Study on treatment of rare-earth ammonium nitrogen wastewater by reverse osmosis
反渗透处理稀土氨氮废水试验研究

According to the quality of washing wastewater from deposited ammonium carbonate (WWDAC) discharged from a rare-earth smelting plant, using NH4Cl and NaCl simulated wastewater batch experiments were conducted to investigate the feasibility of the treatment by reverse osmosis. Simulation experiments indicated that under the identical conditions there was higher removal efficiency for treating NaCl by reverse osmosis, compared to NH4Cl. However, NH4Cl in comparison with NaCl has a higher production rate of water. The result of actual wastewater experiment demonstrated that under the conditions of a constant pressure range and a recovery rate of 65%, the removal efficiency of WWDAC with an NH4Cl concentration of 2.85 g/L treated by RO was 77.3%. The RO treatment could be used as pretreatment of ammonium nitrogen. An analysis showed that the operational cost of wastewater treatment was about 2.7 yuan/m3. About 26% of the wastewater treatment costs could be saved compared to that of ammonium nitrogen wastewater with a close concentration by ammonia stripping.