PROTOZOAN AND METAZOAN COMMUNITIES TREATING A SIMULATED PETROCHEMICALINDUSTRY WASTE-WATER IN A ROTATING-DISC BIOLOGICAL REACTOR

The microfauna of adhered biofilms treating a simulated petrochemical plant wastewater was investigated in relation to the organic loading a nd the toxicity. Experiments in a six-compartment laboratory rotating biological reactor were performed at organic loadings of 0.99, 1.38 an d 1.97 g/l.day. The concentration of organic compounds in the artifici al wastewater (phenol, acetophenone and styrene), toxicity of the wast ewater, number of representative types of microfauna, their biomass an d species diversity were monitored along the reactor. During this stud y 25 species were identified and attributed to seven classes of the th ree types Sarcomastigophora, Ciliophora and Nemathelminthes. Eight spe cies from 18 ciliates have been reported in the literature as being co mmonly found inhabitants of aerobic wastewater treatment plants. An in verse relationship between the number of microfauna representatives an d the organic loading was found. The presence of the most common speci es was related to the reactor operating conditions. A correlation betw een the toxicity of the wastewater measured by the Paramecium express- test and the distribution and abundance of microfauna was established. This express-test made it possible to predict the biological quality of the biofilm of activated sludge. Therefore, it is recommended as on e of the control parameters to monitor systems of biological wastewate r treatment.