Experimental investigation on the chemical reduction of nitrate from groundwater

Abstract

Groundwater is a significant source of water. Adverse health effects have been reported when groundwater with a high nitrate concentration is used for drinking purposes. The objective of this paper was to investigate the effectiveness of a new treatment technology for the reduction of nitrate from groundwater. The optimal operating conditions of chemical nitrate reduction with fine aluminum powder are evaluated through controlled laboratory testing using the standard jar-test apparatus. A maximum of 62% nitrate removal was achieved with the following conditions: 300 mg/l aluminum dose, water temperature of 25°C, pH of 10.7, and initial nitrate concentration of 20 mg/l as N. On completion of the treatment, the concentrations of nitrate, nitrite and ammonia were measured as 8.3, 0.26 and 0.50 mg/l as N, respectively, all within the maximum acceptable concentrations (MAC) of the Canadian guidelines. To ensure adequate quality of the treated water, residue concentrations of total aluminum were also measured for several samples following brief sedimentation, and they averaged 0.07 mg/l. This also complies with the Canadian MAC of 0.1 mg/l. In conclusion, chemical nitrate reduction with aluminum powder is demonstrated to be both effective and safe, and the costs associated with the adaptation of this method may be minimized when combined with conventional water softening processes.