MBBR工艺用于污水厂提标改造的低温运行效果

天津市某污水处理厂进行提标改造,出水水质要求达到天津市《城镇污水处理厂污染物排放标准》(DB 12/599—2015)的A类标准,核心生化段采用移动床生物膜反应器(MBBR)工艺进行原位改造,将AAO工艺改为Bardenpho工艺,增设后缺氧区,增强生化系统的脱氮作用,好氧区投加悬浮载体,保障氨氮的稳定达标;深度处理工艺采用气浮、两级臭氧氧化、曝气活性炭滤池以及V型滤池,保障TP、SS、COD稳定达标。实际运行效果显示,在冬季9~11℃的低温条件下,污水厂出水COD、BOD5、氨氮、TN、TP、SS平均值分别为24.52、0.88、0.29、6.82、0.08、2.32 mg/L,稳定达到了提标改造目标。生化段沿程检测结果和硝化试验结果表明,悬浮载体在低温条件下优势突出,硝化速率是活性污泥的10倍,几乎承担了全部的硝化作用,Bardenpho工艺的设计破除了回流比对TN去除的限制,后置缺氧区的TN去除率为24.76%,强化了TN的去除,生化段出水氮素稳定达标。高通量测序结果显示,系统内主要的硝化菌属为Nitrospira,在MBBR区悬浮载体上的相对丰度达到13.14%,而在活性污泥中仅为0.68%。采用MBBR工艺对生化段进行原位改造,能够有效提高系统的硝化能力,是应对冬季低温、确保出水水质达标的有效措施。

Operation Effect of MBBR Applied in Upgrading and Reconstruction of a Wastewater Treatment Plant in Tianjin at Low Temperature

A wastewater treatment plant(WWTP)in Tianjin was upgraded,and the effluent quality was required to meet the level A criteria specified in the Discharge Standard of Pollutants for Municipal Wastewater Treatment Plant(DB 12/599-2015)in Tianjin City.The biochemical unit was reconstructed in situ by applying moving bed biofilm reactor(MBBR)technology,in which the AAO process was changed into Bardenpho process.An additional anoxic zone was added to enhance the nitrogen removal efficiency of the biochemical system,and suspended carriers were added to the aerobic zone to ensure the ammonia nitrogen always meeting the standard.Advanced treatment technologies including air flotation,two-stage ozonation,aerated activated carbon filter and V-type filter were adopted to ensure the TP,SS and COD always meeting the standard.At low temperature of 9-11℃in winter,COD,BOD5,NH3-N,TN,TP and SS in the effluent of the WWTP were 24.52 mg/L,0.88 mg/L,0.29 mg/L,6.82 mg/L,0.08 mg/L and 2.32 mg/L,respectively,which steadily achieved the upgrading target.The suspended carrier had a good performance at low temperature,and the nitrification rate was 10 times that of the activated sludge,indicating that almost all the nitrification was completed by the suspended carrier.The design of Bardenpho process relieved the restriction of reflux ratio to TN removal,and the TN removal efficiency in the post-anaerobic zone was 24.76%,indicating that the TN removal was enhanced and nitrogen in the effluent of the biochemical section reached the standard stably.The main nitrifying bacteria in the system were Nitrospira,which had a relative abundance of 13.14%on the suspended carrier in MBBR,but only 0.68%in activated sludge.The in-situ reconstruction of the biochemical section by MBBR process could effectively improve the nitrification capacity of the system,which was an effective measure to cope with low temperature in winter and ensure the effluent quality to meet the standard.