氧化沟不同A/O分区对脱氮效果影响的模拟实验研究

采用3种不同曝气模式的模拟氧化沟分别形成2、4、7个缺氧-好氧(A/O)分区,研究了3种工况下氧化沟的脱氮方式和脱氮效果.结果表明,在好氧缺氧区体积比例相同的条件下,A/O分区越多,则好氧区平均DO浓度越小,硝化菌活性越低,在2、7个4、A/O分区的3种工况下的硝化菌活性分别为4.80、和3.73mg·g·h4.65-1-1;A/O分区少,则每一分区的缺氧段和好氧段长,进水后反硝化菌利用的有机物就多,在好氧区中的有机物就少,用于硝化的DO量多,从而硝化和脱氮效果好.试验中3种工况的总氮平均去除率分别为60.14%、47.93%、57%,出水总氮平均浓度分别为17.01、22.17和27.92mg·L-1.在氧化沟工艺中,氮的去除途径主要是缺氧反硝化及同步硝化反硝化(SND).分区多,则主要通过同步硝化反硝化脱氮;分区少,则以缺氧反硝化脱氮为主,这是由于碳源限制致使同步硝化反硝化的脱氮效率比缺氧反硝化低.

Simulation study on effects of different A/O partitions of oxidation ditches on nitrogen removal

The three different oxidation ditches with 2, 4 and 7 A/O partitions were simulated via three different aeration modes. The effects of the numbers of partition on the way and efficiency of nitrogen removal were investigated. The results show that the average DO concentration in aerobic zone is small and the activity of nitrobacteria is low with more A/O partitioning under the same ratio of the aerobic and anoxic zone. The nitrobacteria activities are 4.80, 4.65 and 3.73 mg·g^-1·h^-1 when the numbers of A/O partition are 2, 4 and 7, respectively. As the numbers of A/O partition are less, the aerobic and anoxic sections are longer in an A/O partition. Consequently, more organics are used to denitrify, resulting in higher oxygen utilization efficiency and better nitrification and denitrification efficiencies. The average removal efficiency of TN is 60.14%, 47.93% and 33.7% under the three different operation conditions, respectively. The average concentrations of TN are 17.01,22.17 and 27.92 mg·L^-1 in effluent respectively. The ways of nitrogen removal are primarily via anoxic denitrification or simultaneous nitrification and denitrification (SND) in oxidation ditch. TN is removed mainly by SND under larger A/O partitions. On the contrary, anoxic denitrification is predominant in smaller A/O partitions. TN removal efficiency in SND is lower than in anoxic denitrification because of insufficient organics.