Evaluation of the Chemical Drivers behind Membrane Integrity Loss in Halide-Impaired Waters during Chemical Disinfection to Advance Optimal Membrane Structural Design

Purdue University, West Lafayette IN

Investigators

Abstract

160588 Shah In recent years, the role of membrane filtration to treat salt-impaired waters has become more commonplace as freshwater shortages have increased the demand for seawater desalination and water reuse. The process of disinfection and desalination of impaired waters is challenged by the extreme variation in water composition. This project presents a fundamental research framework which will enable future informed design of water treatment strategies under such impaired water conditions, specifically with respect to prolonging membrane lifetime. The central aim of this research project is to integrate governing chemical principles of polymers and aqueous phase chemistry to advance the scientific foundation in membrane engineering applications. The project has the following planned outcomes: (1) prediction of membrane degradation following disinfectant exposure in halide-impaired waters, and, (2) informed design of novel membrane surfaces that are resistant to these effects. To achieve these outcomes, solid membrane materials and model compounds that serve as their chemical analogs will be used to assess chemical kinetics, by-product formation, and morphological and chemical alterations of the membrane surface. Model feedstock waters will contain various mixtures of halide salts (e.g. chloride, bromide, and iodide ions) as well as chemical disinfectants (e.g. free chlorine and chloramines) in order to measure combined chemical effects. The experimental program will identify the effects of water quality (i.e. salinity, temperature) and operational conditions (oxidant dose). This is especially important given that concentration polarization effects observed during membrane filtration can potentially magnify the impact of such parameters. Finally, this project will inform the design of novel membrane surfaces that minimize membrane failure through chemical and structural modifications. The development of such membrane materials would represent a clear technological advancement which could result in significant energy and economic savings to facilities treating impaired waters. Overall, this project will provide desalination industries and water reclamation utilities valuable insight on how impaired waters with high salt (halide) content will effect membrane performance when various disinfection strategies are applied prior to nanofiltration and reverse osmosis treatment.