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The bacteriology of activated sludge

Published online by Cambridge University Press:  15 May 2009

L. A. Allen
L. A. Allen
Affiliation:
Water Pollution Research Laboratory, Langley Road, Watford
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Homogenization of activated sludge greatly increased the apparent bacterial count obtained by plating on a solid medium, and for this reason facilitated the isolation of the predominant flora by liberating the bacteria from the interior of the sludge flocs. The ordinary domestic cream-making machine was found to be quite effective for this purpose.

The high counts obtained indicated that there are probably several hundred thousand million bacteria per gram of dry matter in activated sludge.

Aeration of sewage was found to result in an increase in the total count of bacteria, and a high count was maintained for a considerable time. After aeration for several days fairly rapid and apparently fairly complete separation of the sludge occurred on allowing the liquid to stand, but the supernatant liquor contained large numbers of bacteria. When a fresh quantity of sewage was added to the small quantity of sludge which settled and a second period of aeration commenced, the bacteria were found to associate more quickly with the sludge than they had during the first aeration. Coliform bacteria and spore-forming aerobes formed only a small fraction of the total number of micro-organisms concerned in these changes, and moulds and yeasts never accounted for a large proportion. The predominant bacteria did not produce acid from glucose.

Various media were tested in investigating the bacteriology of activated sludge. None showed any superiority to nutrient agar. Coliform bacteria and aerobic spore-formers were encountered in negligible numbers. The morphological and physiological characters of seventy-one strains of the predominant bacteria were determined. The majority were Gram-negative rods with no action on carbohydrates and were members of the genera Achromobacterium, Chromobacterium, and Pseudomonas. Those isolated from activated sludge soon after its formation from aerated sewage were found to be non-proteolytic, but a proteolytic flora was established after the sludge had been built up for a period of 4 weeks. The characters of the predominant bacteria indicate that they are water types derived from the water supply or the drainage water which enters sewage. Intestinal bacteria appear to be unimportant.

The experiments described in this paper were carried out as part of the programme of the Water Pollution Research Board of the Department of Scientific and Industrial Research, and the results are published by permission of the Department.

Type
Research Article
Information
Journal of Hygiene , Volume 43 , Issue 6 , September 1944 , pp. 424 - 431
Copyright
Copyright © Cambridge University Press 1944

References

REFERENCES

Bergey, D. H. (1934). Manual of Determinative Bacteriology, 4th ed. London.Google Scholar
Buswell, A. M. & Long, H. L. (1923). Microbiology and theory of activated sludge. J. Amer. Wat. Wks Ass. 10, 309.Google Scholar
Butterfield, C. T. (1935). Studies of sewage purification. II. A zoogloea-forming bacterium isolated from activated sludge. Pub. Hlth Rep. 50, 671.CrossRefGoogle Scholar
Butterfield, C. T. (1937). The oxidation of sewage by bacteria in pure culture. J. Bact. 34, 207.CrossRefGoogle ScholarPubMed
Butterfield, C. T., Ruchhoft, C. C. & McNamee, P. D. (1937). Studies of sewage purification. VI. Biochemical oxidation by sludges developed by pure cultures of bacteria isolated from activated sludge. Sewage Wks J. 9, 173.Google Scholar
Harris, F. W., Cockbubn, T. & Anderson, T. (1927). Biological and physical properties of activated sludge. Waterworks, 66, 24.Google Scholar
Heukelekian, H. (1934). Bacterial numbers in activated sludge mixtures. Sewage Wks J. 6, 676.Google Scholar
Heukelekian, H. & Littman, M. L. (1939). Carbon and nitrogen transformations in the purification of sewage by the activated sludge process. II. Morphological and biochemical studies of zoogloeal organisms. Sewage Wks J. 11, 752.Google Scholar
Heukelekian, H. & Schulhoff, H. B. (1938). Studies on the clarification stage of the activated sludge process. IV. Preliminary notes on the clarifying organisms in activated sludge. Sewage Wks J. 10, 43.Google Scholar
Kamm, W. F. (1917). Bacterial purification of sewage. Univ. Ill. Bull., State Water Survey Series, no. 14, 146.Google Scholar
Levine, M. & Soppeland, L. (1926). Bacteria in creamery wastes. la St. Coll. Agric. Engng Exp. Sta. Bull. no. 77.Google Scholar
Russel, R. & Bartow, E. (1916). Bacteriological study of sewage purification by aeration. Univ. Ill. Bull., State Water Survey Series, no. 13, 348.Google Scholar
Taylor, C. B. (1940). Bacteriology of fresh water. I. Distribution of bacteria in English lakes. J. Hyg., Camb., 40, 616.Google Scholar
Taylor, C. B. (1942). Bacteriology of fresh water. III. The types of bacteria present in lakes and streams and their relationship to the bacterial flora of soil. J. Hyg., Camb., 42, 284.CrossRefGoogle Scholar
Topley, W. W. C. & Wilson, G. S. (1936). The Principles of Bacteriology and Immunity, 2nd ed. London.Google Scholar