广州城市污泥中重金属的含量、排放通量及农用风险评价

Heavy metal concentration,emission flux and potential ecological risk assessment for agriculture in Guangzhou

分析了广州市中心城区5个主要的污水处理厂污泥的基本理化性质和7种重金属(Cr、Cu、Mn、Ni、Pb、Cd和Zn)在不同雨期的浓度变化,估算了广州市污水处理厂污泥重金属的年排放通量,并对其污泥农用做了潜在风险评价。结果表明,各污水厂污泥均达到《城镇污水处理厂污染物排放标准》(GB 18918-2002)对重金属的排放要求,污泥的基本理化性质满足《城镇污水处理厂污泥处置农用泥质》(CJ/T309-2009)标准,沥滘、猎德、京溪和大坦沙污水厂的污泥重金属满足CJ/T309-2009要求,而西朗污水处理厂2013年12月采集的污泥中Cu和Cd未达标。通过估算,广州市污水处理厂污泥中Cr、Cu、Mn、Ni、Pb、Cd和Zn的年排放通量分别为16.1、18.8、90.3、5.9、7.9、0.2和48.3 t。通过Hakanson生态风险评估,污泥在农用过程中除西朗污水处理厂污泥重金属危害为中等风险,其他厂污泥属于低风险。

This reserch analyzed the physico-chemical properties and concentration variation of 7 heavy metals( Cr,Cu,Mn,Ni,Pb,Cd and Zn) in sewage sludge collected from five dominant municipal sewage treatment plants in Guangzhou downtown during different rainfall periods,estimated the annual emission flux of heavy metals from Guangzhou sewage treatment plants and assessed the potential risk of the sewage sludge for agricultural application. The results show that all the heavy metals concentrations reached the requirement the Discharge Standard of Pollutants for Municipal Wastewater Treatment Plant( GB18918-2002). The physico-chemical properties of sewage sludge met the requirement of Disposal of Sludge from Municipal Wastewater Treatment Plant-Control Standards for Agricultural Use( CJ / T309-2009). Sludge from sewage treatment plants in Lijiao,Liede,Jingxi and Datansha met the requirements of CJ / T 309-2009,while Xilang sewage sludge which collected in December2013 didn’t reach the standard. According to estimation,the annual emissions of Cr,Cu,Mn,Ni,Pb,Cd and Zn from Guangzhou municipal sewage sludge are 16. 1,18. 8,95. 3,5. 9,7. 9,0. 2 and 48. 3 t,respectively. The research assessed the sludge with Hakanson ecological risk assessment method,and the results showed that sludge in Xilang belonged to a medium risk when applied in agriculture while other plants’ sludge belonged to a low risk.