污水处理厂氧化沟工艺的提标改造研究

Study on Upgrading and Reconstruction of Oxidation Ditch Process in Sewage Treatment Plant

某污水处理厂拟对原氧化沟工艺进行提标改造,为降低改造风险,采用推流式反应器分析了改造方案的可行性。结果表明,增设缺氧区能明显提高硝化效果,但对反硝化效果的改善作用却不大,同时除磷效果有所降低。其中硝化效果的提高是因为不设缺氧区时,有机物通过曝气的去除速率较低,为0.6 mg/(gSS.min);而增设缺氧区后,有机物在缺氧区就能基本被去除,速率可达1.8 mg/(gSS.min),从而增加了硝化时间,提高了硝化效果。不设缺氧区时,在进水混合处的低氧区,既能发生反硝化又能释磷,有很好的反硝化和除磷效果。设置缺氧区后,反硝化环境得到强化,聚磷菌对碳源的竞争力减弱,故反硝化效果略有提高,除磷效果有所下降。根据试验结果,建议将氧化沟的第一个表面曝气机改成潜水推流器,这样可使出水水质基本达到一级A排放标准。

The oxidation ditch process adopted in a sewage treatment plant needed upgrading and reconstruction. The experimental study was done by plug flow reactor to reduce risk, and the feasibility analysis was cmTied out. The results show the nitrification effect is improved by adding anoxic zone, but the denitrification effect is not improved significantly, meanwhile, phosphorus removal efficiency is decreased. The reason of improving of nitrification effect is that the removal rate of organic matter by aerating is low, which is 0.6 mg/（gSS · min）. When adding anoxic zone, organic matter is removed mostly by denitrification, the removal rate is 1.8 mg/（ gSS · min）, so nitrification time is increased, and nitrification effect is improved. When anoxic zone is not set, deuitrification and phosphorus release can occur in the mixed zone because of low DO, and good denitrification and phosphorus removal effect are achieved. When adding anoxic zone, denitrification environment is enhanced, competitive ability of PA0s for carbon source is reduced, so denitrification effect is improved slightly, and phosphorus removal effi- ciency is decreased. According to the experimental result, it is advised that the first surface aerating machine of the oxidation ditch can be replaced by submersible water impellers, and the effluent quality can basically meet the first level A discharge standard.