Abstract
The effects of temperature (5-35°C) and the volumetric BOD loading (0.9-5.5kg·m-3·d-1) on the structure of microbial film growing on the solid surface of packing materials and on the characteristics of the effluent were experimentally investigated in the aerobic submerged biofilter. It was clarified that the effluent quality is governed by the population of bacteria, while the growth of protozoa determines the microbial concentration in the biofilter. Au increase in the microbial concentration at a low temperature avoids the deterioration of effluent quality of the biofilter. The apparent retention time in the microbial film is in the order of organic matters > bacteria > protozoa, and the increased temperature shortens each retention time. Bacteria, protozoa and the extra-celler polymer take major part of the suspended solids in the effluent at low temperature, while the organic matters other than those at the high temperature.
