几种模拟处理方式污泥淋出液重金属与养分特征

为了减少城市污泥重金属对农田的污染,更好地实现污泥农业资源化利用,通过盆栽实验研究不同处理(对照、黑网、附Fe黑网、附Fe黑网+K2SO4及附Fe黑网+玉米)对城市污泥淋出液重金属和养分含量等的影响。结果表明,黑网可降低污泥淋出液的Zn﹑Cd总量,且没有减少污泥淋出液中氮、磷和钾的总量。Fe(OH)3可使淋出液中Zn总量降低,但同时也显著减少了淋出液中的磷总量。K2SO4可降低淋出液中的Cu总量,且促进Fe结合磷的释放。玉米的种植可使污泥的总重降低,同时玉米籽粒和茎叶重金属含量达到饲料标准。综合来看,任何处理每次淋出液的Cu、Zn、Pb、Cd浓度均符合农田灌溉水标准,淋出液氮、磷、钾量占原污泥中氮、磷、钾总量的比例(0.98%～9.88%)远远大于重金属元素(Cu,Zn,Pb,Cd)占原污泥对应重金属总量的比例(0.04%～0.41%),污泥淋出液作为农田灌溉水进行肥水利用将是污泥农业资源化利用的适合途径,同时黑网+玉米处理可能是较理想的污泥综合处理利用方式。

Characteristics of heavy metals and nutrients contents in sewage sludge leachates under different simulating treatments

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.