厌氧消化对污泥中重金属及病原微生物的影响研究

Effects of Anaerobic Digestion on Heavy Metals and Bacterial Pathogens in Sewage Sludge

为考察厌氧消化对重金属（Ni,Cd,Cu,Pb,Cr,Zn,Hg,As）的浸出毒性和形态分布及病原微生物灭活和去除的影响,对某污水处理厂的剩余污泥进行了21 d中温批式厌氧消化实验。结果表明：污泥中重金属形态改变不明显,Pb和Hg主要以稳定态存在,Ni,Cu,Cr,As主要以不稳定态存在。根据污泥中重金属的总量、形态分布、稳定性和迁移风险等因素考虑,Ni和Cd应作为优先控制的指标。厌氧消化过程中,8种重金属的浸出率最高不超过1%,浸出浓度低于《危险废物鉴别标准―浸出毒性鉴别》鉴别标准值。研究还显示,厌氧消化后细菌菌落总数降低了88.8%~94.7%,大肠菌群和粪大肠菌群降低都超过99%,沙门氏菌未检出,说明厌氧消化对污泥中的病原微生物具有良好的杀灭和去除作用。

21-day mesophilic batch anaerobic digestion （AD） experiments with residual sludge form a sewage disposal plant were conducted to investigate the influences of AD process on leaching toxicity, speciations of heavy metals （ Ni, Cd, Cu, Pb, Cr, Zn, Hg and As） ,and pathogen inactivation and/or removal. The results showed that the metals had no obvi- ous changes in speciations during the AD process. Pb and Hg mainly existed in stable state, while Ni, Cu, Cr and As mainly existed in unstable state. Ni and Cd should be regarded as the priority pollutants for elimination according to the concentrations, speciations, stability and migration possibility. The leaching rates of 8 kinds of metals were less than 1%, which were lower than the threshold values stipulated by Identification Standards for Hazardous Wastes： Identification for Leaching toxicity. Furthermore, after AD process, the bacterial colony number was reduced by 88.8% -94.7%, both to- tal coliforms and faecal coliforms were reduced by 99%, and salmonella spp. was undetected. It was demonstrated that AD process obviously facilitated pathogen removal and inactivation in sludge.