Selective separation of ammonia from wastewater using a sweep gas-vacuum pressure hybrid type membrane degassing system

This article describes a novel hybrid membrane degassing system that combines sweep gas and vacuum pressure to overcome the limitations of conventional selective ammonia (NH₃) separation from wastewater. Under optimized conditions, the system achieved >2000-fold selectivity for NH₃ over competing cations and enabled recovery ratio greater than 80%. The high selectivity was primarily attributed to the pH-induced conversion of ammonium ions (NH₄⁺) into dissolved NH₃, which was effectively facilitated by the hybrid membrane degassing system. Additionally, the operating conditions and factors affecting the NH₃ recovery ratio were investigated. The optimal conditions for maximizing NH₃ recovery were identified as: hybrid operation mode, lower sweep gas flow rate, lower recovery solution temperature, and CO₂ injection for pH control. In addition, the influence of the operating conditions and feed solution parameters on the NH 3 degassing flux were evaluated. The results of this study demonstrate that the hybrid membrane degassing system can effectively separate and recover NH₃ from industrial wastewater, providing a promising strategy for sustainable ammonia recovery.