Evaluation of Methods for Detecting Coliforms and Fecal Streptococci in Chlorinated Sewage Effluents

Total coliform (TC), fecal coliform (FC), and fecal streptococcus (FS) recoveries in chlorinated secondary sewage effluents were investigated by the membrane filter (MF) and multiple-tube (most probable number, MPN) methods. The LES two-step MF method was found to be comparable to the MPN procedure for determining TC. The TC detection was 1.5 times greater by the LES two-step technique than that obtained by the M-Endo one-step MF procedure. Fecal coliform recovery by the M-FC MF procedure was lower than the recovery obtained by the MPN method. Azide-dextrose broth, brain-heart infusion broth, and peptone yeast-extract casitone used separately with the M-Enterococcus agar MF2 (2-day incubation) procedure were not satisfactory for the recovery of FS. The M-Enterococcus agar procedure with bile broth enrichment (MF2) or prolonged incubation for 3 days (MF3) significantly increased FS recovery and both were comparable to the MPN method. The results cited should be useful in assessing the efficiency of disinfection practices for waste treatment plants employing effluent chlorination. REFERENCE: Lin, S. D. Evaluation of Methods for Detecting Coliforms and Fecal Streptococci in Chlorinated Sewage Effluents. Illinois State Water Survey, Urbana, Report of Investigation 78, 1974. INDEXING TERMS: bacteria, chlorination, enrichment procedure, environmental engineering, fecal coliforms, fecal streptococci, MF and MPN methods, prolonged incubation, sanitary engineering, secondary sewage effluents, total coliforms, water pollution. STATE OF ILLINOIS HON. DANIEL WALKER, Governor DEPARTMENT OF REGISTRATION AND EDUCATION RONALD E. STACKLER, J.D., Director BOARD OF NATURAL RESOURCES AND CONSERVATION Ronald E. Stackler, J.D., Chairman Robert H. Anderson, B.S., Engineering Thomas Park, Ph.D., Biology Charles E. Olmsted, Ph.D., Botany Laurence L. Sloss, Ph.D., Geology H. S. Gutowsky, Ph.D., Chemistry William L. Everitt, E.E., Ph.D., University of Illinois Elbert H. Hadley, Ph.D., Southern Illinois University STATE WATER SURVEY DIVISION WILLIAM C. ACKERMANN, D.Sc, Chief