Using Seawater Reverse Osmosis (SWRO) desalting system for less environmental impacts in Qatar

In Qatar, the multi stage flash (MSF) system which is predominantly used for desalting seawater has negative impacts on the environment due to burning fossil fuels that emit greenhouse gases. Impingement and entrainment of marine organisms at the intake, higher temperatures and salinity as well as chemical pollution at the outfall are the main footprints on the marine environment. The objective of this paper is to show the main benefits on the environment of using the seawater reverse osmosis (SWRO) process over the MSF process for the present desalination capacity of 1.2Mm³/d in 2012. The study showed that the seawater intake would be reduced about 3 times from 8.4Mm³/d to 3.6Mm³/d, which decreases the impingement and entrainment of marine organisms at the intake. Hence the corresponding discharge of brine and cooling water could be reduced from 7.2Mm³/d to 2.4Mm³/d for MSF and SWRO, respectively. Moreover, the thermal pollution of the rejected effluents from MSF plants could be eliminated and the chlorine residual would be reduced dramatically when using SWRO. Finally, the use of SWRO saves up to 75% of energy use, and thus the CO₂ emissions would be reduced from 3.564 to 0.891million (M) tons per year.