Québec City, a UNESCO World Heritage site, is demonstrating that historic cities can also lead the way in environmental innovation. This presentation explores the design and performance of Québec City’s cutting-edge facility that co-digests wastewater sludge and source-separated food waste to produce renewable natural gas (RNG) — a landmark achievement in circular urban infrastructure.

The facility processes 96,000 tons of sludge annually from the local Water Resource Recovery Facility, alongside 87,000 tons of food waste collected directly from residents. A critical component of the project’s success lies in its ability to separate digestate into clean solid and liquid fractions. High-quality liquid separation is essential, as the filtrate must meet stringent purity standards to be refined into ammonium sulfate — a valuable liquid fertilizer.

To meet these demands, the City invested in six advanced 8-channel Rotary Press units (totaling 48 dewatering channels), selected for their reliability, efficiency, and low maintenance requirements. Since operations began in spring 2023, performance testing has confirmed the technology’s ability to support both operational resilience and sustainability goals.

Presenters will share practical insights on plant design, capacity planning, spatial and energy optimization, capital and O&M costs, redundancy strategies, and start-up challenges. As a model of forward-thinking infrastructure within a historic cityscape, this case study offers valuable lessons for municipalities seeking to align waste management, climate action, and heritage preservation through integrated bioresource strategies.