| With the development of my country’s economy and social life,the output of my country’s domestic waste has increased year by year.As one of the main ways to deal with waste,the sanitary landfill method will bring about the generation of landfill leachate.Landfill leachate is a kind of highly polluting and highly toxic sewage.The current landfill leachate treatment technology is unstable and costly.Therefore,it is urgent to explore a more stable,economical and green landfill leachate treatment technology.In this study,a two-stage A/O system was used,and landfill leachate raw liquid was used as influent water.The A/O process and short-range denitrification anaerobic ammonium oxidation process were used to study the denitrification of landfill leachate treatment in three stages.To explore the removal effect of pollutants at different stages,and to analyze the microbial population structure of sludge at different stages through high-throughput sequencing,the main conclusions are as follows:(1)The membrane-hanging stage lasted 36 days in total,and the average influent COD concentration was 386.06mg/L.When the membrane-hanging was successful,the COD removal rate could reach 70% stably,the average influent ammonia nitrogen concentration was 76.41mg/L,and the ammonia nitrogen removal rate could reach60%.%,it was found that the time for ammonia nitrogen to reach the pollutant removal rate standard in the film-forming stage lags behind the time for COD to reach the standard.The sludge concentration of the filler increased from 53.5mg/L to 284.5mg/L.The suspended packing in the reactor also changed from light yellow to brownish yellow.The change of effluent water quality and the change of packing appearance all proved the success of film formation.In the sludge domestication stage,the domestication and stable operation lasted 72 days.In the stable operation stage,the average effluent COD concentration was 2541mg/L,and the removal rate was 70.46%;the average effluent ammonia nitrogen concentration was 49.85mg/L,and the removal rate was 95.33%;the average effluent TN concentration was 186.64mg/L,and the removal rate was 87.51%.The biofilm concentration of the average suspended filler in the system increased from298mg/L at the initial stage of acclimatization to 1082mg/L.(2)Anaerobic ammonium oxidation sludge was added to the anoxic zone 2 for shortrange denitrification anammox research.The operation phase lasted 46 days,and the parameter adjustment phase lasted 24 days.The average removal rate of COD is 66.84%,which is slightly lower than that of the previous stage due to the large change of influent water quality.The average concentration of ammonia nitrogen in the effluent is41.14mg/L,and the removal rate is 97.68%.The average concentration of TN effluent is117.81mg/L,and the removal rate is 93.91%,which is higher than that of the previous stage.In the anoxic zone II,the highest nitrite accumulation rate was 66.79%,the lowest was 19.30%,and the average accumulation rate was 41.29%.The contribution rate is12.45%.In the material balance calculation,the removal amount of COD in A1,O1,A2,O2,and secondary sedimentation tank section is 28.65g/d,2.75g/d,4.27g/d,1.2g/d,0.25g/d,respectively,The removal amounts of TN in A1,O1,A2,O2,and secondary sedimentation tanks are 8.59g/d,0.88g/d,0.77g/d,0.22g/d,and 0.02g/d,respectively.In the stage of parameter adjustment,the optimal working condition is that the reflux ratio of nitrification liquid is 300%,and the influent C/N is 4.Under this working condition,the concentration of COD in the effluent is 2015.82mg/L,and the removal rate of COD is 70.75%.The concentration of ammonia nitrogen in the effluent is 32.34mg/L,and the removal rate of ammonia nitrogen is 98.23%;the concentration of total nitrogen in the effluent is 100.42mg/L,the removal rate of TN is 94.84%,and the average denitrification contribution rate of anammox is 15.31%.(3)Using 16 sr RNA high-throughput sequencing technology to analyze the structure of microbial populations at different stages.In the analysis of the microbial population structure at the phylum level,the dominant phylum in the two stages was Proteobacteria,and the abundance of Bacteroidota on the biofilm on the filler in the coupling stage decreased from 14.2% to 9.04% %,the abundance of Actinobacteriota increased from3.32% to 7.68%,and the abundance of Planctomycetota,which belongs to the anammox functional bacteria,increased from 1.46% to 5.63%.In the analysis of the microbial population structure at the genus level,the functional genus Thauera with short-range denitrification appeared in both stages.During the stable operation stage,the dominant bacterial genera on the microbial genus level on the suspended packing biofilm in the anoxic zone 2 are Azoarcus,Truepera,Thauera,Lentimicrobium,SM1A02;the microbial genus level of the suspended packing biofilm coupled with anaerobic ammonium oxidation The dominant bacterial genera on the map are Azoarcus,JTB255＿marine＿benthic＿group,Truepera,Thauera.The anammox functional bacteria on the filler of the anoxic second pond was Candidatus＿Kuenenia,and its abundance accounted for 1.81%.In this paper,a two-stage A/O process was used to treat landfill leachate,and a shortrange denitrification coupled with anammox for denitrification was carried out in the second anoxic zone,and the feasibility of the coupling in the continuous flow reactor was verified.The practical engineering application of this technology provides a reference. |
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