Saline waste disposal reuse for desalination plants for the chlor-alkali industry. The particular case of pozo izquierdo SWRO desalination plant

Abstract

Seawater desalination has become an important and ever-increasing industry which faces up the environmental situation of water scarcity present in some Mediterranean countries and in the Canary Islands (Spain). This activity presents several environmental drawbacks and negative impacts on marine ecosystems, originated mainly by the discharge into the sea of the generated brine. This emphasizes the need of introducing, in the short-term, new management proposals for this particular case which should be both economically viable and effective, not only for new setting up plants, but also for those already installed. As an alternative to brine disposal, an adequate system has been proposed and developed for the reuse of this saline waste coming from reverse osmosis desalination plants in the chlor-alkali industry by NaCl electrolysis in membrane cells. In this paper, the various treatment phases, necessary for the adaptation of this residue as an alternative raw material resource in the chlor-alkali manufacturing industry, are described. This study has been adapted to Pozo Izquierdo Reverse Osmosis Desalination Plant, in Gran Canaria. This new and different residue reuse as raw material supposes the production and exploitation of new chemical resources, as for example: chlorine, hydrogen gas, and caustic soda.