METHODS FOR NITRATE REMOVAL FROM GROUND WATER

Abstract

Groundwater is one of the most important sources of drinking water in rural area of India, and in urban area maximum of domestic water is procured from ground water. Therefore India is largest extractor of ground water in the world. When ground water is used for drinking purpose, contamination in groundwater is not looked after seriously. Though groundwater at shallow depth is considered as most suitable for domestic use, but due to continuous extraction of groundwater in last decade in uncontrolled manner and groundwater level gone much deeper in aquifer. The quality of groundwater in deeper aquifer varies from place to place and contamination is becoming more concentrated. As per Central Groundwater Board survey, in 387 districts in various states has contaminated groundwater containing arsenic, fluoride, nitrate and iron. In Maharashtra most of the districts exceeds in Nitrate contamination above permissible limit of 45 mg/l. Because of this government has banned the villagers to consume groundwater from such contaminated hand pumps. & tube wells. In India for increasing agricultural production huge amount of fertilizers up to 14% of global total is consumed, therefore Nitrate contamination in groundwater is increasing day by day. Concentration of nitrate above 50 mg/l in drinking water
generate various health implications such as infant mortality, spontaneous abortion, birth defects, abdominal pain, diarrhea, vomiting, changes in immune system and methemoglobinemia. Because of various sources of nitrate contamination occurring in groundwater Nitrate removal is one of the emerging challenge. There are various methods of removal of Nitrate from wastewater as well as from drinking water. Distillation, reverse osmosis, ion exchange, electro dialysis, blending, chemical denitrification are the in-home methods for removal of nitrate from drinking water. With the advancement in water treatment technologies, adsorption using activated carbon, carbon nanotubes, biological nitrogen and phosphorus removal, membrane techniques are also used now days in many places. Catalytic denitrification, electroctalytic reduction for denitrification, denitrification using membranebioreactor, combined ion exchange & membrane bioreactor for denitrification, denitrification using nanofilteration are some of immerging technologies. Reverse osmosis, ion exchange, distillation are the method of nitrate removal requiring high initial cost as well as maintenance cost. On the other hand biological denitrification is promising technology widely used for nitrate removal from municipal wastewater. Despite the development in these
technologies, a need remains for a low cost, low maintenance, efficient method to treat nitrate contaminated groundwater.