Ammonia Recovery with Sweeping Gas Membrane Distillation: Energy and Removal Efficiency Analysis

Membrane distillation (MD) is a thermally driven phase separation process. In sweeping gas membrane distillation (SGMD), an air stream is utilized to capture and remove volatile compounds on the sweeping gas stream. SGMD is an attractive, compact, and efficient process to replace conventional ammonia removal processes such as air stripping or to reduce energy consumption related to nutrient removal of existing processes in wastewater treatment plants. In this study, we present an energetic analysis of humidity-assisted SGMD to remove ammonia from wastewater. We developed a numerical simulation to optimize the design and operating conditions (inlet feed temperature, air flow D rate, brine flow rate, and humidity level of the sweeping gas stream) of the process. We show that operating under multiple stages in series the process can achieve an ammonia removal rate greater than 90% at high air-to-water ratios while maintaining low energy consumption. SGMD is a promising way to separate ammonia from wastewater compared to conventional ammonia stripping processes.