NOVEL TECHNOLOGY OF NH3-N REMOVAL AND RECOVERY IN RARE EARTH AND
NON-FERROUS INDUSTRY WASTEWATER: FUNDAMENTAL, SIMULATION AND
COMMERCIAL PROJECTS
ABSTRACT
Over 2 million tons of NH3-N was discharged in China per year recently. Rare earth and non-ferrous
industry wastewater containing NH3-N and heavy metals is an important 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 (NH 4)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 NH 3-N wastewater of
rare earth elements, vanadium, chromium, zirconium, nickel, cobalt, molybdenum, niobium and tantalum
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..
KEYWORDS
Ammonia-nitrogen (NH3-N) removal, Wastewater, Nitrogen recovery