日本污水脱氮除磷深度处理工艺分析

Analysis on sewage advanced treatment process for nitrogen and phosphorus removal in Japan

为提高进入琵琶湖水体水质和有效恢复并保持琵琶湖流域水生态环境,日本滋贺县10家下水道污水处理厂全部采用脱氮除磷深度处理工艺。湖南中部净化中心目前规模为26.85万t/d,采用缺氧-好氧循环硝化/反硝化(AO)、厌氧-缺氧-好氧(AAO)和多段进水多级缺氧-好氧硝化/反硝化(SMAO)3种深度处理工艺。AAO工艺是国内城镇污水处理厂广泛采用的二级生化工艺,AO、SMAO工艺在国内还没有应用实例。AO、AAO工艺采用内循环硝化/反硝化反应脱氮,SMAO工艺采用无内循环的多段进水多级硝化/反硝化反应脱氮。AO、SMAO工艺采用化学方式除磷,PAC添加浓度约50mg/L。AAO工艺采用化学和生物组合方式除磷,PAC添加浓度降低到约30 mg/L。AO、AAO工艺出水BOD、CODMn、SS、TN和TP均值分别约为0.9 mg/L、5.2 mg/L、<1 mg/L、6.5 mg/L和0.06 mg/L,相应的去除率约为99.5%、94.2%、>99.5%、78.0%和98.1%。SMAO工艺出水TN约为2.5 mg/L,TN去除率提高到91.6%,其他指标和AO、AAO工艺基本相同。

In order to improve influent water quality of Lake Biwa,and also to restore and maintain the water ecological environment of its watershed,sewage advanced treatment process for nitrogen and phosphorus removal were used in all ten sewage treatment plants in Shiga Japan. Three kinds of sewage advanced treatment processes for nitrogen and phosphorus removal,anoxic-oxic circulating nitrification and denitrifiation process( AO),anaerobic-anoxic-oxic process( AAO) as well as step feed multi-level anoxic-oxic nitrification and denitrification process( SMAO),were employed in Konan-Chubu wastewater reclamation center with a scale of 268 500 t/d. AAO process is widely used as biochemical treatment process for municipal wastewater treatment plant in China. However,there is no engineering application of AO and SMAO process in our country. Nitrogen is removed by internal circulation nitrification and denitrification reaction for AO and AAO processes,however,by step feed multi-level nitrification and denitrification reaction with no internal circulation for SMAO process. Phosphorus is removed by chemical method with addition of coagulant such as PAC for AO and SMAO process,and the addition amount of PAC is about 50 mg / L. However,phosphorus removal was achieved by using combination of chemical and biological methods for AAO process,and the addition amount of PAC can be decreased to about 30 mg / L. The average BOD,CODMn,SS,TN and TP for the effluent of AO and AAO process were about 0. 9 mg / L,5. 2 mg / L,< 1 mg / L,6. 5 mg / L and0. 06 mg / L,respectively,and the corresponding removal rates were 99. 5%,94. 2%,> 99. 5%,78. 0% and 98. 1%,respective. The average TN for the effluent was about 2. 5 mg / L for SMAO process,the corresponding TN removal rate increased to 91. 6%,and other water quality data were the same as AO and AAO process basically.