Reducing flux decline and fouling of direct contact membrane distillation by utilizing thermal brine from MSF desalination plant

Abstract

Fouling and scaling is one of the major challenges in membrane distillation process. This study investigates the utilizing of thermal rejected brine produced from multi-stage flash distillation (MSF) to minimize fouling and scaling on membranes in direct contact membrane distillation (DCMD) settings. The effect of operating parameters on permeate flux and the extent of scaling during long time operation was considered and compared when real seawater and reject thermal brine were used. The deposit morphology of scaling was observed using different analytical methods, including scanning electron microscopy and contact angle measurement. Thermal brine showed enhanced performance in terms of flux and scaling compared to seawater. It was found that flux is reduced by 8% compared to 12-20% when the feed to the DCMD was brine was used as compared to seawater. In addition, thermal brine feed showed better anti-fouling behavior compared to the fresh seawater which contains different organic and inorganic contaminants.Furthermore, utilizing waste heat contained in the thermal brine to raise the temperature of the feed was advantageous in increasing the energy efficiency of DCMD process.