What to Do with Waste: The Anaerobic Digester at Work

As part of a circular water economy, Holland BPW strives to use and reuse every part of the water reclamation process so that nothing is wasted. Every byproduct of our process has a second life that benefits the community and environment in some way.

Water reclamation is the process of renewing wastewater so that it can return safely to the natural environment. Our reclamation process creates two byproducts – solids and water. The reclaimed water is disinfected and discharged to Lake Macatawa. Our solids are sent for agricultural land application as much as possible, with the rest sent to a landfill. As landfill costs have increased over the years, we have sought to reduce the volume of solids we dispose of. Our new anaerobic digester reduces the volume of solid waste produced by our process while generating biogas, a beneficial byproduct.

Environmental Benefits

Since the digester came online at the end of 2023, we have already seen a 50-55% reduction in the volume of solids that must be disposed. This is both cost effective and sustainable, reducing the need for landfill disposal and the amount of trucking needed to transport solids to their destination.

Solids also take up space at our facility. With fewer solids to house, our plant now has more room to grow in its existing footprint. This increase in space will help to meet our community’s future water reclamation needs.

Byproducts

In addition to reducing the amount of solids, the anaerobic digester provides new opportunities to reuse byproducts from water reclamation in a way that supports the environment. Reducing the volume of solids through the digester also has two byproducts that can be reused: biosolids and biogas.

The anaerobic digester uses trillions of anaerobic microorganisms that feast on solid waste to reduce the volume of our solids. As the microorganisms digest their food, they produce biogas and convert the remaining solids into a nutrient-rich product known as biosolids.

Biogas

Biogas is a methane rich gas that is created by the microorganisms that break down the solids in the anaerobic digester. We use the methane captured from the digestion as a renewable energy source to generate an average of 500 kW of electricity, or approximately 40% of the Water Reclamation Facility’s electric usage. Additionally, we capture the waste heat from the electric generation and use it to heat the digester as well as two of the buildings on site.

Biosolids

The anaerobic digester is successfully impacting the amount of biosolids we produce. It has cut the amount down by 55%. Biosolids are a renewable resource that adds natural structure back into soil. Today, our biosolids are certified as Class B, so we land-apply them to agricultural fields growing crops not for direct human consumption and we send the remainder to a landfill.

Better, Higher Use

As we continue to realize our vision of a circular economy, we will find higher uses for our biosolids. Our team plans to pursue a Class A Exceptional Quality Biosolids designation from the Michigan Department of Environment, Great Lakes, and Energy. Class A biosolids are cleaned to a higher standard than Class B and can be used as a fertilizer or soil amendment without restriction, increasing opportunities for reuse and eliminating the need to send solids to the landfill.

We look forward to continually innovating and finding new creative uses that minimize our environmental impact and reclaim what goes down the drain.

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