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

Laboratory-scale anaerobic upflow filters were operated at hydraulic r etention 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 inde ntical conditions in parallel, and disassembled at certain intervals t o determine amount and activity of biomass after effluent quality and methane production reached steady state. The amount of biomass per vol ume of filter still increased with time in the range of 1500-8000 mg v olatile solids (VS)/liter with solid retention time longer than 100 da ys. Biomass was grouped into biofilm in the bottom (BTM), biofilm in t he top (TOP), and non-attached biomass (FREE). BTM showed the largest amount while TOP showed the highest specific methanogenic activity. Gr owth yields estimated by taking into account biomass increase within t he filter were 0.13-0.15, 0.10 and 0.039 (VS/COD) for the filter fed w ith glucose, egg albumin and acetate, respectively.