Final design of an advanced solar dryer for salt recovery from brine effluent of an MED desalination plant

The AQUASOL-Enhanced Zero Discharge Seawater Desalination using Hybrid Solar Technology (EVK1-CT2001-00102) project is one more attempt at using solar energy for water desalination, improving the economics and the environmental performance of a MED desalination plant. Within the project, an advanced solar dryer is being studied, to promote brine concentration and/or ultimate salt recovery from the MED brine effluent, thus contributing to the production of salt, adding one more valuable output to the whole system. This is achieved using the fact that the effluent of the MED plant has a higher salt concentration than the initial sea water, and that the whole system might be installed side by side with a classical saltworks, thus reducing the number of intermediate evaporation steps in a conventional salt production process. Taking into account the specificities of salt production in a classical saltworks, an optimised design based on a passive approach was studied, allowing for an improved system able to deal with a constant brine flow. The construction and preliminary evaluation of a small advanced solar dryer (ASD) prototype permitted a performance assessment of five different configurations for a covered evaporation channel, leading to a final design of a full-scale ASD prototype, erected at Lesvos (Greece). The study of a 1:25 scale model of this final prototype enabled the evaluation and introduction of additional internal flow enhancement strategies. Design choices and final design of the full-scale ASD prototype will be presented.