Recovering water from brine: Assessments of feasibility and applicability to irrigation processes

Abstract

This study investigated the recovery of moisture from brine drying processes and evaluated the applicability of recovered water for irrigation purposes, while taking into consideration applicable Chilean regulations. For moisture recovery, a heat exchanger was installed on the outside of the solar dryer and connected to an air extractor that ejected the vapor produced during the process; the objective of this setup was to condense vapor produced while drying brine inside the solar dryer. Using refrigerated circulation (0.136 L/s flow), 312 g of freshwater was recovered. Overall condensation performance was 17.2%, with each kg of condensed water requiring 40,480 J/s of transferred condensation heat, a logarithmic mean temperature difference of 12.9 °C, and 7.9 kWh of specific energy consumption. The condensed water was subsequently assessed according to Chilean regulations for irrigation-water quality, as well as through phytotoxicity analyses using lettuce (Lactuca sativa) seeds. All evaluated quality parameters met legal requirements, and the condensed water was nontoxic for L. sativa seeds. The return-on-investment for the process was 5.4 years, and the produced freshwater costed 0.35 US$/L.