Desalination of brackish groundwater for a prairie community using electrodialysis reversal

Abstract

In October 1987, the Prairie Farm Rehabilitation Administration, a branch of Agriculture Canada with a mandate to drought proof the prairies of Canada, retained CH2M HILL Engineering Ltd. to investigate desalination of the regional aquifer for supplementing the City of Melville's water supply. Reverse Osmosis (RO) and Electrodialysis Reversal (EDR) processes both had potential advantages for this desalting application and a parallel pilot test programme was therefore conducted to evaluate the two systems. This paper discusses the pretreatment and design considerations for both processes and describes the results of over 2000 hours of RO and EDR pilot plant testing. System performance and operational experiences are described together with the process design criteria and cost estimates for the full-scale plants. In general, the EDR system was less susceptible to fouling and was considered to be more amenable to the start/stop operation, and long periods without use, which was required in the Melville application. Pilot testing proved to be extremely important in establishing design information that could not have been predicted by membrane performance programmes. Based on the pilot testing results, the EDR process was preferred for desalting the Melville groundwater supply and a 22 L/s full-scale EDR plant was installed and commissioned in May 1990. Full-scale operating data is given and shows that the EDR system delivered the design product flow rate and quality.