| Landfill leachate is a black and odorous water body formed by microbial degradation,infiltration of rain and snow water,surface water,and groundwater in the process of landfilling under the action of external force.It has the characteristics of low C/N,high salinity,high heavy metals,and unstable water quality and water quality.Direct discharge into water will cause harm to water bodies and human health.The traditional biological denitrification and nitrification-denitrification method consumes a large amount of carbon sources and neutralizing reagents in the treatment of landfill leachate,which increases the treatment cost.Simultaneous short-path nitrification-anammox-denitrification（Simultaneous partial nitrification,ANAMMOX and denitrification,SNAD）process has the advantages of no external carbon source,small aeration volume,low capital construction cost,low sludge output,and saving neutralizing reagents Etc.In this study,the SNAD process was used as the main process,and the SHARON-ANAMMOX process was used as the control.Methods When the HRT was gradually reduced from the initial 48h to 36h,24h,and 12h,the salinity was gradually increased from the initial 2.86 g·L-1 to 5 g·L-1,10 g·L-1,and 15 g·L-1 after the operation was stable.,20g·L-1,25 g·L-1.The influent and effluent concentrations of ammonia nitrogen,nitrite nitrogen,nitrate nitrogen,total nitrogen,t COD,and s COD in landfill leachate treated by two processes under various working conditions and the removal rate of each nitrogen volume load and the SNAD process reactor at each salinity were investigated.The microbial diversity and community changes were investigated to explore the feasibility of the SNAD process to treat landfill leachate under high salinity conditions.The research results show that:（1）When the two processes are used to treat landfill leachate,the HRT can be shortened from 48h to 12h and can have a good denitrification effect after adaptation.However,the recovery time increases with the shortening of HRT,and the increase in water intake should not exceed 50%each time.The nitrosation of the SHARON-ANAMMOX process is almost not affected by HRT,and is suitable for treating sewage with large changes in water volume;（2）The upper limit of the salinity that the two processes can handle for landfill leachate are both 20 g·L-1.The SNAD process uses aeration The nitrogen removal rate can reach 56.26%under the salinity of 25 g·L-1,but it will increase the treatment cost.The inhibitory effect of salinity on nitrosation reaction is stronger than that of SHARON-ANAMMOX process,which is the key to limiting the denitrification rate;（3）When salinity increases,microorganisms will increase the EPS secretion content,especially the hydrophobic substance PN to resist the high osmotic pressure environment,by increasing the cohesion between cells to form large granular sludge and biofilm to maintain the stability of the flora.The freshwater anammox bacteria Candidatus Brocadia developed salt tolerance through salinity acclimation,and the removal rate of total nitrogen from landfill leachate can reach 56.26%under high salinity. |
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