Taking the tail water of a large wastewater treatment plant in Xinxiang city, Henan Province of China, as the research object, the deep nitrogen and phosphorus removal by constructed wetlands (CWs) for this tail water was studied. Polyhydroxybutyrate valerate (PHBV) and pyrite were selected as the main functional fillers of wetland system to construct a mixotrophic denitrification system by combining heterotrophic denitrification and autotrophic denitrification. Water quality index monitoring and high-throughput sequencing technology were used to explore the removal performance and microbial community structure. The PHBV+pyrite experimental group and PHBV+ceramite control group were set up for continuous operation for 77 days. Results show that when hydraulic retention time (HRT) was 2 hours, NO₃⁻-N, TN, TP and COD concentration are 8.39±1.72 mg/L, 10.41±1.58 mg/L, 0.37 mg/L and 15.7 mg/L, respectively, the average effluent TN concentration reaches at 2.22 mg/L, TP concentration reaches 0.28 mg/L and COD concentration is 32.7 mg/L. The nitrogen removal efficiency of CWs in PHBV+ pyrite group (78.55%) is obviously better than that in PHBV+ceramite group (51.25%), basically meeting the surface water environmental quality standard (GB 3838–2002) Class V. Analysis of the microbial community structure shows that the PHBV + pyrite group advantage bacterium in artificial wetland are autotrophic bacteria Desulfobacter and heterotrophic bacteria unclassified_k__norank_d__Bacteria, the abundance are 23.98% and 12.30% respectively. Mixotrophic denitrification is achieved through coordination of autotrophic and heterotrophic bacteria, in which autotrophic denitrification led by Desulfobacter related to sulfur metabolism may play a major role in systematic nitrogen removal. These results can provide reference for the engineering practice of biological nitrogen and phosphorus removal in tail water of PHBV+pyrite-based CWs.

以河南省新乡市某大型污水处理厂尾水为研究对象, 开展模拟人工湿地尾水深度脱氮除磷研究。选用聚羟基丁酸戊酸酯(PHBV)和硫铁矿作为湿地系统的主要功能填料, 构建异养反硝化与自养反硝化相结合的混合营养反硝化系统。通过水质指标监测和高通量测序等手段, 探究工艺运行效果与微生物群落结构机制。构建PHBV+硫铁矿组(实验组)和PHBV+陶粒组(对照组), 反应器连续运行 77天, 结果表明, 当水力停留时间(HRT)为2小时 , 进水水质为NO₃⁻-N=8.39±1.72 mg/L, TN=10.41±1.58 mg/L, TP=0.37 mg/L, COD=15.7 mg/L 时, 平均出水TN浓度达到2.22 mg/L, TP浓度达到0.28 mg/L, COD浓度为32.7 mg/L, PHBV+硫铁矿组人工湿地脱氮效率(78.55%)明显优于PHBV+陶粒组(51.25%), 基本上达到地表水环境质量标准(GB 3838—2002) V类。微生物群落结构分析表明, PHBV+硫铁矿组人工湿地中的优势菌属为自养菌Desulfobacter和异养菌unclassified_k__norank_d__Bacteria, 丰度分别为 23.98%和12.30%, 通过自养与异养菌的协同, 实现混合营养反硝化, 其中与硫代谢相关Desulfobacter主导的自养反硝化在系统脱氮中可能起主要作用。研究结果可为PHBV+硫铁矿基人工湿地尾水生物脱氮除磷的工程实践提供参考。