Environmental Pollution and Health Hazards

Since the more stringent regulations on ammonia for industrial wastewater has implemented, recovery of ammonia from ammonia-rich wastewater has attracted much attention because of the idea of a circular economy. For example, the practice of semiconductor industry by using membrane distillation has generated solution of ammonium sulfate ((NH4)2SO4) more than 2000 tons/month by a company. However, (NH4)2SO4 can be re-used for only industrial propose, resulting in shortcoming in their circular economy route. This study employs vacuum stripping using a Rotating Packed Bed (RPB) to recover ammonia from ammonium sulfate wastewater into a high quality of anhydrous ammonia (Anhydrous NH3) and sodium sulfate (NaSO4), which both anhydrous NH3 and NaSO4 have a wide variety of industrial uses. The results showed that the required operation time to achieve removal efficiency above 90% and concentration of NH4-N below 5000 ppm has been reduced from 12 to 8.3h at the initial condition of 2000 L/day (2.08 tons/day) and initial NH4-N concentration of 60,000-70,000 ppm, temperature of 55 °C and pH>13. Therefore, this study provides a new pathway for circular economy solutions for high-quality ammonium products recovered from the ammonia-rich industrial wastewater.