秸秆沼渣中重金属的安全风险分析

Safety Risk Analysis of Heavy Metals in Straw Biogas Residue

通过对沼渣中重金属进行含量和风险分析,以期达到评价沼渣的农用安全性的目的。研究了不同混合比例的秸秆和牛粪原料中温厌氧发酵过程中,进料类型、物料比例、预处理方式等对沼渣内重金属含量产生的影响。在不同类型的出料沼渣中重金属最高含量为:Cd 0.796 mg·kg-1,Cr 55.4 mg·kg-1,Pb 13.1 mg·kg-1,Hg 2.02mg·kg-1,As 23.8 mg·kg-1。沼渣基本符合我国《城镇垃圾农用控制标准》,但是Cu和Zn含量较高;重金属风险评价显示,沼渣农用存在着金属积累的风险,需处理后再农用。

Agricultural safe application of straw biogas residue was evaluated through the analysis of heavy metal content in the biogas residue.The influence of different mixing ratio of straw and cow dung,feeding type,and pretreatment on the heavy metal content in the biogas residue were studied under mesophilic temperature.The maximum levels of heavy metals in our tested biogas residue were Cd 0.796 mg · kg-1,Cr 55.4 mg · kg-1,Pb 13.1mg · kg-1,Hg 2.02 mg · kg-1,As 23.8 mg · kg-1,which could meet the standards requirement of “Control Standards of Urban Wastes for Agricultural Use”,while the content of Cu and Zn were higher than the control standard.Heavy metals assessment showed that there was a risk of metal accumulation in biogas residue,and so need to be treated before use in agricultural.