污染河道水质强化脱氮生化工艺研究

Biological process for the denitrification enhancement of the polluted river

应用生化工艺对河道污染水体进行修复是目前最经济的一条途径,但其面临的一个突出问题是在生物脱氮过程中可利用碳源不足,从而影响其处理效果。本研究采用分段进水生物接触氧化工艺来强化受污染水脱氮性能,与传统单点进水方式相比,两段进水对有机物和总氮去除率有显著提升,CODMn平均去除率从50.6%提升到66.3%;总氮平均去除率从31.4%提升到60.9%。沿程统计硝化细菌和反硝化细菌数量,硝化细菌主要集中在曝气区,数量为5.58×106,反硝化细菌主要集中在非曝气区的中后段,数量为6.49×105。同时检测沿程溶解氧和各氮素浓度,溶解氧浓度沿程降低,最后出水仅为0.2 mg/L;氨氮在曝气区转化为硝态氮,在非曝气区硝态氮还原成氮气,其结果进一步证实了硝化细菌和反硝化细菌的分布特征。

Biological process is one of the most economical methods for polluted river treatment. However, the traditional bio-denitrification efficiency is still very low due to the carbon deficiency in this process. In this work, two step-feeding contact biological process is used to treat polluted water. The average CODMn removal efficiency of two step-feeding contact biological process is improved to 66.3% comparing with that of 50.6% of regular single feeding process, while the average total nitrogen removal efficiency of two step-feeding contact biological process is 29.5% higher than that of regular single feeding process. The num- ber of nitrifying bacteria and denitrifying bacteria in the reactor was counted and presented in this paper. The number of nitrifying bacteria is 5.58x10~, and it is concentrated in aeration zone. Most of denitrifying bacteria is in the middle and last part of non-aeration zone, and its number is 6.49x105. Ammonia nitro- gen in aeration zone is transformed into nitrate nitrogen in aeration zone, while nitrate nitrogen is denitri- fled into nitrogen in anoxic zone, which further proves the distribution of nitrifying bacteria and denitrifying bacteria. The dissolved oxygen and nitrogen concentration in the different zone of the reactor are also moni- tored. The oxygen concentration in the reactor decreased gradually along the flow direction, and it is only 0.2 mg/L in the effluent. Therefore, two phase step-feeding process is illustrated to be more effective in or- ganic and nitrogen removal than regular single feeding process.