多段AAO+深床反硝化滤池在城市污水处理厂提标扩容的设计

Design of Multi-stage AAO and Deep Bed Denitrification Filter in Upgrading and Capacity Expansion of Municipal Wastewater Treatment Plant

河北省某污水处理厂原设计规模为4×10^(4)m^(3)/d,主体工艺采用CAST+V型滤池,出水标准执行GB一级A排放标准。根据提标扩容要求,扩建后日处理规模增至7×10^(4)m^(3)/d,出水指标达到河北省地方标准《大清河流域水污染物排放标准》(DB 13/2795-2018)中的重点控制区排放限值。通过对新增处理量、出水水质指标及现状运行情况的分析,采取新增厌缺氧池及改造CAST池为脱氮除磷效果更好的多段AAO工艺,同时深度处理单元调整为高效沉淀+深床反硝化滤池,以确保水质稳定达标。结果表明,多段AAO+深床反硝化滤池工艺在排放标准大幅提高、处理规模增大的情况下,通过分阶段实施,可顺利实现污水厂不停产扩容改造,具有显著的经济和社会效益。改造后处理规模由4×10^(4)m^(3)/d增至7×10^(4)m^(3)/d,出水水质提高至类地表水Ⅳ类标准,其中COD均低于22 mg/L,总磷均值低于0.19 mg/L,总氮均值低于10 mg/L。

The original design scale of a wastewater treatment plant in Hebei Province was 4×10^(4)m^(3)/d.CAST and V type filter was used as the main process and the effluent standard was implemented according to GB first calss A discharge standard.According to the requirements of upgrading and capacity expansion,the daily treatment capacity will be increased to 7×10^(4)m^(3)/d after expansion,and the effluent index will reach the discharge limit of key control areas standard of Hebei Province in DB 13/2795-2018.Based on the analysis of the new treatment capacity,effluent quality index and current operation situation,we add a new anoxic pool and transform CAST cell into multi-stage AAO which has a better nitrogen and phosphorus removal effect,and then we use a high-efficiency sedimentation and a deep bed denitrification filter to ensure the water quality reaching the standard stably.The results show that the multi-stage AAO and deep bed denitrification filter process can smoothly realize the continuous production and capacity expansion of the sewage treatment plant through phased implementation even greatly improving the discharge standard and increasing the treatment scale,so it has remarkable economic and social benefits.After the transformation,the treatment capacity increased from 4×10^(4)m^(3)/d to 7×10^(4)m^(3)/d,and the effluent quality was improved to class IV standard of surface water,in which the average value of COD was lower than 22 mg/L,the average value of total phosphorus was lower than 0.19 mg/L,and the average value of total nitrogen was lower than 10 mg/L.