Components change of sewage sludge by month and land application in Shaanxi Yangling Sewage Treatment Plant

Chinese. 为了合理解决杨凌污水处理厂污泥的处置问题，推动城市污泥的资源化和无害化利用，通过现场调查采样及室内分析的方法，对杨凌污水处理厂污泥中的N、P、K和有机质及重金属Ni、Cd、Pb、Zn、Cu、Cr、As、Hg进行了10个月（2005-02~11）的连续监测。结果表明，污泥中含有较高的有机质、全氮、全磷，其含量分别为361.41~529.38，20.13~35.42及3.11~7.48 g/kg；重金属Ni、Cd、Pb、Zn、Cu、Cr和As的含量分别为22.86~38.03，0.68~5.07，29.53~76.16，297.42~313.73，124.37~200.66，43.23~255.00及6.02~15.97 mg/kg，Hg含量在此期间未检测出；重金属含量均未超过我国污泥农用控制标准。污水污泥的水浸出液pH值为6.78~7.01，为微酸近中性。重金属活性的大小顺序为：NiCd PbZnCuAs。对杨凌污水污泥成份动态监测结果表明，该污泥是优质的有机肥源，可以经过进一步稳定化处理后在农田和林地施用。

English. It is suggested that the heavy metal limits in sewage sludge for land application should be modified to promote the safety reuse of sewage sludge in China. The contents of nutrition (N, P, K) and heavy metals (Cd, Pb, Zn, Cu, Cr, As and Hg) in the sewage sludge of Yangling Sewage Treatment Plant were investigated from February to November, 2005. The results showed that it had high organic matter, total nitrogen (TN) and total phosphor (TP), in which the contents of organic matter, total nitrogen (TN) and total phosphor (TP) were 361.41－529.38, 20.13－35.42, and 3.11－7.48 g/kg, respectively; the contents of Ni, Cd, Pb, Zn, Cu, Cr and As were 22.86－38.03, 0.68－5.07, 29.53－76.16, 297.42－313.73, 124.37－200.66, 43.23－255.00, and 6.02－15.97 mg/kg, respectively; however, the contents of Hg in sewage sludge samples were not determined in near a year time. All the heavy metals' contents were lower than the heavy metal limits for agricultural application of China. The pH value of water extracts of the sewage sludge was 6.78－7.01, nearly a little acidic or neutral. The active order of heavy metals was: NiCdPbZnCuAs. So the sludge was “high quality” organic fertilizer and was suitable for land application after stability treatment.