利用聚磷活性污泥去除废水中的铅[ρ(Pb2+)=150.0 mg·L-1],研究了反应体系内不同溶解氧状况和初始pH值对污泥除铅的效率和稳定性的影响.结果表明,厌氧条件下,pH 6时,铅的去除率随时间增长呈上升趋势,32 d后铅去除率达99.8%,其中有机物及硫化物结合态铅、残渣态分别占41.8%和52.6%,污泥中铅的稳定性良好.好氧条件下,在相对较短时间内铅的去除率随pH上升而增加,反应2 h时,pH 6、pH 4和pH 2对应的铅的去除率分别为99.9%、96.9%和30.3%;而好氧32 d后pH 6、pH 4和pH 2的污泥中残渣态铅含量分别为3 072.3、4 726.8和2 359.1 mg·kg-1,分别占污泥中总铅的41.8%、65.8%和88.8%.综合考虑除铅率和除铅后污泥稳定性,好氧且pH 4理论上是聚磷污泥除铅的最佳条件.
Phosphorus-accumulating activated sludge was used to remove lead [ρ(Cu2 +) = 150.0 mg·L-1] in wastewater in this experiment.The efficiency ratio and stability of Pb removal were studied at different dissolved oxygen concentration and different initial pH.The result showed that under anaerobic condition and pH 6,the Pb removal efficiency ratio increased with time elapsing,the value reached 99.8% after 32 days.Lead in form of organic and sulfide-bound lead and residual lead in residual sludge accounted for 41.8% and 52.6%,respectively,and the lead in the sludge showed a good stability.While under aerobic condition,the lead removal efficiency ratio increased with the increase of pH within the first 2 hours,the values reached 99.9%,96.9% and 30.3% at pH 6,pH 4 and pH 2,respectively.In contrast,the residual lead was 3 072.3,4 726.8 and 2 359.1 mg·kg-1 under aerobic condition after 32 days,accounting for 41.8%,65.8% and 88.8% of total lead in the sludge.Taking the lead removal efficiency ratio and lead stability into account,aerobic condition at pH 4 is the best for removing lead with phosphorus-accumulating sludge in theory.