In 1990 – 1991, The Wallace Group conducted a 24-hour per day, 90-day pilot plant operation to compare three alternative methods: (1) electrodialysis reversal (EDR), (2) reverse osmosis (RO), and (3) membrane softening (MS). At the time, the market for desalting brackish groundwater was split, approximately 50-50 between the EDR and RO processes. Our proposed operation was for surface water.

The pilot testing showed that Brazos River water could be desalted successfully with either MS membrane or EDR technology. Both pilot systems operated with a minimum of problems, producing product water that exceeded State and Federal drinking water standards.

However, RO and its modified process MS provided a better technology (than EDR) for the removal of pathogens and organics, including organic THM precursors. Its product water was deemed healthier and more likely to comply with future regulations. Because of this, RO was the favored technology.

History has now shown our pilot study to be exceedingly correct. The use of EDR systems in municipal applications has diminished, and the use of the now developed reverse osmosis type membranes has flourished, in surface water, wastewater, brackish groundwater, and groundwater under the influence of surface water.