Development of a chemo-denitritification process for wastewater

A physico-chemical method for removing nitrite nitrogen from wastewater has been developed. The process depends upon the reaction between ferrous sulfate and nitrite in acidified wastewater. The ferrous ions reduce nitrite nitrogen to gaseous nitrogen compounds such as nitric oxide which are evolved from solution. After the nitrogen has been removed, the pH of the wastestream is raised to the point at which the iron which was added precipitates from solution.

The proposed chemo-denitritification system was demonstrated on a continuous flow basis at the bench scale level. Operating parameters for successful denitritification were found to include a three hour detention period, a reactor pH of less than 3.25, and an Fe :N0^ -N molar ratio of ten. Operation at other values of these parameters produced unacceptable concentrations of either nitrite or nitrate in the system effluent.

Edgar Smith has developed a modified biological nitrification process which converts the ammonium nitrogen of wastewater to nitrite. The combination of the proposed chemo-denitritification process with Smith's nitritification process is potentially more economical than the conventional biological nitrification-denitrification process from which it was derived.