Energy Recovery Devices in Seawater Reverse Osmosis Desalination Plants with Emphasis on Efficiency and Economical Analysis of Isobaric versus Centrifugal Devices - Dissertation Example

The reduction in energy consumption of desalination plants that were based on the SWRO technology emerged as a major driver of the technology revolution in this field. The improvement of membrane life and salt rejection, increase in recovery, and decrease in energy consumption have been the primary criteria for sifting through available technologies for incorporation in desalination plants. Many developments have, ever since, occurred in this direction. The membrane life has multiplied and the Total Dissolved Solids in the product are now as low as 100 mg/L.

In addition, recoveries of 40-50% have been achieved. By recycling energy, many SWRO desalination plants have significantly lowered their total energy consumption. With the help of energy recovery devices (ERDs), it is now possible to decrease power consumption and increase the efficiency of the seawater reverse osmosis desalination plant.The first large-scale municipal SWRO plant was installed in 1980 in Jeddah, Saudi Arabia. This plant consumed 8 kilowatt-hours of energy per cubic meter of water produced.

This consumed energy was less than half of what was usually consumed by other conventional distillation processes. However, SWRO desalination technology has one disadvantage. The seawater, which is to be desalinated, is pressurized with the help of high-pressure pumps. A large amount of energy is consumed during this process. Once the desalination is complete, the remaining reject water has to be eliminated as waste. Since the brine reject produced in this process has high pressure, simply dumping it back into the sea is a waste of energy.

This pressure can be reused and thus, the energy could be recycled. This idea led to the innovation of energy recovery devices (ERDs) that prevent the wastage of energy in the SWRO process. The hydraulic energy in the highly pressurized reject brine can be re-used with the help of ERDs, and energy consumption can thus be reduced to significantly high amounts.