Grand Rapids building $30 million bio-digester

Feb 3, 2017

As locally owned Founders Brewing Company continues to grow so has its stream of highly concentrated food waste.  In response Grand Rapids' wastewater division is preparing to build a new bio-digester at its water resource recovery facility to handle that waste. The bio-digester, including a new pipe and sludge treatment system, is expected to cost the city nearly $30 million.

The city's environmental services manager, Mike Lunn says, while that is a lot of money to spend, the bio-digester financially was the lesser of two evils.

“We could have expanded the waste water plant to handle that load, so that would have been about a $90 million dollar project, so we looked at digesters and said, “you know this is $20 million, essentially, plus some add-ons bringing it up to $30 million, and not only do we get the benefit of being able to handle these loads, we don’t have the added costs of operating a new train, in fact we reduce costs,” Lunn said. 

According to the Saskatchewan Research Council, a bio-digester is like a mechanical stomach.  It’s an anaerobic digestion system that breaks down organic waste and converts that waste into methane gas. That methane can then be harvested, turned into renewable energy, and sold for a profit. Which Lunn says, is what makes the bio-digester a good investment for the city.

“We turn that carbon and bio-solids into methane," Lunn said. "We’ll take that methane and out of that we’ll get about 1.6 megawatts of electricity, and then in phosphorus recovery we will set up a system to recover phosphorus, and we’ll likely be able to sell that because phosphorus as you know only has a few mines left, and it is in limited supply.”

City officials say they hope to have the system running by 2018.