磁性杂化絮凝剂结构调控与作用机制研究

Sludge reflux flocculation and magnetic flocculation are both useful methods to strengthen the flocculation effect in wastewater treatment process, but they both have the disadvantage of low efficiency in recycling flocculant. Based on the achievement the applicant has already made in broadening application scope and enhancing flocculation performance of the covalently bound inorganic and organic composite flocculant, this project intends to graft magnetic substances to the flocculant structure by covalently bounds. The magnetic hybrid flocculant can be used to remove pollutants with high efficiency, and the high reflux rate of the flocculant can be realized when the magnetic substance was recycled. The method of regulating the species and structure of the magnetic hybrid flocculant will be investigated to realize high removal efficiency in removing low molecular weight organic matter, nitrate and phosphate. The structure and flocculation performance will be characterized systematically to balance the magnetic properties and flocculation properties of the flocculant. The optimum preparation parameters will be obtained. In molecular level, the density function theory and molecular dynamic simulation will also be used to build models of flocculation systems to guide the structure design and optimization of the flocculant. The interaction mechanism between flocculant and target pollutants will be investigated, and the coordination mechanism of magnetic effect and enmeshment effect in flocculation process will be elucidated. The development and application of magnetic hybrid flocculant will integrate sludge reflux flocculation and magnetic flocculation into one process, laying the foundation for the further development and study on the new technology of flocculation with high efficiency and low cost.

水处理工艺中污泥回流絮凝和磁絮凝均是强化絮凝的有效方法，但二者均存在絮凝剂有效成分回流/回收利用率低的缺点。针对上述问题，申请者结合已取得的共价键型杂化絮凝剂在絮凝应用范围和效果方面的突破，拟将磁性物质以共价键接入絮凝剂结构中，利用该磁性杂化絮凝剂快速高效去除水中污染物，磁性物质回收利用时实现絮凝剂有效成分高效回流。研究磁性杂化絮凝剂结构调控方法，实现磁性杂化絮凝剂对小分子难降解有机物、氮、磷高效去除。系统表征磁性杂化絮凝剂的结构特征和效果，平衡絮凝剂的磁性与絮凝性能并使之协同进行，优化絮凝剂制备条件。在分子层面，利用密度泛函和分子动力学等理论建立模型，通过理论计算指导磁性杂化絮凝剂的设计和优化，探讨絮凝剂与目标污染物的作用机理，阐明絮凝过程中磁性作用与网捕卷扫絮凝的协同机制。磁性杂化絮凝剂的研制和应用将污泥回流絮凝和磁絮凝合二为一，并为进一步开发和研究高效低耗的絮凝新工艺奠定基础。

水处理工艺中污泥回流絮凝和磁絮凝均是强化絮凝的有效方法，但二者均存在絮凝剂有效成分回流/回收利用率低的缺点。针对上述问题，本项目研发出磁性组分与无机-有机杂化絮凝剂通过共价键相连的新型磁性杂化絮凝剂，以便将污泥回流絮凝和磁絮凝合二为一，强化絮凝效果并高效回收絮凝剂有效成分。研究了磁性杂化絮凝剂的制备方法并对絮凝剂的物化性质和结构进行了详细表征，利用二级生物出水验证了絮凝剂对小分子难降解有机物、氮、磷的去除效果，利用分子模拟从分子层面揭示了絮凝组分对硝氮的去除路径和作用机理，利用数值模拟阐明了磁性组分协同强化网捕卷扫的机制，并利用多种再生方法考察了磁性杂化絮凝剂的再生能力。本项目结论归纳如下：. 通过共沉淀法耦合缓慢滴碱法一步制备了磁性杂化絮凝剂，通过多种手段对其物化性质和结构进行了详细表征，发现磁性杂化絮凝剂由纳米磁性颗粒和絮状体构成，磁性组分与絮凝组分通过Fe-O-Si共价键连接，其zeta电位显著高于传统絮凝剂，具有更强的电中和能力。. 磁性杂化絮凝剂能够快速高效地实现二级出水深度处理。相比常规絮凝剂和磁性絮凝剂，磁性杂化絮凝剂对二级生物出水中的浊度、UV254、TP和DOC均显示出最优去除效果，尤其能够去除其他絮凝剂无法去除的溶解性污染物硝氮。常规絮凝剂需要15分钟以上的沉降时间，而磁性杂化絮凝剂仅需要5分钟，显著缩短了水力停留时间和减小絮凝单元占地面积。. 深入阐释了磁性杂化絮凝剂中絮凝组分与磁性组分的协同强化作用。利用分子模拟从分子层面揭示了絮凝组分通过静电作用和去水合作用去除硝氮的机制，利用数值模拟阐明了磁性组分通过增强絮体间互相作用势能来强化絮凝的原理。. 磁性杂化絮凝剂具有良好的再生性能。化学法和微生物法对磁性杂化絮凝剂的再生效果良好，但是会导致废液产生、絮体微生物污染、难分离等问题。进一步提出了道南渗析耦合微生物的再生新方法，取得良好的再生效果并具有潜在的应用前景。