Critical density index for the solar production of bittern from seawater

Abstract

Solar extraction of common salt from seawater has been practiced for centuries in a rather crude manner because the process was not performed in stages to obtain a pure salt. The common practice in developing countries is to carry through with the evaporation process to the stage of dryness to facilitate harvesting the salt mix. If salt is harvested prior to the deposition of impurities during the evaporation process then the resulting bittern would provide chemicals which could have many commercial applications particularly in treatment industries. This paper describes an effective procedure for the separation of common salt and impurities. Sufficiently sensitive indicators that would signal the start and deposition of impurities in the course of the solar evaporation process were established. These indicators are particularly useful in regions where advanced desalting technology is not readily available.

Water bridge solar evaporator with salt-resistance and heat localization for efficient desalination

“…Along with continuous evaporation, salt circulation to the water layer is prohibited when saturated brine generated around the evaporating surface, inducing inevitable salt precipitation. 61,62…”

“…Along with continuous evaporation, salt circulation to the water layer is prohibited when saturated brine generated around the evaporating surface, inducing inevitable salt precipitation. 61,62 To avoid salt precipitation in high-salinity brine, heat insulation is compromised in most of the currently reported solar desalination systems, resulting in decreased evaporation rate with the increase in brine salinity. With respect to our system, due to the presence of bridge-shaped water layer, salt resistance and heat localization are achieved simultaneously even for 15 wt% and 20 wt% brine.…”