污泥中重金属污染程度和生态风险评估优化

Assessment Optimization of the Contamination Degree and Ecological Risk of Heavy Metals in Sewage Sludge

重金属是城市污水处理厂污泥中的一种典型无机污染物。对重金属污染程度和生态风险的准确识别对于污泥的安全处理或处置至关重要。目前,有关污泥中重金属污染程度和生态风险的评估方法主要包括2种:总量因子法和形态因子法,但各方法之间缺乏统一的分类等级。此外,有关污泥中重金属污染程度和生态风险评估的总量因子法和形态因子法不够完善。该研究首先在参考河流底泥和土壤中重金属污染程度和生态风险评估研究成果的基础上,进一步完善污水处理厂污泥中重金属污染程度和生态风险评估方法,并建立统一的分类等级。然后,以南昌市4个主要污水处理厂污泥为研究对象,应用上述建立的方法对污泥中重金属的污染程度和生态风险进行评估。最后,依据评估结果对总量因子法和形态因子法之间的关联性和一致性进行探讨。研究结果表明:在评估Cu、Zn、Ni和Cr单一重金属污染程度时,总量因子法和形态因子法呈现显著正相关和较高的一致性;在评估Zn和Ni单一重金属生态风险时,总量因子法和形态因子法呈现显著正相关和较高的一致性;在评估重金属综合污染程度和生态风险时,总量因子法和形态因子法呈现正相关和较高的一致性。该研究的开展将进一步为污水处理厂污泥中重金属的污染程度和生态风险评估提供理论参考,与此同时可为南昌市污水处理厂污泥中重金属的污染风险管理提供数据支撑。

Heavy metals are typical inorganic pollutants in sewage sludge.The accurate identification of heavy metals’pollution degree and ecological risk is crucial for the safety treatment and disposal of sewage sludge.At present,the evaluation models of heavy metals’pollution degree and ecological risk in sewage sludge can be divided into two kinds:the total content indices and the speciation indices.However,there is lack of a unified classification level among these methods.In addition,the evaluation methods of heavy metals’pollution degree and ecological risk in sewage sludge,including the total content indices and the speciation indices,are inadequate.This study firstly further improved the assessment methods of pollution degree and ecological risk of heavy metal in sewage sludge and established the unified classification level,referring to the research results of the contamination level and ecological risk assessment of heavy metal in river sediment and soil.Then,the improved evaluation methods were applied to the assessment of heavy metals’contamination degree and ecological risk in sewage sludges collected from four main sewage treatment plants located in Nanchang City.According to the evaluation results,the correlation and correspondence between total content index and speciation index were explored.The research results showed that when assessing the pollution degree of Cu,Zn,Ni and Cr,significant positive correlations and higher correspondences were found between above two approaches;when assessing the ecological risk of Zn and Ni,significant positive correlations and higher correspondences were found between above two approaches;when assessing the pollution degree and ecological risk of multi-metal(Cu,Zn,Pb,Cd,Ni and Cr),significant positive correlations and higher correspondences were found between above two approaches.This research will further provide theoretical reference for the assessment of the contamination level and ecological risk of heavy metals in sewage sludge.Meanwhile,it can provide data support for the pollution risk management of heavy metals in sewage sludge produced in wastewater treatment plants located in Nanchang City.