The North Shore Water Reclamation District (District) provides wastewater services to over 300,000 residents in northern Illinois at three water reclamation facilities and a regional biosolids dryer facility. Challenges such as aging assets, capacity limitations due to new permit limits, and growing PFAS concerns, prompted the District to take a fresh look at its biosolids management program.
The Biosolids Master Plan (BMP) will define how the District plans to navigate the next 20+ years of biosolids management and align the modernization, expansion, and optimization of existing facilities to meet their goals. The District engaged BC to develop the BMP in a two-phase approach. In Phase 1, an in-depth understanding of the District’s existing program and future obstacles was established. Programmatic bottlenecks and pain points were identified through a condition assessment and by creating a baseline of the existing program. A biosolids regulatory and market assessment revealed the external influences and future potential considerations for biosolids end use. Phase 2 built upon the findings of Phase 1 to look at a universe of applicable technologies to build out regional and local alternatives for evaluation. Through a series of collaborative workshops, the District and BC screened and refined end-to-end solids management alternatives using BC’s Solids Water Energy Evaluation Tool (SWEET), and a preferred alternative was selected with the help of the multicriteria decision analysis (MCDA) framework.
The preferred alternative expands digestion to 100% of the District’s solids and consolidates stabilization, biogas utilization, and drying at a central facility. The alternative adopts advanced thermophilic digestion and thermal drying to modernize the District’s system and includes an optional pyrolysis system to treat PFAS. This approach directly addresses the current operational challenges at the District’s drying facility by improving sludge consistency and reducing solids volume and hauling, while also producing a new resource and revenue stream through the production of renewable natural gas. The preferred alternative and its associated capital plan stagger the BMP construction projects to maximize the usable life of existing equipment and to optimize the District’s capital investments. The BMP also incorporates a trigger map to guide future implementation decisions throughout and beyond the 20-year planning period. This alternative is estimated to save the District nearly $2 million in annual O&M costs while providing multidimensional benefits to the District and its stakeholders.