Performance of microaerobic granular sludge system for pentachlorophenol (PCP) degradation responding to PCP loading shock

The microaerobic granular sludge for pentachlorophenol (PCP) degradation was obtained in our laboratory which had excellent effect and physical-chemical properties at PCP loading of 3.0x10(-2) kg.m(-3).d(-1). In this paper, the effects of PCP loading shock on the operation of microaerobic granular sludge system, dechlorination intermediate product, fermentation climax community and flocculation performance of sludge were studied with the PCP loading of 5.0x10(-2) kg.m(-3).d(-1) and 8.0x10(-2) kg.m(-3).d(-1). The results showed that the activity of microaerobic granular sludge decreased due to the shock of PCP loading, leading to the reduction of COD and PCP removal efficiency, the accumulation of dechlorination intermediate and short chain fatty acids, and the decrease of sludge flocculation performance. Acidogenic fermentation climax community changed from acetic acid type to acid fermentation and the activity of microaerobic granular sludge could be recovered just for 2 days under the PCP loading of 5.0x10(-2) kg.m(-3).d(-1), whereas the climax community converted to mixed fermentation of propionic acid and butyric acid and the activity of microaerobic granular sludge struggled to recover the previous level after 8 days under the PCP loading of 8.0x10(-2) kg.m(-3).d(-1).