Innovative Approach to Converting a Conventional Trickling Filter Plant to Remove Nitrogen

Presentation Description: The City of Hayward’s Water Resource Recovery Facility is undergoing a transformation—one that redefines wastewater for the San Francisco Bay Area. This ambitious program spans more than 30 facilities within the treatment plant and addresses pending nutrient regulations facing the San Francisco Bay Area, while also performing a comprehensive upgrade to the entire facility to address aging infrastructure, changing process flow schematics, and improving hydraulic capacity. In addition, construction began in Spring 2025 on a new state-of-the-art Administration Building, with a new water quality laboratory, that will centralize SCADA systems with a new central control station. The presentation will highlight the design and construction of the new biological nutrient removal (BNR) system and the many ancillary supporting systems required to deliver needed performance enhancements.
A key technical focus is the implementation of a novel trickling filter-BNR hybrid process which was designed to comply with the pending nutrient limits while maximizing use of existing infrastructure. This innovative approach leverages the existing trickling filter (circa 2009) through its anticipated remaining life to meet existing TSS and BOD limits as well as pending nutrient limits while deferring major capital investments. By extending the filter’s operational life through 2040, the City gains flexibility to adapt to future regulatory changes and transition to full BNR treatment when required. This approach will likely require fully abandoning the trickling filter process in favor or more BNR tanks in the future.
The team applied for WIFIA funding and presenters will share insights into costs and funding mechanisms. The team will share the latest benefits and challenges that were encountered with applying for federal funding of the project, and how the team balanced minimizing costs with ensuring a facility that would be simple and reliable to operate.