Water system can fight UAE algae's red tide

A new desalination plant in Sharjah is set to reduce red tide, with the latest technology utilised to remove pollutants.

United Arab Emirates- Fujairah - February 3, 2010:

NATIONAL: This pressure vessel injects air and pressure into sea water at the Vedia Water-OTV & Sidem Seawater Treatment Plant in Fujairah on Wednesday, February 3, 2010. The new plant has devised a way to deal with red tide interference in water desalination. Amy Leang/The National

ABU DHABI // The capital's second desalination plant on the Gulf of Oman coast will have advanced technology never before used in the Middle East to treat harmful blooms of marine algae. Its installation was prompted by the red algae, or red tide, which hit the UAE's east coast for eight months from August 2008. Water desalination plants incurred large losses as the algae clogged filters.

The Abu Dhabi Water Resources Master Plan estimated losses of more than US$100,000 (Dh368,000) a day for the industry. "Production in some plants decreased by 30 to 40 per cent," said Mohammad Naji, deputy engineering manager at Veolia Water, the Dubai-based company behind the new system. "The red algae stuck to the sand filters and they became less effective." To combat the problem, a system known as dissolved air flotation (DAF) is being tested at the new desalination plant in Fujairah, a technique which has been used successfully elsewhere in the world.

The use of DAF means that, rather than washing sand filters every day, one wash will be required every 38 hours. "This means our plant has less losses, less power consumption and no disturbance of the production," said Mr Naji. Testing at a small pilot plant with a capacity of 28 cubic metres per hour started 18 months ago. Construction of a facility with a capacity of 16,000 cubic metres per hour started at the end of 2008.

The new plant, Fujairah F2, is at Qidfa, approximately 5km south of Khor Fakkan. At full capacity, the plant will be able to produce 2,000 MW of electricity and 130 million imperial gallons of water per day. Veolia Water was responsible for the design and building of two desalination plants within the project. "It is like opening a bottle of soda water," said Michel Bouissou, the project director for the Fujairah F2 Plant.

He explained that as the mixture of water and compressed air is released at atmospheric pressure, tiny air bubbles float to the surface. The chemicals in the mix - ferric chloride, sulphuric acid and some polychloride - ensure that pollutants dissolved in the water adhere to the air bubbles. "When the bubbles float up, they take away the red algae and other pollutants with them," he said. The system features 16 large concrete tanks, each capable of handling a flow of 1,000 cubic metres per hour. Water travels through the system at a speed of 30 metres per hour.

Testing will start next month and the system is expected to be fully operational at the end of May. Abu Dhabi already has one plant at Qidfa. Operated by the Emirates SembCorp Water and Power Company, it has a net power generation capacity of 500 MW and 100 million imperial gallons of water per day. The emirate taps the water of the Gulf of Oman as it becomes increasingly clear that the shallow and salty Arabian Gulf cannot indefinitely sustain the infrastructure needed to quench GCC countries' demands.

Algae, also known as phytoplancton, are tiny micro-organisms invisible to the naked eye. Since many are a vital food source for other marine creatures, their numbers are kept in check. Sometimes, however, due to a variety of natural or man-made reasons, the ocean's balance is disrupted and species from one organisms start multiplying rapidly, causing an algal bloom. vtodorova@thenational.ae