甲烷为唯一电子供体驱动硝酸盐/亚硝酸生物还原及微生物群落结构分析

Methane⁃driven microbial nitrate/nitrite reduction and microbial community structure analysis

反硝化厌氧甲烷微生物生长缓慢、倍增时间长,难以在短时间内成功富集.为快速大量富集以甲烷为唯一电子供体的硝酸盐/亚硝酸盐还原微生物,选择甲烷通量适宜的中空纤维膜材料并设计高效无泡曝气膜生物膜反应器(MBfR).在反应器运行初期,两个反应器分别手动添加200 mg·L^-1的硝酸盐和亚硝酸盐,两个反应器进行闭合自循环的76 d内,均可在10 d内将200 mg·L^-1的硝酸盐和亚硝酸盐完全去除.稳定后,200 mg·L^-1硝酸盐可在2 d之内全部还原,还原速率略快于亚硝酸盐.在MBfR运行第77~124 d,改为序批式生物反应器方式运行,两个反应器内反硝化速率均可达到50 mg·L^-1·d^-1,表明以甲烷为唯一电子供体驱动的反硝化微生物成功富集并挂膜.在微生物富集过程MBfR出水中均检出挥发性脂肪酸(VFAs),以硝酸盐和亚硝酸盐为电子受体的反应器最高VFAs含量分别可达948 mg·L^-1和997 mg·L^-1.高通量测序结果发现,以硝酸盐为电子受体的反应器内产酸菌Propionispora和Proteiniphilum的丰度可以达到39.1%和3.1%,而在以亚硝酸盐作为电子受体时,产酸菌Propionispora和Proteiniphilum丰度分别为80.9%和2.4%,是反应器内部的优势菌属.而异养反硝化菌Pseudomonas在两组微生物富集阶段均具有较高丰度.由此推测在本研究中甲烷为唯一电子供体驱动的硝酸盐/亚硝酸盐生物还原过程由VFAs作为中间产物介导完成.本研究结果可为推进污水脱氮技术的发展提供参考.

The denitrifying anaerobic methane oxidation(DAMO)organisms are difficult to enrich successfully in a short time due to their slowly growth.In order to rapidly and massively enrich the functional bacteria of nitrate/nitrite type anaerobic methane oxidation,choosing suitable hollow fiber material according to methane flux to build new membrane biofilm reavtors.During the initial 76 days,two MBfRs both could reduce 200 mg·L^-1 NO-3⁃N or NO-2⁃N within 10 days.Using nitrate as electron acceptor could be stabilized to remove all 200 mg·L^-1 within 2 days,which was slightly faster than nitrite.Both groups of microorganisms could achieve the reduction efficiency of 50 mg·L^-1·d^-1 in SBR running period during day 77 to 124.and the success of microbial enrichment and membrane hanging could be observed.The whole enrichment process was accompanied by the detection of volatile fatty acids(VFAs)in the effluent.The maximum VFAs concentration in the reactor with nitrate or nitrite as electron acceptor could reach to 948 mg·L^-1 and 997 mg·L^-1,respectively.The high-throughput sequencing results showed that the abundance of Propionispora and Proteiniphilum could reach 39.1% and 3.1% in the MBfR with nitrate as electron accepter,while the abundance of the same genera could reach 80.9%and 2.4% when the electron accepter changed to nitrite,which were always the dominant genera in the MBfRs.The denitrifying bacteria Pseudomonas was a dominant genus detected in both two microbial enrichment stages.It could be speculated that VFAs were most likely intermediates during the nitrate/nitrite type anaerobic methane oxidation process.This research results can provide reference to promote the development of wastewater denitrification technology.