Salt production by the evaporation of SWRO brine in Eilat: a success story

Abstract

Mekorot Water Company owns and operates a SWRO plant in Eilat for the production of 10,000 m 3/d of desalinated water. This peculiar plant, commissioned during June 1997, is practically dual purpose, for the production of desalinated water and also for the manufacture of high-quality table salt by the Israel Salt Company. The feed to the desalination plant is a blend of 80% seawater and 20% BWRO brine from adjacent BWRO plants. The brine from the SWRO plant is blended with seawater, and this stream is fed to a series of evaporation ponds, and thereafter to the salt processing factory of the salt company. A brine discharge line and other discharge facilities are not needed. Their cost is spared. Also potential non-homogenous salinity distribution profile of the sea is prevented, leaving the sea fauna and flora at this beautiful resort city untouched. The salt production in this configuration increased by 30% compared to salt production from seawater alone. The salt produced is of the highest quality within the range of the most severe standards. It was not easy to reach these goals, and many difficulties were tackled during the first year of operation. These difficulties and the applied solutions are discussed. Also discussed are aspects of the contract between Mekorot, a governmental corporation, and the salt company, which is a private sector corporation. Issues such as operation of the seawater intake serving both the desalination plant and the evaporation ponds, the sharing of the electric power bills, the investment in the intake and the supply piping, requirements imposed on the quality of brine delivered to the evaporation pond, restrictions imposed on the dosed chemicals in the desalination plant, transfer of data between the companies and mutual responsibility are also presented. The paper stresses that salt production from SWRO brine is a lucrative application for the Gulf countries where similar site-specific conditions prevail: strong solar radiation, very low precipitation, low cost desert land, short and easy transportation to ports, and relatively good accessibility to Asian nations, which are large consumers of salt. Today the brine from desalination sites is polluting the Gulf, imposing ever-increasing environmental problems and difficulties in the operation of desalination plants. The paper analyzes the advantages of salt production vis-a-vis seawater pollution and the investment associated with brine discharge.