新型多功能混凝剂及其微污染有机物强化絮凝原理

Coagulation (flocculation) is one of the widely used techniques in water and wastewater treatment, and is important research direction in the field of environmental engineering. In view of the complex and volatile water pollution status, rapid development of science and technology and increasingly rigorous water quality standards, traditional coagulation technology and old water plant processes are facing tough challenges. Therefore, there is an urgent need to strengthen the improvement of coagulation technique and development of new process principles. . The presence of micro-pollutants including disinfection byproducts in drinking water poses a great threat to safe water supply. Focused on the forefront hot issues of complex and dynamic reaction in multi-media and multi-interface systems, the proposed project is aimed at one of the highlighting problems in water quality and safety control, that is, enhanced removal of organic micro-pollutants. The main content of this project includes dynamic real-time monitoring of multiple water quality parameters, efficient multi-functional coagulant species design and coagulation mechanism investigation, and studies on the floc formation and structure regulation at different stages and reaction process strengthening and optimization of dynamic and complex water quality processes. Through in-depth study of interactions occurred within the system consisting with aqua-particles, micro-pollutants, and multi-functional coagulant and water solution, to understand the collaborative optimization of coagulation with other water treatment processes, in order to promote the new enhanced micro-polluted organic flocculation technology process and technical principle establishment as well as the development of the discipline.

混凝（絮凝）是水与废水处理中得到广泛应用的技术之一，是环境工程领域的重要研究内容。水质污染的复杂多变、科学技术的迅速发展与日趋严格的水质标准，对传统混凝技术和老旧水厂处理工艺提出了严峻的挑战，迫切需要对混凝技术进行强化提高和发展新的工艺原理。本课题基于水源微污染现状和消毒副产物控制及安全供水的目标要求，从多介质、多界面、多体系的复杂动态反应过程的前沿热点问题出发，针对水质安全的重点突出难题--微污染有机物的强化去除，以多重水质参数的动态实时监测、高效多功能混凝形态设计与作用机理研究、不同阶段絮体的形成与结构调控、反应过程的强化与复杂水质动态处理工艺的组合优化为本项目的重点内容。通过对水体颗粒物-微污染物-多功能混凝剂-水溶液的复杂相互作用进行系统深入的研究，以及与其他水处理过程的协同与优化，以此推动新型强化微污染有机物絮凝技术与工艺原理的建立以及学科的创新性发展。

项目从多介质多界面多体系的复杂动态反应过程的前沿热点问题出发，确定最佳混凝剂形态、投量以及形态转化调控方法，优化应用过程中的工艺参数等，最终形成适应于不同水源水质与工艺特点的基于混凝剂与污染物形态匹配的强化混凝关键技术。探索了水源水质对混凝过程的影响及无机复合药剂的应用，建立了纳米羟基聚合铝混凝剂与特征基团小分子有机物络合效应机制，评价了不同形态聚合氯化铝去除有机物性能，制备了纳米磁性聚合铝混凝剂，研究了其混凝特性，并探讨了纳米材料复合混凝剂对新兴微污染物的去除。发现对于浊度较低，有机物含量较高的水体，当Al13投加量达到4.0mg/L时，剩余浊度达到最低，投加量相比于水厂PACl具有明显的优势 (投药量降为1/7)，高效聚合铝的投加量在4.0 mg/L-10.0 mg/L时剩余浊度保持稳定。使用Al13时，在浊度去除率达到最优时 ，剩余DOC含量在1.2 mg/L左右，Al13具有明显优势。针对不同形态聚合氯化铝去除有机物性能评价，不同形态铝盐混凝剂（单体、低聚体、Al13及高聚物）对天然有机物腐殖酸（HA）的去除效果差异并不显著。由于具有较高的正电荷密度，预制的无机高分子混凝剂PACl和Al13在低投加量（1.0mg/L）时对HA的去除效果比传统单体铝盐混凝剂略好，在去除单宁酸时表现尤为突出。针对含羧基有机物与铝系混凝剂的络合效应进行了研究，以揭示具有特征基团的有机物与铝系混凝剂的作用机理。纳米羟基聚合铝中主要成分Al13稳定存在的条件为pH≤6，当pH﹥6后，Al13发生解聚和再聚合，体系中出现了铝的低聚体Al7Ox(OH)y3+和高聚体Al14Ox(OH) y3+。制备了纳米磁性聚合铝混凝剂，研究了其混凝特性，相对于PACl，MPACl在浊度以及有机物去除效率上均有提高，尤其对于PACl2.0 + FSCSP (50 mg/L)的复配混凝剂，浊度去除率可以达到98%，有机物去除率可以达到92%。磁粉的掺入可以强化PACl2.0的吸附架桥和网捕卷扫能力。研究考察了HRP@Fe3O4介导混凝对BPA和EE2的去除性能及重复利用率，三次重复利用对BPA和EE2的去除率均为40%。高岭土对BPA的去除有有轻微的抑制作用，结合高岭土对酶活性的影响可以得知，加入高岭土后酶活性降低，是因为一部分酶被吸附在高岭土上，遮蔽了活性部位，从而导致酶失活，降低了去除率。