Someone has finally come up with an upcycling use for old CD discs. Din Ping Tsai, a physicist at National Taiwan University, has developed a small, low-power method for treating wastewater using UV light and zinc oxide applied to the CDs. Using old CDs as a substrate to coat with zinc oxide provides a low cost layer which can be spun as water is applied, creating a thin film of water which more effectively interacts with the photocatalytic layer of zinc oxide nanorods. In tests, the device was able to break down over 95% of the contaminants after an hour of treatment.
Though this could be a wonderful application for old CDs, it's unlikely to solve the waste accumulation from billions of old CDs. The number used for this treatment system, even if it becomes widely adopted, is going to be a tiny fraction of the total production of CDs (which, at present is about 20 billion CDs per year).
"The spinning disk reactor is small, consumes little power, and processes contaminated water more efficiently than other photocatalytic wastewater treatment methods, Tsai says. The device could be used on a small scale to clean water contaminated with domestic sewage, urban run-off, industrial effluents, and farm waste. Going forward, the team is also working on ways to increase the efficiency of the reactor, and Tsai estimates that the system could soon be improved to work even faster, perhaps by creating layers of stacked disks."
While the system seems best suited to small installations, rather than big, municipal facilities, it is nevertheless an interesting system, and the ability to also deal with an e-waste issue at the same time as creating equipment for effective wastewater treatemt is a positive synergy.
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