|Llama dung may help clean polluted water
UPON TYNE, England, Feb. 6 (UPI) -- British researchers say llama droppings may soon help
villagers in the Andes fight water pollution from silver and tin mines.
The scientists say their time-tested method, already in use in England with horse and cow
manure, can empower small, local groups to create "bioreactors" from bacteria in
the dung to purify the extremely acidic water from abandoned mines.
"We're doing this to try and give help to people who would otherwise be stuck with an
environmental nightmare," said lead researcher Paul Younger, a hydrogeochemical
engineer at the University of Newcastle upon Tyne. "We're hoping this will help
provide low-cost solutions that can really empower local communities to take the
environment into their own hands."
The bioreactors are simply ponds that contain limestone gravel buried under a layer of
compost with manure in it. Bacteria living in the bioreactors use dissolved sulphate --
which is always found in mine water in abundance -- as an energy source, much the same way
humans use oxygen.
This microbial activity produces sulphide molecules that trap and precipitate out
dissolved metals. The limestone helps the bacteria neutralize the acidic mine water while
the compost serves as the bacteria's food source.
The bioreactor technique developed by Younger was originally designed to help former coal
and iron mining communities in northeast England. It has proven so successful that the
researchers are now trying to customize it for similar problems in other countries -- in
this case, Bolivia.
"From the day I took up my first university post," Younger explained, "I
instinctively sought opportunities to place my technological insights and skills at the
disposal of grass roots organizations and individuals who are striving to take control of
their own destinies, to the long-term benefit of the ecosystems on which we all ultimately
Damage from an abandoned mine named Mina Milluni in the Andes is seriously polluting the
main water supply of Bolivia's capital, La Paz. Mina Milluni closed abruptly in 1985 as a
consequence of the global slump in tin prices which occurred that year.
"The former mining company has neither the financial resources nor the legal
responsibility to remediate the polluted drainage," Younger said. "The problem
will continue indefinitely unless some local champions decide to find solutions of their
While the city's waterworks efficiently cleans the water, some of it is used untreated by
impoverished local residents for domestic and agricultural purposes. Younger is working
with Bolivian engineers to see if bioreactors can help, but the natural obstacles are
considerable. The mine lies well above sea level, so at night temperatures dip below
freezing for much of the year, impairing water flow into the bioreactors.
Bioreactors in Britain also depend on cows or horses for manure, animals that do not do
well in the thin air of the Andes.
However, any herbivorous mammal appears to do the trick, and llama droppings do just as
well than cow manure, if not better, Younger told UPI.
The researchers experimented with four small llama-based bioreactors for a five-month
period in 2000. A continuous flow of acid drainage was filtered through the tanks between
June and November, the coldest time of the year in the Bolivian Andes.
The findings from the experiment were extremely encouraging, Younger said. The bacteria
generate enough heat to counteract freezing, and the llama droppings promoted bacterial
activity as hoped, making the water significantly less acid. The water entering the
bioreactors was roughly as acidic as vinegar, or pH 3.2, and upon leaving was about pH
6.3, less acidic than rainwater.
"That's good -- that's exactly what you hope to hear," said Bob Kleinmann,
director of the environmental science and technology division for the National Energy
Technology Laboratory in Pittsburgh. "That gives hope for the system."
Younger and his colleagues are trying to find funding to support the Bolivian engineers to
develop larger bioreactors.
(Reported by Charles Choi in New York.)