Severn-Trent wins Chilean mining desalination contract

US water and wastewater treatment company Severn Trent Services has been awarded a contract to provide a seawater desalination plant that will serve the potable and process water needs of the Minera Esperanza copper and gold mine in Antofagasta, Chile.

The plant will draw seawater from the Pacific Ocean, which will be treated using ultrafiltration (UF) and reverse osmosis (RO) systems. The seawater will be pumped 145 km to the mine located at 2,200 m above sea-level.

At the mine site, 5% of the seawater will be processed to obtain the product water. Construction of the 634,000-gpd (2,400 m³/d) plant, owned by Antofagasta PLC of London (70%) and Marubeni Corporation of Tokyo (30%), is expected to be completed in the fourth quarter of 2010. The equipment will be installed and commissioned by Proequipos Ltda of Santiago, Chile.

The Minera Esperanza project is one of the world’s first such projects in which 16-in membranes have been used rather than standard 8-in membranes. By using larger-diameter RO membranes, fewer membranes and pressure vessels are required to produce the same flow of water. Using 16-in membranes also will require fewer pipe connections, shorter pipe runs and a smaller building to house the seawater desalination system.

Two Severn Trent Services UAT™ 705,000-gpd (2,671 m³/d) UF trains using Dow™ UF membranes and two Severn Trent Services UAT 634,000-gpd (2,400 m³/d) RO trains using Dow FilmTec™ 16-in membranes will be installed at the plant. The UF pretreatment system will not require a coagulant and will operate at 90% recovery, while the single-pass RO system will operate at 45% recovery, producing water quality below 400 ppm total dissolved solids.