In-situ stabilisation followed by ex-situ composting for treatment and disposal of heavy metals polluted sediments.
An innovative in-situ stabilisation treatment followed by ex-situ sediment composting was tested for its ability to treat and dispose of heavy-metal-polluted sediments in a river near the Chinese Pearl Delta. First, polluted sediments were treated in-situ to stabilise the heavy metals. Then the treated sediments were dredged, dewatered and sent for high temperature aerobic composting (HTAC) treatment. Finally, the compost products were used as a fertiliser for river bank plants. The stabilisation efficiency of heavy metals during the process was investigated and the results are as follows: (1) using in-situ stabilisation, the extraction concentrations of Cu, Zn and Pb were reduced by 65.0%, 82.2% and 90.0%, respectively, which are much lower than the national standard given in the Identification Standard for Hazardous Waste (GB5085.3-1996); (2) chemical fraction analysis showed that heavy metals were further stabilized during the HTAC treatment; (3) the concentrations of Cu, Zn and Pb in rainwater leachate through the river bank met the level of class V in the Environmental Quality Standards for Surface Water in China (GB3838-2002). Therefore, using this new process, the toxicities of heavy metals in sediments were reduced markedly.
Yu
Guangwei
G
School of Environmental Science and Engineering, Sun Yat-sen University, Guangzhou 510275, China. ygwqlan@126.com
Lei
Hengyi
H
Bai
Tao
T
Li
Zhong
Z
Yu
Qiang
Q
Song
Xianqiang
X
D002681:China; D003247:Conservation of Natural Resources / Q000379:methods; D019015:Geologic Sediments / Q000737:chemistry*; D019216:Metals, Heavy / Q000737:chemistry*; D045483:Rivers; D014874:Water Pollutants, Chemical / Q000737:chemistry*
D019216:Metals, Heavy; D014874:Water Pollutants, Chemical