Sustainable seawater desalination by permeate gap membrane distillation technology

Fresh and accessible water for all is an essential part of the world we live in. Water production is linked to energy consumption fundamentally and vice versa. Over recent years, water-energy nexus draws more attention in many research and policy areas as two of the leading sustainable development goals (SDGs). At the current time, more than 2 billion people are living with the risk of reduced access to potable water supplies and it is predicted that by 2050, at least one in four people is likely to live in a country suffered from drinkable water shortages. Consequently, the demand for alternative water sources, including desalinated water and recycled water has increased in recent years. However, one of the main challenges on the current desalination process is on the sustainable operation, that means utilizing less energy-intensive technologies in conjunction with the low-grade waste heat or renewable sources and with minimum environmental side effects.<br><br>This research investigates the potential of using permeate gap membrane distillation (PGMD) technology for sustainable seawater desalination by experimental and numerical analysis of lab and pilot scales PGMD setups, respectively in plate-and-frame and spiral-wound configurations with 0.04, 0.1 and 10 m2 effective membrane areas. The achieved results of the lab-scale study have been applied to estimate the specific thermal energy consumption (STEC) and the effective operating parameters of the conventional PGMD system to achieve the highest system efficiency. Besides, the primary findings have been assisted for the optimum experimental design of the pilot scale spiral-wound PGMD module to be integrated into the renewable energy sources. As an emerging and innovative part of this project and to approach further to sustainable desalination concept, the potential of combined water and power (CWP) production with PGMD configuration has been investigated. The hydraulic pressure has been generated within the module by controlling the permeate gap hydraulic pressure via considering some restrictions at the permeate line. The experimental study has been established by investigation of the performance of different hydrophobic commercial membranes in the CWP process under the constant operating conditions. The achieved results not only explored the effect of produced permeate hydraulic pressure on the permeate flux and power density but also investigated the influence of membrane sample's structure in the CWP process. Overall, the all accomplished stages within this Ph.D. candidature on design, development and theoretical study of PGMD desalination rigs for fresh water production and the CWP purposes, provide a substantial contribution in the field of sustainable water desalination by MD technology. Trust that the resulted publications within the duration of this Ph.D. project, have contributed effectively to develop the sustainability concept on the future desalination systems further.