Environmental biology

Extraction of copper from sewage sludge using biodegradable chelant EDDS

ZHANG Lihua , ZHU Zhiliang , ZHANG Ronghua , ZHENG Chengsong , ZHANG Hua , QIU Yanling , ZHAO Jianfu


Received September 28, 2007,Revised December 02, 2007, Accepted , Available online

Volume 20,2008,Pages 970-974

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[S,S]-Ethylenediaminedisuccinic acid (EDDS), a biodegradable chelant, was used to separate the heavy metals from the sewage sludge based on chemical extraction technology. Under various conditions, the extraction experiments were carried out for the sewage sludge from Shanghai Taopu MunicipalWastewater Plant, China. The influences of pH and the concentration of EDDS on the extraction e ciency for copper (Cu) were discussed. The results showed that EDDS had higher extraction e ciency for Cu from the sewage sludge than other heavy metals. The system pH and the concentration of EDDS had a significant e ect on the extraction e ciency. The extraction e ciency of Cu increased gradually with the increase of system pH and reached a higher e ciency within pH range of 3–10. The extraction e ciency maintained at approximately 70% when the pH > 4.5 and the molar ratio of EDDS to total heavy metals was 10:1. From the fractional analysis of the heavy metals in sewage sludge before and after the extraction, it was found that the extracted Cu mainly came from the following four fractions, i.e. water soluble, acid-soluble, reducible, and oxidizable fractions.

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