零价铁活化过碳酸钠深度处理老龄垃圾渗滤液超滤出水

Zero-valent iron activated sodium percarbonate for deep treatment of ultrafiltration effluent from aged landfill leachate

垃圾填埋场老龄垃圾渗滤液超滤出水(UALL)中部分COD极难降解,导致渗滤液难以达标排放.本研究选取佛山市某大型垃圾填埋场老龄垃圾渗滤液超滤出水为研究对象,利用零价铁(ZVI)活化过碳酸钠(SPC)降解该废水中的COD,考察了ZVI和SPC投加量及初始pH值等因素对COD降解效果的影响,并深入探究了COD高效降解的机理.结果表明,零价铁活化过碳酸钠体系可有效降解COD,在初始pH=2.0、ZVI投加量=0.5 g·L^(-1)、SPC投加量=0.9 g·L^(-1)、t=60 min的条件下,垃圾渗滤液中COD的去除率最高可达61.02%.机理分析表明,在ZVI/SPC体系中,COD的去除主要依靠氧化作用,具体表现为一条由羟基自由基(·OH)主导的自由基降解途径和另一条由Fe(IV)氧化的非自由基降解途径.本研究结果可为实际老龄垃圾渗滤液中COD降解的工程化应用提供理论指导和技术支撑.

Efficient degradation of recalcitrant chemical oxygen demand(COD)in ultrafiltration effluent from aged landfill leachate poses a significant challenge in meeting discharge standards.In this study,the ultrafiltration effluent from an aged landfill in Foshan(China)was selected as the research object.The zero-valent iron(ZVI)-activated sodium percarbonate(SPC)was used to degrade COD in ultrafiltration effluent from aged landfill leachate(UALL).The effects of various factors such as dosages of ZVI and SPC and initial pH on the degradation of COD were investigated.Moreover,the mechanism for the efficient degradation of COD was explored.The results showed that the ZVI-activated SPC could effectively degrade COD.For the initial pH and dosages of ZVI and SPC of 2.0,0.5 g·L^(-1) and 0.9 g·L^(-1),respectively,the COD removal rate in the waste leachate could reach up to 61.02%in 60 min.Mechanistic analysis showed that,in the ZVI/SPC system,the removal of COD mainly relied on oxidation,which was manifested as a free radical degradation pathway that was dominated by·OH and another non-free radical degradation pathway oxidized by Fe(IV).The results of this study can provide theoretical guidance and technical support for the engineering applications of removing COD in real-life aged waste leachate.