Can Toxic Mine Waste Be Safely Turned into Fuel?

(3BL Media/Justmeans) - One of the cornerstones of a sustainable society is the complete eradication of the concept of waste. After all, nature has no waste; everything gets used one way or another. It’s only when people came along that the whole idea got started. Already, a number of factories have become zero waste and a few intrepid homeowners put out the equivalent of one shopping bag of trash per year, so it is possible, at least in principle. Food can be composted or turned into fuel. Aluminum, paper and plastic can be recycled. Heavier metals like steel and lead can be reclaimed and reused. But what about the really nasty stuff, like toxic waste?

Last year, a professor at Texas A&M University came up with a process to turn nuclear waste into energy. The process would utilize subcritical fission to break down the most dangerous components, the transuranics, over a period of years, producing energy in the process.

There are also people using mushrooms to clean up oil spills and plastic waste.

It seems like we need to recruit the help of Mother Nature in addressing some of our biggest mistakes. It heralds the emergence of a new field of bio-processing.

Now, a group of universities in western England and Wales have come up with a research project to decontaminate the water that has been tainted as the result of the tin mining process. At the same time, the project aims to harvest useful heavy metals and produce biofuels as a byproduct.

The group, which is known as the GW4 Alliance, is a collaboration of the universities of Bath, Bristol, Cardiff and Exeter, working together with Plymouth Marine Laboratory (PML), the Coal Authority and waste management group Veolia. Their objective is the treatment of wastewater from the Wheal Jane tin mine in Cornwall. The intention is to collect samples of the water and grow algae in it in a laboratory setting.

If the project if successful, they will have the underlying science worked out for a process that takes in contaminated water, and, after treatment, produces heavy metals, biofuel, and clean water.

“It’s a win-win solution to a significant environmental problem,” said Dr Chris Chuck from the University of Bath’s Centre for Sustainable Chemical Technologies.

The Wheal Jane mine closed in 1992. The government has been spending $3 million per year trying to clean it up ever since.

It appears that the algae found around the mine has unique properties that allow it to absorb metals. If the project is successful, the process could find widespread application around the world.

“Acidic waste run-off from mines is not a regional issue restricted to Cornwall, it’s a global problem,” said Dr Mike Allen, director of the Algal Biotechnology and Innovation Centre at PML. “It’s a particular problem in the developing world, where costly clean-up and remediation activities are ignored because of their high cost and low return.”

If the process could yield commercially useful by-products, as this process aims to do, that could eliminate a major economic hurdle that has forestalled the cleanup of countless mines and industrial facilities.

Algae-based biofuels are being produced in many quarters, though high costs have hampered widespread expansion. If applications like this can be developed that synergistically produce other benefits, while helping to address the thorny issue of mine remediation; that could help to widen the pipeline.

Another challenge the fledgling industry faces, is limited the land footprint required for commercial production. Perhaps this approach could provide useful capacity.

There are still many challenges that stand between this hypothetical process and commercial application. To produce biofuel, the water must be treated at high temperature and pressure, which will require energy and potentially costly equipment. And it remains to be seen whether, when all factors are considered and brought up to commercial scale production, the business model will be a profitable one.

But the synergistic nature of the approach holds potential. Says Dr. Chris Bryan, lecturer in sustainable mining and minerals resourcing at the University of Exeter’s Environment and Sustainability Institute, “By growing algae in mine water, which is currently expensive to remediate, we are providing an alternative economic model to traditional algal cultivation. The aim is to reduce the treatment costs while generating value at the same time from the algal biomass.”

Image credit: Marlene Thoms: Flickr Creative Commons