Treatment of wastewater containing high concentrations of ammonia nitrogen using ion exchange resins

Nitrogen in water will induce active biogeochemical effects, such as denitrification and anammox, which release N2O, a greenhouse gas, leading to increasing global warming. Therefore, it is necessary to find an economical and efficient method to treat ammonia nitrogen in the field of wastewater treatment. In this study, two cation exchange resins, D61 and D708, were selected to analyze external environment conditions suitable for the adsorption of ammonia nitrogen by conducting orthogonal experiments. The kinetic and thermodynamic mechanisms were discussed, and cation exchange resins with a high selectivity to NH4+ were selected. The optimum adsorption temperature, pH, and rotation speed for the D61 resin were found to be 32 degrees C, 5, and 150 r/min, respectively. The optimum adsorption temperature and rotation speed for the D708 resin were 40 degrees C and 150 r/min, respectively. The kinetic data could be accurately described using the pseudo-second-order kinetic equation. The results showed that physical and chemical adsorption mechanisms may coexist in the adsorption of NH4+-N. The adsorption process can easily occur and that it is not limited by the pH or rotational speed. The maximum adsorption capacities of the D61 and D708 resins were 44.93 and 31.34 mg/g, respectively; removing ammonia nitrogen from 1 m3 of wastewater requires only 100-110 g of ion exchange resin. The cost is $1.78/m(3) of raw wastewater treated. This is a good alternative to other nitrogen removal systems, particularly in comparison with conventional physicochemical methods and the nitrification-denitrification biochemical process employed currently.