污泥重金属提取剂浸提效率及经济性比较

Comparative study on the extraction efficiency and economic performance by different agents in the extraction process of heavy metals in sewage sludge

污泥中重金属的潜在危害严重影响其处理处置效果,因此本文研究了各种提取剂对污泥重金属的浸提效果,并依据经济可提取指数与浸提效果进行了经济性分析。结果表明,无机酸提取剂对污泥重金属的浸提效果随其p H值升高而降低,H+浓度是影响其浸提率的主要因素。低分子量有机酸提取剂对污泥中重金属的浸提效率随其浓度增加而增大,其对3种重金属的提取效率顺序为Zn>Cr>Cu。Zn是最易被提取的重金属,草酸对污泥重金属的浸提效果优于柠檬酸。污泥重金属浸提率与高分子量有机酸提取剂浓度呈正相关,其对3种重金属的提取效率顺序为Zn>Cu>Cr。污泥重金属的浸提一般应优先选用有机酸提取剂,对污泥重金属Zn的提取宜选用柠檬酸和草酸,对污泥重金属Cr和Cu的提取一般应选用柠檬酸和乙二胺四乙酸。

The potential risk of heavy metals in sewage sludge will seriously influence sludge treatment and disposal process,therefore,the extraction of heavy metal by different agents was investigated, and the extraction rate and economical extractable index （EEI） were then studied. The results showed that the extraction efficiency of heavy metal would decrease with the increase of pH of inorganic acid. H＋ concentration is a significant factor during the extraction process. The extraction rate of heavy metal advanced when the concentrations of low molecular weight （LMW） organic acids rose. Zn was favorable to be extracted than Cr and Cu. In addition,the extraction efficiency of oxalic acid is better than that of citric acid. However,Zn and Cu were preferentially to be extracted than Cr in the extraction process by high molecular weight （HMW） organic acids. There is a positive correlation between the extraction efficiency and HMW organic acid concentrations. Organic acids were suitable in the heavy metal extraction. Furthermore,citric acid and oxalic acid have good performances in Zn extraction while citric acid and EDTA should be utilized in priority in Cr and Cu extraction, respectively.