Impacts of variable operating conditions on flux and energy efficiency of air gap membrane distillation for brine management

Abstract

In this research paper, we investigate the efficiency of brine treatment using Air Gap Membrane Distillation (AGMD) under varying operational conditions. The study evaluates the performance of the AGMD by examining key metrics, i.e., flux, Salt Rejection Rate (SRR), and Specific Thermal Energy Consumption (STEC) across different flow rates starting from 0.5 L/min to 3.0 L/min and brine salinities ranging from 45 to 65 g/L. To ensure a comprehensive assessment, the membrane was subjected to Scanning Electron Microscopy (SEM) imaging and Fourier-Transform Infrared Spectroscopy (FTIR), both before and after 72 h of testing, providing insights into morphological changes and fouling. Flux varied between 4.7 and 14.0 kg/h/m2, SRR ranged from 80 to 99.9%, and STEC values were lowest at 1.0 L/min. Optimal performance was observed at 2.0 L/min with brine concentration up to 55 g/L, achieving flux of 9.8 kg/h/m2, SRR > 98%, and STEC between 28,793 and 46,069 kWh/m2. SEM and FTIR analysis further highlight the impact of operational parameters on membrane integrity and durability. Experiments were limited to six-hour runs, sufficient for initial fouling dynamics but not long-term degradation. This study offers valuable contributions to the optimization of AGMD processes, aiming to enhance the efficiency and sustainability of desalination technologies.