Process for reducing the nitrate content in water

Abstract

Abstract The present invention provides a process for reducing the nitrate content in water, wherein water containing nitrate is contacted with an anion exchanger containing chloride and/or bicarbonate ions to remove the nitrate, whereafter the exhausted anion exchanger is regenerated, the spent eluate either (a) being divided into two or more portions at least one of which is rich in sulphate and at least one of which is rich in nitrate, the sulphate-rich portion being dumped to drain or being passed to a reaction vessel or vessels in which sulphate ions present therein are precipitated out as calcium salt by the addition of a water-soluble calcium salt or by adding an aqueous slurry of calcium hydroxide and in which denitrification is carried out on the nitrate-rich portion by means of appropriate anaerobic bacteria, a carbon source for the bacteria also being introduced into the reaction vessel and pH correction being carried out, if necessary, or (b) in which reductions of the sulphate and nitrate ion concentrations are carried out on the recovered eluate without dilution into one or more portions, the content of chloride and/or bicarbonate being supplemented by the addition of appropriate sources of chloride and/or bicarbonate, whereafter some or all the solution is recycled to the anion exchanger for use as eluent in a subsequent ion exchange cycle.

Inventors

• 👤 George S. Solt
• 👤 Abraham Klapwijk

Bibliographic Details