基于厌氧氨氧化的城镇生活污水深度脱氮工艺研究

随着城镇生活污水排放标准的日益严格，现有城市污水处理厂普遍面临提标改造的挑战，较多污水处理厂采用三级脱氮工艺降低出水中氮素含量.本研究以磁混凝预处理后的生活污水为研究对象，采用厌氧氨氧化工艺作为三级脱氮工艺，构建含有生物膜和絮体污泥的UASB反应器，处理A/O（二级生化单元）出水，研究串联、分流进水以及回流等条件下系统的脱氮及有机物去除性能，并通过微生物群落分析揭示各阶段的菌群结构变化.结果表明，当UASB串联A/O时，系统出水氨氮、TN和COD分别为1.21、10.02和30.00 mg·L^-1.当进水分流比为15%时，提升了UASB的脱氮速率（从0.04升高至0.06 kg·m^-3·d^-1），UASB分别贡献了系统TN、NH₄⁺-N和COD去除总量的23.4%、20%和20.7%，当系统出水回流到A区时，能进一步降低出水污染物浓度，NH₄⁺-N仅为1 mg·L^-1，TN为12.03 mg·L^-1.微生物群落结构分析结果表明，在A/O反应器内Proteobacteria为主要菌门，UASB内Planctomycetes门实现富集，生物膜中Planctomycetes丰度为1.93%~8.39%，厌氧氨氧化细菌（以Candidatus Kuenenia为代表）在生物膜和污泥絮体中丰度分别为0.77%~2.19%和0.01%~1.49%.本研究结果表明，基于厌氧氨氧化的三级脱氮工艺能够实现生活污水的深度脱氮，在不增加曝气与碳源投加成本的同时高效去除氨氮、总氮，可为城市生活污水处理厂改造升级提供技术支撑.

Advanced nitrogen removal based on anammox process treating municipal wastewater

To meet more stringent national discharge standards for municipal domestic sewage, the existing municipal wastewater treatment plant (WWTP) is generally faced with challenges of upgrading, and tertiary treatment is thus implemented to further reduce nitrogen concentration. In this study, domestic sewage pretreated by magnetic coagulation was used for advanced biological treatment. Anammox process established in a UASB containing biofilm and activated sludge was applied as tertiary treatment process following an A/O process. The performance of nitrogen and organic matter removals of the combined system was studied under the conditions of serial connections, influent bypass and reflux, and the shifts of microbial community was investigated as well. Results showed that NH₄⁺-N, TN and COD in system effluent was as low as 1.21, 10.02 and 30.00 mg·L^-1, respectively, with the UASB followed the A/O reactor directly. When the influent bypass ratio was at 15%, the nitrogen removal rate in the UASB was enhanced from 0.04 to 0.06 kg·m^-3·d^-1, and the tertiary anammox process contributed to 23.4%, 20% and 20.7% on TN, NH₄⁺-N and COD reduction, respectively. When the effluent of the system was returned back to the A zone, the pollutant concentrations in the effluent can be further reduced at TN of 12.03 mg·L^-1 and NH₄⁺-N of only 1 mg·L^-1. Based on the microbial community structure analysis, Proteobacteria was the main phylum in the A/O reactor, Plantomycetes was enriched in the UASB, and the abundance of Planctomycetes in biofilm is 1.93%~8.39%. The abundance of anammox bacteria, represented by Candidatus Kuenenia, was 0.77%~2.19% in biofilm and 0.01%~1.45% in activated sludge, respectively. The tertiary-stage nitrogen removal process based on anammox realized the advanced nitrogen removal from domestic sewage, with no additional carbon and aeration costs, which was expected to provide technical support for the upgrading municipal WWTP.