Methane gas is not your usual waste

By: Frank Waugh Email
By: Frank Waugh Email

When you pour something down the drain or flush the toilet, it ultimately ends up at the Waste Water Treatment Plant.

While you may never give it a second thought, there is energy in all that waste.

Not everything is waste at the Waste Water Treatment Plant. In fact, one of the byproducts is actually valuable.

Nancy Clay, Operations Manager at Waste Water Treatment, says, "There are two kinds of bugs, as I like to call them, acid formers and then the methane formers."

It is the methane that is valuable, and it is produced during a process called anaerobic digestion. In simple terms, these bugs break down the solid waste in the giant tanks.

Al Greek, Division Manager at Environmental Services, says, “As a part of that early process to digest the solids, they would collect out of the waste streams they put in anaerobic digestion. So, anaerobic digestion has always been a part of the South Bend Waste Water facility."

Excess gas is burned off while a portion of the gas is used in boilers that help keep the tanks at the proper temperature.

Clay says, "In the winter, absolutely, you have to heat them. If the temperature is not optimum, the bugs don't do what they are supposed to do, and they won't break down the solids and make the gas."

Happy bugs break down more material, and their methane production saves money.

Greek says, "Just checking our records for the last year, we have probably saved over $100,000 of purchased natural gas by using methane, so there is a direct advantage to burning methane rather than purchasing natural gas."

Engineer Becky Schaefer is working with the city to upgrade the aging facility and make it more efficient.

She says, "The new system, the mixing will be improved, which will actually increase gas production."

Greek says, "We are actually going to put in scrubbing equipment, and it will clean the gas and when it is clean, it should be the equivalent like natural gas, so we will be able to use this without doing damage in any of our equipment that we want to burn it in…When this upgrade is completed, we should be able to burn twice as much gas as we are burning right now, so then it could be a couple hundred dollars a year in savings."

Schaefer says, "We have been studying different options for upgrading the digesters and using the gas for the last three years, and the good thing about those studies is that the city realized that they are on the right path, they have always been on the right path."

It is a path that makes waste a little greener.

Greek says, “By burning this methane gas, it's all part of reducing the carbon footprint, and it also makes sense."

The upgrade is expected to take several years, and according to Becky Schaefer, early estimates show that, with the upgrade, the plant could produce enough methane yearly to heat approximately 1,500 homes.


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