Highly Selective Ammonia Separation Via a Hybrid Sweep Gas–Vacuum Pressure Membrane Degassing System

Abstract

This article describes a novel hybrid membrane degassing system that employs a sweep gas and vacuum pressure to achieve highly selective ammonia (NH3) separation from wastewater. The separation performance of the system is investigated in terms of NH3 selectivity, recovery ratio, and ammonia degassing flux under various operating parameters and feed solution conditions. The hybrid membrane degassing system demonstrated excellent NH3 selectivity, achieving >2000 times higher selectivity for ammonium ions than for competing sodium and calcium ions. Additionally, operating conditions and factors affecting the NH3 recovery ratio—including the degassing membrane type used (sweep gas, vacuum, or hybrid), carbon dioxide injection in the recovery solution, recovery solution temperature, and sweep-gas flow rate. In addition, the influence of the operating conditions and feed solution parameters on the NH3 degassing flux were evaluated. Results indicated that the hybrid membrane degassing system effectively separated and recovered NH3 from simulated industrial wastewater upon parameter optimization, offering a promising approach for sustainable resource recovery and environmental protection.

Keywords: Ammonia, wastewater, Membrane degassing, Selective separation, Sweep gas and vacuum