(740d) Novel Process of NH3-N Removal and Recovery in Non-Ferrous Industry Wastewater: Fundamental, Simulation and Commercial Projects

Over 2 million tons of NH₃-N was discharged in China per year recently. Non-ferrous industry wastewater containing NH₃-N and heavy metals is a major contributor of high concentration NH₃-N. Combining distillation and air-stripping technology, NH₃-N is removed and recovered based on relative volatility difference of NH₃ and H₂O in this study. Phase equilibrium, heat equilibrium are calculated to determine process parameters. Hydrodynamic performance like flow field distribution is also calculated. Then, design parameters for distillation trays or structured packing are determined based on calculations and simulations. Besides, the phase diagram of (NH₄)₂SO₄-NH₄Cl-H₂O in 60℃-100℃, the typical salts composition of nonferrous wastewater, is studied to ensure commercial plants’ continuous operation. NH₃-N removal tower with different high efficient column internals are designed to fit different wastewater treatment requirement. The novel process have been used in treatment of NH₃-N wastewater of vanadium, chromium, zirconium, nickel, cobalt, molybdenum, niobium, tantalum and rare earth industry. The projects operation results shows the novel process reached a nearly zero-emission effect with >99.5% NH₃-N was removed and then recovered as ammonia or ammonia salts.