生物淋滤对污泥表面特征及重金属形态的影响

Changes in Surface Properties of Sewage Sludge and Forms of Heavy Metals after Bioleaching

剩余污泥中较高的重金属含量制约了其后续资源化利用。为此,以去除不同形态的重金属为目的,考察了生物淋滤前后各形态重金属含量的变化,以及生物淋滤对污泥EPS含量、比表面积、Zeta电位等的影响。结果表明,生物淋滤可有效降低重金属的迁移性和生物有效性;p H值降至1.98引起了碳酸盐结合态重金属含量的降低;EPS中蛋白质、腐殖质、多糖含量分别减少至3.92、3.43、18.54 mg/g VSS,这是残渣态重金属含量降低的主要原因;Zeta电位升高至-1.92μV,平均粒径增大至33.17μm、比表面积减小至0.217 m2/cm3也均有利于重金属的去除。

The high contents of heavy metals in excess sludge restrict its recycling. To remove dif- ferent forms of heavy metals, the variation in the contents of heavy metals before and after bioleaching as well as the effects of bioleaching on EPS content, Zeta potential and specific surface area of excess sludge were investigated. The results indicated that bioleaehing could effectively decrease the migration and bio- availability of heavy metals. The contents of carbonate-bound heavy metals were reduced by decreasing pH value to 1.98. The contents of protein, humus and polysaecharides in EPS were decreased to 3.92, 3.43 and 18.54 mg/gVSS respectively, which was the major cause of the decrease in contents of residu- al-form heavy metals. The increase in Zeta potential and average particle size to - 1.92 μV and 33.17 μm respectively and the decrease in specific surface area to 0. 217 m2/cm3 were all advantageous to re- move heavy metals from excess sludge.