Bacteria Farts Power Wastewater Plant in Fort Wayne
July 10, 2018
|Biogas is stored in spherical white tanks, at the Fort Wayne wastewater treatment plant. (Provided by City of Fort Wayne)|
Wastewater and water facilities consume around 3% of all power in the United States.
That’s a lot! And many water utilities spend millions of dollars on their electric bill.
But, Fort Wayne’s water utility is tapping into a growing trend to reduce those costs and protect the environment. Doug Fasick, a senior programs manager for Fort Wayne’s city utilities, gave a tour of the city’s wastewater treatment plant, starting with the plants wet well.
“This is where all the water is coming in from the collection system throughout the city,” says Fasick.
From here, sewage is piped into what looks like a giant above ground swimming pool filled with water. Two ducks swim in it side by side.
“Yeah, they eat…whatever’s in there,” Fasick says.
This tank is the primary settler. Fats are scrapped off the top and the rest of the sludge is diverted to the digesters.
“Think of a digester like your stomach,” says Fasick.
This is where Fort Wayne’s wastewater treatment plant gets interesting: here, lots and lots of bacteria eat, or decompose, all this sludge. And after they eat, they create methane.
The plant captures that methane and turns it into electricity, powering the plant.
“We’ve cut our consumption requirements by a third, so we’ve saved some money there with out electric utility,” Fasick says.
Overall, the Fort Wayne utility cut its monthly electric bill by $40,000.
There’s environmental benefits, too. Methane is a planet-warming greenhouse gas. Before the plant ran on biogas, it just burned the methane, changing it into carbon dioxide, and released it into the atmosphere.
The plant converted to this system in 2015 with the help of Dana Kirk, a professor of Biosystems and agricultural engineering at Michigan State University.
“We’ve been working with them to evaluate different kinds of organic wastes, or what we call feedstocks, to see what the energy potential is,” Kirk says.
Bacteria make a different amount of methane based on what they’re eating. For example, sugar and food waste creates more methane than manure or human waste. Kirk says its important that utilities get that balance right if they’re going to get the most bang for their buck out of a biogas recycling program.
Kirk also says these programs are becoming more popular with wastewater plants around the country.
“Converting and producing their power on site to treat, you know, the wastewater is something that’s very interesting to a lot of communities around the country,” says Kirk. “It’s kind of the model for the next 20-50 years in that industry.”
And it’s a growing trend in Indiana. West Lafayette has a similar deal with Purdue University to convert its food waste into energy. Marion County has a smaller program and just got a grant from the state to expand it. And Evansville is also expanding its program.
“We’ve actually been using biogas as a fuel source for pumps that would normally run off, like, gasoline or natural gas,” says Allen Mounts, director of Evansville’s water and sewer utilities.
They’ll soon be able to process fats, oils and grease from area restaurants for power.
Mounts says the savings help pay for infrastructure upgrades and the cost of complying with federal clean water regulations.
“We’re pretty much on our own to figure it out. Certainly a group of Indiana utility directors have been trying to elevate the awareness with people at the state level,” says Mounts.
But for now, Mounts says they need to save every dollar they can.
Back at the wastewater plant in Fort Wayne, Fasick shows off final steps of the biogas process: the iron sponge.
“When it comes from the digesters over to here, it’s run through this system to clean it up,” Fasick says.
The iron filters impurities and moisture out of the gas. Then it’s piped to a generator and — boom — it powers the wastewater plant.
Moving forward, the Fort Wayne utility is expanding its program, too. It just made a deal to take waste from the Nestlé plant in Anderson, so it can generate even more power from biogas.
Article cited from: https://goo.gl/3A6mSu