Integrated solution for DWTP reverse osmosis brine management: CO2 stripping followed by membrane distillation

Abstract

DWTP RO brine disposal options have been studied in this work in terms of technical and economic feasibility. Different pretreatment sequences combining acidification and aeration were carried out and evaluated batchwise in a plate and frame DCMD system at feed and permeate temperatures of 54°C and 21°C respectively. Results showed that acidification provides a simple and inexpensive process in which the initial volume can be reduced by 50% before salts start to precipitate. Aeration followed by acidification provided a volume reduction of 66%, which cannot justify its high OPEX. However, further research in bubbling conditions has the potential to make it a viable process. These pretreatments followed by MD have the potential to become a solid ZLD alternative. Unfortunately, costs derived from brine discharge into the sea are too low to impulse investigation of these technologies.