Performance Analysis of Membrane Distillation in Desalinating and Concentrating Brine on a Pilot Scale

Investigating desalination and brine concentration using advanced membrane and thermal processes is crucial for reducing energy consumption and costs in the desalination industry. Emerging technologies such as forward osmosis (FO), osmotically assisted forward osmosis (OAFO), pressure-assisted forward osmosis (PAFO), electrodialysis (ED), membrane distillation (MD), and solvent extraction desalination (SED) have shown promise at the lab and pilot scales but are not yet commercially viable due to operational and economic challenges. In our study, we focused on MD to evaluate desalination performance using various saline feeds, including fresh, brackish, seawater, and desalination brine from Kuwait, applying both electrical and solar heating methods. Results revealed higher water flux for brackish water compared to seawater and brine, with salt rejection unaffected by increased salinity. Energy consumption was more influenced by feed quantity than by salinity. The water flux ranged from 1.5 to 2 L per square metre per hour (L.m²h-1), with a water recovery of 3.3 to 4% in electrical heating mode of operation. Solar mode operation of the MD system showed a water flux of 0.95 to 1 L.m²h-1, with an average recovery of 2.75%. Our findings highlight the practical potential of MD for solar desalination and brine concentration in remote areas and small-scale industrial waste treatment.