GRAND RAPIDS, Mich. — On one of the most humid days of the year, it feels even more so inside the new biodigester in Grand Rapids. The biodigester has to be kept at 98 degrees. No more, no less.
The sweat is dripping down the face of Mike Grenier, the city’s environmental services manager. Even though the heat and humidity make for a miserable combination, Grenier is anything but miserable.
Grenier and many others have been working on this biodigester for years. Wednesday, the city finally got the chance to show it off to the public through a media tour.
“We’re very excited to start talking about our digestion process that we just installed in the plant,” Grenier said.
“What that does is it takes the municipal solids from the bottom of our tanks, and goes ahead and breaks those down using bacteria to produce methane that we can clean and sell as well as reduce our solids that limit what has to go to the landfill.”
Grenier says the biodigester helps reduce the amount of solids the city’s environmental services department sends to the landfill by 30% to 40%. In addition to the cost savings that comes with that reduction, Grenier also says the city has made about $2.5 million in revenue this year from selling natural gas to DTE Energy after the biodigester first came online over the winter.
“We should be able to sell $4 million a year once we have everything dialed in and working like it's supposed to. That said, natural gas prices are all over the place right now. But those are the estimates that are that we're working with,” Grenier said.
A room-by-room tour of the Grand Rapids biodigester
Anyone who pays a sewer bill in the City of Grand Rapids would then benefit from that cost savings and revenue from the biodigester. Grenier says the biodigester should limit people’s sewer bills from going up and it may even drive their sewer bills down.
When the project was first announced, there were concerns about odor. People living near a biodigester in Lowell had just complained about the odor coming from that facility.
The wastewater plant in Grand Rapids does give off an odor on its own, especially in the summer months, but Grenier says the Grand Rapids biodigester was designed specifically not to give off any additional odors.
Grenier says the biodigester as it stands is a foundation for things to come, including the possibility of expansion in the future. The cities of Grand Rapids and Wyoming are teaming up to study what the future of solids handling looks like.
But for now, Grenier and the rest of his team in the environmental services department is celebrating what it’s taken to make it this far, through the construction and the delays.
“Staff has been working very, very hard on this. It's literally every day 24/7 we've got somebody that's leaning on this rock,” he said.
“We believe that we’ve built the foundation going forward for the city. As far as new treatment technologies go, it's put us where we normally are as a leader in technology inside the industry. It's what we do. It's what we're good at. It's what we've been tasked for by the city. My staff has worked their butts off, and I'm very proud of them, and they should be proud of themselves.”
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