What To Do With Your Old CDs: Turn Sewage Into Clean Water
If you find yourself scratching your head over what to do with that CD collection you haven't touched in years, know that a team of researchers in Taiwan will put those retired optical disks to good use. Scientists from the National Taiwan University are using old CDs to grow zinc oxide, which breaks down organic pollutants in sewage water.
Din Ping Tsai, a physicist at National Taiwan University, and his colleagues have built a water treatment device that utilizes the flat, smooth surface of a CD to their advantage. According to Phys.org, the compact disks are ideal for growing zinc oxide nanorods, which can break down organic molecules efficiently in the presence of UV light. The nanorods are extremely small - just a thousandth the width of a human hair - and are an inexpensive semiconductor that can function as a photocatalyst.
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Photocatalytic water decontamination is a method of sewage treatment whose popularity has grown over the years. But this is the first time someone has used CDs as a platform for the process.
"Optical disks are cheap, readily available, and very commonly used," Tsai explained. They're also durable, portable and can rotate quickly, allowing water to fan out into a thin layer more quickly which light can then pass through more easily.
According to Zee News, the water treatment device is just one cubic foot in volume. It consists of the zinc oxide-coated CD, a UV light source and a system that recirculates the water to further break down the pollutants.
To test the CD sewage cleanup device, researchers treated a half-liter solution of methyl orange dye, an organic compound used to test photocatalytic reactions, for one hour. They discovered that over 95 percent of the contaminants had broken down after just 60 minutes. That's about 150 ml of waste water per minute.
According to researchers, the novel device consumes little power and can process sewage water more efficiently than other photocatalytic wastewater treatment techniques.
One of the world's most pervasive problems is inadequate access to clean water and sanitation, and it's only expected to get worse in the upcoming decades. According to UN Water, roughly one out of three people globally lives without basic hygiene. The number of cause of illness and death worldwide is diarrhea, 88 percent of which is caused by lack of access to sanitation facilities and unsafe drinking water.
Scientists are always trying to come up with innovative ways to create access to clean, potable water. There's even a gel that can kill bacteria in water quickly without a power source. The scientists from National Taiwan University who came up with the CD water treatment device will present their findings at the next Optical Society's Annual Meeting in Orlando, Fla.
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