柠檬酸、草酸和乙酸对污泥中镉、铅、铜和锌的去除效果

Removal effects of citric acid,oxalic acid and acetic acid on Cd,Pb,Cu and Zn in sewage sludge

研究了柠檬酸、草酸和乙酸对污泥中Cd、Pb、Cu和Zn等重金属的去除效果,并分析了污泥中重金属的形态变化和生物有效性.结果表明,随着反应时间和酸浓度的增加,污泥中重金属(Cu除外)的去除率也相应增加.污泥加入柠檬酸溶液反应7h即可去除污泥中52.0%的Pb和74.2%的Zn,24h后可去除76.0%的Pb和92.5%的Zn,草酸和乙酸对重金属的去除率较低.柠檬酸去除的Pb和Zn主要以稳定态存在,并导致污泥中不稳定态重金属的比例上升,其中可交换态重金属浓度有不同程度的增加.虽然有机酸对Cd和Cu的去除率较低,但反应后可交换态Cd和Cu的浓度仍有小幅增加.

This paper studied the effects of applying citric acid, oxalic acid and acetic acid on the removal of heavy metals Cd, Pb, Cu and Zn from sewage sludge, and the form transformation and bioavailability of these heavy metals before and after the application of tested organic acids. The results showed that the removal rates of tested heavy metals except Cu increased with increasing acid concentration and action time. Among the tested organic acids, citric acid was more effective in removing heavy metals from sewage sludge, with the removal rate of 52. 0% for Pb and 74. 2% for Zn after a 7-hour action, and 76. 0% for Pb and 92.5% for Zn after 24-hour action. The removal rates of the heavy metals by oxalic acid and acetic acid were relatively low. The Pb and Zn removed by citric acid were mainly in stable form, resulting in a relative increase of their unstable and exchangeable forms in the sludge. Though the removal rate of Cu and Cd was lower, their exchangea, hie forms still had somewhat increase after the action of tested organic acids.