Critical density index for the solar production of bittern from seawater

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.