高级氧化-PRB修复填埋场复合污染地下水的可行性

A feasibility study on the remediation of complex contaminated groundwater in landfill sites using advanced oxidation-permeable reactive barrier(PRB)approach

以杭州市某生活垃圾填埋场一期地下水中复合污染的COD,NH_(4)^(+),Mn^(2+)为对象,联用了非均相Fenton氧化和渗透性反应墙(PRB),设计了活性炭(AC),生物炭(BC),BC+Fe_(3)O_(4)3种不同的氧化反应催化剂组合并将其兼做PRB氧化层活性填料,下游串联沸石吸附层.批试验和柱试验结果显示,H_(2)O_(2)可直接预氧化47%的COD.氧化层中COD在催化氧化和吸附共同作用下被削减;Mn^(2+)受多孔碳材料灰分释放影响先沉淀后溶解,然后被吸附;AC和BC表面的官能团-OH和-COOH参与了反应.吸附层中NH_(4)^(+)和Mn^(2+)与沸石离子交换引起了沸石骨架结构变化,且沸石表面的官能团-NH和-OH也参与了兜底吸附.BC+Fe_(3)O_(4)氧化层与沸石吸附层长度比为1:3的串联组合对三种污染物的去除率均较高,且PRB失效时间(即污染物出流浓度达到入流的10%且超过限值的时间)最迟,填料失效时的有效利用率最高,是最优工艺.

The complex contamination of COD,NH_(4)^(+),and Mn^(2+)in the groundwater of a landfill site in Hangzhou was investigated in this study.A combination of heterogeneous Fenton oxidation and a permeable reactive barrier(PRB)was applied.Three different catalytic oxidation catalyst combinations—activated carbon(AC),biochar(BC),and BC+Fe_(3)O_(4)—were designed and used as active filling materials in the oxidation layer of the PRB,followed by a downstream zeolite adsorption layer.Results from batch and column tests showed that 47%of COD was directly pre-oxidized by H_(2)O_(2).COD in the oxidation layer was reduced through the combined effects of catalytic oxidation and adsorption.The transport of Mn^(2+)was influenced by the ash content released from porous carbon materials,resulting in initial precipitation followed by dissolution and subsequent adsorption.Functional groups on the surfaces of AC and BC,such as-OH and-COOH,were involved in the reaction.In the adsorption layer,NH_(4)^(+)and Mn^(2+)were exchanged with zeolite ions,leading to changes in the zeolite framework structure.The functional groups-NH and-OH on the zeolite surface were also involved in thorough adsorption.The series combination of the BC+Fe_(3)O_(4)oxidation layer and the zeolite adsorption layer,with a length ratio of 1:3,was found to exhibit higher removal rates for all three contaminants,the latest PRB breakthrough time(i.e.,when the effluent concentration was reduced to 10%of the influent concentration and exceeded the limit),and the highest utilization efficiency at breakthrough,making it the optimal process.