From: Allison Winter, ENN
Published September 23, 2012 08:09 AM

Combatting Sewer Stench

Have you ever caught a big whiff of stink when walking down city streets? As you look around you wonder what is that awful stench and where is it coming from? Well, if it smells like rotten eggs, it is most likely it is coming from the underground sewers.

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Fortunately, according to new research from the International Water Association (IWA) Conference in Busan, Korea this week, attempts are being made to combat this stinky problem.

Sewer gases range from ammonia to methane, carbon dioxide and sulfur dioxide. But the rotten egg smell that we often encounter comes from hydrogen sulfide. Hydrogen sulfide can be detected by human olfactory senses in very low concentrations therefore people can become very sensitive to these concentrations.

Not only is it annoying to catch the stench of sewer odor, but the leaking gases from these pipes are costing billions of dollars worldwide in odor control. The gases can also corrode sewer pipes, which also cause problems for systems in warmer climates.

One experimental treatment to deal with the smell is a new chemical cocktail known as Cloevis. The mixture has been tried on sewers in the Gold Coast region of Australia where the chemical stopped 99% of the rotten egg smell emitted from these pipes.

Lead researcher, Professor Zhiguo Yuan from the University of Queensland, told IWA delegates that one week after dosing for a few hours, the gas level increased to less than one fifth of its emissions prior to the treatment. This trial has been repeatedly observed over a period of five months and has been successful. "We are currently looking to commercialise Cloevis and are doing a further four trials of the mix in the US and Canada," Professor Yuan says. "Our partners over there are very excited by Cloevis' potential."

Researchers also are looking into chemical free methods for managing hydrogen sulfide gas. Professor Yuan, says "We probably won't stop all bad smells from sewers forever but we're well on the way to reducing their extent."

Other solutions deal with managing bad smells from sewers and wastewater drains once they have escaped. Dr Valentina Lazarova and her team from France used jasmine-smelling micro sprays to mask the smells.

After 1000 questionnaires and face-to-face interviews, 70% of the population said they were satisfied or very satisfied with the trials and 96% wanted the project to continue.

While more research and experiments need to be conducted, hopefully a solution to sewer stink will come to a city near you!

Read more at EurekAlert.

Manhole cover image via Shutterstock. 

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