Integrated water recycling system will likely be clear winner in UAE
By Dr. Shadi Hasan
March 8, 2014
The UAE has long relied on desalination of seawater to meet its daily need for fresh water. Desalinated seawater, particularly by means of thermal desalination, provides the major proportion of the water needed for domestic purposes in the country. However, the country has another resource to meet its further domestic water needs – wastewater.
Much of the water used in our communities and businesses goes down the drains and pipes as wastewater, to be treated and returned to the environment. Of the 290 million cubic meters of wastewater produced every year in Abu Dhabi – the equivalent of 116,000 Olympic-sized swimming pools – approximately 60 per cent is treated and reused in a limited capacity, mostly for irrigation and cooling.
But the Government has decided this is no longer enough given the growing demand for fresh water, and has planned to recycle 100 per cent of wastewater in the coming years.
To make this a reality, we need to reduce the running costs of wastewater treatment plants. The process is currently lengthy, energy intensive, and costly – all of which makes it tempting not to bother, and just desalinate more seawater.
Current treatment facilities occupy a huge land area, because they need to include a separate unit to remove each pollutant.
They contain equipment to screen incoming sewage from collectors, numerous tanks for primary (physical-chemical) treatment, tanks for secondary (biological) treatment, sedimentation tanks after biological treatment, special facilities for nutrient removal and disinfection.
Each of these units produces waste, and another unit is then needed to deal with this waste. Managing that waste can account for up to 60 per cent of the total cost of running the entire plant. And the cleaner you want your treated wastewater, the more the plant costs to run.
It is for that reason that I am leading a research project at Masdar Institute that is developing the first UAE-specific all-in-one wastewater treatment system. This system aims to treat wastewater in a way that costs much less than the usual treatment methods.
It will do this by integrating a number of existing treatment technologies into a single complex but complementary system. It uses interacting biological processes, membrane filtration, and electrical treatment – meaning there is no need for multiple units and their operating costs.
Not only does it produce high-quality water, but it also provides biosolids that can be used as fertilizer. Preliminary lab-scale experiments have already been showing promising savings in running costs.
The challenge now is to see how such a plant will operate in the UAE. The unique temperature, salinity and pH of UAE wastewater will play a significant role in the functions of the microorganisms that are critical to the wastewater treatment process, and will have to be closely monitored to see how they impact on the treatment process.
We also need to ensure that the quality of treated water and biosolids that this system produces complies with the UAE’s regulations and standards.
It is our hope that this research will deliver outcomes of immediate use not only to Abu Dhabi and the UAE, but also worldwide. Through student participation, this research will also help train highly qualified and well-trained engineers who can contribute to the UAE’s critical water-treatment sector.
The success of this project will push further towards system development resulting in a sustainable, cost-effective, energy saving, efficient and environmentally friendly system treating all kinds of wastewaters.
Dr Shadi Hasan is an assistant professor of chemical and environmental engineering in the Masdar Institute of Science and Technology.