Digester gas is an underutilized byproduct at many wastewater treatment facilities across Canada and the U.S. Unison Solutions has more than two decades of success in helping groups take advantage of that resource.
One of the company’s most recent success stories features Capital Region Water and its Advanced Wastewater Treatment Facility in Harrisburg, Pennsylvania, which is capable of treating 45 million gallons per day.
Unison designed and delivered a 400 scfm biogas pretreatment and upgrading system capable of injecting pipeline-quality renewable natural gas (RNG) directly into the local utility grid. Commissioned in October 2025, the project represents a significant step in Capital Region Water’s long-term strategy to modernize infrastructure and reduce environmental impact.
Built-In Operational Flexibility
The system was designed to deliver important flexibility.
Digester gas first is scrubbed of hydrogen sulfide, moisture, VOCs and siloxanes.
The design allows the biogas to be diverted to on-site heating via the plant’s existing hot water boiler or routed directly to the upgrading system.
When destined for the pipeline, biogas is compressed and carbon dioxide removed through a three-stage membrane separation process. At full capacity, the system delivers approximately 2,700 GGE of RNG per day to the local distribution network. Capital Region Water hailed this capacity as an opportunity to “provide a sustainable energy source while creating new non-rate revenue for our community.”
Engineered Specifically for Harrisburg
Unison’s in-house engineers and design team assess each site’s needs and opportunities as they put together a custom design.
For Harrisburg, Unison fabricated purpose-built equipment enclosures — not repurposed shipping containers — with wider bases, as well as heating and ventilation systems rated for Class I, Division 1 hazardous environments.
An integrated electrical room was completed at Unison’s facility prior to shipment, which significantly reduced on-site installation complexity and start-up time.
The design also utilized the plant’s existing gas storage sphere as an intermediate buffer, minimizing new infrastructure requirements.
Proven Before It Ships
Every component was designed, fabricated, assembled and factory-tested at Unison’s Dubuque, Iowa, facility before arriving on site.
That in-house expertise and process reduce installation risk, shortens commissioning timelines, and gives plant operators a system that’s been proven before it’s ever powered up in the field.
For wastewater utilities, landfills and food processors looking to monetize digester gas or advance renewable energy goals, the Harrisburg project shows what a purpose-engineered solution — backed by Unison’s more than 25 years of biogas experience — can deliver.
