Extraction of copper from sewage sludge using biodegradable chelant EDDS
ZHANG Lihua , ZHU Zhiliang , ZHANG Ronghua , ZHENG Chengsong , ZHANG Hua , QIU Yanling , ZHAO Jianfu
DOI:
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.
