SCIENTISTS FROM the University of Newcastle upon Tyne have developed a method to remediate polluted mine water using llama droppings as a principal component.
It is hoped the technique will help clean groundwater in Bolivia polluted by abandoned silver and tin mines in the Andes.Water from the disused Mina Milluni, in the Cordillera Real, is even a threat to the main water supply of the capital La Paz.
Paul Younger, professor of hydrogeochemical engineering at the university, said: 'We've just completed a very successful six-month field trial and are now looking for funding to take the project forward.'
He and colleagues have adapted a technique used in the Durham coalfields in north east England. The bacterial sulphate reduction technique employs 'low-tech' bioreactors comprising compost and limestone.
Bacteria in the compost use dissolved sulphate, which is abundant in mine water, as an energy source to produce sulphide. This reacts with iron in the water, trapping it safely in the compost bed as iron sulphide. The process raises the pH of the water and generates alkalinity.
'The problems of implementing this technology at Milluni are considerable, ' said Younger, not least because of the altitude and sterile environment - not even lichen grows in the region.
'Lying at about 4,400m above sea level, nocturnal freezing is the norm for much of the year, ' he explained.
Because supplies of compost materials used in the UK, such as horse and cow manure and composted tree bark mulch, are not readily available, the Newcastle team is investigating llama droppings as an alternative.
With no available data on their performance in acid mine drainage remediation systems, Younger and his colleagues undertook a series of trials which, he said, were extremely encouraging. The results were comparable to those achieved in north east England, 'which is all the more surprising given the sterile environment'