Study On The Distribution Of Organic Toxicity In Solid Phase Of Acclimated Sludge In The Process Of Treating BPA Wastewater

Land utilization of excess sludge has become a vital way of resource recovery. However, the toxicity of sludge has become the most critical restriction for subsequent reuse. Base on this issue, Laboratory-scale batch experiments were conducted to investigate the formation process and spatial distribution characteristics of organic toxicity in acclimated sludge treating the hydrophobic toxic organic(BPA). to provide theoretical basis for the reduction of organic toxicity in situ or subsequent disposal.The reactor was operated in as SBR. acclimated with synthetic wastewater containing 2.5mg/L BPA. The influent concentration of BPA was 5mg/L.7.5mg/L.20mg/L and 40mg/L respectively. The effluent COD. concentration of BPA in water and solid phases(outer EPS and inner EPS+intracellular) and organic toxicity were analyzed in every stage. The effect of retention time on effluent COD. concentration of BPA in water and solid phases(outer EPS and inner EPS+intracellular) and organic toxicity in a single cycle were also analyzed. In addition, the variation of toxicity caused by adsorption or degradation in unacclimated inactivated sludge, unacclimated activated sludge and acclimated activated sludge were analyzed.The result showed that BPA removal efficiency of acclimated activated sludge is better than that of unacclimated activated sludge. The removal process of BPA in the activated sludge system was characterized by a quick adsorption on the activated sludge and subsequent biodegradation. In the process of biodegradation. no accumulation of BPA and toxicity was in outer EPS(the proportion of 22.27% in solid phase). In the process of operation, there are toxicity accumulated mostly in inner EPS+intracellular with no BPA accumulated, which indicated that there are toxic degradation products of BPA or toxic matter secreted by microbial cells in inner EPS+intracellular. Adsorption and degradation both caused significant accumulation of toxicity. at the end of each operation cycle, the toxicity accumulated in acclimated activated sludge system was mainly resulted from toxic degradation products of BPA.