Research Article
Shirui Luo, Yunsong Pang an
Abstract
The recently demonstrated non-membrane, low-temperature directional solvent extraction (DSE) is promising toreduce desalination cost by eliminating the need of membranes and utilizing low-temperature energy sources fromsolar energy or waste heat. This paper investigates the technical feasibility of a continuous DSE water desalinationprocess using decanoic and octanoic acid as directional solvents (DS). A continuous lab-scale DSE prototype isrealized with the aid of electro-coalescence (EC) with a capacity of producing 28 ml/h of freshwater. A preliminaryeconomic analysis shows that the operational cost of DSE desalination is estimated to be ~$3.03/m3. Our resultsreveal 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 efficiencyand effectiveness. Both aspects will be critical to increase water production rate and decrease energy cost of DSEdesalination. Our cost analysis indicates that the desalination cost of DSE can reach ~$0.25/m3, if the DSperformance can be improved by four-folds and the EC efficiency is increased to 90%. In summary, the current worklays a framework upon which further research on the continuous DSE desalination process can be based. Once it ismature and widely deployed, DSE is promising to lower the desalination cost by utilizing low-temperature wasteheat, which will contribute significantly to ameliorating the global water scarcity problem.