紫外/氯预氧化-水力调控强化絮凝处理含藻水的效能与机制研究

The increasing occurrence of harmful algal blooms in drinking water source seriously inhibits flocculation efficiency, which has become one of the worldwide water treatment problems. The development of effective technology for improving algae removal is prospected. Recently, UV/chlorine process has been widely used as novel oxidants to degrade many pollutants. UV/chlorine process also owns strong inactivation abilities on algae cells. Due to inactivated algae cells are easy to be destabilized, UV/chlorine process is expected to be a promising treatment technology to improve flocculation efficiency. However, there are no publications focusing on the pretreatment of algae-containing water by UV/chlorine process to assist flocculation. In this project, UV/chlorine process was firstly used as a preoxidation process to enhance algae removal by coagulation-sedimentation process. The optimizations of flocculation hydraulic conditions were also applied to improve the algae and turbidity removal efficiency. The effects of UV/chlorine process on the removal efficiency of algae cells, variation of NOM components will be investigated. The impacts of flocculation hydraulic conditions on flocs evolution and size distribution will also be analyzed. Furthermore, the synergistic flocculation mechanisms of UV/chlorine process combined with flocculation hydraulic conditions control on the removal of algae and colloid will be proposed, based on the changes of algae cell morphology, NOM characteristics, size distribution, as well as colloid surface properties. In addition, a hydraulic condition based flocs evolution prediction model will be established by the addition the hydraulic parameters on the classical DLCA model. This study provides a potential technology and theoretical support for simultaneous removal of algae and turbidity of algae containing water. Therefore, this project is of great significance to improve drinking water quality and ensure the safety of water supply.

我国水体的藻类污染普遍存在，严重干扰了絮凝效率，导致絮体生成慢、结构松散，含藻水处理已成为水处理难点之一。紫外/氯高级氧化技术可有效灭活藻细胞且降解水中污染物，同时，紫外/氯预氧化结合调控絮凝水力条件可进一步提高絮凝效率，具有极大可行性，但将其用于含藻水强化絮凝的研究尚未开展。本项目以含藻水为研究对象，系统研究紫外/氯预氧化对藻细胞、有机物和胶体表面电性的影响，揭示预氧化强化絮凝的作用机制；利用原位识别技术，分析预氧化后絮凝水力条件对絮体形态、结构、粒径分布的影响，阐明紫外/氯预氧化与调控絮凝水力学条件的协同絮凝机制；利用Matlab平台，在DLCA模型中增加水力学参数，建立基于水力调控的絮体生长预测模型。建立絮凝工艺参数、原水水质与除藻除藻效率的数学关系式，实现絮凝参数优化。本项目为含藻水同步除藻除浊提供可行的技术方案和理论支撑，对提高饮用水水质、保障供水安全具有重要意义。

饮用水源水中的藻类污染物增加了给水处理难度，威胁供水安全，高藻水处理已成为保障供水安全的关键问题之一。本项目系统研究了紫外/氯预氧化-水力调控强化絮凝处理含藻水的效能与机制。在投氯量均为1mg/L时，相比预氯化后絮凝，紫外/氯预氧化能将絮凝过程中藻类和浊度的去除效率分别提高11.5%和7.3%。紫外/氯处理能打断针状藻类，并证明体系中存在含氯自由基和羟基自由基，有效降解水中溶解性有机物浓度，提高水中zeta电位，从而促进大而紧实的絮体形成，全面揭示了紫外/氯的强化絮凝机制；利用原位图像捕捉识别技术，对絮体形成过程进行了深入探究，明确水力调控对絮体生长的影响。在此基础上，本项目以含藻水库原水为对象，构建连续流紫外/氯预氧化-絮凝-沉淀反应器进行长期运行研究，得到关键工艺参数调控方案。本项目研究成果为高藻水污染防控提供基础数据和技术支持。