回流比对DN-PN-ANAMMOX工艺处理中晚期垃圾渗滤液的影响

Effect of Recycle Ratios on Partial Nitrification-Anammox with Pre-Denitrification of Mature Leachate Treatment

为了进一步提升反硝化-部分亚硝化-厌氧氨氧化(denitrification partial nitrification and anaerobic ammonia oxidation,DN-PN-ANAMMOX)工艺处理含有高浓度NH_(4)^(+)-N的中晚期渗滤液的脱氮能力,以当地垃圾填埋场的中晚期渗滤液为试验用水,考察了在不同回流比下该工艺对有机物和氮素的去除以及各功能区微生物群落的变化.结果表明:当回流比由5调至9时,COD_(Cr)(chemical oxygen demand)的去除率由47%逐渐升至53%,其中前置UASB(Up-flow Anaerobic Sludge Bed Blanket,上流式厌氧污泥床反应器)去除COD_(Cr)的占比为41%,为后续的PN-ANAMMOX工艺提供了低碳环境.然而在回流比调至9时,由于高回流比的稀释作用使得游离氨(free ammonia,FA)的质量浓度下降〔ρ(FA)<2 mg L〕,导致了其无法抑制PN区NO_(2)^(-)-N氧化菌(nitrite oxidizing bacteria,NOB)的活性,部分亚硝化工艺的稳定性下降且NO_(2)^(-)-N积累率降至50%以下,对后续的ANAMMOX区脱氮性能产生不利影响,ANAMMOX区氮去除速率随之降至4.29 kg(m^(3)·d).研究显示:采用具有回流的DN-PN-ANAMMOX工艺处理ρ(NH_(4)^(+)-N)高达1900 mg L的中晚期垃圾渗滤液的最佳回流比为8,ANAMMOX区的氮去除速率达到7.41 kg(m^(3)·d),出水ρ(TN)(8.83 mg L)更低;同时,在回流比为8时,Pseudomonas、Nitrosomonas和Candidatus_Kuenenia分别在DN-PN-ANAMMOX工艺的前置UASB、PN区及ANAMMOX区得到最优的富集.

In order to further enhance the ability of denitrification partial nitrification and anaerobic ammonia oxidation(DN-PN-ANAMMOX)process for the treatment of mature landfill leachate containing high NH_(4)^(+)-N,the local landfill leachate was used as test water to remove organic matter and nitrogen.Meanwhile,under different recycle ratios,the change of microbial communities was thoroughly investigated.The results showed that the removal efficiency of COD_(Cr)(chemical oxygen demand)gradually increased from 47%to 53%as the recycle ratio increased from 5 to 9.The COD_(Cr) removed by UASB was 41%,providing a low-carbon environment for the subsequent PN-ANAMMOX process.However,with the increase in the reflux ratio to 9,the dilution effect made the concentration of FA(free ammonia)lower than 2 mg L,which cannot suppress NOB(nitrite oxidizing bacteria)activity in the PN zone.The stability of partial nitrification decreased and the nitrite accumulation efficiency decreased to less than 50%,which was harmful to the subsequent anammox zone.Therefore,the nitrogen removal rate of the anammox zone decreased to 4.29 kg(m^(3)·d).The research proved that the optimal recycle ratio was 8,and DN-PN-ANAMMOX process with recycle treated the mature leachate with 1900 mg L NH_(4)^(+)-N successfully.The nitrogen removal rate of anammox region reached 7.41 kg(m^(3)·d),and the effluent total nitrogen was the lowest(8.83 mg L).When the recycle ratio was 8,the optimal enrichment of Pseudomonas,Nitrosomonas and Candidatus_Kuenenia was achieved in the UASB,PN and ANAMMOX zones,respectively.