进水碳氮比对CANON型人工湿地脱氮性能的影响

通过逐步提高进水中的有机碳源浓度,探讨进水碳氮比(C/N)对基于亚硝化的全程自养脱氮(CANON)型潮汐流人工湿地(TFCW)脱氮效能及其微生物特性的影响.结果表明: 进水C/N可显著影响CANON型TFCW中脱氮功能微生物的数量与活性,进而影响其氮素转化速率.当进水C/N由0.0增至6.0时,TFCW中反硝化功能基因的丰度随之增加,系统反硝化性能提高,TFCW中逐渐形成同步亚硝化、厌氧氨氧化与反硝化(SNAD)耦合反应体系,其脱氮效果得以强化.当进水C/N＞6.0时,好氧氨氧化菌活性受到抑制,数量逐渐减少,TFCW中的厌氧氨氧化作用与反硝化作用受阻,系统脱氮性能恶化.当进水C/N为6.0时,TFCW中的SNAD作用可得到最大限度的强化,其总氮(TN)去除率和去除负荷分别达(93.3±2.3)%和(149.30±8.00) mg·L^-1·d^-1,高于CANON系统中TN去除率的理论值.

Effect of influent C/N on nitrogen removal performance in tidal flow constructed wetland via CANON process

This study was conducted to explore nitrogen transformation and associated microbial characteristics in a tidal flow constructed wetland (TFCW) with the complete autotrophic nitrogen removal over nitrite (CANON) process under influent COD/TN (C/N) constraints. The influent C/N increased from 0.0 to 10.0 via the addition of glucose in the influent as a source of organics. The results showed that influent C/N significantly affected nitrogen transformation rates in the TFCW throughout the experiment. As the influent C/N increased from 0.0 to 6.0, the absolute abundance of functional genes involved in denitrification could be enriched as a consequence of the addition of organics in influent, and then the simultaneous nitrification, anammox, and denitrification (SNAD) processes occurred in the TFCW, resulting in the enhancement of nitrogen removal in the system. However, as the influent C/N was more than 6.0, the activity of aerobic ammonia-oxidizing bacteria was inhibited and its quantity reduced, leading to the deterioration in nitrogen removal of the system. When the influent C/N was 6.0, the SNAD process was enhanced most effectively in the system owing to the development of multiple and complete nitrogen removal pathways in the TFCW. The TFCW respectively had the best TN removal efficiency and removal loading rate (93.3±2.3)% and (149.30±8.00) mg·L^-1·d^-1], indicating that the results had been than the maximal TN removal efficiency in a CANON process under ideal conditions.