Since the start of the decade, the UAE’s unprecedented population growth has put its public services infrastructure under extreme pressure, and the wastewater sector has been no exception.
In 2008, wastewater generation in Dubai reached crisis point and stories of beaches being polluted as a result of sewage trucks illegally dumping their loads in storm-water drains were reported by newspapers worldwide.
The treatment plant at Al-Aweer in Dubai is designed to handle 260,000 cubic metres a day (cm/d) of wastewater, but by the end of 2008 it was treating about 475,000 cm/d, with flow peaking at 500,000 cm/d at weekends. At the start of 2009, as an emergency measure, an area of desert was designated to receive 65,000 cm/d of raw sewage from tankers.
The two existing plants in Abu Dhabi are similarly overloaded. The Al-Mafraq plant, which handles the wastewater for Abu Dhabi city, is designed to treat 360,000 cm/d, but in 2008 inflow peaked at 475,000 cm/d. The Al‑Zakher facility, which serves Al-Ain municipality, is also overcharged, treating 135,000 cm/d, more than double the 54,000 cm/d it is designed to handle.
“The Sharjah facility has been expanded seven times since it was built but can still barely cope with the inflows”
Dubai Municipality and Abu Dhabi Sewerage Services Company, which is responsible for drainage services in the UAE capital, are in the process of adding new capacity, both by expanding the existing facilities and constructing new treatment plants.
The first phase of a new 300,000-cm/d plant at Jebel Ali in Dubai has already been commissioned and will ease some of the strain on the Al-Aweer facility. In expectation of continued population growth, the plant has been designed to be expandable to 1.2 million cm/d by 2030.
In Abu Dhabi, four major new treatment plants are scheduled to come on line in 2010‑11. Two 300,000-cm/d facilities are under construction at Al-Wathba to meet the drainage needs of Abu Dhabi city. Al-Ain is also getting two new plants: an 80,000 cm/d facility at Al-Saad and a 130,000 cm/d unit at Al-Hamah.
The contracts to build the plants were awarded to private developers on a build-own‑operate-transfer basis under a 25-year -concession.
Sharjah is also planning to add new treatment capacity. With the emirate’s population growing at 6 per cent a year, or an average 100,000 new residents, the pressure on the existing wastewater treatment network is growing.
The main treatment plant, the Sharjah Municipality Drainage Facility, has been expanded seven times since it was commissioned in 1978.
The facility’s current capacity is about 230,000 cm/d, but it can still barely cope with the inflows. An eighth expansion to the existing plant is being planned, along with a new AED1.2bn plant in Al-Saja industrial area, which will have a capacity of 300,000 cm/d.
The plant is due to open in 2012. The municipality will build the plant in three phases, each with a capacity to treat 100,000 cm/d of wastewater.
The other four emirates have experienced more moderate population growth and, unlike Abu Dhabi, Dubai and Sharjah, which invested in centralised sewerage systems in the 1970s and 1980s, they continued to use septic tanks for sewage collection until recently.
Ajman and Fujairah municipalities have used concession agreements to engage inter-national wastewater companies to install sewerage networks in their territories, but as yet there are no centralised wastewater collection, conveyance and treatment systems operating in Ras al-Khaimah or Umm al-Quwain.
The reuse of treated sewage effluent is an area of growing interest in the UAE, due to the scarcity of fresh water in the country. Abu Dhabi aims to reuse all of its treated sewage effluent by early 2010.
The primary applications are for irrigation, firefighting and industrial cooling, but the authorities are keen for it to be used for district cooling in place of the more expensive desalinated water.
About 70 per cent of treated sewage effluent is reused in Dubai, while Abu Dhabi recycles up to 90 per cent. The majority of sludge is sent to landfill, although small amounts are -recycled as fertiliser.