历史遗留含砷危险废渣安全处置工程案例

An Engineering Case of the Safe Disposal of Arsenic Hazardous Waste Residue Left Over by History

在对原场址含砷废渣进行详细调查的基础上,确定了化学氧化+稳定化固化+就地安全填埋的处置方案。项目选择过硫酸钠为氧化剂,很好地将高毒性的三价砷氧化为相对低毒性的五价砷,通过稳定化固化试验研究,确定了七水硫酸亚铁为稳定剂,其最佳添加量为8%,水泥为固化剂,其最佳添加量为10%(质量比)。根据国内外安全填埋场的设计经验,填埋场采用HDPE双层防渗技术,并设计了雨污分流系统、地下水导排系统、渗滤液收集处理系统、封场系统,该项目设计合理,对周围环境的影响小,取得了良好的社会效益和环境效益,并对含砷废渣处理处置工程设计中应注意的问题提出了建议。

On the basis of the detailed investigation of the properties of arsenic waste residue in site,the disposal scheme of ＇chemical oxidation ＋ stabilization/solidification ＋ in-situ safe landfill＇ was chosen in this project. Trivalent arsenic with high toxicity was primely oxidized into pentavalent arsenic with relatively low toxicity by using sodium persulfate as oxidant. Based on the experimental study of stabilization/solidification,the ferrous sulfa was selected as the stabilizer,and the optimum adding amount is 8%; the cement was selected as curing agent,and the optimum adding amount is 10%（ weight ratio）. According to the domestic and international experience of safe landfill design,the double-layer high density polyethylene membrane as impervious layer was used in this project. The rainfall-wastewater distributary system,underground water drainage system,leachate collection-diversion system,and final cover system were also designed. To conclude,this project was reasonable designed,and achieved good social and environmental benefits with minimum impact on the surrounding environment. Finally,some suggestions are put forward for the engineering design of the disposal of arsenic waste residue.