Oman Wastewater Services Company (Haya Water) has signed a contract with Spain’s Cadagua and the local Galfar Engineering & Contracting to build a wastewater treatment plant at Darsait.

Haya Water awarded the OMR37m ($96m) contract on 31 October 2010 and signed the contract on 19 January 2011. Cadagua and Galfar Engineering & Contracting will design, build, operate and maintain the 50,000-cubic-metre-a-day (cm/d) Darsait plant in Muscat.

At the signing ceremony, Sultan bin Hamdoun al-Harthy, chairman of Haya Water, said the project should be up and running within three years. The group will continue to operate the project for a further two and half years.

The contract award marks Cadagua’s third in the region. The company was selected by the Royal Commission for Jubail and Yanbu to build a 50,400 cm/d seawater reverse osmosis plant in Saudi Arabia. More recently, Cadagua won a contract to build a desalination plant in Ajman in the UAE.

Bids to build the Darsait project were submitted in February. Athens-based Consolidated Contractors Company (CCC) with France’s Veolia priced the contract at RO59.6m.

France’s Degremont bid RO65.2m. A team of South Korea’s Doosan Heavy Industries & Construction and the local Bahwan Engineering Group submitted two prices, RO77.8m and RO78.9m.

The Darsait catchment is situated within the Greater Muttrah province and covers the areas of Wadi al-Kabir, Hamriya, Ruwi, Bait al-Falaj, Darsait, coastal Darsait, Aynt, Muttrah, Muscat, Sidab and Al-Bustan.

All the areas in the Darsait catchment will be provided with sanitary sewer networks that will discharge their collected wastewater into Darsait sewage treatment plant.

Currently, there is an existing sewer network at Darsait catchment that covers the areas of Ruwi, Bait al-Falaj, most parts of Darsait, small portions of Muttrah and small parts of Wadi al-Kabir.

The remaining portions of Darsait, Wadi al-Kabir and Hamriya areas will be provided with a new sewer network, which is under construction and expected to be completed by the end of 2012.

The main treatment process at Darsait sewage treatment plant will be based on membrane biological reactor (MBR) technology in water treatment. Oman has pioneered the use of MBR. Haya Water already has the world’s largest operational MBR project in operation in the sultanate with a capacity of 55,000 cm/d.