Biodigester development enters homestretch

The city began its $38 million biodigester project in 2017 to convert food waste to energy. Courtesy city of Grand Rapids

The city of Grand Rapids’ ability to manage municipal solids in an environmentally sustainable manner — and produce natural gas, electricity and phosphorus through its new biodigester — is on the horizon.

The city began its $38 million biodigester project in 2017 to convert food waste to energy. As the project enters its final stages of production, the Grand Rapids City Commission on last week authorized the extension of a professional services contract with The Christman Company to align with the biodigester’s final completion timetable. The project remains under budget with no additional funding associated with the contract extension.

According to City Engineer Tim Burkman, 95% of the biodigestion equipment has been installed, and commissioning is now underway. While biodigester construction is expected to wrap by Wednesday, Christman’s contract extension through December will keep the team intact through the biological startup of the digesters, including all stages of the process of seeding, digestion and commissioning.

“Final process completion, as well as associated coordination with the related renewable natural gas and phosphorus recovery projects, are ongoing, hence the extension request,” he said. “This is due to revised phasing, extended equipment delivery schedules and COVID-19-related delays.”

During his biodigester project update to the City Commission, Burkman reported on the following milestones:

  • Sludge thickening equipment has been relocated from an existing building at the Water Resource Recovery Facility to the biodigestion facility.
  • Testing of the first biodigester tank and associated equipment is underway.
  • Seeding, or introducing microorganisms to breakdown the organic material of wastewater, is planned for the first digester tank in early April.
  • More than 75 hours of training has been provided to staff on the various equipment and components, including biogas storage, combined heat and power, specialized pumps, odor control, polymer thickening agents, chemical analysis tools, software and safety protocols.
  • Dozens of staff, including operators, mechanics, technicians and support staff are preparing for biodigester startup.
  • The combined heat and power system is operational and will be ready to function as soon as the biodigestion process begins.
  • 90% of the equipment to recover phosphorous and to generate renewable natural gas is in place and is ready to go online when the biodigestion process begins.

“The progress we’ve made, despite COVID-19 in the past 12 months, is a testament to the importance of this project and the work of the team behind it,” said Mike Grenier, environmental services manager for the city of Grand Rapids. “The size and scope of it may seem intimidating to those not intimately involved with it, but ultimately, the rewards we will see will benefit our community and region in many ways.

“Not only is it the right thing to do for the environment, but it ensures we will have treatment capacity for regional growth. The city will recognize significant cost savings in the process. Add to that the potential to generate revenue, and it becomes clearer why this has been an important undertaking for Grand Rapids and the region.”

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