碳氮比对MBBR系统脱氮性能及微生物群落的影响

EFFECTS OF CARBON TO NITROGEN RATIO ON DENITRIFICATION PERFORMANCE AND MICROBIAL COMMUNITY IN AN MBBR SYSTEM

采用不同碳氮比(C/N)的合成废水,比较了连续流和序批式2种运行方式下单级移动床生物膜反应器(MBBR)的脱氮性能差异。结合宏基因组测序技术,对不同阶段载体上的生物膜进行了微生物群落和功能基因丰度分析,并分析了反应器内主要的氮素代谢通路,旨在探讨不同C/N和运行方式对MBBR系统脱氮性能和生物膜群落结构的影响。结果显示:C/N的变化对MBBR工艺NH_(4)^(+)-N去除影响不大,各阶段NH_(4)^(+)-N去除率均保持在95%以上,但同步硝化反硝化(SND)效率因受到反硝化性能的限制,各阶段存在较大差异。此外,SBMBBR反应器中总无机氮(TIN)去除率始终高于CFMBBR反应器,原因可能是反硝化过程中起关键作用的narGHI、napAB、nirK、nirS、norBC和nosZ功能基因的序列数总和存在差异。不同运行方式下的反应器中主要优势菌门和菌种差异明显,也是SBMBBR与CFMBBR反应器之间脱氮性能差异较大的重要原因之一。该结果可为MBBR反应器处理较低C/N的城市生活废水的优化设计和运行提供参考。

Compared the denitrification performance of single-stage moving bed biofilm reactors(MBBR)under two different operation modes,continuous flow,and sequencing batch,by adding synthetic wastewater with different carbon-to-nitrogen(C/N)ratios.Metagenomic sequencing technology was utilized to analyze the microbial community and functional gene abundance of biofilms on carriers in different phases,as well as to analyze the major nitrogen metabolism pathways in the reactor,with the aim of investigating the effects of different C/N ratios and operation modes on the denitrification performance and biofilm community structure of the MBBR system.Results showed that the variation of C/N ratio had little effect on ammonia nitrogen removal of the MBBR process,with ammonia nitrogen removal rates remaining above 95%in all phases.However,there was a significant difference in simultaneous nitrification and denitrification(SND)efficiencies among phases,due to the limitation of denitrification performance.In addition,the total inorganic nitrogen removal rate of the sequencing batch MBBR(SBMBBR)was always higher than that of the continuous flow MBBR(CFMBBR),which may be due to the differences in the total number of functional genes,such as narGHI,napAB,nirK,nirS,norBC,and nosZ,which play a crucial role in denitrification.There were significant differences in the dominant bacterial phyla and species under different operation modes,which was also a major reason for the significant difference in denitrification performance between SBMBBR and CFMBBR.These results can provide useful references for the optimization design and operation of MBBR for the treatment of urban domestic wastewater with lower C/N ratios.