Nutritional Requirements in the Biological Stabilization of Industrial
Wastes II Treatment with Domestic Sewage*
' .      E.   N.   HELMERS,   J.   D.   FRAME,
/ ', A.  E.   GREENBERG  AND   C.   N.   SAWYER
E. I. Du Pont de Nemours and Co., Inc., Wilmington, Delaware
Many of the problems in the design and operation of a municipal sewage treatment plant arise not because of the nature of the domestic sewage load but because of the peculiarities of the various industrial wastes that are often combined with it. The treatment of a strictly domestic sewage has become a well-developed art, but we are only beginning to appreciate the complications of treating industrial wastes and industrial waste-sewage mixtures. The effects of industrial wastes on biological processes are of special importance because of the wide use of biological methods for treating municipal sewage and the frequent deleterious effects of industrial wastes on the normal operation of these processes.
The problems created by industrial wastes in the municipal sewage plant must be resolved either by developing, through experience and research, satisfactory methods for treating the combination or by eMminating such wastes from the system. In most instances, the former solution will be the most economical and to the best advantage of both the industry and the municipality.
A property of several important industrial wastes which limits the amount that can be treated successfully in combination with domestic sewage is a deficiency of certain nutritional elements essential for bacterial growth—notably nitrogen and phosphorus. The primary ob¬ jective of the laboratory studies with which this paper is concerned was to develop a method of ascertaining maximum amount of such wastes that can be treated in mixture with any given domestic sewage by the activated sludge process. Secondary objectives were to determine maximum  nutritional   requirements  of  the  activated  sludge  and   the
' Contribution from the Sedgwick Memorial Laboratories, Mass. Inst, of Tech., Cambridge, Mass.
375     '