| The disadvantages of traditional nitrification and denitrification technology,have greatly hindered its practical application because of its high energy consumption,high investment and operation cost,and large sludge production.At the same time,the traditional nitrification denitrification process is often inefficient in the treatment of aged landfill leachate,because the organic carbon in the aged landfill leachate is not enough for complete denitrification.The CANON process can save 50%alkali and 62.5%oxygen consumption without adding organic carbon source.However,CANON process can only remove 89%of nitrogen and produce 11%of nitrate in theory,and the actual landfill leachate contains organic carbon sources with different substrate concentrations.The simultaneous shortcut nitrification,anaerobic partial nitrification（ANAMMOX,and denitrification,snad）process is based on CANON process by adding additional organic carbon source and introducing appropriate amount of denitrifying bacteria.Compared with CANON process,snad process can remove organic matter and total nitrogen simultaneously.However,most of the researches on SNAD process used SBR reactor,and there are few reports on the start-up of SNAD process in biological aerated filter（SBAF）.In this experiment,biological aerated filter（BAF）reactor,inoculated with nitrous sludge and volcanic rock filler enriched with anammox bacteria,was used to realize the start-up and stable operation of CANON system and SNAD system at room temperature,and the change of EPS content secreted by microorganisms was analyzed.After the start-up,the removal of nitrogen and COD in landfill leachate by SNAD process was studied.The microbial composition in SBAF was studied by fluorescence quantitative PCR and high-throughput sequencing technology.The main results are as follows.（1）After 38 days of operation,the biological aerated filter（BAF）achieved the collaborative denitrification of nitrification and ANAMMOX,and the total nitrogen removal load reached 1.1kg·(m-3·d-1).Then,through the optimization of the aeration rate and aeration stop time,the optimal operation condition was determined when the influent NH4+-N was 300 mg·L-1 and HRT was 6 h,the aeration rate was 0.4 L·min-1,the aeration time and aeration stop time were adjusted to 40 min and 80 min respectively,and the optimal effluent quality was achieved.The average ammonia oxidation rate and total nitrogen removal rate were 89.9%and 78.4%respectively,and the average total nitrogen removal load was 1.9 kg·(m-3·d-1)。（2）When the concentration of organic matter is less than 60 mg·L-1,the activity of AOB and anammox can be enhanced,and autotrophic nitrogen removal and denitrification can be well coupled.Fluorescent quantitative PCR results showed that Anammox and AOB were always in the dominant position in BAF.Denitrification accounts for a relatively low proportion of nitrogen removal in the reactor,and most of the total nitrogen removal depends on Anammox.（3）The results of high-throughput sequencing showed that the relative abundance of Denitisoma,Thermoanaerobaculum and Candidatus＿Kuenenia in the middle layer of the reactor decreased gradually with the increase of influent leachate ratio,while the relative abundance of Nitrospira increased.As a result,the effluent effect deteriorated,and the total nitrogen removal rate decreased to 71.2%.In conclusion,this experiment investigated the changes of microbial community structure of snad system caused by late landfill leachate,in order to provide reference and basis for the application of biological aerated filter snad process in engineering practice,and to develop an efficient and economic treatment method,so as to improve the efficiency of leachate treatment and reduce the treatment cost,and promote the development of low consumption treatment of landfill leachate. |
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