Industrial Desalination Plant of the Year
Escondida SWRO, Chile
What is it?
A 216,000m³/d seawater reverse osmosis plant serving the Escondida copper mine in Chile’s Atacama Desert. The plant is the largest desalination facility in Latin America.
Who is involved?
The plant was built by Bechtel for client Minera Escondida, whose major shareholders are BHP Billiton and Rio Tinto. Doosan Heavy supplied nine SWRO units, while the pre-treatment system, consisting of 60 dual media filters, was furnished by Doosan Enpure. Flowserve supplied the pumps as well as 27 DWEER energy recovery devices. BEL supplied the pressure vessels. Black & Veatch acted as the engineer of record.
What makes it special?
The expansion of the world’s largest copper mine, at Escondida in Chile’s parched Atacama Desert, was entirely dependent on securing a reliable water supply. By drought-proofing its operations via a seawater desalination plant, Minera Escondida can now go a long way to meeting the rising global demand for copper, driven by anticipated economic expansion in China and the US.
State-of-the-art slurry tunnelling machines were used at the intake and outfall locations so as to minimise the impact on the coastal zone, which supports abundant marine life. The largest diameter offshore drill in the world was used to bore shafts in the sea floor, eliminating the need for more disruptive offshore construction techniques.
Making the physical connection between the ocean and the mine, some 180km distant and at an altitude of 3,100 metres, was a true engineering feat, carried out in the world’s most seismically active region. The successful commissioning of the Escondida desal plant proves that large-scale desal for mining operations is viable in Chile, and paves the way for a raft of similar facilities to serve other mine sites.
Distinction
Sadara SWRO, Saudi Arabia
What is it?
A 178,000m³/d seawater reverse osmosis plant serving the Sadara Chemical Company’s massive manufacturing facility in the industrial city of Jubail, on the Gulf coast of Saudi Arabia. The facility reached full commercial operation in 2016.
Who is involved?
The plant is owned and operated under a 20-year build-own-operate contract by Marafiq, the power and water utility company for the cities of Jubail and Yanbu. The offtaker for the water is Sadara, the Dow/Aramco joint venture based in Jubail. The plant was built by Veolia, which also supplied the DAF pre-treatment system. UF membranes were supplied by Pentair and RO membranes by Dow. ERI supplied energy recovery systems.
What makes it special?
The delivery of the project through a dedicated single-user build-own-operate contract leverages the financial strength of a secure utility to guarantee a supply of high-quality water on a performance-linked basis. The choice of contract structure demonstrates a high degree of confidence in Marafiq as a reliable provider of utility services.
The site deploys an array of high-end pre-treatment technologies – dissolved air flotation followed by self-cleaning microfiltration and ultrafiltration stages – to allow the plant to handle large volumes of water from a feedsource at the extreme reaches of salinity and temperature for a desalination plant.
The installing of a unique dual-train SWRO-then-BWRO process allows for a water recovery level approaching 50%, while a rotary isobaric pressure exchanger gives a specific power consumption of just 5.1kWh/m³, an impressive achievement for a plant of this scale dealing with hostile feedwater conditions.
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