Water. Desalination + reuse
Issue link: https://fhpublishing.uberflip.com/i/827133
Water. desalination + reuse June 2017 FAR SITE 27 Q & A T I M H A R P E R "I am halfway between the lab and the boardroom on this" • We take existing membranes, mainly polymer-based, and add a thin coating of graphene oxide. A number of things happen. First, we create a super-oleophobic surface which reduces fouling: the graphene oxide platelets crinkle up a little bit and pick up the underlying roughness of the membrane. At the same time, because the graphene oxide is hydrophobic, it creates a surface that has a permanent lm of water on it, which helps to repel oil. As a result, any oil droplets that form tend to be sheered o• . The third thing that happens is that between the platelets of the graphene oxide we create some super-hydrophilic channels, and you get a nano capillary e• ect. Water passes through these faster than through free space. • The coating slows membrane fouling by a factor of four, results in higher • ux rate through ltration membranes, and provides new applications for ltration. • Others are taking graphene and trying to open out some pores in it, and then having the problem of guring out how to turn that into some kind of membrane. We coat existing membranes. That's the di• erence that gets us to market ve to 10 years quicker than most of the people looking at other graphene applications. • I started o• in electron microscopy at the European Space Agency. My job was to try to break things like electronic components and coatings, and then to take them apart, atom by atom, to nd out what the problem was. That turned into nanotechnology. I advised quite a few of the graphene manufacturers on commercialisation and application. I guess that's my speciality: as a scientist with a commercial background and venture capital experience, I am halfway between the lab and the boardroom on this. • There are two things that we have to do in parallel. One is to apply the coating to a number of membranes, and that's why we have moved into the University of Leeds, UK, which has water testing facilities. We will start running standard water industry tests that people in the industry will recognise. At the same time, the Centre for Process Innovation in Sedge eld, in northeast England, UK, is developing methods of scalable manufacturing. Our business model is mainly licensing-based. We don't want to compete with major membrane manufacturers. So we are developing a number of technologies that will enable us to licence our technology in a production-based format that's compatible with what people are already using. What is G2O Water Technologies' approach to graphene? What's the benefi t? Why do you believe that this is the best way to use graphene for desalination? What's your own professional background? What's next for G20 Water Technologies? Tim Harper, G2O Water Technologies CEO, and a former scientist at the European Space Agency, says coating membranes is the best use of graphene for desalination DAD's adsorption technology, using waste heat from a boiler to power the process. Adsorption can generate vacuum and low temperature for optimal ZLD with minimal chemical use, eliminating the need for external refrigeration, and potentially reducing the op- erating costs to less than 20 per cent of those of a conventional crystalliser system. The pilot ZLD system is expected to be installed in August, and to begin operating in October 2017. ZLD pilot will be installed in August and begin operating in October 2017 "We are replacing the vacuum pump with adsorption, and using waste heat instead of electricity. Our electricity consumption should be sig- ni cantly lower, around 6 kWh/ m3, compared to a conventional ZLD's 60 to 120 kWh/m3," says Childress. MEDAD chief executive Joseph Ng adds: "We're not trying to reinvent the wheel, we complement concentrators and crystallisers. We are replacing the vacuum pump and chiller, thereby reducing pre-treatment chemicals, which account for about 95 per cent of traditional ZLD operating costs." While MEDAD's adsorption technologies apply to desalina- tion and wastewater treatment, the company is increasingly focused on wastewater ZLD markets, including • ue gas desulfurisation (FGD) in India and China, where it sees a big commercial opportunity. "We are very e• ective in FGD discharge, fracking wastewa- ter, rare earth solution mining, and in other situations, such as cruise ship scrubbers, where there is abundant low-grade waste heat and they want ZLD," Ng says. "There is an urgent need for ZLD in China and India. The pain factor is high, and MEDAD's operating expenditure (OPEX) is much lower than a traditional ZLD system." The company, in which KAUST and NUS own minority stakes, aims over the next two years to expand its commer- cial projects around the globe. Although primarily a technology company, it will act as the main engineering partner on projects on a turnkey basis.