Characteristics of heavy metals and nutrients contents in sewage sludge leachates under different simulating treatments
几种模拟处理方式污泥淋出液重金属与养分特征

In order to reduce the contamination of agricultural lands by heavy metals from sewage sludge and to realize its nutrients recycling,pot experiments were conducted to elucidate effects of different treatments on heavy metals and nutrients contents in the sewage sludge leachates.In the sludge containers,black nylon net(BNN),Fe-coated BNN(Fe-BNN),Fe-BNN plus K2SO4 and Fe-BNN plus maize growth were set up.Results showed that,BNN significantly reduced the contents of Zn,Cd in the sludge leachates and didn’t decrease the contents of N,P and K.Fe-coating reduced Zn content in leachates,but also decreased its P content.K2SO4 addition decreased Cu content in leachates and improved the release of P.The growth of maize decreased remarkably the weight of the sludge and produced corn grains and stems and leaves which conformed to the Chinese standard for feeds.The concentrations of Cu,Zn,Pb,Cd in all leachates were conformed to the Chinese standards for irrigation water quality.The ratios of the leached N,P and K nutrients to the total N,P and K in the initial sewage sludge(0.98%~9.88%) were by far higher than that for heavy metals(Cu,Zn,Pb,Cd)(0.04%~0.41%).The use of the leachate,as fertile irrigation water,is an interesting new way to recover the sludge nutrients for agricultural re-use.Meanwhile,the treatment of BNN + maize is a good way for comprehensive recycling of sewage sludge in agriculture.