Bacteria eat copper

RESEARCHERS at the University of Abertay Dundee have discovered a new species of bacterium which they believe could help solve a major pollution problem in one of Scotland's key industries.

The bacterium, yet to be named, is one of a group of micro-organisms which feed on rocks and metal, and can eat copper. This is attracting great interest from the electronics industry, which under European legislation will have to reduce the amount of copper in its waste water.

A manufacturer of printed circuit boards, Exacta Circuits in the Scottish borders, is working with Phil Collier of the university's school of molecular and life sciences to run trials of the new bug at its plant.

The company makes the printed circuit boards which are at the heart of almost every electronic device in modern technology. The manufacturing process involves electroplating and etching copper on plastic boards, which are then rinsed in water, and during this process, some of the copper dissolves. The factory waste water contains copper levels of up to three parts per million, but this will now have to be cut to under one part per million.

A UAD research team visited the factory and isolated about 30 different micro-organisms from water samples, identifying ten types which can stand high levels of copper. Each of these was tested, and the hitherto unidentified bacterium was found to be capable of removing as much as 80 per cent of the copper.

Dr Collier said there were many similar bacteria, known as chemolithotrophs for their ability to eat minerals dissolved in water.

"This one is special because it feeds on the copper, chemically changing the metal to release the energy it needs to grow. In doing so, it takes the copper out of the water."

The researchers, who include experts from the university's waste water technology centre, are now planning to build a pilot plant, and are investigating ways of increasing the amount of copper taken out of the water.