不同电子受体浓度对反硝化除磷的影响及动力学特性

Effect of different electron acceptor concentrations on denitrifying phosphorus removal and dynamic characteristic

以A^2/O-移动床生物膜反应器(MBBR)长期稳定运行的反硝化除磷污泥为研究对象,通过在厌氧段投加乙酸钠、缺氧段投加NO_3^--N,考察反硝化聚磷菌(DPAOs)在不同电子受体浓度(NO_3^--N:10、20、30、40、50 mg·L^(-1))下的脱氮除磷特性以及内碳源转化利用规律。实验结果表明:缺氧段电子受体不足导致吸磷受限,微生物由于处于饥饿状态出现糖原(GLY)降解,增加二次释磷的风险;而电子受体过量会抑制DPAOs的生物活性,降低内碳源的转化利用效率和同步脱氮除磷效果。当NO_3^--N浓度为30～40 mg·L^(-1)时,NO_3^--N和PO_4^(3-)-P去除率分别为92.28%～96.37%和99.39%～100%,聚-β-羟基链烷酸脂(poly-β-hydroxyalkanoate,PHAs)利用率为84.6%～86.2%,达到较好的同步脱氮除磷效果且实现了内碳源的高效利用。动力学参数对比结果表明,不同电子受体浓度下比吸磷速率(PUR)和比反硝化速率(DNR)在4.32～8.18 mg·(g·h)^(-1)、1.81～6.08 mg·(g·h)^(-1)(以VSS计)范围内波动,且NO_3^--N/PO_4^(3-)-P比值可间接反映DPAOs生物活性。

By adding sodium acetate in anaerobic phase and NO3-N in anoxic phase, the denitrification and phosphorus removal characteristics and internal carbon source transformation rules of denitrifying phosphorus accumulating bacteria （DPAOs） were investigated under different electron acceptor concentrations （NO3-N： 10, 20, 30, 40, 50 mg·L-1）, where the denitrifying phosphorus removal activated sludge was taken from an anaerobic/anoxic/oxic-moving bed biofilm reactor （A2/O-MBBR） system under long-term steady operation. The results showed that the lack of electron acceptor of anoxic phase led to restriction of phosphorus absorption, and the risk of second phosphorus release increased due to glycogen （GLY） degradation in hunger state. However, the overdose of electron acceptor inhibited DPAOs bioactivity and reduced the conversion and utilization efficiency of internal carbon source which limited the simultaneous phosphorus and nitrogen removals. When the NO3-N concentration changed from 30 to 40 mg·L-1 under the condition of this research, NO3-N and PO43-P removal rates ranged from 92.28% to 96.37% and 99.39% to 100% respectively with PHAs （poly-β-hydroxyalkanoate） utilization rate of 84.6% to 86.2%, which achieved better simultaneous denitrification and phosphorus removals and realized efficient utilization of internal carbon source. The results of dynamic parameters comparison revealed that phosphorus uptake rate （PUR） and denitrification rate （DNR） fluctuated in 4.32 to 8.18 mg·（g·h）-1 （calculated by VSS） and 1.8 to 6.08 mg·（g·h）-1 under different NO3-N concentrations, and the ratio of NO3-N/PO43-P indirectly reflected DPAOs bioactivity.