A state-of-art overview of multi-stage flash desalination and water treatment: Principles, challenges, and heat recovery in hybrid systems

One of the most reliable techniques in thermal desalination is the multistage flash desalination process, especially in North Africa, the Middle East, and Gulf Regions. In the current work, in the beginning, the VOSviewer program was used to carry out a bibliometric analysis to show how multistage flashing systems have evolved and the issues they have with their solutions. The visualization showed that the United Kingdom, the United States, and Saudi Arabia are the countries with the most publication numbers. This paper aims to give a complete overview of the challenges facing multistage flash desalination and the energy utilization methods as well. Several operational or constructional parameters affect the productivity, energy consumption, and the distillate total dissolved solids. One of these parameters is the scale formation, which decreases the heat exchange area affecting the condenser's effectiveness and affecting the water quality when those crystal deposits grow on the walls or the demister. Scale inhibition methods and the influence of varied geometries of a single component in the multistage flashing module are reviewed in this article, as well as the state-of-the-art of the most evident characteristics that affect the entire profile of the multistage flashing plants. On the other hand, combining different systems as a hybrid system always results in better energy utilization, especially for thermal-based systems, and lower operating costs. Heat as an energy source is often associated with low grid energy exhaust. For multistage flashing desalination, hybrid systems are developed to use another system exhaust as a heat source or use the hot brine of multistage flashing as a preheater for another system. As for a hybrid system, the daily water output reached 5.74 m3/day, and the green hydrogen amount of 20.39 kg/day, depending on the area of solar collectors.