spring garden desalination plant, barbados

SPRING GARDEN DESALINATIONPLANT, BARBADOS• To augment the existing groundwater supplies, acomplete brackish water RO desalination systemfor delivering 30,000 m 3 / day of potable water fora period of 15 years was provided on abuild-own-operate or privatised basis to the client,the Barbados Water Authority (BWA).• The plant is the largest such brackish waterdesalination facility in the Caribbean. It started upsuccessfully on 15th February 2000. The projectscope included detailed design, engineering,manufacturing, installation, start-up andcommissioning, and operation and maintenance.• Water from the desalination plant passes all ofthe internationally accepted biological and othertest for water quality and the plant can supplydrinking water for up to 20% of the island’s264,000 people.• In addition to its overall aesthetics, thedesalination plant features virtually noiselessproduction and a low cost of operation.The RO Desalination processWellWaterPretreatmentCartridgeFiltersFilteredWaterEnergyRecoverPumpConcentratedStreamROMembranesWater IntakeThe brackish feedwater for the desalination plant ispumped from ten separate 80 foot deep wells, locatedbehind the plant.PretreatmentBefore the actual desalination occurs, the brackish wellwater requires pretreatment. This is primarily toremove the suspended solids and particulates whichmay foul the reverse osmosis (RO) membranes.In addition, antiscalant is included in the pretreatmentto prevent mineral scale build-up, allowing thedesalination plant to run at higher water recoveries.HydratedLimeDesaltedStreamSodiumHypochloriteSite StorageBarbados WaterAuthority (BWA)ReservoirIn the desalination system, up to 75% of the pressurizedfeed water is recovered as fresh water. The remainingportion of the high pressure feedwater concentrate ispassed through an energy-recovery turbine tominimize electrical consumption before it is returnedto the sea via deep well injection.Post treatmentThe desalinated water is further treated for publicconsumption by a lime dosing step, which adds backsome mineral content to the water and ensures goodtaste. The water is then chlorinated by dosing with asmall amount of sodium hypochlorite.DesalinationThe heart of the plant is the RO system. RO is a widelyaccepted membrane-based technology for separatingthe incoming feed water into a desalted stream andconcentrated stream by the application for pressure.The RO system design at the Spring Garden plantutilizes a combination of advanced membranesoperating at low pressure and a single array to reducethe plant’s overall energy requirements and providehigh quality drinking water.DistributionAfter post-treament, the potable water is transferredto the site storage tank where it is constantly tested toensure consistent water quality, conforming to allWorld Health Organisation (WHO) drinking waterquality standards. The water is then transferred to theBWA reservoir for distribution.