Nitrate Ion Removal from Water Wells

The city of Natal, Brazil, is supplied by water from water wells contaminated by the nitrate ion.

Concentrations are in the range of 15 to 80 mg / l of nitrate as nitrogen, well above the limit allowed by the World Health Organization (10 mg / l).

Intake of water contaminated by nitrate causes various diseases and diseases.

Which inexpensive water treatment technologies can solve the problem of high nitrate concentrations in public water supply?