Anaerobic Digester Savings

Our anaerobic digester, the large round structure located at the Holland Area Water Reclamation Facility, has been operational since 2023. The digester reduces the mass of wastewater solids retained at the plant using microorganisms that break down waste in an oxygen-free environment. The process produces biogas (methane) that generates renewable heat and electricity, and creates Class A biosolids that can be used as fertilizer. The digester saves the community money by reducing the volume and potency of solid waste that needs to be disposed.

Some quick facts from our 2025 performance:

Reducing Solids

• In the state fiscal year from Oct 2024 – Sep 2025, the Holland BPW produced 1,655 dry tons of solids for disposal. That’s one third of the fiscal year prior to the digester when we produced 4,924 dry tons.
• 55% of the solids generated during the water reclamation process are converted to biogas using the anaerobic digester.

Financial Success

• The digester budgeted cost was $33.7M and spending to date is $31.4M.
• The digester project qualified for green project reserve under Michigan’s State Revolving Fund (SRF) program and certain credits under the Inflation Reduction Act’s (IRA) elective/direct pay provision for tax exempt entities. The SRF green project reserve included loan forgiveness of 20% or $6 million. Documents necessary to claim the IRA credits were submitted during FY2025 and an accrued receivable was established for the $11.5M credit, which included approximately $0.5M of interest income.

Better Control of Odor

• As the digester breaks down the volatile portion of the solids, odor potential is reduced as there are fewer volatile solids to break down post digestion.