曝气量及亚硝酸盐浓度对SBBR单级自养脱氮系统性能的影响

为了提高单级自养脱氮工艺的脱氮性能及稳定性,采用SBBR反应器,通过连续试验及间歇试验研究了曝气量对单级自养脱氮系统脱氮效率及脱氮负荷的影响,分析了反应器内不同曝气条件下氨氮降解特征、亚硝酸盐质量浓度与氨氮降解速率的关系,并探讨了污泥的亚硝酸盐氧化活性与SBBR反应器稳定性的关系。连续试验结果表明,曝气量从48 L/h提高到88 L/h,总氮平均去除率由72.46%增长至93.00%,总氮平均去除负荷由0.29 kg N/(m3·d)提高至0.57kg N/(m3·d)。间歇试验结果表明:氨氮降解速率随曝气量增加而提高,出水氨氮及总氮质量浓度随曝气量增加而降低;同时曝气期DO质量浓度随曝气量增加而有所升高;在整个SBBR周期内未出现亚硝酸盐积累的现象,亚硝酸氮质量浓度一直较低(低于2.00mg/L),向反应器中添加亚硝酸盐可以促进氨氮的降解;随曝气量增加,由于污泥的亚硝酸盐氧化活性较低,硝化作用产生的硝酸盐并未大幅增长,系统表现出了较好的稳定性;氨氮未完全降解时,反应器内DO质量浓度曲线缓慢下降或基本保持不变,当氨氮完全被去除时,系统不再耗氧,DO质量浓度迅速升高,曲线出现拐点,DO拐点对单级自养脱氮控制有重要参考价值。

On the effects of the aeration rate and the nitrite concentration rate on the behavior of CANON process in SBBR

To improve the performance and stability of the total autotrophic nitrogen removal via nitrite (CANON) process,the paper is intended to make identification and investigation of the effects of the aeration rate on the nitrogen removal efficiency and the nitrogen removal on-loading efficiency of the CANON process through continuous and batch experiments in the SBBR.At the same time,it has also analyzed and discussed the relationship between the ammonia degradation and the nitrite concentration,in addition to the study of the correlation between the nitrite-oxidizing activity and the SBBR stability.In such a situation,the total nitrogen removal efficiency of SBBR on the average can increase from 72.46％ to 93.00％ with the nitrogen removal loading rate rising from 0.29 kg N/(m3 · d) to 0.57 kg N/(m3 · d) with the increase of the aeration rate from 48 L/h to 88 L/h.Thus,the results of the batch experiments prove that the ammonia degradation rate tends to increase with the increase of aeration rate,but the concentration of ammonia and the total nitrogen in the effluent tends to decrease with the increase of aeration rate.What is more,the DO concentration rate during the aeration period of a SBBR cycle tends to increase with the increase of aeration rate,too.Nevertheless,the nitrite accumulation wouldn't occur until the whole period of the reaction with the nitrite concentration is over and then tends to keep below 2 mg/L.Besides,the addition of nitrite to the reactor can also accelerate the ammonia degradation,demonstrating that the low nitrogen removal rate of SBBR can also be resulted from the low nitrite concentration.Moreover,when the aeration rate is stepwise elevated,the ammonia degradation can be gradually improved,though nitrate may not increase significantly because of the very low nitrite-oxidizing activity.Thus,the CANON process proves to be highly stable.Therefore,DO concentration can keep its constant value or tends to get reduced slowly before ammonia is completely depleted,therefore,when ammonia is exhausted,the DO concentration rate may increase abruptly,which is of great significance to the CANON process control.