局部循环供氧生物膜技术处理分散污水脱氮除磷分析

Nitrogen and Phosphorus Removal Effect of Decentralized Sewage Treatment Using Biofilm Technology with Integration of Local Circulating and Oxygen-supply

针对现代农业科技示范区污水特点,在处理农村生活污水的"两级回流连续供氧生物膜"工艺基础上设计"两级交替回流局部循环供氧生物膜"工艺,并对该工艺处理分散污水的脱氮除磷效能进行了实际应用研究。系统采用沉淀池和循环池交替回流技术,简化调节池为集水池,改造水解酸化池为水解酸化调节池,在平均处理量100 t/d,水力停留时间(HRT)为2 d的情况下,稳定运行2 a结果表明:工艺对有机污染物、NH_3-N、总氮和总磷的去除率分别为71.6%、64.4%、45.5%和72.0%;出水有机污染物、NH3-N、总氮和总磷的平均质量浓度分别为15.3、9.2、17.2、0.8 mg/L,出水符合城镇污水处理厂污染物排放(GB 18918—2002)一级B标准。进水有机污染物与总氮比值、有机污染物与总磷比值与总磷、有机污染物和NH3-N去除率呈正相关关系,与总氮去除率呈负相关关系。实践证实,该工艺对波动较大的冬季低温期及复杂水质期高冲击、高负荷的特殊分散污水具有较好的脱氮除磷和有机物去除能力。

Simultaneous nitrogen and phosphorus removal performance of a kind of biomembrane process integrated with partial circulatory aeration and two-stage treated water returning alternately was studied by utilizing the technology to treat typical decentralized wastewater from Modern Agricultural Science and Technology Innovation Base in Tianjin. The system with a total effective volume of 234 m^3 was composed of collecting tank,hydrolysis acidification balance tank,partial aerobic tank,secondary sedimentation tank and circulation tank. Sewage pumps in collecting tank were controlled by PLC automatic control system. Sludge pumps in secondary sedimentation tank worked 10 min every 2 h controlled by PLC automatic control system. Circulating water pumps in circulation tank controlled by PLC automatic control system could maintain necessary water flowing when inflowing and sludge returning were simultaneously stopped. The nominal air delivery of clover roots blowers in equipment room was 2. 0 m^3/ h. Hydrolysis acidification balance tank and partial aerobic tank were both filled with combined bio-carrier at a filling height of 2 m and the filling percentage and hydraulic load of the two tanks were 60%,1. 25 m^3/（ m^3·d）and 70%,2. 0 m^3/（ m^3·d）,respectively. The operation of the whole system was controlled by PLC.Pumps for inflow worked intermittently and total time of it＇s working was 6 h every day. Aeration was continuous and partial. Since June,2013,the test running was completed,the system was always operating formally in the way of intermittent inflow,partial aeration and alternate wastewate return. The raw decentralized wastewater was discharged from office buiding,research activities building,expert floor,restaurant,guest house and industry incubator and except for those from restaurants and toilets,which were firstly discharged into oil separation tank and septic tank for pre-treating,the most wasdischarged directly into the system to treat. The designed treating capacity of this system was 150 m^3/ d and the maximum influent quantity,minimum influent quantity and average influent quantity in reality was 140 m^3/ d,80 m^3/ d and 100 m^3/ d,respectively. The return ratio was controlled at 2 ∶ 1 by PLC.Through long tem operation of two years,the results showed that the average removal percentages for BOD5,NH3-N,TN and TP were 71. 6%,64. 4%,45. 5% and 72. 0%,respectively,and the average effluent concentrations of BOD5,NH3-N,TN and TP were 15. 3 mg / L,9. 2 mg / L,17. 2 mg / L and0. 8 mg / L,respectively. It was indicated that the quality of treated effluent was up to ＂Discharge Standard of Pollutants for Municipal Wastewater Treatment Plant＂level 1B and treated water can be used as irrigation water. Nitrogen and phosphorus removal function was also well established when treating decentralized wastewater with high fluctuation and high loading. And it was further observed that removal percentages for BOD5,NH3-N and TP were increased with the increase of BOD5/ TN and removal percentage for TN was decreased with the increase of BOD5/ TN and BOD5/ TP,while TN / TP was not one of main contributors to affecting removal percentage of BOD5,NH3-N,TN and TP.