STINKING sewers could smell sweeter with regular squirts of concentrated bacteria. The bugs deodorise the pipes because they gobble up human waste, starving out the native bacteria that create that distinctive "bad eggs" aroma.
In-Pipe Technology of Wheaton, Illinois, is trying out this idea in Tampa, Florida. A continuous supply of bacterial deodorant squirts into the pipes from dosing units sited strategically throughout the sewage collection system. Around the size of a small TV, each dosing port houses a cocktail of between 10 and 14 species of bacteria. These out-chomp the smelly natives and take over.
"All our bugs are native to sewage, but only in low numbers," says Dan Williamson, founder of In-Pipe Technology. "We're reinforcing what's already there so that they dominate the bad boys," he says. Because they stop hydrogen sulphide building up, the bugs halt corrosion. "The sulphide dissolves to form sulphuric acid, and so you get corrosion as well," says Williamson.
Another bonus, says the company, is that the bugs act as a sewage works deep inside the pipe network. The company claims that the bacteria will consume more than half the usual solids before they reach the plant.
Investigators from the Civil Engineering Research Foundation in Washington DC are now assessing the technology independently.
Author: Andy Coghlan
New Scientist issue: 27th January 2001
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