A2O缺氧池添加天然碳源玉米芯的脱氮特征

基于低碳源污水易硝化难反硝化的问题,构建了在A²O缺氧池添加天然碳源玉米芯的中试系统,采用物料衡算、反硝化速率测定和微生物群落分析等方法,研究了该系统的脱氮效能和反硝化体系特征.结果表明,TN去除率提升13%,出水从16.2降至10.0mg/L;同时不会造成出水氨氮和色度超标的风险.物料衡算表明,COD碳源的氧化消耗量和出水排放量降低,更多的碳源用于反硝化和污泥增殖,从而提升了氮素的去除量,其中反硝化的提升贡献更大.缺氧池形成了悬浮污泥加生物膜的复合型脱氮体系:在污水自身碳源存在时,生物膜和悬浮污泥的反硝化速率分别为24.89和32.42mg/(L?h),可实现快速脱氮;当自身碳源消耗殆尽,二者的反硝化速率分别是4.71和1.73mg/(L×h),单位生物量反硝化速率分别是1.58和59.1mg NO₃^--N/(g VSS×h),表明玉米芯主要被生物膜利用以维持反硝化进行.该体系的主要反硝化菌属为Azospira,此外在生物膜表面还富集了能够附着生长的Iamia和Haliangium,以及能够降解玉米芯木质素的Sulfuritalea等反硝化菌属.

Nitrogen removal characteristic of A2O system with natural corncob supplemented into anoxic zone as carbon source

Given that low carbon source sewage has advantage of nitrification rather than denitrification, natural carbon source corncob was added into anoxic zone of a pilot A²O to explore the denitrification potency and characteristics, by means of mass balance, denitrification rate and microbial community analysis. The results showed that TN removal efficiency increased by 13%, and effluent TN decreased from 16.2 to 10.0mg/L. Meanwhile, there was no exceeding risk of ammonia nitrogen and chroma in effluent. Mass balance demonstrated that the consumption amount of oxidation and effluent residual of COD both decreased, while its utilization rates for denitrification and sludge proliferation increased, which stimulated nitrogen removal amount. Therein, nitrogen removal was mainly contributed by denitrification. An integrated denitrification system was established in this reactor: the denitrification rates of newly formed biofilm and suspended sludge were 24.89 and 32.42mg/(L×h) separately in the presence of influent carbon source, which achieved this system with rapid denitrification; while influent carbon source was depleted, the denitrification rates were 4.71 and 1.73mg/(L×h) respectively, and their denitrification rates per biomass amount were 1.58 and 59.1mg NO₃^--N/(g VSS×h) accordingly, which indicated that corncob was primarily used by biofilm for maintaining denitrification process. The most dominant denitrifier in this system was Azospira. Morover, denitrifiers like Iamia and Haliangium, capable of adhering to growth, enriched on the biofilm, and Sulfuritalea, which could degrade corncob’s lignin, assembled on the biofilm as well.