不同电子受体诱导活性污泥生物质内源减量

Sludge reduction induced by adenosine triphosphate yield in electron transport pathways with different terminal electron acceptors

活性污泥法是世界上应用最广泛的污水处理工艺.该工艺在净化水质的同时会产生大量的剩余污泥,而剩余污泥处理处置已成为该工艺发展的瓶颈.尽管现有污泥减量技术能够降低污泥产量,但是这些技术自身涉及能量和化学品的消耗,有悖于可持续污水处理的理念.在新陈代谢中,细菌合成取决于电子传递过程中所产生的能量(三磷酸腺苷ATP).不同电子受体因电子传递路径差异导致能量产率不同而影响细菌产率.本研究基于上述分析,以低溶解氧活性污泥工艺为研究对象开展不同电子受体诱导污泥减量性能与机制研究.在低溶解氧下的活性污泥微生物种群结构中,29.7%的微生物为缺氧菌,这些缺氧菌能够利用NOx^-为电子受体.基于热力学电子当量模型及电子传递模型推导出:微生物利用NOx^-作为电子受体时的能量(ATP)产量仅为以O2为电子受体时的2/3.胞外蛋白质组学揭示:低溶解氧系统中,微生物胞外蛋白中涉及电子传递和质子传递的蛋白丰度为8%和4%;而传统活性污泥系统中这个比例仅为2.9%和2%.NOx^-作为电子受体时,更多的蛋白参与了电子传递过程.在低溶解氧系统和常规活性污泥系统中具有氧化还原催化活性的蛋白占23.7%和10.7%.这证实微生物以NOx^-作为电子受体时电子传递活性更加活跃.电子受体的改变诱导了分解代谢与合成代谢之间的基质分配发生变化,微生物以NOx^-作为电子受体参与细胞合成的电子供体fs明显小于O2为电子受体的值.微生物以NOx^-作为电子受体时,更少的能量和物质用于细胞合成,更多的能量被耗散掉.在无需额外的能量和资源消耗下,低溶解氧活性污泥系统获得15.4%的污泥减量效率.本研究成功地诱导微生物转换电子受体实现污泥减量.

Existing sludge reduction technologies go against sustainable wastewater treatment because these technologies themselves involve energy inputs and chemicals consumption. Bacterial yield depends on adenosine triphosphate (ATP) synthesis in metabolism. The sludge minimization induced by ATP yield with different terminal electron acceptors was investigated to reduce energy and chemicals consumption in activated sludge process with low dissolved oxygen (LDO). The results indicated that anoxic bacteria accounted for 29.7% of the total microorganisms under LDO conditions. Anoxic bacteria utilized NOx ? as electron acceptor instead of O2obtaining a lower ATP yield due to the energy transfer efficiency of NOx ? was only 2/3 of that associated with O2 during electron transport. 8.0% of extracellular protein as electron carriers participated in the electron transport process of bacteria in the LDO system;however, only 2.9% of them presented in the conventional activated sludge system. The abundance of catalytic activity proteins involving biological oxidation-reduction in the LDO system sample was twice as much as that of the control system sample. LDO level stimulated the energy metabolism of bacteria by enhancing ATP synthesis, electron transport chain activity, and dehydrogenase activity. More energy was dissipated when NOx ? replaced O2 as electron acceptor, and then fewer cells were generated. Sludge reduction of the LDO system reached 15.4%. Sludge reduction induced by the different electron acceptors was successfully achieved based on bacterial energetics without extra energy and chemicals inputs.