Studies on the Utilization of Single Cell Proteins

Part I. Amino acid contents of dried activated sludges from industrial and domestic wastes

Abstract

Eighteen amino acids were determined by microbioassay technique on some preparations of dried activated sludges obtained from the treatment for the purification of the waste food and some other industries and those from domestic sewage to evaluate them as nutrient source. By laboratory treatment of activated sludge, over 90% of the suspended solids, and of COD and BOD was removed from each raw slop of plants of soybean-oil, fermentation, milk, yeast, chlorophyl, and raw silk refinement. Greater deviations of the contents of each amino acids, crude protein, and ash were observed among the samples taken from the actual treated plants than those obtained in laboratories, however, the content of sulfur-containing amino acids was generally lower than that of the reference protein, and some of the samples also revealed inferiority in lysine and tryptophan levels. The surplus of the sludge possible to be produced in Japan was calculated based on the production and consumption of various industries, and on the total amount of BOD regarding to the kinds of sludges to which the waste treatment by activated sludge have already been applied or those to which the method is assumed to be applicable.