14 september 2015

Beach wells for large-scale RO plant

Desalination of seawater provides a viable solution when faced with potable water scarcity.

Sur Boy
Thanks to innovative technologies, desalination has become increasingly more ecologically and economically efficient.

Limited resources and growing needs for water have triggered an increased focus on water conservation in the Sultanate of Oman. The Sur Desalination Plant has put much effort into reducing the environmental impact of the desalination process.  To that end, two avenues were selected – an innovative water intake based on beach wells and an energy recuperation and reuse system through Energy Recovery Devices (ERD).

Project background

In 2007, Veolia was awarded the contract to Build, Own and Operate Sur’s Desalination plant, the first independent desalination project in Oman. Work and commissioning were completed in January 2010 and Veolia has been operating the plant since, on a 20-year contract, providing 80,000 m3/d of drinking water to the region’s 350,000 inhabitants.
In 2014, Veolia in partnership with the national Oman Power and Water Procurement Company (OPWP) celebrated the extension of the contract and announced that an additional 51,000 m3/d would be added to the existing capacity, bringing the total to 131,000 m3/d.

Natural filtration provided by beach well catchment system

High performance Energy Recovery Devices

An innovative approach

Sur is the world’s biggest RO plant connected to beach wells, an innovative water intake system based on natural filtration. Rather than pumping water from the sea through open intake pipes, 80-meter deep beach wells pump it directly onshore from the ground. The natural sand filtration allows for a lighter pretreatment and provides a better water quality: the highly-flexible pumping design ensures constant salinity, low temperature variation and low pH, making for a very stable quality of seawater, even during red-tide algal bloom periods or oil and hydrocarbons spillage in the area.

The durability of the RO membranes is optimized thanks to very low colloidal clogging. The high-quality raw seawater also allows for much lower pretreatment process installation costs as well as a decrease of 64% in the total chemical consumption for this treatment step.

The high-pressure pumps used in the reverse osmosis process tend to require a lot of energy, so reducing the energy consumption of the plant was a key requirement at Sur. To optimize and reduce the final product price and the impact on the environment, highly-efficient Energy Recovery Devices (ERD) were integrated in the RO building. With 24 energy recovery facilities, the DWEER ERD system allows a high recovery grade of 97% of the energy, and vibrations and noise diminution below 85 DB.
One of the main challenges at Sur was to reduce the environmental impact of the desalination process. Veolia provided an innovative solution covering the whole production cycle, from water intake to the reduction of energy consumption and recuperation.