COMPARATIVE PERFORMANCE OF ANAEROBIC FILTERS AT MESOPHILIC AND THERMOPHILIC TEMPERATURES

Anaerobic filters were operated at mesophilic and thermophilic tempera tures with hydraulic retention times (HRTs) of 12, 24, and 48 hours ov er a COD loading range from 2.75 g/L/ day to 49.5 g/L/day (172 to 3 09 0 lb/1 000 cu ft/day). The purpose of the research was to determine th e effect of HRT and organic (COD) loading as independent variables. Re sults indicated that the mesophilic systems were more sensitive to HRT than were the thermophilic systems, with significant decreases in per formance of the mesophilic systems with decreases in HRT. The thermoph ilic reactors showed virtually no reduction in performance with decrea sed HRT. The increase in organic load produced a reduction in removal efficiency at all HRTs for the mesophilic reactors. The effect of orga nic load was more significant at the lower HRTs for the mesophilic rea ctors. The thermophilic units, on the other hand, displayed a reductio n in chemical oxygen demand (COD) only at the high loadings while at a n HRT of 48 hours. The increase in loadings showed little effect at th e lower HRTs (24 and 12 hours) when the systems were able to flush the inhibitory substances from the reactors. Overall, the thermophilic sy stems were able to treat the waste at more than twice the COD loading rate of the mesophilic systems.