Study On The Effect Of NZVI/AC On The Enrichment And Denitrification Of AnAOB

Compared with the traditional biological denitrification process,ANAMMOX does not require exogenous organic matter,has low energy consumption and low sludge output,and has broad application prospects in the field of wastewater biological denitrification.However,anammox bacteria grow slowly,have a long doubling time,are small in size,and are easy to lose.Their weak environmental adaptability leads to a long start-up time for the anammox process and difficulty in stable operation,which seriously hinders the large-scale application of the process.For this reason,we have carried out research on how to quickly start the reactor and efficiently enrich anammox bacteria.This article uses the ANAMMOX-EGSB reactor to explore how to quickly start the reactor after adding anaerobic sludge,and the effect of the EGSB reaction system on the rapid enrichment of anammox bacteria afte r adding nano zero valent iron activated carbon(n ZVI/AC),and investigate the addition of n ZVI/AC influence on the morphology of granular sludge,anammox performance,and system denitrification efficiency;and optimize the dosage ratio of n ZVI/AC,and then reveal the mechanism of n ZVI/AC on anammox performance;finally through the diversity structure of microbial community analyze and investigate the promoting effect of n ZVI/AC dosing on the enrichment of anammox bacteria,and reveal the response law of microbial population to n ZVI/AC.The following research results are obtained through analysis:(1)At the initial stage of reactor startup,simply dosing anaerobic sludge containing anammox bacteria,because there is a certain amount of dissolved oxygen in the reactor,the denitrification effect is not obvious.After further adding an appropriate amount of aerobic activated sludge,the dissolved oxygen concentration in the reactor decreased and the denitrification effect was improved.After a large amount of anaerobic sludge containing anammox bacteria is added again,the denitrification effect is further improved.(2)After the successful start-up of the EGSB reactor,the removal rate of ammonia nitrogen and nitros nitrogen is above 90%,and the total nitrogen removal effect is maintained above 85%.After 141 days of cultivation,the total nitrogen removal load of the reactor without n ZVI/AC material was 1.19 kg N/m~3·d,and the total nitrogen removal load of the reactor with n ZVI/AC material was 1.28kg N/m~3·d.The addition of n ZVI/AC materials can promote the removal of nitrogen from the reactor.At the same time,the addition of n ZVI/AC materials increased the abundance of two types of anammox bacteria,Candidatus Kuenenia and unclassified＿f＿＿Brocadiaceae,reduced the diversity of microorganisms,and had a better enrichment effect on anammox bacteria.From day 45 to day 100,the abundance of Candidatus Kuenenia increased from 11.88%to 21.43%,and the abundance of unclassified＿f＿＿Brocadiaceae increased from 1.07%to 6.21%.(3)Adding nZVI/AC has an inhibitory effect on anammox bacteria at the initial stage.After a certain adaptation period(1 week),the denitrification effect of anammox bacteria is improved.The optimal n ZVI/AC ratio is 0.8,the total nitrogen removal rate is increased from 20.23%to 89.13%,the ammonia nitrogen removal rate is increased from-24.17%to 97.26%,and the nitrous nitrogen removal rate is increased from 34.99%to 99.88%.