CAST工艺处理低C／N生活污水的强化脱氮性能

Enhancing nitrogen removal performance of CAST for low ratio of C/N municipal wastewater treatment

研究了不同运行条件对CAST工艺处理低C/N实际生活污水脱氮性能的影响,并对pH值和ORP的变化规律进行了分析。结果表明,传统4 h运行模式下,提高原水C/N比,TN去除效果并无显著提高;对于低C/N生活污水,降低充水比有利于提高出水TN去除率,然而,充水比降至16%时,系统因低负荷运行发生污泥膨胀。在不投加外碳源的情况下,采用分段进水交替A/O运行模式可大幅改善系统脱氮性能,且TN去除率随着交替次数的增多而提高,交替4次平均去除率达87.23%。系统采用实时控制方式运行时,可根据有机物降解、氨氧化及反硝化时pH值和ORP曲线上是否出现拐点,来判断反应系统的曝气以及搅拌时间是否过长、适当或不足。

The nitrogen removal performance of CAST treating low C/N wastewater under different operation conditions was investigated and the profiles of pH and ORP were analyzed. The results showed that TN removal rate couldn＇ t be improved by increasing the C/N ratio of wastewater when the system operated in traditional mold. Decreasing the filling ratio of wastewater was helpful for increasing TN removal rate, while sludge bulking and nitrate accumulation happened because of the operation under long-term condition of low carbon source and incomplete denitrification when the filling ratio was 16%. Nitrogen removal efficiency could be greatly enhanced by alternating anoxie-aerobic process with step feeding without adding external carbon source, and it was in- creased by increasing feed frequency with the maximum value of 87.23%. When real-time control strategy was employed, the judgment on the ending of nitrification and denitrification could be based on the inflection point on the varied curve of ORP and pH during organic degradation, ammonia oxidation and nitrate reduction, and thus reducing aeration and mixing time for the purpose of energy saving.