Research Initiation: Micromixing Effects in Fast Aluminum Neutralization-Precipitation

该项目的目的是确定将流动和小规模混合的数学模型与水处理过程中铝中和沉淀的动力学模型相结合，是否可以预测小型间歇式涡轮反应器中快速碱中和过程中铝形态的性质。虽然平衡化学模型已经提高了对铝系统的化学性质及其作为处理饮用水的化学混凝剂的功效的理解，目前的方法无法预测在用铝混凝剂处理饮用水过程中，可变混合和反应物注射技术对最终铝产品分布的普遍影响。本项目涉及近均质碱中和实验（停止流动技术）中铝产品转化动力学的研究。膜过滤技术和光子相关光谱将用于监测铝聚合物和沉淀颗粒的形成。动力学数据将被纳入试验动力学表达式，并与湍流反应器中铝和碱的大规模和小规模混合（“微混合”）的规范相结合。该数学模型的预测结果将与大型铝中和研究中使用可变混合和反应物注入技术的铝产品形态的实验结果进行比较。这项工作的结果很可能应用于改善水和废水处理过程和系统的工程设计。

The objective of this project is to determine whether combining mathematical models of flow and small scale mixing with kinetic models for the neutralization-precipitation of aluminum in water treatment processes could predict the nature of the speciation of aluminum that occurs during fast-base neutralization in small, batch turbine reactors. While equilibrium chemical models have advanced the understanding of the chemistry of the aluminum system and its efficacy as a chemical coagulant for the treatment of potable waters, current approaches are unable to provide a prediction of the commonly observed effects of variable mixing and reactant injection techniques on final aluminum product distribution during treatment of drinking waters with aluminum coagulants. This project involves a study of the kinetics of aluminum product transformation in near-homogeneous base neutralization experiments (stopped-flow technique). Membrane filtration techniques and photon correlation spectroscopy will be used to monitor the formation of aluminum polymers and precipitate particles. The kinetic data will be incorporated in trial kinetic expressions and combined with specification for large and small scale mixing ("micromixing") of aluminum and base in turbulent reactors. The predictions of this mathematical model will be compared with experimental results for aluminum product speciation in larger scale aluminum neutralization studies with variable mixing and reactant injection techniques. Results of this work are likely to be applied toward improving the engineering design of water and wastewater treatment processes and systems.