Pedosphere 16(6): 756--761, 2006
ISSN 1002-0160/CN 32-1315/P
©2006 Soil Science Society of China
Published by Elsevier B.V. and Science Press
| Extractable fractions of metals in sewage sludges from five typical urban wastewater treatment plants of China |
WANG Chao1,2 , LI Xiao-Chen2, WANG Pei-Fang2, ZOU Li-Min2 and MA Hai-Tao2 |
1 Key Laboratory of Integrated Regulation and Resource Department on Shallow Lakes, Ministry of Education, Nanjing 210098 (China). E-mail: twang@hhu.edu.cn;
2 School of Environmental Science and Engineering, Hohai University, Nanjing 210098 (China) |
| ABSTRACT |
| Metal content and bioavailability are often the limiting factors for application of sewage sludge in agricultural fields. Sewage sludge samples were collected from five typical urban wastewater treatment plants in China to investigate their contents and distribution of various chemical fractions of Cu, Zn, Ni, Cr, Pb and Mo by using the BCR (Community Bureau of Reference) sequential extraction procedure. The sludges contained considerable amounts of organic matter (31.8%-48.0%), total N (16.3-26.4 g kg-1) and total P (15.1-23.9 g kg-1), indicating high potential agricultural benefits of their practical applications. However, total Zn and Ni contents in the sludge exceeded the values permitted in China's control standards for pollutants in sludges from agricultural use (GB 4284-1984). The residual fraction was the predominant fraction for Mo, Ni and Cr, the oxidizable fraction was the primary fraction for Cu and Pb, and the exchangeable and reducible fractions were principal for Zn. The distribution of different chemical fractions among the sludge samples reflected differences in their physicochemical properties, especially pH. The sludge pH was negatively correlated with the percentages of reducible fraction of Cu and exchangeable fraction of Zn. The sludges from these plants might not be suitable for agricultural applications due to their high contents of Zn, Ni and Cr, as well as high potential of mobility and bioavailability of Zn. |
| Key Words: fractions, heavy metals, sequential extraction, sewage sludge |
| Citation: Wang, C., Li, X. C., Wang, P. F., Zou, L. M. and Ma, H. T. 2006. Extractable fractions of metals in sewage sludges from five typical urban wastewater treatment plants of China. Pedosphere. 16(6): 756-761. |
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