Group Title: Citrus Station mimeo report - Florida Citrus Experiment Station ; 60-2
Title: The potential of dried activated citrus sludge as an animal feed
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Permanent Link: http://ufdc.ufl.edu/UF00072391/00001
 Material Information
Title: The potential of dried activated citrus sludge as an animal feed
Series Title: Citrus Station mimeo report
Physical Description: 4 leaves : ; 28 cm.
Language: English
Creator: Dougherty, Marshall H
McNary, Robert R
Citrus Experiment Station (Lake Alfred, Fla.)
Florida Citrus Commission
Publisher: Florida Citrus Experiment Station :
Florida Citrus Commission
Place of Publication: Lake Alfred FL
Publication Date: 1959
 Subjects
Subject: Citrus fruit industry -- Waste disposal -- Florida   ( lcsh )
Citrus fruit industry -- By-products -- Florida   ( lcsh )
Animal feeding -- Florida   ( lcsh )
Genre: government publication (state, provincial, terriorial, dependent)   ( marcgt )
bibliography   ( marcgt )
non-fiction   ( marcgt )
 Notes
Bibliography: Includes bibliographical references (leaf 4).
Statement of Responsibility: Marshall H. Dougherty and Robert R. McNary.
General Note: Caption title.
General Note: "September 16, 1959."
 Record Information
Bibliographic ID: UF00072391
Volume ID: VID00001
Source Institution: University of Florida
Rights Management: All rights reserved by the source institution and holding location.
Resource Identifier: oclc - 74894467

Full Text


Citrus Station Mimeo Report 60-2
September 16, 1959

The Potential of Dried Activated Citrus Sludge as an Animal Feed

Marshall H. Dougherty and Robert R. McNary

Previous work done on both the laboratory scale (1) and pilot-plant scale
(2) has shown that citrus waste waters can be readily treated by the activated
sludge process. Preliminary work on the excess sludge from the treatment of
citrus waste waters with an intermediate scale activated sludge plant (1) indi-
cated that the sludge contained vitamins of the B group which would give it a
value between that of dried whey and dried distillers' solubles if used as a
chicken feed supplement. The sludge upon which these analyses were made was
produced using a temporary arrangement which was set up strictly for sludge
production. It was believed that the conditions for maximum vitamin production
were not always present and that a further study of the vitamin content should
be made on excess sludge produced in a properly designed activated sludge system
operating under normal conditions. An investigation on the possible effects of
varying the amounts of inorganic nutrients on the vitamin content of the sludge
was also felt necessary.


Apparatus and Procedure

The samples of excess sludge for this vitamin study were produced using the
small, laboratory-scale, three-stage activated sludge system that was used in
previous work (1).

Since it has been reported (3) that the addition of cobalt to a fermentation
culture medium would increase the production of vitamin B12, varying amounts of
cobalt, as cobaltous chloride, were added to the raw waste during this study. The
amounts used were varied along with the nitrogen and phosphate nutrients. Reported
additions of nitrogen and phosphorus in this study do not include naturally occurr-
ing amounts from the diluted orange juice used. Roberts and Gaddum (4) reported
that orange juice contains an average of 0.030% phosphorus (300 ppm) and 0.094%
organic nitrogen (940 ppm).

After a healthy culture had been established, the runs were started. On the
first day of each calendar month the amounts of nutrients and cobalt to be used
for that month's run were set. The system was allowed to run under these nutri-
ent conditions for the first two weeks of the month with no sludge being withdrawn.
During the last two weeks of the month sludge withdrawals were made from the
bottom of the clarifier at the rate of one liter per day. It was calculated
mathematically that at the end of the first two-week period over 99.9% of the
liquid of the previous period had been washed through the system. It was con-
cluded, therefore, that the properties of the sludge withdrawn during the second
two-week period would not be noticeably influenced by the previous nutrient level.

For six of the first seven months of this study the withdrawn sludge was
filtered each day and dried in an oven at 10500 for 24 hr. Sample No. 6 was
dried in a vacuum oven at 6500 for 24 hr but the oven proved to be mechanically
faulty, thereby halting this method of drying and the loss of this sample. For
the last eight months the withdrawn sludge was filtered each day and stored in a

Florida Citrus Experiment Station
and Florida Citrus Commission,
Lake Alfred, Florida,
929 9/16/59 MHD








refrigerator. At the conclusion of each monthly run all of the sludge collected
was dried on a drum dryer. Oven-dried sludge samples were ground in a mill and
drum-dried samples were pulverized in a blender and stored in bottles for later
vitamin and protein analyses. Thus, 14 samples were obtained for analysis.

The thiamin content of the dry sludge samples was determined by the thio-
chrome method (5), niacin by a colorimetric method (6) and riboflavin, panto-
thenic acid, and vitamin B12, microbiologically (7) (8) (9). The culture media
used in the microbiological analyses were obtained in dehydrated form from Difco
Laboratories, Detroit, Michigan. The crude protein content was arrived at by
multiplying the percentage Kjeldahl nitrogen by a factor of 6.25.

Results of the B group vitamin and protein analyses on 14 samples of dried
activated sludge are given in Table 1. Comparisons of these data demonstrate
the effect of the different variables on the vitamin and protein content of the
dry material. The method of drying influenced greatly the amounts of thiamin and
vitamin B12 found in the dry product. Drying in an oven at 1050C for 24 hr was
apparently too harsh and destroyed a large portion of these vitamins. Since dry-
ing the sludge on a drum dryer exposed it to a higher temperature than the oven
method, it appears that the length of time the material is exposed to an elevated
temperature is critical. It has been reported (10) that, under the conditions at
which these products were dried, thiamin will decompose and vitamin B12 will lose
activity. The method of drying did not appear to effect the amount of the other
vitamins and protein in the dry sludge.

The addition of nitrogen had a depressing effect on the thiamin content of
the sludge. For example, treatment conditions resulting in sample No. 9, con-
taining 4.3 mcg of thiamin/g, differed from those resulting in sample No. 8,
containing 7.4 mcg/g, only by the addition of 10 ppm nitrogen. However, the
addition of nitrogen was beneficial in the production of the other B vitamins
and, as was expected, was a direct influence on the protein content. The highest
protein content was obtained when using the highest nitrogen level.

Phosphate addition decreased the production of thiamin, riboflavin, and
protein but increased the vitamin B12 and niacin production.

The addition of cobalt to the system brought about a very large increase in
vitamin B12, even when the material was treated harshly by drying it in the oven.
The effect of the cobalt was much more pronounced, however, when added with small
amounts of nitrogen or phosphate. Cobalt also increased the thiamin production
but its effect on the other vitamins and protein was negligible.

The effect of the addition of nitrogen and phosphate together was to add the
effects of each individual nutrient. In the results given in the last section of
Table 1 the amount of nitrogen used was, in all cases, at least double that of
the phosphate. In the production of riboflavin and protein where nitrogen was
beneficial and phosphate detrimental, the excess of nitrogen used offset the
effect of the phosphate. In the cases of vitamin B12 and niacin, where both
nutrients were beneficial to their production, and in the case of thiamin, where
bcth were detrimental, the effects of the nutrients were additive.


Florida Citrus Experiment Station
and Florida Citrus Commission,
Lhke Alfred, Florida.
929 a 9/16/59 MHD






-3-


The pantothenic acid results were not included in Table 1 because they showed
no definite pattern to indicate that the nutrients used or the method of drying
had any effect on the amount of that ingredient found in the dried sludge. The
mean value for pantothenic acid was 20.67 mcg/g and the standard deviation was
10.76 mcg/g.

Discussion

Results to date indicate that excess sludge obtained from the treatment of
citrus waste waters by the activated sludge process contains appreciable amounts
of B group vitamins and large quantities of protein.

The value of this dried sludge as an animal feed supplement would probably
be in its protein content, which is similar to that of cotton seed meal, now
used as a protein supplement in animal feeds.

If the excess sludge could be used as a chicken feed supplement, the value
would probably lie more in the vitamin B12 content. The proportions of the
different amino acids are more important in poultry feeds than is the total
amount of protein.

Although the results of the vitamin and protein analyses indicate that dry,
excess, activated citrus sludge might be used as a source of these substances in
animal or chicken feed supplements, a few unanswered questions stand between the
theoretical and the actual use of the material for this purpose. These questions
involve such subjects as (a) toxicity, (b) storage life, (c) azdn6 aoid content,
(d) production and demand, (e) production costs, (f) monetary value of the pro-
duct and (g) the production of a material having a constant vitamin and protein
content. The answers to some of these questions lie in the use of a much larger
activated sludge system than was available in these studies.

Conclusions

1. The dry, excess sludge from the treatment of citrus waste waters by the
activated sludge process contains significant quantities of the B group vitamins
(thiamin, niacin, riboflavin, pantothenic acid, and vitamin B12) plus a high
protein value.

2. The quantities of vitamins and protein found were much larger than those
found in earlier investigations.

3. The vitamin B12 content places it in a position to be considered as a
vitamin B12 supplement in chicken feeds.

4. The vitamin content is directly affected by any inorganic nitrogen or
phosphate added to the system as nutrients.

5. The addition of small quantities of cobalt to the system increased the
vitamin B12 and thiamin content of the final dry sludge.


Florida Citrus Experiment Station
and Florida Citrus Commission,
Lake Alfred, Florida.
929 b 9/16/59 MHD






-4-


6. Exposure of the material during drying to 10500 for 24 hr will destroy
a large portion of the vitamin B12 and thiamin. Drum drying is superior to oven
drying.

7. The protein content of the dry citrus sludge ranged from 28.90% to 43.83%,
which is high enough for it to be considered as a protein supplement in animal
feeds. The protein content is increased by increasing the amount of nutrient
nitrogen used.


References
1. Dougherty, M. H., R. W. Wolford, and R. R. McNary. "Citrus Waste Water
Treatment by Activated Sludge". Sewage and Industrial Wastes, 2n, 7, 821
(July 1955).

2. McNary, R. R., R. W. Wolford, and M. H. Dougherty. "Pilot Plant Treat-
ment of Citrus Waste Waters by Activated Sludge". Sewage and Industrial Wastes,
28, 7, 894 (July 1956).
3. Hendlin, D. and M. L. Ruger. "The Effect of Cobalt on the Microbial
Synthesis of LLD-Active Substances". Science, ll,, 541 (May 19, 1950).

4. Roberts, J. A. and L. W. Gaddum. "Composition of Citrus Fruit Juices".
Ind. Eng. Chem., 29, 574 (1937).

5. "Methods of Vitamin Assay". p. 73. Interscience Publishers, Inc.,
New York, N. Y. (1947).

6. Dann, J. W. and P. Handler. "The Quantitative Estimation of Nicotinic
Acid in Animal Tissues". Jour. Biol. Chem., 140, 201 (1941).

7. "Official Methods of Analysis". 8th Ed., p. 823, Association of Official
Agricultural Chemists, Washington, D. C. (1955).

8. Skeggs, H. R. and L. D. Wright. "The Use of Lactobacillus Arabinosus in
the Microbiological Determination of Pantothenic Acid". Jour. Biol. Chem., 156,
21 (1944).

9. Jour. Assn. Office. Agr. Chemists, 36, 1, 96 (1953).

10. "The Vitamins". Vol. I, p. 401, and Vol. III, p. 407, Academic Press,
Inc., New York, N. Y. (1954).







Florida Citrus Experiment Station
and Florida Citrus Commission,
Lake Alfred, Florida.
929 c 9/16/59 MI1D







Table 1.
vitamin B12,


Effect of nitrogen and phosphate nutrients, cobalt and method of drying on the thiamin,
niacin, riboflavin and protein content of dry excess activated citrus sludge


NaN03 Na3PO4 CoCI Drying Vitamin
Sample used used used method Thiamin B12 Niacin Riboflavin Protein
No. (ppm N) (ppm P04) (ppm Co) mcg/g mcg/g mcg/g mcg/g %
The Effect of Drying Method
4 0 0 0 Oven 0.15 1.99 9.15 26.00 33.11
14 0 0 0 Drum 3.30 12.62 8.10 23.20 34.27
The Effect of Nitrogen
8 O 10 2 Drum 7.40 17.50 10.90 21.28 29.19
9 10 10 2 Drum 4.30 19.63 12.10 26.28 33.81
4 O 0 0 Oven 0.15 1.99 9.15 26.00 33.11
3 10 0 0 Oven 0.00 2.63 9.15 32.00 37.61
The Effect of Phosphate
15 0 0 2 Drum 9.60 13.94 7.75 24.00 31.24
8 0 10 2 Drum 7.40 17.50 10.90 21.28 29.19
The Effect of Cobalt
4 O 0 0 Oven 0.15 1.99 9.15 26.00 33.11
5 0 0 1 Oven 0.46 9.13 7.65 20.00 28.90
3 10 0 0 Oven 0.00 2.63 9.15 32.00 37.61
7 10 0 2 Oven 2.70 13.40 9.00 21.60 33.11
10 10 10 1 Drum 4.60 17.88 9.09 25.20 31.01
9 10 10 2 Drum 4.30 19.63 12.10 26.28 33.81
14 0 0 0 Drum 3.30 12.62 8.10 23.20 34.27
15 0 0 2 Drum 9.60 13.94 7.75 24.00 31.24
The Effect of Nitrogen + Phosphate
4 0 0 0 Oven 0.15 1.99 9.15 26.00 33.11
2 25 10 0 Oven 0.59 2.06 9.89 31.20 36.13
1 50 21.6 0 Oven 0.28 2.21 10.68 37.60 42.55
14 0 0 0 Drum 3.30 12.62 8.10 23.20 34.27
13 25 12.5 0 Drum 2.30 23.13 9.52 32.80 41.73
12 50 25 0 Drum 1.10 19.00 10.66 24.00 40.33
11 100 50 0 Drum 0.38 24.88 11.42 36.80 43.83

Florida Citrus Experiment Station
and Florida Citrus Commission,
Lake Alfred, Florida. 929 d 9/16/59 MHD




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