Aaron Brennan

Publication Date



The anaerobic side stream reactor (ASSR) process was continuously operated and tested as a pilot scale system, treating 500 gallons of raw wastewater per day. Addition of an ASSR to a conventional activated sludge (CAS) system has been shown to reduce overall waste sludge generation in previous bench scale experiments. This study aimed to specifically test the feasibility of the ASSR process at the pilot scale while comparing it to a full scale CAS plant. The ASSR process differs from the similar Cannibal® process in that it utilizes an SRT in the side stream reactor of only 2 days rather than 10 days, reducing the overall footprint and energy requirements of the reactor significantly. In addition to overall sludge yield comparison between the ASSR and CAS processes, digestibility of activated sludge, biogas generation, suspended organics, soluble organics, and solids removal effectiveness were examined. It was found that the pilot scale ASSR process generated about 42% less waste sludge than the full scale CAS WWTP. No significant effect on process removal effectiveness of total or soluble organics was observed. In addition, batch digestion of the two sludges showed pronounced differences in biogas generation; ASSR sludge produced about 78% more biogas than the CAS system during a 2 week digestion period.