不同接种物对富集反硝化型甲烷厌氧氧化微生物的影响

在厌氧条件下,反硝化型甲烷厌氧氧化过程(Denitrifying anaerobic methane oxidation,DAMO)以CH_4为电子供体,以NO_3~-或NO_2~-作为电子受体,可同时实现甲烷氧化和废水中脱氮.本文利用两种电子受体(NO_3~-、NO_2~-)及不同接种污泥成功富集了4种DAMO培养物,研究了不同接种物对富集DAMO微生物的影响.结果表明,NO_3~-对富集DAMO古菌具有重要作用,而NO_2~-则对DAMO细菌的富集过程有较大影响.其次,在富集培养过程中,NH_4~+的存在会获得厌氧氨氧化(Anaerobic ammonium oxidation,Anammox)细菌与DAMO古菌的混培物,并形成协同关系,而DAMO细菌却因与Anammox细菌竞争而被淘汰.当NH_4~+不再加入,NO_3~-成为唯一氮源时,DAMO细菌重新出现并与DAMO古菌形成一种新的协同关系.此外,以淡水河道底泥、淡水湖泊底泥及水稻田土壤的混合物作为接种污泥而得到的DAMO富集培养物,其脱氮速率比以淡水河道底泥、活性污泥及厌氧消化污泥的混合物作为接种污泥的富集培养物高出3.3倍,但后者在驯化时间上缩短了36%.

Effects of different inoculum on the enrichment of denitrifying anaerobic methane oxidation (DAMO) organisms

Denitrifying anaerobic methane oxidation (DAMO) is an anaerobic process using CH₄ as the electron donor and NO₃^- or NO₂^- as the electron acceptor. It is expected to be an environment-friendly and cost-effective alternative to traditional biological nitrogen removal techniques. In this study the effects of two different electron acceptors and inocula on DAMO organisms were investigated. Four different DAMO cultures were enriched with different electron acceptors and different inocula. The electron acceptors, NO₃^- and NO₂^-, were found to play an important role in the selection of DAMO archaea and DAMO bacteria, respectively. NH₄⁺ was also added to investigate its influence on the selection. In the presence of NH₄⁺, DAMO archaea could form a synergetic relationship with Anammox bacteria, while DAMO bacteria might be eliminated in the competition with Anammox bacteria for NO₂^- (produced from nitrate reduction). When NH₄⁺ was removed from the system and NO₃^- was the sole nitrogen resource, DAMO bacteria reappeared and formed a new synergetic relationship with DAMO archaea. In addition, the culture enriched from the mixture of freshwater river sediment, freshwater lake sediment and paddy soil was proved to have a 330% higher nitrogen consumption rate than that enriched from the mixture of fresh water river sediment, activated sludge and digested sludge from wastewater treatment plant (WWTP), but the latter could shorten the acclimation time by 36%.