Llama droppings take the place of horse or cow dung
Paul Younger, professor of hydrogeochemical engineering at Newcastle University, UK, thought of the idea to help poor communities improve the quality of their water supply.
The system uses a compost bed of limestone and dung to help absorb the high levels of acid found in polluted waters seeping from South American mines.
The technique has been developed in the North East of England, where former mining communities were worried about water draining from disused pits and harming the local environment.
The Bolivian mine leaking the pollution is Mina Milluni, closed in 1985 as global prices slumped.
It is contaminating waters in the Cordillera Real area of the Andes, and affecting the water supply to the capital city La Paz.
Although the city waterworks can remove iron from the supply, it is feared toxic elements such as cadmium are entering the water supply.
'Droppings abundant'
Professor Younger has been working on experiments with local engineer, Marcos Arce, to assess the feasibility of treating the acid water using the llama droppings.
Professor Younger said: "The problems of implementing this technology at Milluni are considerable - it lies at about 4,400 metres above sea level, and nocturnal freezing is normal for much of the year.
"Supplies of compost materials similar to those that have been used successfully in the UK, such as horse and cow manure, with composted tree mulch, are not readily available in the Bolivian Andes.
"However, llama droppings are abundant, though it hardly needs stating that no previous data exists on their performance in acid mine drainage remediation systems."
Professor Younger and his colleagues have created a series of tanks in which a five-month trial was carried out.
The results show sulphate reductions of 16% and the acidity of the water dropped from 3.2 to 6.3 on the pH scale.
The scientist is now attempting to raise funds to develop more "low-tech bioreactors" at the Bolivian site, and at others affected by similar pollution from metal mines.