2024-03-19 15:11Press release

Casella Feedstock Agreement Key to Maine Biodigester Coming Online

Digested biosolids being loadedDigested biosolids being loaded

Viridi Energy, a leading renewable natural gas (RNG) platform, announced today that it has acquired a legacy biosolids digester plant in Brunswick, Maine, with plans to transform the site into an industry-leading waste-to-RNG facility. The facility will generate valuable renewable energy and help power the local community, offer a sustainable and cost-effective solution for managing biosolids, and support compliance with local regulations aimed at mitigating per-and polyfluoroalkyl substance (PFAS) contamination in the region.

Casella will manage feedstock collection and delivery logistics for an estimated 85,000 tons of biosolids per year collected from a network of wastewater treatment plants. At Viridi’s overhauled Brunswick facility, the biosolids will be transformed, via anaerobic digestion, into enough energy to heat more than 3,000 homes for a year. The facility will also supply electricity directly to Brunswick Landing, the 3,300-acre campus featuring more than 1.6 million square feet of commercial, industrial, and professional office space that is home to both the Brunswick facility and more than 160 other companies.

“Viridi continues to lead the industry with innovative solutions that help overcome challenges in both the waste management and energy sectors and this project signals the team’s ongoing emphasis on diversifying our waste feedstocks and expanding our processing capabilities to meet growing renewable energy needs,” said Dan Crouse, CEO of Viridi. “We are excited to be working with Casella, whose established track record in successfully managing multifaceted waste streams will be pivotal to our success. Casella has been at the forefront of finding a sustainable solution to this issue since the law prohibiting land application of biosolids was enacted and has played a significant role in bringing this vital piece of infrastructure online.”  

In addition to fulfilling a growing demand for RNG, this project will yield numerous environmental benefits across Maine. Once completed, the facility will offer an innovative solution for managing waste that complies with Maine’s PFAS regulations while allowing Casella to once again put the material to a higher and better use for its customers rather than send it directly to disposal.

With Maine laws now prohibiting the practice of land-applying biosolids digestate in agricultural settings because of PFAS concerns, wastewater treatment facilities are facing the choice between two less sustainable alternatives: trucking the material long distances or landfilling it, where it requires stabilization and takes up large volumes of space – a strategy that is especially problematic in landfill-constrained Maine.

The anaerobic digestion solution offered at Viridi's Brunswick facility is expected to reduce the volume of the biosolids by nearly 90 percent, from 85,000 wet tons down to 10,000 tons once the material has been digested and dried. Once processed, Casella will transport this more stable, post-process digestate to landfill in a form that preserves landfill capacity, lessens the need for stabilization material, and reduces transportation distances.

“Our agreement with Viridi represents a major step toward finding a sustainable solution for Maine’s biosolids,” said John W. Casella, Chairman & CEO of Casella Waste Systems, Inc. “The need for efficient, responsible biosolids treatment and disposal solutions has never been more pressing. We are pleased to be working with Viridi to provide a comprehensive approach for managing this waste stream in a safe, sustainable, and beneficial way.”

With the development of this relationship, Viridi and Casella are providing a sustainable pathway for Maine municipalities to reduce uncertainties in managing their biosolids. Viridi is currently conducting siting, permitting, and environmental due diligence at the Brunswick site. Retrofit construction of the Brunswick facility is expected to be complete by the second half of 2025, with full operations slated to commence in 2026.

About Casella Waste Systems, Inc.

Casella Waste Systems, Inc., headquartered in Rutland, Vermont, is one of the largest recyclers and most experienced fully integrated resource management companies in the Eastern United States. Founded in 1975 as a single truck collection service, Casella has grown its operations to provide solid waste collection and disposal, transfer, recycling, and organics services to more than one million residential, commercial, municipal, institutional, and industrial customers and provides professional resource management services to over 10,000 customer locations in more than 40 states.


Jeff Weld
Vice President of Communications
Jeff Weld