游离氨与游离亚硝酸对中试膜生物反应器短程硝化及微生物群落结构的影响

为探究FA(游离氨)与FNA(游离亚硝酸)对短程硝化及微生物群落结构的影响，采用中试MBR(膜生物反应器)，以高浓度NH₄+-N废水为处理对象，考察MBR对NH₄+-N的去除效果，通过计算FA与FNA浓度，分析其对短程硝化的影响，利用16S rRNA基因高通量测序技术分析微生物群落结构并对功能基因进行预测. 结果表明:①通过将NH₄+-N容积负荷逐渐从0.11 kg/(m3·d)提升至0.75 kg/(m3·d)，MBR在第18天实现了全程硝化向短程硝化的转变. ②MBR稳定运行过程中，FA和FNA浓度分别维持在1.03~3.52和0.033~0.118 mg/L，NAR(亚硝酸盐积累率)为65.70%~80.24%，实现了NO₂--N的稳定积累，此时NH₄+-N去除率为87.92%~97.18%. ③进水由模拟废水向实际工业废水的转变没有对NAR产生较大影响，表明中试MBR具有较强的适应能力. ④16S rRNA基因高通量测序分析结果表明，维持MBR内FA和FNA浓度能够富集AOB(氨氧化菌)Nitrosomonas(7.99%)，抑制NOB(亚硝酸盐氧化菌)活性，进而实现短程硝化；MBR运行第50天时，Amo(氨单加氧酶)功能基因相对丰度为第0天时的371倍，进一步验证了短程硝化过程的实现. 研究显示，FA与FNA对NOB的抑制在维持中试MBR短程硝化中起重要作用，微生物群落结构的变化与MBR内FA和FNA浓度有关. 

Effects of Free Ammonia and Free Nitrous Acid on Partial Nitrification and Microbial Community Structure in Pilot-Scale MBR

A pilot-scale membrane bioreactor (MBR) was used to treat wastewater with high ammonia nitrogen (NH₄+-N) concentration to explore the effects of free ammonia (FA) and free nitrous acid (FNA) concentrations on partial nitrification and microbial community structure. The removal efficiency of NH₄+-N in the MBR was investigated. The effect of partial nitrification was analyzed by calculating the concentration of FA and FNA. 16S rRNA gene high-throughput sequencing technology was used to analyze microbial community structure and predict functional genes. The results showed that: (1) The NH₄+-N volume load gradually increased from 0.11 to 0.75 kg/(m3·d), and the MBR realized the conversion of complete nitrification into partial nitrification on the 18th day. (2) During the stable operation of the MBR, FA and FNA concentrations were maintained at 1.03-3.52 and 0.033-0.118 mg/L, respectively, the nitrite accumulation rate (NAR) was 65.70%-80.24%, and the steady accumulation of nitrite nitrogen (NO₂--N) was realized. Meanwhile, the NH₄+-N removal efficiency reached 87.92%-97.18%. (3) The change of influent from simulated wastewater to actual industrial wastewater had no significant influence on NAR, indicating that the pilot-scale MBR had strong adaptability. (4) The 16S rRNA gene high-throughput sequencing analysis results showed that, by maintaining the concentration of FA and FNA in MBR, ammonia oxidizing bacteria (AOB) Nitrosomonas (7.99%) could be enriched, and the activity of nitrite oxidizing bacteria (NOB) could be inhibited to achieve partial nitrification. On the 50th day of operation, the relative abundance of Amo (ammonia monooxygenase) functional gene was 371 times that on of day 0, which further verified that the partial nitrification process was realized. The study demonstrated that the inhibition of FA and FNA on NOB played an important role in maintaining partial nitrification in MBR. The change of microbial community structure was related to the concentration of FA and FNA in the MBR.