
problems arise almost as rapidly as old ones are solved.
The second difficulty is the large part usually played
by subjective judgment in deciding on control methods.
Expert and layman alike are swayed by personal bias
and interest in judging the merits of cases where factual
data are lacking or unobtainable. Determining the rela-
tive importance of esthetic and recreational values as
contrasted with local economic considerations is es-
pecially difficult but frequently necessary. There is no
evidence that rational means for solving such dilemmas
will ever be wholly satisfactory, because the questions
are societal rather than technical. Unfortunately, pollu-
tion usually affects downstream neighbors more serious-
ly than those responsible for it, and this factor has
sometimes influenced regulatory measures.

Pollution Control Objectives

It sometimes seems that so much emphasis is placed
on the necessity for waste treatment that the object of
the treatment is forgotten. Streams comprise a highly
important natural resource, and one of their most essen-
tial functions is to carry away and assimilate the water-


borne wastes of mankind. But streams serve many hu-
man needs, and their use for waste disposal should not
interfere with their other functions. Unfortunately, there
are many instances where such a heavy load of pollu-
tion is carried by streams that their value for other uses
is impaired or destroyed. The paramount objective of
all pollution control measures should therefore be to
maintain those stream conditions that will best serve
the over-all interests of particular localities. It is eco-
nomically unrealistic to expect streams in highly indus-
tralized areas to be in as good condition as those flow-
ing through agricultural or forest lands. On the other
hand, gross pollution is an offense to human decency,
and such conditions should be corrected by appropriate
controls.

Establishment of water quality criteria best suited
to the needs of any region is not a simple task. It is
never easy to please all people, because of the inevita-
ble conflict between desires and possibilities, and the
inadequate public understanding of the complex techni-
cal and economic problems involved. Competent engi-
neers with experience in this field know how to collect
the data needed to make sound recommendations. Their
decisions will include public health, economic, recrea-
tional and esthetic considerations. They will suggest
the kind and degree of waste treatment required to main-
tain the stream conditions their studies have shown to
be desirable. But their findings probably will not satis-
fy all the local people. Some will not be pleased by
the predicted degree of improvement; some will quarrel
with specific proposals; others will complain that the
cost is too high. These factors are not insignificant,
because they have often had their effect in modifying
careful engineering conclusions.

Development of criteria of desirable water quality
should be undertaken only by those experts in stream
sanitation who also know how to reconcile economic
questions and to place a reasonable value on intangi-
bles. Intangible values, however, should never be a
primary factor in evaluating the economics of a stream
improvement program; they should instead be regarded
as an extra benefit afforded by meeting other more
essential requirements. The cost of building and operat-








ing waste treatment facilities of every description has
increased greatly over the past decade, and the public,
as well as some engineers, do not always seem to
understand that the cost of treating wastes, whether
industrial or municipal, always falls upon the taxpayer.
For this reason, it has become increasingly important
to recognize that streams constitute an essential part
of every waste treatment plant. The problem of the engi-
neer is to recommend that degree of waste treatment
which will utilize the self-purification capacity of the
receiving water to the fullest practical extent consistent
with optimum local conditions.

Self-Purification of Streams

Flowing water has always had a curious fascination
for mankind. Troubled spirits are calmed as we gaze at
a meandering stream or watch the tumble of water in a
rocky chasm. When we contemplate the soothing play
of water we do not often think about the complex phe-
nomena that are constantly taking place in it. But most
streams contain a great variety of living things which
depend on water to supply their food and other needs.
Microscopic plants and animals feed upon the dissolved
and suspended matter in stream water, and in turn be-
come food for larger species. A complex cycle of life
and death goes on continuously in streams, and varia-
tions in the cycle are dependent upon the supply of
available food.

The kinds of aquatic life in streams vary widely
with their natural environments. Streams rising in the
granite formations of New England support different
species from those originating in the swamps of the
southeast or in the great plains. Indeed, some streams
that have been untouched by human agencies contain
a very scanty variety of life forms.

The aquatic life in a stream maintains a natural
balance with its environment. As food material increases
in quantity or complexity, the number and variety of
microorganisms increase rapidly to consume it. This,
in turn, multiplies the food supply of the larger animals.
If the available food remains at a fairly high level, a
great variety of aquatic forms will continue to exist in
balance with each other. On the other hand, if the food
supply diminishes in quantity, the stream population
will decline until a new balance is struck between the
organisms and the available food.

Pollution of streams occurs when any material is
present in such quantity that natural balance is dis-
turbed to the extent that desirable aquatic life is de-
stroyed or driven away. Streams can be said to be pol-


luted only when the kind or amount of substances dis-
charged to them is continually greater than a reason-
able fraction of their capacity for self-purification.

Relation of Pollution Load to Stream Resources

Natural purification of streams is affected to a vari-
able extent by a number of factors, but availability of
dissolved oxygen is by far the most important in prac-
tically every case. In theory, it should be a relatively
simple matter to relate the aggregate B.O.D. of the
daily pollution load to the oxygen resources of a stream,
but in practice the problem is quite complicated.

Practical application of the familiar Streeter-Phelps
formulas(11 describing the rates of deoxygenation and
reaeration is limited by the variability of the so-called
constants k1 and k2. A number of investigators (How-
land4,6), Howland and Farr5), LeBosquet and Tsivog-
ou(7), Moore, Thomas and Snow(9), Streeter(12), and
Thomas(14'15) have proposed simplified procedures
for solving the equations and evaluating the constants.
These methods should lead to wider application of
established techniques for determining self-purification
capacity.

Velz has made important contributions on the statis-
tical analysis(18) of stream conditions in their relation
to the capacity of streams to assimilate wastes. He has
listed(17) the following stream liabilities: characteris-
tics, quantity and fluctuation of the pollution load; tate
of oxidation at various temperatures; effects of imme-
diate demand or lagging demand; effect of changes in
time of passage of pollution induced by variations in
channel cross section and fluctuations in runoff, includ-
ing the effect of dams on low-flow augmentation; extrac-
tion and storage of B.O.D. by biological growths, and
sludge deposits. The assets available to balance these
liabilities are the dissolved oxygen in the stream, and
that contributed by runoff, tributaries and reaeration.
He stresses the danger of generalizing about self-puri-
fication capacity without giving proper weight to such
factors as sludge deposits and drought probability. In
another paper (19) he describes a statistical method for
pollution control that permits optimum utilization of
stream capacity.

It is apparent that optimum use of stream resources
will not result unless stream capacity has been deter-
mined by a comprehensive survey. Such a survey will
suggest the most economically sound drought-frequency
interval upon which to base waste treatment require-
ments. Comprehensive scream surveys, though rather
costly, represent the best approach to rational selection







of water quality criteria, and they will be used increas- to develop an inflexibility that cannot be readily ad-


ingly as treatment costs continue to mount. It cannot
be emphasized too strongly that stream resources should
be utilized fully to the extent that unsatisfactory con-
ditions will not occur oftener than once in five to ten
years. To require a higher degree of waste treatment
would be to increase tax burdens unjustifiably.

Vorietis of Pollution Controls

The earliest practical stream control was an attempt
to limit discharge of oxidizable matter to a definite
ratio of waste to stream flow. Figures ranging from 2
to 10 c. f. a. of flow per thousand population were sug-
gested, depending on the degree of turbulence of the
receiving water. This type of control was proposed be-
fore the mechanism of deoxygenarion was completely
developed, and it could not take proper account of
self-purification.

At present, many states have adopted one or an-
other variety of stream classification. This is a highly
useful administrative device, but it is not a sound way
toregulate pollution. Temporary classification of streams
to systematize a clean-up program can be quite helpful,
but permanent classification can be self-defeating. A
progress report of the Committee on Water Quality Cri-
teria of the California Water Pollution Control Board( 3
points out that there is a tendency for a general pattern
of water quality zones to develop in iny area of varied
topography, but it cites the following disadvantages of
stream classification: uses of water are not uniform
within a zone; effects of pollution are not uniformly
dispersed throughout a zone; successful pollution con-
trol programs must recognize that the need for economy
in waste disposal is as exacting as the need for water
quality protection; zones tend to become permanent
and do not lend themselves to reclaiming degraded
streams. Another objection would be the tendency for
the arbitrary line dividing two zones to move slowly
farther and farther into the better of the two zones, as,
for example, where a stream flows from the countryside
into an industrial area.

A movement has been in progress for some time to
place definite limitations upon certain physical, chemi-
cal and biological characteristics of waste water, and
to call these limitations "standards." It is unfortunate
that the word "standard" has such a strong appeal for
administrators; perhaps this has come about as a result
of the general desire in this country to standardize
everything from machine screws to thought patterns.
But standards are basically improper when applied to
pollution control, because their legal connotation tends


justed to the dynamics of scream ecology. In addition,
they promote avoidance of that thoughtful appraisal that
is due each pollution problem if the beat public inter-
est is to be served. This viewpoint is supported by a
number of authorities and organizations who have dealt
with the question of standards(.13'8'20)

This by no means suggests that all qualifications
of waste water should be discarded forthwith. It does
emphasize that each situation should be dealt with on
its own merits, and that promulgation of general stan-
dards prevents reaching the best solution in specific
cases. In approaching the problem of stream water qual-
ity, the first step should be a comprehensive survey to
provide data that canbe used to determine those stream
conditions that will be most appropriate for a given
area. The recommended conditions will, in most cases,
be better than those existing, but the survey will indi-
care a water quality that is reasonably attainable. It
should therefore be the objective of the pollution control
agency to provide this desirable quality, but the time
required to reach the goal may be long or short, depend-
ing on local conditions. This does not prevent the
agency from setting successively higher goals if eco-
nomic circumstances and the general welfare warrant
them. Once an immediate objective has been decided,
water use can be allocated among municipalities and
industries in terms of the pollution load that can be
assimilated by a given stream section. Data that can
be used to define these allocations will be provided
by the survey.

The language of the report of the Board of Technical
Advisers to the International Joint Commission(2) is
especially pertinent to this subject. The report states
that stream quality objectives could be set and main-
tained for a long period, but the requirements for ef-
fluents might change with conditions. The objectives
adopted are based upon the conditions that follow thor-
ough admixture of effluents with the receiving water.
The flexibility of the objectives is shown by the far-
sighted wording used. The report states that "adequate
protection should be provided if..." the river water is
maintained within a designated range of physical and
chemical characteristics. Similarly for effluents, the
desired "quality in the receiving waters will probably
be attained if..." effluents are held within a range of
specific compositions. This kind of procedure should
result in maximum beneficial use of stream water.

Biological Indices

In recent years, considerable attention has been








given to the perfectly reasonable proposition that aquat-
iclife should be capable of yielding a satisfactory index
of stream conditions. Ithasbeen maintained that streams
supporting a diversified aquatic population distributed
among those flora and fauna that persist only in clean
water should provide a wholly acceptable water quality.
Actual investigations have demonstrated that there is
a practical biological technique that can be employed
to distinguish degrees of pollution.

A significant comprehensive study in this field was
undertaken by the Academy of Natural Science of Phila-
delphia(1'. It was sponsored by the Pennsylvania Sani-
tary Water Board, following a recommendation by the
Pollution Abatement Committee of the Pennsylvania
State Chamber of Commerce. This investigation showed
that stream biota can be used to indicate a wide range
of stream conditions from healthy to grossly polluted.
It was concluded that direct measure of the biodynamic
cycle discloses the presence or absence of all major
taxonomic groups that play a role in the cycle; that
chemical and physical characteristics ofhealthy streams
vary widely and cannot be reduced to a simple standard;
that there is no practical way to test for all toxic agents
in a stream, and it is seldom that a single agent acts
independently as a limiting factor; and that the biody-
namic measure will reflect water conditions that existed
for a considerable time, whereas a water sample repre-
sents only the condition at the time it was taken.

Application of biological methods in pollution con-
trol would disclose the rate of change of water quality
in terms of the biota it supports. This would provide an
invaluable record both for industries and administrative
agencies. A simplified survey method is being develop-
ed by the Academy that should broaden its practical ap-
plicability. The new technique involves suspension of
a coated plate in the stream to collect a representative
sample of the phytoplankton and other free-swimming
organisms.

Van Horn(16) has discussed biological indices and
listed organisms characteristic of various degrees of
pollution. He emphasizes that biological methods are
not intended to supplant, but rather to supplement other
measurements, because of the inherent complexity of
the phenomena involved. Chemical data maybe consid-
ered as describing the cause, and biological data the
effect, of a stream condition. Tarzwell and Palmer(3)
note that a number of algae have been recognized as
indicators of general water conditions, and suggest
basic research to select those forms that can be relied
upon to give specific information on impending changes
in water quality. They also recommend development


of a year-round biological sampling service.

Instruments as Control Devices

The measures that can be used to control pollution
are of two broad, more or less interdependent kinds.
The first includes all the precautions that should be
taken to reduce pollution at its source. The second is
appropriate treatment of residual wastes. Instrumenta-
tion can be used effectively to regulate pollution con-
trol devices in many ways.

Stream pollution problems arise almost wholly from
the discharge of water-borne wastes. A variety of in-
struments, some evolved from laboratory analytical tools,
is available for measuring certain important characteris-
tics of waste water, and of natural streams and lakes.
Although commercial instruments for measuring every
significant variable are not yet being marketed, it is
probable that research will develop practical devices
for complete control of waste water.

It should be obvious that pollution from industrial
sources can best be abated by reducing the quantity of
water-borne waste. This means careful control of manu-
facturing operations to keep discharges to a minimum
consistent with satisfactory product quality. A waste
water survey will generally disclose places where un-
necessary waste is occurring. This may range from
extravagant use of water to serious losses of raw mate-
rial and semi-finished products.

The advantages of instrument control over manual
operation of processes are too obvious to need much
discussion. It is difficult to imagine a process that
would not require one or more instruments for satisfac-
tory operation, and many modern processes could not be
operated at all without accurate instrument control. It
is true that instruments sometimes fail to operate prop-
erly, but where adequate maintenance is provided they
are generally more dependable than an operator: their
response is faster and their attention does not wander.

The basis of all process control is measurement,
but adaptation of a measuring device to a control instru-
ment is not always easy, because measurement can be
performed with a minimum of power but control cannot.
Development of a powerful control action by amplifica-
tion of the minute impulse of a measuring device results
in design problems that often require a high degree of
ingenuity. Nevertheless, keen competition among instru-
ment manufacturers has provided the engineer with de-
vices that can control a wide range of process varia-
bles. It is instructive, and in a sense prophetic, to







observe the rapidity with which devices long consider- cive importance of the items suggested might not be


ed to be useful only as laboratory analytical tools are
being convened into control instruments.

Instrument control of processes to prevent waste
may range from a simple warning device, such as a pH
element for sounding an alarm when acid or alkali ex-
ceeds a limiting value, to full process control. Where a
plant must be installed to modify residual wastes, in-
strument control can be quite effective, even though
waste treatment control is usually much more complex
than manufacturing process control, because of unpre-
dictable variations in volume or composition. Where
maximum limits have been established for certain com-
ponents of an effluent, instruments can sometimes be
employed to indicate a number of variables.

There is a growing conviction that streams them-
selves must provide the final criteria of what may be
discharged to them. This attitude reflects an acknowl-
edgment of the economic importance of streams as an
agency for assimilation of the wastes of civilization.
At the same time, it recognizes the rights of down-
stream riparian owners; the capacity of streams for self-
purification; and the esthetic and recreational values
of undefiled bodies of natural water.

Our knowledge of the specific effects on stream
ecology of most materials regarded as pollutants is
rather meager, and the data we have are limited to
fairly definite conditions. For this reason, it seems
illogical and uneconomical to set arbitrary limits for
various constituents of plant effluents where knowledge
of their effects is lacking. Such requirements are some-
what more defensible if they relate to the concentration
of a given waste component after thorough dispersion
in the receiving water.

Certain of the physical and chemical factors that
affect aquatic life are fairly fundamental, and might be
combined to provide a broad index of stream condition.
Four factors affect stream biota directly: temperature,
pH, dissolved solids and dissolved oxygen. The effects
of two others, turbidity and color, are usually indirect
through their influence on photosynthesis. If the varia-
tion of these five factors, plus stream stage and effluent
flow race, were continuously recorded, there would be
available a history that would be invaluable in deciding
responsibility for unsatisfactory conditions. The rela-


agreed upon unanimously, and means for combining
them into an index of water quality might be difficult,
but the proposal is worthy of research attention. Sub-
stances that cause serious effects in minute concen-
tration, such as direct-acting toxins and taste-producing
compounds, could not be evaluated in this manner, but
these always pose special problems.

Devices for continuously recording temperature, pH,
stream stage and flow rate are commonplace. Instru-
ments for recording dissolved oxygen and conductivity
are available but somewhat unfamiliar. Turbidity and
color present a more difficult problem. Although there
are instruments for measuring both, turbidiry is a func-
tion of the size, shape and number of suspended par-
ticles, and color measurement depends on transmitted
light. Variation of these physical properties might cause
calibration difficulties.

This combination of instrument-measured factors
would serve an important purpose by providing an in-
disputable permanent record of stream and effluent
quality. The function of waste treatment is not only to
overcome local pollution problems but to effect a grad-
ual improvement in the quality of surface waters. Means
for obtaining a continuous record of conditions would
help immeasurably in achieving this objective.


Summary

This paper has emphasized the economic importance
of fully utilizing that fraction of stream resources that
will provide those stream conditions that a comprehen-
sive survey has indicated to be appropriate for a given
locality. It has outlined reasons for abandoning so-called
fixed standards of stream and effluent quality, and sub-
stituting therefore flexible, but attainable, quality ob-
jectives. The supplemental information that can be pro-
vided by biological indices of pollution has been stress-
ed, and general methods have been proposed for instru-
ment control of pollution.

Acknowledgment

This paper is a contribution from the Fellowship
the American Iron and Steel Institute has sustained at
Mellon Institute since 1938.




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