Electrodeionization has been around for a long time. The primary benefit is that there are no moving parts and the process separates the positive and negative ions for you. The contaminants go to their preferred electrical charge and then removed by membrane technologies.
I think the issue we face with EDI is its lifespan. Some systems only last for about 5 years when facing wastewater with heavy levels of contamination.
I’d like to see what could happen with Liqui-Cel technology and EDI myself. I’ve heard good things about it. http://www.liquicel.com/uploads/documents/TB46_Rev%201%2010-05%20RO%20LMC%20EDI1.pdf