生物淋滤脱除污泥重金属镉的试验研究

城市污水污泥中含有植物所需的大量营养元素,农业资源化利用潜力巨大,但污泥中的重金属含量常常超标,重金属会在土壤和水体中迁移,对生态环境存在污染风险,有必要采取一定的措施脱除污泥中的重金属以提高污泥土地利用的安全性。针对石家庄桥西污水处理厂污泥含镉量高的特性,以单质硫、七水硫酸亚铁及其混合物为底物加入污泥中震荡培养,根据酸化效果筛选出最佳底物,通过对污水污泥加富培养和驯化制成接种物,初步研究了初始pH值、接种物浓度、转速对镉的脱除效果,结果表明,以7.5g/LS+2.5g/LFeSO4·7H2O为底物,含固率8%的污泥在初始pH值6.0,接种物浓度10%,转速180r/min的条件下淋滤60h,污泥中镉脱除率达94.6%。采用生物淋滤方法可以有效脱除污泥中的重金属。

Removal Cd from Sewage Sludge by Bioleaching

Land application has attracted increasing concerns from scientists about the final disposal of municipal sewage sludge due to its characteristics of abundant organic ,mineral nutrients and heavy metals simultaneously. The heavy metals such as chromium, cadmium and lead at levels higher than the recommended levels are always the major contaminants to soil, water and foods on sites of sewage sludge applied. Heavy metals must be removal prior to land application. Bioleaching method was applied to reduce Cd level in sewage sludge from Shijiazhuang Qiaoxi waste water treatment plant in this paper. The solid and Cd contents of tested sewage sludge were 8% and 19.059mg/kg respectively. The indigenous thiobacillus was isolated from native sludge and enriched by selected mediums. Results showed that 7.5g/L S＋2.5g/L FeSO4·7H2O was better substrate than s and FeSO4·7H2O and other mixed substrate of s and FeSO4·7H2O to remove Cd. The initial pH, inoculum concentration and centrifugal speed had significant impacts on Cd removal rate. After 60h bioleaching, Cd removal of treatment of pH6.0＋inoculum10 % ＋centrifugal speed 180r/min reached 94.6%. Therefore, it could be inferred that bioleaching could be one of the practical options to remove heavy metals from sewage sludge.