Closing the Loop – Reuse in Dubai

A holistic approach was undertaken by MWH for the new International City development's water resources. MWH built a dynamic water balance of the various water usages, to optimise the level of water infrastructure. This paper gives details of how the water balance model was developed and used to determine the level of water infrastructure required to utilise the energy intensive desalinated potable water three times:• Drinking and washing• District cooling• Irrigation and toilet flushingThis paper includes details of the advanced reuse technology used within International City water infrastructure. The wastewater will be treated by Membrane Bioreactor (MBR) technology, at full capacity (Average Dry Weather Flow (ADWF) 110ML/d). This will be one of the largest MBR plants in the world with a peak design flow of 220ML/d. The permeate from the MBR will be used for irrigation or treated further with Reverse Osmosis (RO), again this will be one of the largest reuse RO installations in the world, producing a peak permeate flow of 70Ml/d. The MBR has been designed with Biological Nutrient Removal (BNR) to thus ensure any Brine (RO waste) is suitable for discharge to an inland marine estuarine water course.