Ca(II)介导的活性污泥微生物种群与胞外多聚物的变化对改进活性污泥絮凝性能的作用

The activated sludge system is a widely used process for biological wastewater treatment, commonly employed for treating wastewaters derived from domestic and industrial sources.The bioflocculation of sludge plays a major role in the treatment efficiency performance of activated sludge wastewater treatment plants. Invalid sludge bioflocculation has been widely studied, but the current state of knowledge about its causes has not yet allowed the formulation of deterministic cause-effect relationships that can be used as solving measures. In certain biological systems, enhancing agents such as calcium (Ca) are applied to improve bioflocculation of sludge. This project will investigate Ca-induced changes of microbial population and extracellular polymeric substances in bioflocculation of activated sludge using an integrated approach combining microbial ecology, chemical and environmental engineering methodologies. The specific aims of this study are to (i) assess the importance of Ca ions for sludge microorganism population, (ii) evaluate the effects of Ca ions on the composition and surface physicochemical properties ( hydrophobicity and Zeta potential ) of sludge EPS, (iii) determine the distribution and speciation of Ca ions in the sludge and EPS, (ⅳ) develop a model to describe the dynamics in the relationship between the microbial population, EPS and Ca-induced aggregation. The results from this project can be used to optimize Ca-assisted bioflocculation in the activated sludge process in terms of efficiency and cost, leading to reduction in the volume of sewage sludge and exploitation of high-loading wastewater biological treatment.

活性污泥工艺是目前应用最广泛的废水生物处理技术。活性污泥不能有效絮凝形成正常絮体几乎是每个污水处理厂都遇到且难以解决的问题。活性污泥的絮凝性能直接制约着废水生物处理设施的正常运行。运用微生物生态、环境化学及环境工程等多学科交叉方法，研究Ca(II)介导的活性污泥微生物种群与胞外多聚物的变化对活性污泥絮凝性能的改进、污水生物处理系统功能稳定性的保持等作用。研究内容包括：Ca(II)对活性污泥微生物种群变动的影响；Ca(II)对活性污泥微生物所分泌EPS组分及表面理化性质(疏水性、Zeta电位等)的影响，Ca(II)在活性污泥、EPS中的形态及空间分布；活性污泥微生物种群、EPS与Ca(II)间动态平衡与反馈关系的建立、保持等。研究结果为Ca(II)强化活性污泥生物絮凝工艺技术的建立提供重要的理论支撑，这些机理的揭示对污水污泥减容、高负荷污水生物处理工艺的开发及稳定运行都有很好的借鉴作用。

活性污泥工艺是目前应用最广泛的废水生物处理技术，普遍用于城市污水和工业废水处理。研究高效低耗、持续稳定的活性污泥絮凝性能的强化技术，对于维持废水生物处理系统的正常运行、水体环境质量的改善有着极其重要的意义。运用微生物生态学、环境工程学及环境化学等多学科交叉的方法，研究Ca2+ 介导的活性污泥微生物种群与胞外多聚物的变化对活性污泥絮凝性能的改进、污水生物处理系统运行稳定性的作用。主要研究内容包括Ca2+对活性污泥微生物种群变动的影响；Ca2+对活性污泥微生物分泌EPS的数量、组分及基团的影响；Ca2+在活性污泥和EPS中的形态及分布；及添加Ca2+于生产性活性污泥系统，改进活性污泥生物活性、维持活性污泥系统稳定性的机理验证。结果表明：外源添加100-150 mg/L Ca2+有助于提高活性污泥絮凝性能、沉降性能及污染物的去除性能，维持活性污泥系统的运行稳定性。一方面，100-150 mg/L Ca2+促进了活性污泥微生物种群多样性增加，脱氮功能菌大量富集，大量分泌EPS的微生物数量增多，EPS组分中尽管蛋白质含量没有显著性增加，但氨基酸组成发生了变化，酪氨酸的含量显著增加，TB-EPS中多糖含量显著增加，这些变化有利于 Ca2+与EPS络合。另一方面，Ca2+在活性污泥和EPS中可以Ca3(PO4)2和碳酸钙（CaCO3）形式存在，增加污泥絮体密度，从而改善了活性污泥的絮凝、沉降性能。当进水中Ca2+浓度进一步增加至200 mg/L时，活性污泥微生物种群多样性下降， Bacillus和Pseudomonas等具有很强蛋白质水解活性的细菌大量富集，导致污泥絮凝、沉降性能恶化。研究结果为Ca2+强化活性污泥生物絮凝工艺技术的建立提供重要的理论支撑，这些机理的揭示对污水污泥减容、高负荷污水生物处理工艺的开发及稳定运行都具有重要的借鉴作用。