Two strategies exist for seeding low-temperature anaerobic reactors: the use of specialist psychrophilic biomass or mesophilic bioreactor sludge acclimated to low temperature. We sought to determine the low-temperature limitation of anaerobic sludge from a bioreactor acclimated to UK temperatures (<15 °C). Anaerobic incubation tests using low-strength real domestic wastewater (DWW) and various alternative soluble COD sources were conducted at 4, 8 and 15 °C; methanogenesis and acidogenesis were monitored separately. Production of methane and acetate was observed; decreasing temperature resulted in decreased yields and increased ‘start-up’ times. At 4 °C methanogenesis not hydrolysis/acidogenesis was rate-limiting. The final methane yields at 4 °C were less than 35% of the theoretical potential whilst at 8 and 15 °C more than 75 and 100% of the theoretical yield was achieved respectively. We propose that the lower temperature limit for DWW treatment with anaerobic bioreactor sludge lies between 8 and 4 °C and that 8 °C is the threshold for reliable operation.
Low-temperature limitation of bioreactor sludge in anaerobic treatment of domestic wastewater
Emma J. Bowen, Jan Dolfing, Russell J. Davenport, Fiona L. Read, Thomas P. Curtis; Low-temperature limitation of bioreactor sludge in anaerobic treatment of domestic wastewater. Water Sci Technol 1 March 2014; 69 (5): 1004–1013. doi: https://doi.org/10.2166/wst.2013.821
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