Your Green Life: "WLSSD's Bio-Filter"

By KBJR News 1

August 4, 2010 Updated Aug 4, 2010 at 2:16 PM CST


Cleaning up waste water can be an odorous task. And at WLSSD that is one of the major responsibilities that they have as a facility.

In this weeks "Your Green Life" Meteorologist Jeff Edmondson takes a look at how they naturally take the odor out of the air.

The Wastewater that WLSSD ingests and cleans up every year is vital to keeping our drinking water clean and fresh, but this process also gives off a unique odor. Since 1996 they have been cleaning the air using a biological process.

"We needed to provide some relief to the neighbors for odor control", said Al Parrella.

And this bio filter is the most environmentally friendly option they could have made.

"Back in the 90s the alternatives that were considered were either chemical treatment which could be a packed tower wet scrubber or some chemical treatment or this biological treatment", said Al.

According to the engineers the chemicals used for treating the odor required a significant amount of energy to produce. Instead, the biofilter is an easy biological process of purifying and oxidizing the air.

"You just expose the odorous air as evenly as possible through that for a period for about 40 seconds, and that for a solution and for it to oxidize", said Al.

Within the 40 seconds the odorous air travels through layers of rock, compost and woodchips. But over time this biological process can inhibit the filtration.

"The surface of the biofilter is raked evenly when its rebuilt. After 2 1/2 or 3 years you can see hills and valleys start to form. That means those areas are turning into compost and the whole to mush", said Al.

And the materials required for rebuilding it come from their on site yard waste collection.
In Duluth, I'm Meteorologist Jeff Edmondson, The Northlands NewsCenter.

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