强化混凝去除饮用水源水中重金属锑时絮体成长的计算机模拟及其影响机制研究

For prevention and control of heavy metals in drinking waters, enhanced coagulation technique has received widespread attention, as it can give full play to the potential of conventional water treatment processes and then lead to high-quality treated water with low cost. In this project, computer simulation of floc growth will be introduced into experimental study of antimony removal by enhanced coagulation for the first time. To investigate characteristics of virtual-floc morphological evolution, flocculation mesoscopic simulation and floc fractal aggregation/breakage simulation will be conducted, respectively. Then simulation results will be used to analyze the impact of floc growth and particle breakage behaviors on floc morphological characteristics and antimony removal effect during enhanced coagulation jar tests and pilot-scale tests. This can help us to explore transformation rules of targeted pollutant morphology and coagulating mechanisms for antimony removal by enhanced coagulation from a new perspective. Moreover, an efficient and economic proposal of antimony removal by enhanced coagulation will be developed by testing antimony removal stability and estimating running costs in the continuously operational period of pilot-scale plant at the scene of water sources. The study of this project would hopefully deepen the understanding of dynamics of removing antimony by enhanced coagulation, and solid/liquid separation properties. Also, it could provide an important theoretical and technical support for treatment process improvement and positive emergency solution in water treatment plants.

在饮用水源水重金属污染防控时，强化混凝技术能充分发挥常规处理工艺的潜力，以低成本换来高标准的出水水质，受到广泛关注。本项目首次尝试将絮体成长的计算机模拟引入到强化混凝除锑的试验研究中，通过絮凝介观尺度模拟以及对絮体分形凝聚和破碎行为的模拟，考察虚拟絮体形态的演变特征，并将模拟结果用于分析强化混凝小试和中试试验时絮体成长及颗粒破碎行为对其形态特征和除锑效果的影响，进而以全新的视角探讨强化混凝除锑时目标污染物的形态转化规律及作用机制。此外，通过在水源现场测试中试试验装置连续运行时除锑稳定性及估算运行成本，设计研制出高效经济的强化混凝除锑方案。本项目研究有望深化认识强化混凝除锑的动力学及固液分离特性，为实现水厂工艺改造和积极应对解决突发事故等提供重要的理论与技术支持。

强化混凝技术可充分发挥常规处理工艺的潜力，以低成本换来高标准的出水水质，故在饮用水源水重金属污染防控方面受到广泛关注。本项目借助计算机模拟技术（包括颗粒凝聚过程的模拟、絮凝介观尺度模拟及絮体破碎再形成行为的模拟）分析了强化混凝小试和中试试验时絮体成长及颗粒破碎行为对其形态特征和除锑效果的影响，进而从一个全新的视角对强化混凝除锑时目标污染物的形态转化规律及作用机制进行了探讨。同时，还研制出了高效经济的强化混凝除锑方案，且相关成果已运用于湖南省个别水厂的提质改造中。.研究发现，计算机模拟技术在深化认识高分子絮凝剂强化混凝除Sb(V)作用机制方面可提供有效辅助；絮体平均粒径和分形维数的变化主要取决于主导混凝机理，且能通过作用于混凝效果而影响沉后水中悬浮态Sb(V)含量，但对最终除Sb(V)效果（主要为溶解态）的影响极为有限。研究还发现，原水pH值和PFS投量对Sb(V)的去除有重要影响，表现为较低pH值和较高PFS投量均有利于提高Sb(V)的去除率，而温度和混凝搅拌强度的作用却较小，并且助凝剂PAM的投加会在一定程度上削弱去除效果；由于竞争吸附作用的存在,共存阴离子与腐植酸（HA）均对Sb(V)的混凝去除产生负面效应；PFS除Sb(V)过程较为符合准二级动力学模型。在实际运行中，还需尽量避免沉后水因微小絮体过多影响后续工艺的运行工况及出水水质等。.本项目研究有望深化认识强化混凝除锑的动力学及固液分离特性，为实现水厂工艺改造和积极应对解决突发事故等提供重要的理论与技术支持。