对城市污水厂污泥加酸处理,探索污泥中重金属铬、镉、铅的释放.结果发现,亚硝酸对污泥中各种重金属的释放均表现出最佳效率,其对回流污泥、脱水污泥(脱水前加药)的总Cr去除率分别达到81.7%和47.0%;对总Cd的去除率分别达到61.1%和92.9%;对总Pb的去除率分别达到41.8%和85.5%,均远高于未加酸的对比样.采用亚硝酸与硝酸联合处理回流污泥,与单一酸处理相比,效率无增加,但是处理破碎的回流污泥,效率非常明显,对Cr、Cd和Pb的平均去除率分别达到86.9%,71.3%和77.2%.螯合剂对酸处理污泥过程重金属的释放影响表明,酒石酸、柠檬酸和EDTA对Cd的释放有一定的促进作用,而对Cr和Pb基本无促进作用.在酸处理2~4 h后, Cd和Cr的释放接近完成,而Pb的释放需要12 h以上才能基本完成.%The release of heavy metals Cr,Cd and Pb from municipal sewage sludge by treated with vari-ous acids was studied.The results showed that nitrite show the highest efficiency for the release of the heavy metals,which can removal the total Cr of returning activated sludge and dewatered sludge reached 81.7%and 47.0%respectively.Nitrite can also removal 61.1%and 92.9%of the total Cd,41.8%and 85.5%of the total Pb for returning activated sludge and dewatered sludge respectively.There was no pro-motion efficiency of returning activated sludge but had significant positive effect when the sludge treated by the combination of nitrous acid and nitric acid.The average removal efficiency of Cr,Cd and Pb were 86.9%,71.3%and 77.2%respectively when the sludge treated by the combination of nitrous acid and nitric acid.The effects of chelating agents on the release of heavy metals from acid treated sludge showed that tartaric acid,citric acid and EDTA could promote the release of Cd,but had no effect on Cr and Pb. With the acid treatment of about 2~4 h,the release of Cd and Cr is close to completion,and the release of Pb requires more than 12 h to be completed.
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