铁炭微电解系统填料板结形成机理及微生物再生技术的研究

After long-term run of Fe0/GAC micro-electrolysis system, the packing particles would be passivated completely which would affect the wastewater treatment efficiency seriously. However, the formation mechanism and key influencing factors of packing particles passivation is unclear, and there is no cost-effective control technique for the packing particles passivation. Our research shows that the passive film, which comprised of high compact crystalline compounds of Fe3(PO4)2, FePO4 and FeS, was formed by the reaction and coprecipitation of SO42- and PO43- with iron corrosion products on the surface of packing particles. In preliminary experiments, we found that Fe3(PO4)2 and FePO4 in passive film could be decomposed by the acclimated dephosphorization bacteria under anaerobic conditions, and the P element was released by the form of PO43- ion. In addition, the recent studies suggested that low valence S element could be oxidized to SO42- and released by sulfur oxidizing bacteria. Therefore, we put forward hypothesis that the passivated packing particles were regenerated through the decomposition of passive film by bacteria. We intend to acclimate and screen regeneration bacteria for the passivated packing particles on the base of the studies about the formation mechanism and key influencing factors of the packing particles passivation. And the molecular biology technique was applied to analyze the microbial community structure of regeneration bacteria, which could verify the feasibility of microbial regeneration technology for the passivated packing particles. This study will provide new ideas and new direction to solve the problem of iron-carbon fillers passivation.

铁炭微电解长期运行后填料会板结钝化并严重影响废水处理效率，但是填料板结钝化机理及关键影响因素不详，并且尚无经济高效的填料板结钝化防治技术。我们的研究显示，废水中SO42-和PO43-容易与铁腐蚀产物反应共沉淀到填料表面形成由Fe3(PO4)2, FePO4和FeS等化合物组成的钝化膜，即无机离子是填料板结钝化的关键影响因子之一。在预实验中，我们发现：在厌氧条件下驯化出的脱磷菌能分解Fe3(PO4)2和FePO4，并以PO43-离子的形式释放P元素。同时近年的研究表明硫氧化菌能将低价态的S元素氧化为SO42-并释放。因此，我们提出"微生物分解钝化膜，再生板结填料"的假设。我们拟在研究填料板结钝化机理及关键影响因素的基础上，驯化筛选高效的板结填料再生菌，并应用分子生物学技术分析再生菌的微生物群落结构特征，验证板结填料微生物再生技术的可行性。此研究将为解决填料板结钝化问题提供新思路和新方向。

为了解决铁炭微电解长期运行后填料发生板结钝化的问题，重点研究了填料板结钝化机理及关键影响因素，并且提出经济高效的微生物原位再生技术。研究结果，废水中SO42-和PO43-容易与铁腐蚀产物反应共沉淀到填料表面形成由Fe3(PO4)2, FePO4和FeS等化合物组成的钝化膜，即无机离子是填料板结钝化的关键影响因子。在厌氧条件下微生物分解有机物产生小分子有机酸，从而溶解Fe3(PO4)2和FePO4晶体，并以PO43-离子的形式释放P元素。另外，硫氧化菌能将低价态的S元素氧化为SO42-并释放，即可以解决FeS组分的钝化膜。从而达到实现微生物原位再生板结铁炭填料的目的。研究过程中发现通过改性零价铁材料（即在零价铁表面负载纳米级铜），可以极大地提高零价铁的反应活性，克服零价铁技术的缺点。此研究为解决填料板结钝化问题提供了技术支撑。