COMPARATIVE PERFORMANCE OF ANAEROBIC FILTERS AT MESOPHILIC AND THERMOPHILIC TEMPERATURES

Anaerobic filters were operated at mesophilic and thermophilic temperatures with hydraulic retention times (HRTs) of 12, 24, and 48 hours over a COD loading range from 2.75 g/L/ day to 49.5 g/L/day (172 to 3 090 lb/1 000 cu ft/day). The purpose of the research was to determine the effect of HRT and organic (COD) loading as independent variables. Results indicated that the mesophilic systems were more sensitive to HRT than were the thermophilic systems, with significant decreases in performance of the mesophilic systems with decreases in HRT. The thermophilic reactors showed virtually no reduction in performance with decreased HRT. The increase in organic load produced a reduction in removal efficiency at all HRTs for the mesophilic reactors. The effect of organic load was more significant at the lower HRTs for the mesophilic reactors. The thermophilic units, on the other hand, displayed a reduction in chemical oxygen demand (COD) only at the high loadings while at an HRT of 48 hours. The increase in loadings showed little effect at the lower HRTs (24 and 12 hours) when the systems were able to flush the inhibitory substances from the reactors. Overall, the thermophilic systems were able to treat the waste at more than twice the COD loading rate of the mesophilic systems.