According to the US’s National Safety Council Environmental Health Centre, the number of personal computers alone that are expected to become obsolete this year is estimated at 41.9 million, which is predicted to rise to 61.3 million by 2007.

A proportion of electronic equipment that arrives at recycling depots can be reused once repaired, and some are cannibalised for parts, whilst the rest of the waste is reprocessed to extract the metal, plastic and glass that they contain (see related story). Reprocessing involves repeating various steps such as grinding, shredding and separating materials. However, at a certain point, it becomes too expensive to continue purifying the materials, and recycling companies can lose money by spending more on reprocessing than is justified by current market values.

“Our model allows us to find the pricing threshold for reprocessing,” said Julie Ann Stuart, an assistant professor of industrial engineering at Purdue University, and one of the developers of the programme. “So, if the price of copper fluctuates, it helps us find how low the value could be to justify reprocessing.”

“We are the first to look at the reprocessing decision,” said Stuart, pointing out that recyclers tend to rely more on instinct than analytical tools. “There has been no formal way to decide questions like: when do you process something more than once? What level of purity do you want?”

Though the recycling of electronic hardware is not commonly required by law, last year Massachusetts enacted the nation’s first ban on dumping computer monitors and other glass picture tubes at landfills, and it is expected that such policies will become more common in the future. Such changes in legislation would drastically increase the flow of electrical products to usually small-scale recycling operations, ill-equipped to handle the surge in demand on their service. “A contributing factor to the closing of some recycling companies has been excessive material handling and inventory,” said Stuart.

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