Denitrification Anaerobic Methane Oxidation Process And Its Enhancement In SBR And MBR

Denitrifying anaerobic methane oxidation?DAMO?couples methane oxidation and nitrate/nitrite reduction processes and has the dual functions of nitrogen removal and greenhouse gas emission reduction.It plays an important role in the research of the global carbon and nitrogen cycle,the reduction of greenhouse gases,and the development of new technologies for the nitrogen removal from wastewater.However,the problems that it is difficult for DAMO to grow,the rate of nitrogen removal is too low to meet actual needs,and the lack of knowledge of long-term culture performance limits its application to engineering.So we conducted a long-term comparison of the cultivation of DAMO microbial reactors in order to further understand the differences in the process rate and microbiological characteristics of nitrate and nitrite type DAMO in SBR.And a membrane bioreactor?MBR?was designed to investigate the DAMO performance.Furthermore we studied the enhancement effect of running mode in SBR.The main conclusions are as follows:?1?Under the same conditions,nitrate and nitrite were used as electron acceptor of DAMO in the long-term operation of SBR.As a result a The reactor containing only the substrate of nitrate cultures the mixture system of DAMO archaea and DAMO bacteria,and the dominant microorganism cultured in the reactor containing nitrite substrate is the DAMO bacteria.Morover,the DAMO archaeal mixed system reached stability 150days later than the DAMO bacteria,and the time of rate increase was 70 days longer than that of the bacteria.As for the performance of nitrogen removal,the maximum nitrogen removal rate of DAMO bacteria reached 80.9 mg-N/?L·d?,and that of DAMO was 32.6 mg-N/?L·d?.The final nitrogen removal rate of DAMO archaea system was only about 40%of that of DAMO bacteria and the DAMO bacterial copy number is one order of magnitude higher than the DAMO archaea.Further studies on the microbial enrichment rate and operational efficiency of DAMO system with nitrate as electron acceptor still need further study.?2?In the long-term culture,DAMO archaea and DAMO bacteria can stably coexist,and DAMO archaea may be the limiting factor in the nitrogen removal activity of the mixed system.After the rate of the DAMO bacteria mixture system of DAMO was stable,the nitrogen removal activity did not decrease during the 800 d and there was no accumulation of nitrite in the reaction system.?3?MBR can stably cultivate DAMO bacteria but also has certain advantages.The low-speed fluctuation time is reduced by half compared with the original SBR time,and the time for rapid improvement to achieve final stabilization is short.The kinetic parameter of NO₂^--N half saturation constant Ks is 0.62 mg/L,far less than the reported value of 12.6 mg/L.Further more,no severe membrane fouling occurs in the MBR operation for one year.?4?Sludge removal has obvious effect on nitrogen removal performance and functional microbial community optimization in nitrite type DAMO process in SBR.Compared with the control group,the denitrification rate of the control group is significantly increased,from 17.00 mg-N/?L·d?before the control to 70.61 mg-N/?L·d?,showing the application potential of the process.And the contrast activity of the control group is significantly improved.The highest level of the control group was 5.88 times higher than that in the control group.After adjustment,he copies of DAMO bacteria increased from 1.17×108 copies/g sed to 4.02×108 copies/g sed,increasing by 3.44times.But also,the proportion of DAMO bacteria increased from 38.3%to 67.7%,and the purity increased by 1.77 times.