New system recovers and re-uses electronic wastes

Concern is rising among governments worldwide about electronic wastes - discarded computers, televisions, mobile phones, audio equipment and batteries - leaching lead and other substances that may seep into groundwater supplies.

Just one colour computer monitor or television can contain up to 3.5 kg of lead. Consider that amount in light of the estimated 12 million tonnes of 'e-wastes' that the US Environmental Protection Agency estimates may soon be dumped into American landfills. Worry has reached such a level that some European countries are forcing manufacturers to take back discarded electronics, and in the US, California and Massachusetts have banned their disposal in municipal solid waste landfills.

But some officials are looking beyond these stop-gap measures to find a solution. A study under way at the Georgia Institute of Technology may offer a model for other states and nations.

Researchers are conducting the study in co-operation with the Pollution Prevention Assistance Division of the Georgia Department of Natural Resources, which is funding the project with additional support from the National Science Foundation.

Researchers have devised a 'reverse production' system that creates infrastructure to recover and re-use every material contained within e-wastes - metals such as lead, copper, aluminium and gold, and various plastics, glass and wire.

Such 'closed loop' manufacturing and recovery offers a win-win situation for everyone, researchers said.

Less of the Earth will be mined for raw materials, and groundwater will be protected. But this simple concept requires a lot of brand new thinking, said Jane Ammons, a professor in the School of Industrial and Systems Engineering and a governor-appointed member of the Georgia Computer Equipment Disposal and Recycling Council.

She and colleague Matthew Realff, an associate professor in the School of Chemical Engineering, are devising methods to plan reverse production systems that will collect e-trash, tear apart devices ('de-manufacture it') and use the components and materials again - all while making the process economically viable.

Though this system is being designed for Georgia, its application elsewhere has sparked interest nationally and internationally.

Officials in Taiwan and Belgium have consulted with the researchers, as have several multi-national electronics and logistics firms.

The project is building on other research that Ammons and Realff are conducting. Their fundamental work in reverse production systems has been funded by the National Science Foundation. Ammons' related research is funded by the National Science Foundation (NSF) as one of four 'Advance' chaired professors at Georgia Tech. Advance is a program to improve the career success of women faculty in science and engineering.

Also, Ammons and Realff are applying their findings from other studies to the e-waste project.

For example, they have modelled the regional and national infrastructure necessary for cost-effective and environmentally beneficial collection and the recycling of carpet to extract nylon fibre, caprolactam monomer and other products.

"It's a matter of seeing a waste as a resource," Ammons said.

Key to their approach is the ongoing development of a mathematical model to predict the economic success of recovery efforts. Modelling is necessary given the uncertainty inherent in a host of variables - quantities, locations, types and conditions of old parts, and numerous aspects of transportation (distance, costs of fuel, labour, insurance, etc).

Ammons and Realff have involved experts, many of them from Georgia recycling and salvaging businesses, to probe the complicated interplay between manufacturing, de-manufacturing and logistics.

Realff's expertise is the design and operation of processes that recover the maximum amount possible of useable product from e-waste. He has devised ways to separate metals, as well as different qualities of plastic from crushed, ground-up components.

Realff and his students measure density and surface properties in novel ways. For example, they measure how far pieces fly off a conveyer belt and how well air bubbles stick to them.

This information enables more accurate representations of recycling tasks to be incorporated into the strategic models and the synthesis of lower-cost alternatives, Realff explained.

"For chemical engineers, this is a challenging problem that has not been widely studied," he said. "It's exciting. We are creating a new architecture for separation systems." From this work, new industries and an infrastructure can be created to recover value not only from e-waste, but also from automobiles and other durable goods, Realff added.

Now into the second and final year of the Georgia project, Ammons, Realff and their students are tweaking and testing their mathematical model (which for some problems has required computers to determine more than 300,000 variables) by testing hundreds of 'what-if' scenarios.

The researchers are continuing their collaboration under a new grant from the National Science Foundation; it will help broaden their model to other reverse production system problems.