亚硝酸盐型厌氧甲烷氧化过程强化新视角:排泥及其微生物机制研究

亚硝酸盐型厌氧甲烷氧化(Nitrite-dependent anaerobic methane oxidation, n-DAMO)是微生物在厌氧条件下利用甲烷还原亚硝酸盐的过程.本研究通过排泥的策略对n-DAMO过程进行强化,并比较分析了反应器中微生物的群落结构及功能微生物数量.结果发现,与对照组相比,排泥后实验组反应器的脱氮速率从17.00 mg·L~(-1)·d~(-1)提高到73.10 mg·L~(-1)·d~(-1).排泥后反应器中n-DAMO细菌的相对丰度从38.3%上升到67.7%,功能微生物的基因拷贝数由1.404×10~8 copies·g~(-1)增长到4.854×10~8 copies·g~(-1),污泥比活性提高了2.95倍.与之相反,初始反应器中其余优势微生物Unclassified_GCA004、Unclassified_Rhodocyclaceae、Unclassified_Fimbriimonadaceae与Methylosinu相对丰度分别下降为原来的27.66%、32.65%、4.35%、20.27%.结果表明,排泥可以有效地强化n-DAMO过程,同时促进功能微生物的生长,主要原因在于排泥排出了非目标微生物,使得目标微生物大量生长.本研究为强化n-DAMO过程及加快n-DAMO微生物的富集提供了一条新思路,并为进一步推动n-DAMO过程的工程应用提供了理论基础.

New insight into the enhancement of nitrite-dependent anaerobic methane oxidation: Withdrawing sludge and its microbial mechanism

Specific microorganisms involving in nitrite-dependent anaerobic methane oxidation (n-DAMO) process could utilize methane to reduce nitrite under anaerobic condition. In this study, the effect of withdrawing sludge on n-DAMO process was investigated and its microorganism community as well as functional microorganism abundance were analyzed. Compared with control group, the nitrogen removal rate of experimental group increased from 17.00 mg·L^-1·d^-1 to 73.10 mg·L^-1·d^-1 significantly after withdrawing sludge. Microorganism community analysis showed that the relative abundance of n-DAMO bacteria increased from 38.3% to 67.7% after withdrawing sludge. Functional microorganism abundance increased from 1.404×10⁸ copies·g^-1 to 4.854×10⁸ copies·g^-1 and sludge specific activity increased by 295%. In contrast, the relative abundances of unclassified_GCA004, unclassified_Rhodocyclacea,unclassified_Fimbriimonadaceae and Methylosinu decreased to 27.66%, 32.65%, 4.35% and 20.27%, respectively, after withdrawing sludge. The results indicate that withdrawing sludge can strengthen n-DAMO process and promote functional microorganism growth, which might be due to the increase of n-DAMO functional microorganisms abundance in the system. This study gives a new insight to strengthen n-DAMO process and accelerate n-DAMO microorganism enrichment, which provides theoretical basis for the application of n-DAMO process.