Water. Desalination + reuse
Issue link: https://fhpublishing.uberflip.com/i/827133
26 FAR SITE June 2017 Water. desalination + reuse Adsorption pilot phase two will focus on zero liquid discharge The adsorption pilot at a solar manufacturing facility near Riyadh, Saudi Arabia, has focused in phase one on recovering reverse osmosis reject brine. Recovery rates are critical at the site, which is 100 miles from the coastline. COMPANY KEYPOINTS • MEDAD was spun out of National University of Singapore (NUS) in 2012 • It has acquired patents from NUS and King Abdullah University of Science and Technology • In 2016 it began a commercial pilot, collaborating with King Abdulaziz City for Science and Technology ADSORPTION RESULTS • Powered by low-grade heat such as boiler exhaust or solar thermal • The phase one pilot achieved gain output ratio (GOR) up to 55 per cent higher than traditional multi-effect distillation (MED) • Phase two of the pilot will hybridise a traditional zero liquid discharge (ZLD) system by replacing the vacuum pump and chiller MEDAD Technologies, a special- ist in adsorption, has worked to commercialise a multi-e ect dis- tillation adsorption desalination (MED-AD) system since spinning o from the National University of Singapore (NUS) in 2012. The company initially ac- quired patents from NUS, and later added patents from King Abdullah University of Science and Technology (KAUST), a„ er professor Ng Kim Choon, the technology's inventor, moved there in 2013 to continue his research in the ˆ eld. The company began a com- mercial pilot in Saudi Arabia in September 2016, in collaboration with King Abdulaziz City for Sci- ence and Technology. The 100 m3/d project, for recovering re- verse osmosis (RO) reject brine, is situated 100 miles inland, in a solar manufacturing facility near the capital city, Riyadh. "Recovery rates are critical at the site because it's so far inland," says Kris Childress, MEDAD director of business development. "We achieved a recovery rate of 87 per cent with our adsorption technology." The patent-applied adsorption system uses multiple beds of powerful adsorbents to achieve a continuous evaporative desali- nation process. The pilot uses electricity only for pumps and valves The adsorption system is powered by low-grade heat of 85 degrees centigrade from varied sources such as boiler exhaust or solar thermal, and can concentrate feed water up to crystallisation levels. It does not require steam. Adsorption- hybridised MED operates below the temperature of its cooling water because it adsorbs vapour at saturation pressures below 10 degrees centigrade, while using cooling water of 30 to 35 degrees centigrade. The pilot, which uses electricity only for pumps and valves, has a gain output ratio (GOR) that is 50 to 55 per cent higher than a traditional MED process. The pilot is now moving into phase two, a zero liquid discharge (ZLD) system com- prising multiple concentrators/ crystallisers. One of these will be hybridised by replacing the mechanical vapour compressor and mechanical chiller with ME- LOOK MEDAD has ambitious targets for phase two of the pilot, aiming to bring electricity consumption for the ZLD system to 6 kWh/m3