细胞冻融破碎对城市污泥中重金属浸出浓度的影响

利用反复冻融的方法对污泥细胞进行破碎,考察处理前后污泥重金属的浸出浓度和形态分布的变化,并通过扫描电镜和红外光谱分析污泥中微生物细胞形貌和有机化合物含量的变化.结果显示,经过细胞破碎处理后,污泥中重金属的浸出浓度增大,锌、镍、铬、镉和铜的浸出浓度比原始污泥分别增加了9.7%、5.1%、25%、9%和50%.不稳定态增加,锌和镍的不稳定态分别增加了20.4%和37.9%,锌、镍、铬和铜的有机态分别减少了4.2%、8.2%、1.2%和5.1%.细胞发生了形貌上的变化,细胞体破碎程度严重.细胞EPS以及污泥中的蛋白质、羧酸、多聚糖等有机基团含量明显减少.细胞破碎后污泥浸出浓度增加的主要原因是污泥中有机态的重金属转化成了其他不稳定态的重金属.

Effect of repeated freezing and thawing on leaching concentration of heavy metals in municipal sewage sludge

The effect of cell fragmentation by repeated freezing and thawing on the leaching concentration and fractionation of heavy metals in the municipal sewage sludge was investigated. The cell appearance and extracellular polymers (EPS) groups were observed and analyzed using SEM and FTIR. The results showed that the leaching concentration of heavy metals increased after the treatment. The concentration of Zinc (Zn), Nickel (Ni), Chromium (Cr), Cadmium (Cd) and Copper (Cu) raised respectively by 9.7%, 5.1%, 25%, 9.0% and 50%. The fractionation showed that the concentration of the instable species of Zn and Ni raised respectively by 20.4% and 37.9%. The organic forms of Zn, Ni, Cr, and Cu were decreased respectively by 4.4%, 8.2%, 1.2% and 5.1%. The fragmentation of cell in the sludge was obvious. The reduction of EPS, as well as proteins, carboxylic acids and glycans in the sludge, was evident. The transformation from the organic forms of the heavy metals in the sludge to their instable forms after cell fragmentation was the main reason to the increase of the leaching concentration.