FILAMENTOUS BACTERIA AND PROTOZOA FOUND IN THE ROTATING BIOLOGICAL CONTACTOR

Slime samples from 66 rotating biological contactors(RBC) in 20 states in USA were examined. For the filamentous bacteria, Beggiatoa, Sphaer otilus, Type 0041, Type 1701 and Nocardia were observed in decreasing order of frequency. For the protozoa, flagellates, Opercularia, Diflug ia, Arcella, Paramecium and Epistylis were present in decreasing order of frequency. Organisms differed in abundance along the RBC stages. U sing linear regression, Beggiatoa, Type 0041(negative), and flagellate d protozoa showed signigicant correlations(p<0.05) with organic loadin g, while Sphaerotilus and Opercularia did not. In an attempt to establ ish an indicator organism system, RBC organisms were grouped based upo n the organic loading preference. Beggiatoa and flagellated protozoa w ere grouped as the organism associated with high organic loading. Type 0041, and Arcella and Difflugia were grouped as the organism associat ed with moderately low organic loading. The microbial population in th e last stage was investigated in association with the effluent duality . Flagellates and Opercularia were more frequently observed in plants with effluent BOD's above 20mg/l, while Arcella and Difflugia were mor e frequent in the plants with effluent BOD's below 20mg/l.