Enhancing solar-assisted air gap membrane distillation: A sustainable approach to Persian Gulf water desalination.

Abstract

This study presents a novel Solar-Assisted Air Gap Membrane Distillation Desalination System (SAGMDDS) designed for efficient treatment of high-TDS (Total Dissolved Solids) Persian Gulf seawater, leveraging the region's abundant solar irradiance. Unlike conventional setups, this SAGMDDS employs readily available materials and a simple, original module layout to reduce system complexity and cost. Utilizing air gap membrane distillation (AGMD) with polytetrafluoroethylene (PTFE) membranes, the system achieved high desalination efficiency, reducing TDS from 48,000 ppm to 60 ppm, corresponding to over 99.9% salt rejection. The influence of key operational parameters, including feed flow rate, temperature, and air gap uniformity, on performance was evaluated. Critical design challenges such as thermal membrane deformation and uneven condensation leading to air gap collapse, were also addressed through targeted design innovations, including optimized condensate plate inclination angles and spacer reinforcements strategies. Experimental findings highlighted the importance of module configuration. A fragmented, brick-like spacer layout with 90° inclination and 70 L/h feed flow rate at 60 °C yielded the highest permeate flux of 12.3 L/m²·h, while a mesh support structure resulted in the lowest flux (4.5 L/m²·h). This practical and innovative system advances solar-integrated AGMD technology and demonstrates its potential for sustainable desalination in arid, high-salinity regions.