Hybridization of MSF with HDH and MD Desalination Process for Performance Improvement and Mitigation of Environmental Impact

This research proposal is meant to fill an existing gap in the research activities related to recovery of fresh water from the rejected brine from major desalination systems. Multi stage flash desalination units still contribute to a major portion of the desalinated water production in the Kingdom of Saudi Arabia (and Gulf Countries). These systems reject large amounts of brine to the sea from the heat rejection section. This brine is already pre-treated and de-aerated. Therefore, plants reject this high quality treated brine with additives such as anti-scalants, anti-corrosion and anti-fouling agents added to this stream. Brine stream has an adverse effect to the marine life and hence adverse environmental effect. It is therefore proposed to make further use of this stream of salty water through recovering some sweet water using desalination systems that are not affected by high salinity such as Humidification Dehumidification (HDH) systems and membrane distillation systems (MD). They both operate at relatively low top brine temperature and require low-grade energy for their operation. Therefore, recovering a portion of sweet water from the rejected brine stream would be of technical and economic value at low energy expenses. We propose to study analytically the combination of MSF system with either HDH or MD systems to investigate the potential benefits of this combination and propose the most viable and economic choice. Benefits include additional quantity of desalinated water and less brine rejection that is rejected to the sea. Various layout of these systems such as air heated and water heated systems are considered with the possibility of using solar energy for heating. Similarly, direct contact, air gap and water membrane distillation systems will be considered to investigate the most appropriate system for hybridization from both energy based performance and economic merits that is represented by the cost of produced desalinated water.