多级强化地下水修复技术对NH_4^+-N的去除机制

NH_4^+-N Removal Mechanism of Multi-Layer Enhanced Groundwater Remediation Technique

为解决地下水污染修复技术中P&T(抽出处理)和PRB(渗透性反应墙)存在的一些不足,搭建了MET(多级强化地下水修复技术)小试装置,以NH4+-N为目标污染物,研究MET对地下水中NH4+-N的去除效果及机制.结果表明,在进水水力负荷为14.68 m3/(m2·d)、ρ(NH4+-N)为25.0 mg/L的条件下,装置连续运行45 d,NH4+-N去除率呈先降后升、平稳后再下降的趋势,平均值达90%以上.出水ρ(NH4+-N)平均值为2.0 mg/L,其中,硝化作用和微生物同化作用使ρ(NH4+-N)平均下降13.9和5.2mg/L,分别占进水ρ(NH4+-N)的54%和20%;植物作用、基质永久吸附作用和挥发作用分别使ρ(NH4+-N)下降2.9、0.7和0.7mg/L,占进水ρ(NH4+-N)的12%、3%和3%.综上,MET对地下水中NH4+-N的去除率可达90%,实现了高效去除NH4+-N的目标.

In order to overcome shortages of groundwater pollution remediation techniques such as Pump and Treat（ PT） and Permeable Reactive Barriers（ PRB）,the remediation mechanism and effects of NH4＋-N in groundwater were studied by developing a small-scale experimental apparatus for the multi-layer enhance groundwater remediation technique（ MET）. The results showed that,with the influent hydraulic loading of 14. 68 m3/（ m2·d）,ρ（ NH4＋-N） of 25. 0 mg/L and the time of continuous operation of 45 d,NH4＋-N removal rate at first declined,then rose steadily,and then declined,with an average of more than 90%. The ρ（ NH4＋-N） removed by microbial nitrification and microbial assimilation was about 13. 9 and 5. 2 mg/L,respectively,comprising 54% and 20% of the total water ammonia. However,the ρ（ NH4＋-N） removed by plants,permanent substrate adsorption and volatilization was about 2. 9,0. 7 and 0. 7mg/L,respectively,comprising 20%,3% and 3% of the total water ammonia. Thus,the groundwater ammonia removal rate of MET reached 90%,and the goal of efficient removal of NH4＋-N was achieved.