Operation of activated sludge pilot plant for treatment of citrus processing waste water

Material Information

Operation of activated sludge pilot plant for treatment of citrus processing waste water
Series Title:
Citrus Station mimeo report
McNary, Robert R
Wolford, R. W
Dougherty, Marshall H
Citrus Experiment Station (Lake Alfred, Fla.)
Florida Citrus Commission
Place of Publication:
Lake Alfred FL
Florida Citrus Experiment Station :
Florida Citrus Commission
Publication Date:
Physical Description:
2 leaves : ill. ; 28 cm.


Subjects / Keywords:
Citrus fruit industry -- Waste disposal ( lcsh )
Sewage -- Purification -- Activated sludge process ( lcsh )
Fruit -- Processing -- Waste disposal ( lcsh )
City of Lake Alfred ( local )
Wastewater ( jstor )
Activated sludge ( jstor )
Pumps ( jstor )
government publication (state, provincial, terriorial, dependent) ( marcgt )
bibliography ( marcgt )
non-fiction ( marcgt )


Includes bibliographical references (leaf 2).
General Note:
Caption title.
General Note:
"October 4, 1955."
Statement of Responsibility:
R.R. McNary, R.W. Wolford and M.H. Dougherty.

Record Information

Source Institution:
University of Florida
Rights Management:
All applicable rights reserved by the source institution and holding location.
Resource Identifier:
74726667 ( OCLC )


This item has the following downloads:

Full Text

Citrus Station Mimeo Report 56-2
October 4, 1955

Operation of Activated Sludge Pilot Plant for Treatment of Citrus
Processing Waste Water

R. R. McNary, R. W. Wolford and M. H. Dougherty

At the 1953 and 1954 meetings of citrus processors at this Station, data were
presented (1, 2) concerning the treatment of citrus waste water by the activated
sludge process in a small laboratory scale unit. This data has now been published
(3). O'Neal (4) has also reported on the treatment of citrus waste by activated
sludge during a study by the Florida State Board of Health.

Through the courtesy and help of the Fosgate Citrus Concentrate Cooperative,
the authors had the opportunity to study the activated sludge process on a pilot
plant scale using actual waste water from a citrus processing plant. This report
presents the more significant data from this study. Full details are available
to anyone interested in this problem and will be published at a future date.

Description and Operation of Pilot Plant. The pilot plant was located ad-
jacent to the sand absorption beds which received all of the processing waste
water from the Fosgate plant with the exception of the fruit washing, condenser
and other relatively uncontaminated water. This investigation extended over a
period of 43 days. A schematic sketch of the pilot plant is shown on the next
page. The raw waste used in the pilot plant was picked-up by the raw waste pump
B from the citrus waste channel and delivered to a cup suspended over the surge
tank H, a 500 gal. concrete vessel. During the latter 9 days of the run, alka-
line clean-up waste water, temporarily stored in four 50 gal. drums C, was metered
by pump D into the same cup. The raw waste was diluted only during the last three
days of the run by adding tap water through needle valve E to the cup. A small
amount of the raw waste was continuously removed from the cup by the sampling
pump Q and collected in bottle R. The remainder of the waste overflowed from the
cup into the surge tank H where it was mixed by the propeller type agitator F and
kept from becoming septic and odorous by a stream of air from diffuser G. Each
day 3 lb. 10 oz. of sodium nitrate and 1 lb. 1 oz. of trisodium phosphate were
dissolved in 4.2 gal. of water and added to nutrient tank P. This solution was
pumped at the rate of 11 ml./min. to the overflow from the surge tank. The waste
then flowed by gravity to the aeration tank J which also was a 500 gal. concrete
tank. Here the waste and sludge were thoroughly aerated with fine bubbles from
four Saran wrapped diffusers K placed along the side of the tank. The air was
supplied by blower I which had a capacity of 60 cu. ft./min, at the shaft speed
used. The exact amount of air used was not measured because of a lack of a
suitable metering device. The mixed liquor overflowing from the aeration tank
enteredd the 60 gal. clarifier L below the liquid surface. The sludge settling to
.he bottom was worked by a rotating scraper to the center where it was picked up
)y the sludge recirculation pump M and returned to the upstream end of the aeration
tank. Supernatant liquor overflowed into the effluent weirs at the top of the
clarifier and was piped to the sand absorption beds. When excess sludge was being
withdrawn, a by-pass valve in the sludge line was opened.

Florida Citrus Experiment Station
and Florida Citrus Commission, /
Lake Alfred, Florida, i NO 10 19
633- 9/26/55-RRMc

Needle Valve


Raw Waste P


Nutrie t t-1 '---"
Tank Sludge
10 Nu- Re circulation
Gal. Nutrient Pump
p Supply





,, Raw Waste

,I- ----i.

Surge Tank Overflow


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iu LU

Days of Operation

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Experimental Results. The performance of the pilot plant in reducing the
B.O.D. of the raw waste is given in the graph. The average values for the pounds
of B.O.D. per 24 hr. in the raw waste, surge tank overflow and effluent for the
entire run were 22.4, 15.9, and 0.80 respectively. The corresponding averages for
total and organic solids were 25.3 and 22.8 lb./24 hr. for the raw waste, 16.6 and
13.9 lb./24 hr. for the surge tank overflow, and 11.7 and 7.2 lb./24 hr. for the
effluent, respectively. The reductions of total and organic solids during the run
followed the same pattern as B.O.D. reduction, but as usual, were not as complete.

The raw waste was stronger than had been anticipated. It had an average
B.O.D. of 5957 p.p.m., whereas about 2000 had been expected. Furthermore,
it was much more variable in strength than anticipated. The daily composite
samples ranged from 1440 p.p.m. to 22,000 p.p.m. B.O.D. The strongest waste
occurred on the 15th day when a prolonged power failure caused the dumping of a
large volume of partially concentrated juice. In spite of these difficulties,
effective treatment of the waste was obtained, especially during the latter half
of the run. From the 35th day on, alkaline waste, that had been collected during
a plant clean-up period, was added to the raw waste continuously. The system
continued to treat this combined waste satisfactorily. During the last three
days, tap water was added to the raw waste to study the effect of a larger volume
of weaker waste on the plant operation. While the treatment was still effective,
the larger volume of water used was not handled satisfactorily by the clarifier.
The 43 day test period was too short to study many other operating variables.

It is believed that the results indicate that: (a) citrus processing wastes
can be satisfactorily treated by the activated sludge process; (b) alkaline clean-
up water can also be treated if collected separately and added to the system in a
continuous manner; and (c) a thorough survey of the strength and volume of a pro-
cessing plants waste water should be carried out before a treatment plant is de-


The authors wish to express their appreciation for the opportunity to use the
facilities of the Fosgate Citrus Concentrate Cooperative and to Mr. James M. Fiske
and Mr. W. C. Chambers for their assistance and many courtesies. Also, the
assistance of Mr. W. J. Head and Mr. E. J. Farley of the Minute Maid Corporation
in carrying out most of the solids and B.O.D. analyses was invaluable to the
successful progress of this investigation.

Literature Cited
1. Dougherty, M. H., McNary, R. R. and Wolford, R. W. Treatment of citrus pro-
cessing wastes by activated sludge. Fourth Annual Citrus Processors Meeting,
October 6, 1953, Lake Alfred, Florida.
2. Dougherty, M. H., McNary, R. R. and Wolford, R. W. Use of excess activated
sludge from the treatment of citrus processing waste water. Fifth Annual
Citrus Processors Meeting, October 12, 1954, Lake Alfred, Florida.
3. Dougherty, M. H., Wolford, R. W. and McNary, R. R. Citrus waste water treat-
ment by activated sludge. Sewage and Industrial Wastes, 27, No. 7, 821-826
(July, 1955).
4. OtNeal, Ben F. Progress Report No. 1, Citrus Waste Research Program, Florida
State Board of Health, Aug. 5, 1952; Ibid, Final Report, Aug. 10, 1953.

Florida Citrus Experiment Station
and Florida Citrus Commission,
Lake Alfred, Florida.
633a 9/26/55-RRMc