Science

Old CDs to gain new lease of life in ... sewage treatment?

Old CDs to gain new lease of l...
An unlikely tool for sewage treatment (Photo: Stuart Pilbrow)
An unlikely tool for sewage treatment (Photo: Stuart Pilbrow)
View 4 Images
A compact disk coated entirely with zinc nanorods (Photo: Din Ping Tsai, National Taiwan University)
1/4
A compact disk coated entirely with zinc nanorods (Photo: Din Ping Tsai, National Taiwan University)
Electron microscope image showing nanorods growing on the disk. (Image: Din Ping Tsai, National Taiwan University)
2/4
Electron microscope image showing nanorods growing on the disk. (Image: Din Ping Tsai, National Taiwan University)
An unlikely tool for sewage treatment (Photo: Stuart Pilbrow)
3/4
An unlikely tool for sewage treatment (Photo: Stuart Pilbrow)
A nanorod coated disk (left) and an electronic microscope image of the grown nanorods (Images: Din Ping Tsai, National Taiwan University)
4/4
A nanorod coated disk (left) and an electronic microscope image of the grown nanorods (Images: Din Ping Tsai, National Taiwan University)
View gallery - 4 images

A team of Taiwanese researchers is to demonstrate a method of treating sewage using old optical disks such as CDs. The disks are used as a platform to grow minuscule nanorods of zinc oxide, a known photocatalyst capable of breaking down organic matter. By spinning the disks, sewage water spreads into a thin layer through which light can pass, exciting the nanorods into action.

The team of researchers have built a prototype sewage treatment device approximately 1 cubic foot (0.03 cubic meters) in size. It includes an ultraviolet light to catalyze the treatment process, as well as a recirculation system so that the water can be treated numerous times.

The team claims that the prototype has proven capable of breaking down 95 percent of contaminants in a 500-ml solution of dye in an hour, but also that it can treat 150 ml of waste water every minute (a significantly faster rate than the dye test would suggest).

A nanorod coated disk (left) and an electronic microscope image of the grown nanorods (Images: Din Ping Tsai, National Taiwan University)
A nanorod coated disk (left) and an electronic microscope image of the grown nanorods (Images: Din Ping Tsai, National Taiwan University)

National Taiwan University physicist Din Ping Tsai claims the device is more effective than other photocatalytic methods of treating sewage water.

It's suggested similar devices could be used to for domestic-scale sewage treatment, and treating urban run-off, or industrial and agricultural waste. The researchers are hoping to make efficiency gains to increase treatment speed, and are thinking about stacking the disks in layers.

Tsai and team will present their findings at the Annual Meeting of the Optical society in Florida, which commences Oct. 6.

Gizmag would like to contribute to this research by suggesting the following compact disks, which seem particularly apt for the process:

  • Waste Management by t.A.T.u.
  • Consent to Treatment by Blue October
  • Straight Up Sewaside by Das EFX
  • Sunshine Cleaning soundtrack by Michael Penn
  • Spinning Around by Kylie Minogue

However, we're sure our readers can do better.
Source: Optical Society

View gallery - 4 images
3 comments
Seth Miesters
Clever use of a common waste item. Nanotechnology. Too cool.
Canelo Elizondo
Now this is a really clever use for old CDs. I had no idea that this could be done and I am glad that you provided us with this information.
Thank you, Regards, Rod
Bruce Miller
Anaerobic digestion for Methane gas first?