Manitoba’s first dairy-based mesophillic anaerobic digester is in the final stages of testing and is expected to be ready for operation this fall.
It is on the Sweetridge dairy farm south of Winkler.
It is a pioneering project that must withstand the cold Manitoba winter, which many people say will kill the sensitive bacteria critical to the biodigestion process.
The Sweetridge farm, owned and operated by Harold and Miriam Sweetnam, milks 230 cows on a three-times-a-day schedule.
Miriam Sweetnam said they realized a number of years ago that environmental standards aimed at livestock producers were imminent
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“We knew we had to do something about manure on our farm. We knew what was coming. We looked at the (biodigester) idea and decided it made sense.”
Sweetnam said they realized a blend of feedstock was needed for an anaerobic digester to function efficiently. Dairy manure alone wouldn’t do the job.
“So it’s not just our manure. We’re in an area with lots of potatoes, onions, other vegetable crops, dairy processors and many alternative food sources for the digester. And we do bunker silage, so we can feed spoiled silage into the biodigester.”
Getting the right blend of ingredients is important. A sudden change in diet for the bacteria could spell disaster.
There is nothing special or hi-tech about the basic bacteria. The bug colony comes from the day-to-day dairy manure put out by the cows, so the bacteria are right at home in the Sweetridge biodigester.
However, the sudden introduction of another ingredient, even if it has higher potential to generate energy, can disrupt the happy symbiotic process taking place in the digester.
“The recipe going into the biodigester is vital. It’s a challenge to develop and manage that recipe,” she said.
“If you add too much of any one thing, you can knock it all off. The bacteria are so temperamental. They’ve been likened to the stomach of a cow.”
Elsie Jordaan, a PhD candidate at the University of Manitoba, is cooking up the ingredient recipe for the Sweetridge Farms biodigester.
Sweetnam said the biodigester is not as deep into the ground as they would have liked, due to soil conditions.
“We have liquid heating pipes below the floor and in the concrete walls. We’ll heat the biodigester to 36 C with propane at first to get it going,” she said.
“Once everything is up and running, waste heat from the system will be pumped through the pipes to keep it at that temperature.”
The Sweetridge Farms biodigester is a joint project with the University of Manitoba, the federal and provincial governments and Manitoba Hydro.
