Water treatment facilities are simply unable to cope with the large quantities of sewage coming out of Dubai's homes and businesses, Dubai Municipality has admitted, according to NCE's sister magazine, MEED.
According to MEED, the problem is so bad that, "People are starting to complain about the odour," said Aisha al-Abdooli, head of sewage treatment plants at Dubai Municipality, speaking at MEED's Wastewater Treatment & Reuse 2007 conference in Abu Dhabi on 10 December.
The quality of treated effluent is also a concern.
Dubai's Al-Aweer treatment works is operating at 70% above design capacity, producing treated sewage below international standards. Designed to treat 260,000 cubic metres a day (cm/d) of sewage, it now treats 460,000 cm/d.
"We were expecting more than 15 per cent annual growth in inflow [of sewage]," said Al-Abdooli. "It is now probably 25 per cent."
Indicators of biological organisms in the water show very high levels. "The treated effluent quality is at times absolutely shocking," says a water sector consultant. "The biological oxygen demand (BOD) [showing bacterial concentrations] levels are so high it is sometimes easy to believe it is raw effluent they are pumping back around the system."
One international consultant tells MEED his company has prepared a report on the problem and will be advising clients to introduce additional treatment for the effluent from Al-Aweer.
"We need to tell our clients who ask for architectural lawns and grass areas that they need to buy additional treatment until Dubai brings new capacity online," says the consultant.
Dubai Electricity & Water Authority says it will no longer provide drinking water for cooling plants, so developers must use treated sewage effluent. The Dubai Municipality will be unlikely to supply water to all of the Emirate's megaprojects. Designated wastewater treatment plants will allow developers to circumvent the issue.
New plants are in the pipeline. "They are looking at a number of short-term solutions," said Al-Abdooli, including a a 65,000-cm/d aerated lagoon to receive sewage and two membrane bioreactor plants, each with a capacity of 25,000 cm/d.
Longer-term, a 300,000-cm/d treatment plant is due to be commissioned in 2010 and is under construction at Jebel Ali, an area which will see a huge increase in population in the coming years.
A 65,000-cm/d expansion of the Al-Aweer plant will be completed in January 2008 and a third-phase expansion of the plant, which would add capacity of 80,000 cm/d, is under consideration.