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Effect of repeated freezing and thawing on leaching concentration of heavy metals in municipal sewage sludge. |
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Abstract 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.
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Received: 19 March 2010
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[1] |
CHEN Huan-Yu, LIU Jing-Qing, WEI Zong-Yuan, ZHANG Hui-Hui, HE Xiao-Fang, ZHOU Xiao-Yan, QIU Shang-De, HU Bao-Lan, LOU Li-Ping. Radial differences in contaminant distribution in large-diameter pipe scales of main pipelines in drinking water distribution system[J]. CHINA ENVIRONMENTAL SCIENCECE, 2015, 35(9): 2706-2712. |
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