Evaluation of Fecal Streptococci Tests for Chlorinated Secondary Sewage Effluents

Fecal streptococci (FS) recovery on chlorinated secondary sewage effluents was investigated in the laboratory using the membrane filter (MF) and multiple-tube or most probable number (MPN) methods. For chlorinated effluents, the FS counts on membranes with M-Enterococcus agar for 2-day incubation (MF₂) were less than the MPN values. For enrichment purposes, the use of azide dextrose broth, brain-heart infusion broth, and peptone yeast-extract casitone with M-Enterococcus agar MF₂ procedure was not satisfactory for the recovery of FS on chlorinated effluents. The M-Enterococcus agar MF procedure with bile broth enrichment (MF₂) or prolonged incubation for 3 days (MF₃) significantly increased FS recovery on chlorinated effluents and were comparable to the MPN method.