Simulation And Optimization Of Treatment Process For ADC Ammonia Nitrigen Wastewater Based On Aspen Plus

A large amount of wastewater containing high ammonia-nitrogen contents is usually produced in the production line of ADC foaming agent, while without treatment it will cause serious pollution to environment. A conventional steam stripping process is often applied to remove the inorganic nitrogen components from the wastewater after pretreatment, but it consumes a lot of steam and energy. With more attention to environment protection, the treatment of ammonia nitrogen wastewater is gradually becoming more and more urgent.By using Aspen Plus software, this study built the steam stripping process simulation model for ammonia nitrogen wastewater (NH3-N:17000 mg/L) from a domestic company. And the accuracy of simulation model was verified by comparison between simulated results and experimental datas. With the steam stripping preliminary process simulation, this study investigated the impact of some factors on NH3-N removal rate, including the theoretical numbers of stripper, the pH of wastewater, the temperature of wastewater, the flow rate of steam and the operating pressure of stripper etc. According to the results, the operating conditions were optimized as well to reduce the steam and energy consumption. This study also made an analysis of material and heat balance. Through a separate process simulation of ammonia-vapor-sulphuric acid absorbing process, the effects of the theoretical numbers of column, the concentration and flow rate of sulfuric acid etc. on NH3 absorption were explored. And the operating conditions were optimized as well to reduce the sulfuric acid and energy consumption. Finally, this study simulated a novel steam-recycle stripping ammonia removal process coupled with ammonia-vapor-sulphuric acid absorbing process for ammonia-nitrogen wastewater, and analyzed of the material and heat balance.The results indicated that when the pH of wastewater was about11, the temperature of wastewater was 80℃, the stripper operated under atmospheric pressure could reduce the steam and energy consumption. In ammonia absorbed process, the optimal theoretical numbers of column was 10, the higher concentration of sulfuric acid the less usage of sulfuric acid. At last, with the simulation of a novel steam-recycle stripping ammonia removal process coupled with ammonia-vapor-sulphuric acid absorbing process for ammonia-nitrogen wastewater, the steam consumption can be reduced to 48 kg/t wastewater and the remaining ammonia-nitrogen content in treated wastewater can be reduced to near zero level under optimized operating conditions, which will provide guidance for industrial ammonia-nitrogen wastewater treatment.