Hello Carlos In the UK ion ...

Hello Carlos

In the UK ion exchange has been used effectively to reduce nitrate levels once blending with low nitrate sources is not possible.  Assuming Natal has a population of 1 million plus and all the water is supplied from the same wells you are looking at a massive treatment system.  Biological denitrification systems are usually used for wastewater and the plant footprint and operating costs are significant.  Ion exchange and RO are effective but can be expensive in capital and operating costs and there are associated waste brine disposal issues. More recent trends are to chemical denitrification but there are few full scale examples of this.

Technical Report No.6 - Drinking Water Treatment for Nitrate published by the Center for Watershed Resources, University of California, Davis (http://groundwaternitrate.ucdavis.edu/files/139107.pdf) provides and excellent guide to nitrate treatment alternatives with decision trees and costed examples.

Best Regards

Richard