1. Treated Wastewater Management and Reuse: Abu Dhabi Emirate Case Study
MOHAMED DAWOUD
Advisor, Water Resources, Environment Agency – Abu Dhabi
United Arab Emirates
Introduction:
In arid regions treated wastewater is an environmental, social, and economic
resource that needs to be managed in appropriate way. Reusing of treated
effluent that is normally discharged to the environment from municipal
wastewater treatment plants is receiving an increasing attention as a reliable
water resource. The volume of this resource is being considered in the planning
and implementation of water resources projects. Irrigating agricultural crops
with recycled wastewater has been practiced in arid and semi-arid regions and is
rapidly getting popular in the countries of the Arab Regions. In the last three
decades, rapid economic development coupled with population growth and
large agricultural sector expansion have forced the government to rely on non-
conventional water resources such as desalination and treated wastewater as
secondary sources for irrigation water supply. Treated wastewater has the most
potential as marginal water suitable for growing forages, landscaping, fruit
orchards and non-vegetative crops. In Abu Dhabi Emirate, the annual
production of treated wastewater is about 250 million cubic meters produced by
32 tretment plants as shown in Figure (1) which is about 7.2% of the total
Emirate water production. Only about 60% of the treated wastewater is reused
in wetlands, landscaping, and recreation areas due to the capacity of distribution
system after treatment.
Figure 1: Location of Wastewater Treatment plants in Abu Dhabi
Abu Dhabi Emirate is an arid region where the average annual rainfall is less
than 100mm. The water resources components found within the Emirate are
traditional or conventional resources (rainfall, springs, wadis, lakes, and
groundwater) and non-traditional or unconventional resources (desalinated
water and treated wastewater). Groundwater occurs in the Emirate as either
consolidated or unconsolidated surficial deposit aquifers or as
bedrock/structural aquifers and contributes 63.6% to the total water demand,
followed by desalinated water (29.2%) and treated wastewater (7.2%) as shown
in Figure (1). Groundwater supply is decreasing and the imbalance between
supply and demand is being filled by ever increasing amounts of desalinated
water. Although wastewater reclamation and reuse has been recognized as a
promising strategy to alleviating water scarcity and reducing the impacts on the
environment, the actual reuse of treated wastewater is rather limited. In Abu
Dhabi Emirate only 60% of the total treated quantities are reused and the rest
are discharged to environment as show in Figure (2).
Figure 2: Water Resources in Abu Dhabi Emirate.
Present Wastewater Production and Use
Wastewater initially provided the bulk of the water for amenity and landscaping
purposes. However, as the volume increased from the 1990s supply outstripped
the irrigation systems capacity to fully utilize it. Where this occurred irrigation
shortages were made up from desalinated water. The fact that desalinated water
is seven times more expensive to produce had no impact on this allocation
because it was free for municipal uses. Thus there were few incentives to better
manage the recycled water supply or remove the constraints in the distribution
network. Independent calculations of irrigations application in the Abu Dhabi
area put current use at 4,800 mm/year – at least double the amount needed for
urban greening. Until recently the main drawback of the 200 km distribution
network on Abu Dhabi Island was the relatively small size of the pipes. In
addition, the flows are still controlled manually and water is not properly
budgeted and storage reservoir operation (and there are 119 storage reservoirs)
is haphazard – some reservoirs receive excessive flow while others get no flow
at all or very limited flows as shown in Figure (3).
Figure 3: Water Resources Use in Abu Dhabi
Future Wastewater Production and Use
“Learning from land and water projects experiences for smart management”
15-18 December 2013 (Amman-Jordan)
Total Production
240 Mm3/y
32 PlantsGreening, Amenity
Plantation 120 Mm3/y
To Arabian Gulf
100 Mm3/y
To sand dunes (al Ain)
10 Mm3/y
Total Production 350 mM3/y
32 PlantsGreening and amenity
120 Mm3/y
Advanced Treatment
Agriculture and Forestry
230 mm3/Year