The Process and Water Quality Specialists
WRF Use of Pre-formed Chloramines
Membrane biofouling is one of the most challenging limitations of using reverse osmosis membranes for seawater desalination (SWRO). This is in part because significant problems exist with using the most commonly used disinfection methods: free-chlorine degrades polyamide membranes, UV light does not leave the necessary disinfectant residual, and inline chloramines formation has proven infeasible due to the rapid kinetics of bromide oxidation by chlorine (which also leads to membrane degradation). Trussell Technologies, Inc. is investigating the application of pre-formed chloramines for biofouling control at the West Basin Municipal Water District’s seawater desalination plant, where chloramines formed prior to mixing with the main process flow have been shown to be relatively stable. This project is intended to (a) confirm that pre-formed chloramines will not adversely affect SWRO membranes, (b) develop an acceptable method for producing pre-formed chloramines on site, and (c) determine if pre-formed chloramines can be successful in controlling biological growth on the membranes. Thus far, the use of pre-formed chloramines is showing great promise as an effective tool for SWRO biofouling control. If successful, this WateReuse Foundation sponsored project will lay the foundation for a new method to prevent biofouling, which could have a profound impact on the cost of seawater desalination.