Nitrate removal from groundwater by strongly basic anion exchange resin, Duolite A161 (type 1): Feasibility study and optimization

In this study, a powerfully basic anion exchange resin (type 1): Duolite A161 was used in batch mode sorption studies in order to evaluate its efficiency in removing nitrate ions. In the first part of this work, the optimization of the parameters influencing the efficiency of the resin, namely: The dose of the resin (0.5 to 8 g), the stirring speed (10 to 120 rpm), the contact time (5 to 30 min), the initial nitrate concentration (30 to 180 ppm) and the pH (4 to 11), was carried out. The second part was devoted to studying the competitiveness of anions and cations, commonly present in groundwater, namely: sulfates, bicarbonates, chlorides, fluorides, sodium, potassium, calcium, and magnesium; under the predetermined optimum conditions so as to examine its effect on the retention of nitrate ions by the resin. The results confirmed the effectiveness of the strong base anion exchange resin, such that more than 99% elimination of nitrate ions was obtained at 2 g of resin, 100 mg / L of nitrates, with stirring of 30rpm and during 18 min. On the other hand, the presence of anions: sulfates, chlorides, bicarbonates, and fluorides resulted in an average reduction of 13%, 32%, 23%, and 8% respectively. While the presence of cations: sodium, potassium, calcium, and magnesium, had no effect on the effectiveness of the resin. Hence, the strong bases resin (type 1): Duolite A161 is one of the most attractive commercial exchangers, in terms of efficiency in removing nitrate ions from contaminated groundwater.