Blockage Fermentation Broth Strengthens The Efficiency Of Denitrification Of Salty Sewage By Constructed Wetland

In this study,according to the clogging of constructed wetland where it contains a lot of organic matter,the fermentation liquid was prepared with the pre-processed strong alkali environment.A comparative study of the release of carbon and nitrogen sources from different fermentation materials and the effect of denitrification were carried out that clogging fermentation liquid has the ability to improve nitrogen removal efficiency.After adding the clogging fermentation liquid,this paper comprehensively analyzed the effects of salinity and clogging fermentation liquid on the nitrogen removal efficiency of constructed wetland.The dynamic changes of nitrogen removal microorganisms in constructed wetland at different stages were analyzed by qPCR technique and high-throughput sequencing method.Finally,the nitrogen removal pathway based on heterotrophic nitrification and aerobic denitrification was successfully achieved in the constructed wetland,leading to the fact that the nitrogen removal efficiency of saline sewage treatment in constructed wetland was improved.The main results are as follows:(1)Constructed wetland clogging has the characteristics of making high-carbon and low-nitrogen fermentation liquid.In the fermentation environment with pH 12,the organic matter in the clogging can be released quickly.Mixed clogging and Pontederia cordata L by fermentation can achieve the highest yield on the fourth day,the total nitrogen contents were less than 5.5 mg/L,CODCr were higher than 5587.5mg/L.Its nitrogen removal efficiency of denitrification capacity is also the highest compared with other fermentation materials,which can significantly improve the removal rate of nitrogen to 92.73% which is a kind of carbon source that can be applied.(2)In experiments,a constructed wetland system with efficient removal rate for ammonia nitrogen was calculated.The ammonia nitrogen removal rate could reach93.73% without adding clogging fermentation liquid,but the total nitrogen removal rate was only 4%.The addition of the fermentation liquid could increase the removalrate of ammonia nitrogen to more than 99%,and the total nitrogen removal rate saw a significantly increase to more than 90%.(3)The changes of amoA,nxrA,nirS and 16 S rRNA genes in the constructed wetland system with different salinity were quantitatively analyzed by the qPCR experiment.It confirmed that the addition of the fermentation liquid significantly increased the number of denitrifying bacteria.With the impact of salinity,autotrophic ammonia-oxidizing bacteria(AOB)was significantly inhibited.However,the ammonia removal rate of the system still increased after adding the fermentation liquid,which indicated that there exists denitrifying bacteria with better efficiency.(4)With high-throughput sequencing technology and bioinformatics analysis,it found that the denitrifying bacteria in the system mainly consists of aerobic denitrifying and heterotrophic nitrifying bacteria.The main bacteria belong to Proteobacteria,with relative content of 60% to 70%.There were at least 14 categories of aerobic denitrifying bacteria on the level of genus,with relative content between7.29% to 49.47% in different samples.Salinity had a great influence on the nitrogen removal microbial community in constructed wetland.The microbial community richness in the system with 1.8% salinity was much lower than that in the freshwater system.But the environment with high salinity also domesticated a special halophilic aerobic denitrification bacteria which called Zobellella.It was a new discovery in highly efficient nitrogen removal bacteria,which used nitrite nitrogen as the substrate for the reaction.Its substrate was nitrite nitrogen and the relative content accounted for 29.38% ~ 36.49%.(5)The addition of fermentation liquid promoted the aerobic denitrifying bacteria and heterotrophic nitrifying bacteria to become the dominant bacteria.Autotrophic ammonia-oxidizing bacteria faced lots of inferior competitiveness.The traditional nitrification and denitrification processes was not the main nitrogen removal pathway.The main nitrogen removal pathwayin constructed wetland was mainly focus on heterotrophic nitrifying and aerobic denitrifying by this experiment.Moreover,ammonia-oxidizing archaea(AOA),AOB and anaerobic ammonium oxidation bacteria(Anammox)provide a variety of assistance pathway to removal nitrogen.Ithad successfully strengthened the nitrogen removal efficiency of constructed wetland with different salinity sewage and solved the problem of disposal of clogging and waste plant which could be used for resource.