Taipei, Oct. 12 (CNA) Researchers at the Changhua County-based Da-Yeh University have recently made a breakthrough in recycling CD/DVD ROM discs by using a leaching technique that can clean all the coating from the discs in a few minutes without damaging them. The technique, involving alcohol and nitric acid leaching and supersonic cleaning, won a gold medal at the 2009 Taipei International Invention Show and Technomart in late September.
The technique, which won patent rights from the Intellectual Property Office under the Ministry of Economic Affairs, was developed mainly by Yang Yu-hao, a master' degree graduate from Da-Yeh University's Department of Environmental Engineering under the guidance of department head Professor Lee Ching-hua.
According to Lee, the two sides of each DVD disc have to be separated then soaked in alcohol for one minute and moved to a supersonic washing machine to get rid of the memory dye and ink.
The discs are then placed in a nitric acid bath and afterwards in another supersonic cleaner to remove the protective coating and metal reflective layers.
The second leaching is followed by a water wash, which leaves clean, transparent polycarbonate discs.
CDs can be cleaned the same way, but the processing period would be even shorter as CDs do not have two sides that need to be separated first, Lee said.
According to Lee, used CDs and DVDs are sold at about NT$15 (US$0.46) per kg on average, but recycled discs that have been cleaned by means of Yang's technique cost NT$45 per kg.
About 60 million discs are dumped in Taiwan each year.
(By Deborah Kuo)
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