The recently demonstrated non-membrane, low-temperature directional solvent extraction (DSE) is promising to reduce desalination cost by eliminating the need of membranes and utilizing low-temperature energy sources from solar energy or waste heat. This paper investigates the technical feasibility of a continuous DSE water desalination process using decanoic and octanoic acid as directional solvents (DS). A continuous lab-scale DSE prototype is realized with the aid of electro-coalescence (EC) with a capacity of producing 28 ml/h of freshwater. A preliminary economic analysis shows that the operational cost of DSE desalination is estimated to be ~$3.03/m3. Our results reveal two critical technological aspects that need further research to push DSE closer to deployment. These include (1) identifying more effective DSs with higher water yield; (2) optimizing the EC to improve the separation efficiency and effectiveness. Both aspects will be critical to increase water production rate and decrease energy cost of DSE desalination. Our cost analysis indicates that the desalination cost of DSE can reach ~$0.25/m3, if the DS performance can be improved by four-folds and the EC efficiency is increased to 90%. In summary, the current work lays a framework upon which further research on the continuous DSE desalination process can be based. Once it is mature and widely deployed, DSE is promising to lower the desalination cost by utilizing low-temperature waste heat, which will contribute significantly to ameliorating the global water scarcity problem.
|Original language||English (US)|
|Journal||Journal of Chemical Engineering & Process Technology|
|State||Published - 2018|
- Directional solvent extraction
- Waste heat