RESPONSE AND RECOVERY OF ANAEROBIC GRANULES FROM SHOCK LOADING

Bench scale (201.) UASBRs were evaluated for continuous treatment of effluent from a Corn Wet Milling operation (Casco, London, Ontario, Canada). The plant effluent contained low molecular weight carbohydrates and salts (daily averages 780,000 USGPD, 720 ppm TOC). Early in the study, anaerobic granules experienced a 2 days shock loading from large fluctuations in pH, temperature, high BOD and sulfite concentration. After this shock, reactor productivity declined but granules remained active and produced gas. In the days that followed, the granules lost their ability to settle and began to float to the top of the reactor. The effect and recovery of the granules after the shock loading were investigated in two reactors: R1 (with nutrients) and R2 (without nutrients). Nutrient addition resulted in increased biomass accumulation but granules were not regenerated. A control reactor (R4) which did not experience this shock loading maintained normal operation for more than 60 days.