初始pH值对污泥中重金属生物沥滤的影响

Effects of Initial pH on Bioleaching of Heavy Metals from Sewage Sludge

采用序批试验研究了不同初始pH值下污泥中Cu、Pb和Zn的生物沥滤效果。结果表明,不同重金属沥滤效率受初始pH值变化的影响程度从大到小依次为Pb>Cu>Zn。初始pH值对污泥重金属生物沥滤效率有较大影响,但即使在初始pH值高达10的情况下,延长沥滤时间也可实现重金属的沥滤。经生物沥滤后,污泥中TP的流失量随着污泥初始pH值的降低而明显增加,而在pH3￣10范围TN流失却与污泥初始pH值相关性较差。

Sewage sludge can be applied to land in recycling organic matter and nutrients. The presence of heavy metals in sludge, however, is often a major obstacle in final disposal into environment, Bioleaching is a promising approach to reduce the content of heavy metals and the adverse effects of sludge application, The objective of this study was to investigate effects of initial pH on bioleaching of Cu, Pb and Zn from sewage sludge by a batch experiment. The results indicated that the effects on removal of heavy metals followed as Pb〉Cu〉Zn. Although the bioleaching was affected by initial pH obviously, satisfactory bioleaching efficiency of heavy metals could be achieved even for sludge with initial pH of 10 if the bioleaching time was prolonged. In addition, the losses of nutrients in leachate were also discussed in the present study. It showed that the loss of nutrients was influenced by the bioleaching at certain degree. The loss of total phosphorus from sewage sludge increased obviously with the increase of initial pH; however, the concentrations of total nitrogen showed little tendency. The supernatant concentration of total rfitrogen for sewage sludge with initial pH of 2 was 451 mg· L^-1, and that for the other samples were between 289 to 359 mg·La^-1, respectively, revealing low correlation with the initial pH when pH varied from 2 to 10.