CHARACTERIZATION OF ACCUMULATED BIOMASS IN ANAEROBIC FILTER TREATING VARIOUS TYPES OF SUBSTRATES

Laboratory-scale anaerobic upflow filters were operated at hydraulic retention times of 3-9 days to examine the accumulation and activity of biomass in the degradation of about 2000-2500 mg COD/liter of glucose, egg albumin or acetate. Four or six filters were operated under indentical conditions in parallel, and disassembled at certain intervals to determine amount and activity of biomass after effluent quality and methane production reached steady state. The amount of biomass per volume of filter still increased with time in the range of 1500-8000 mg volatile solids (VS)/liter with solid retention time longer than 100 days. Biomass was grouped into biofilm in the bottom (BTM), biofilm in the top (TOP), and non-attached biomass (FREE). BTM showed the largest amount while TOP showed the highest specific methanogenic activity. Growth yields estimated by taking into account biomass increase within the filter were 0.13-0.15, 0.10 and 0.039 (VS/COD) for the filter fed with glucose, egg albumin and acetate, respectively.