Demonstration of Innovation to Improve Pathogen Removal, Validation, and/or Monitoring in Carbon Based Advanced Treatment (CBAT) for Potable Reuse

The goal of this project was to provide utilities and regulators with clear guidance for pathogen reduction crediting for two key processes within carbon-based advanced treatment, including ozone (O3) and biologically activated carbon filtration (BAC). Objectives included (1) validating 4- to 6-log virus reduction credit through ozonation using an ozone to total organic carbon+nitrite (O₃:[TOC+NO_2]) ratio as the dose control method to optimize energy use and bromate formation while maintaining robust virus disinfection; (2) documenting pathogen removal through BAC with different design and operational scenarios; (3) advancing the O₃:(TOC+NO₂) approach with machine learning; and (4) developing an ozone validation protocol for the O₃:(TOC+NO₂) approach. The team compiled a robust dataset of existing studies and conduct bench- and pilot-scale testing at six utilities to confirm O₃:TOC+NO₂ dose control mechanisms and developed a validation protocol that can be used by utilities and regulators to confirm the optimum ozone operational approach. Published in 2025.