PN/A工艺在热水解污泥消化液处理工程中的应用研究

Research on the application of the PN/A process in projects of sludge-digestion liquid treatment by thermal hydrolysis

利用短程硝化厌氧氨氧化(PN/A)工艺在北京某污水处理厂成功启动了处理热水解污泥消化液的工程,调试运行结果表明:在接种生物膜填料数占总填料数18%和生物膜上厌氧氨氧化菌(AnAOB)占比为6.8%的情况下可快速启动PN/A系统,并在3个月内可以达到设计处理水量,总氮去除负荷为0.26kg/(m^(3)·d),总氮去除率达到80%以上.通过定量PCR检测和高通量数据发现AOB和AnAOB丰度不同的空间分布特点,项目调试过程中氨氧化菌(ammonia oxidizing bacteria,AOB)和AnAOB均呈稳定增长的趋势,经过3个月启动培养后絮体中AOB丰度达到1011数量级,生物膜中的AnAOB达到1012数量级.实际运行数据证明该旁侧处理系统对水厂主流区产生积极影响,可降低日处理量为40×10^(4) t的污水厂2.9mg/L的进水总氮.另外,在该项目后期运行过程中出现反应池缺氧段和末端游离氨(free ammonia,FA)浓度不足的情况,导致短程硝化过程不稳定,通过控制反应池首端与末端FA浓度及剩余氨氮浓度,可实现对短程硝化过程的快速恢复.

The partial nitrification-anaerobic ammonium oxidation(PN/A)process was successfully launched in a sewage treatment plant in Beijing for the treatment of sludge-digestion liquid treatment by thermal hydrolysis.The optimal operation conditions were proposed based on the project commissioning.Specifically,the PN/A system could be quickly initiated when the proportion of biofilm-inoculated carrier was 18%of the total carrier and the relative abundance of anaerobic ammonium oxidation bacteria(AnAOB)on the biofilm reached 6.8%.The designed water treatment capacity could be achieved within 3months,where the total nitrogen removal load was 0.26kg/(m³·d)and the total nitrogen removal efficiency reached 80%.Quantitative PCR and high-throughput sequencing analysis showed that different spatial distribution characteristics of AOB and AnAOB abundance,and proportions of both ammonia oxidizing bacteria(AOB)and AnAOB increased steadily during the commissioning;and the respective abundance of AOB in flocs and AnAOB on the biofilm reached the magnitude of 1011 and 1012 after 3 months of cultivation.Data from practical operation demonstrated that the sidestream treatment system has a positive impact on the mainstream,where a 2.9 mg/L decrease of the total nitrogen was observed with the influent for a sewage treatment plant of 40×10^(4) t/d.At the last running stage of the project,an insufficient supply of free ammonia(FA)was observed in the anoxic zone of the reaction tank,which resulted in the unstable performance of the PN/A system.However,the system could be quickly restored by controlling the FA concentration at the beginning and end of the reaction tank and the remaining ammonia nitrogen concentration.