Solar desalination by air-gap membrane distillation: a case study from Algeria

Experiments were conducted with a commercial membrane distillation module, which has an air-gap membrane distillation (AGMD) and spiral-wound configuration. Tests were performed simulating the salinity and temperature of the water using as a case study the Albian aquifer in Algeria. Solar thermal energy from a field of stationary flat-plate solar collectors was supplied to the module. The total productivity of the AGMD system was analyzed for different operational conditions and compared with that from the RO system. The effect of brackish water temperature on the energy consumption was scrutinized, and the energy requirements assessed toward the design of a pilot unit for decentralized autonomous solar desalination. Results showed that for producing a higher volume of distillate, module with less surface area is better. Also, it was found that recovery ratio increases linearly with the temperature difference in both modules. The maximum value was 6% for the highest feed flow rate operated in module 1 with highest surface area. These values are much lower than those obtained with RO processes, which can reach 45%.