By Romina Bevilacqua
"Disks are cheap and can be easily found anywhere," said project principal investigator Din Ping Tsai, a physicist at National Taiwan University, in a press release. "About 20 billion discs are manufactured each year, so the use of old discs for water treatment could become the way to reduce the ecological damage that they cause."
Every month, around 100 tons of CDs become obsolete and millions of these are simply thrown away by landfills around the world. When a CD breaks down, it releases bisphenol-A (BPA), a toxic chemical that has been linked to brain disorders, cancer, and other diseases.
The water purification process proposed by the researcher Tsai involves using the flat surface of a CD as a platform on which to create or grow zinc oxide. Then, when illuminated with UV light on a prototype water treatment device, the zinc oxide acts as a photon catalyst, breaking down organic pollutants in the sewage that is filtered down a hose.
In one test, the researchers found that “more than 95% of the contaminants had decomposed after just 60 minutes. That's about 150 ml of water per minute. " Tsai said the device could be used on a small scale to clean water that is contaminated with domestic residual waste, urban sewage or agricultural waste.
Worldwide, 884 million people do not have access to safe water. And contaminated water causes the number one disease in the world that ultimately leads to death and that is diarrhea, 88% of which is caused by lack of access to sanitation services and from drinking dirty water. So, despite the fact that the technique of taking recycled urine is disgusting, it tries to meet a clear need that is to convert wastewater into drinkable. And in certain parts of the world, the consumption of wastewater has already become a way of life. According to a 2012 New York Times article by Jessica Yu, director of The Last Call of the Oasis project:
“In Israel, more than 80% of household wastewater is recycled, providing almost half of the water used to irrigate the land. A new pilot plant near San Diego in the US and the national “NEWater” program in Singapore show that it is practical to convert wastewater into water that is clean enough to drink. However, in most of the world, this is not done ”.
A 2011 study by the University of California, Santa Cruz, also demonstrates another hurdle: More than 60% of those surveyed refused to drink water that had had some direct contact with sewage.
The position people take on this issue is ironic, according to Carol Nemeroff, a psychologist associated with the study, as “even the pure, fresh spring water was soiled with the excrement of birds and fish. So there is no such type of water that has never been soiled with excrement or urine ". In Orange County, California, recycled wastewater is pumped into cavities underground - this is a completely unnecessary step - so that consumers feel that what comes out of the taps is water gushing from the ground and not from the toilet of another person. Then there is the fact that all the water we consume is recycled: the amount of H2O in Earth's atmosphere does not change; the only thing that changes is the form in which the water can be presented (rain, fresh water or sea water; liquid, gas or solid).
So while Tai and his team deserve all the credit for working to minimize the ecological damage that CDs cause, another hurdle awaiting them will be convincing the world that drinking recycled or purified water is the solution.