Evaluation of Tier 3 Validation Protocol for Membrane Bioreactors to Achieve Higher Pathogen Credit for Potable Reuse

Research has demonstrated the ability of membrane bioreactor (MBR) systems to provide significant virus, protozoa, and bacteria removal. However, a gap exists in the regulatory application of pathogen log removal value (LRV) credits for MBR systems within potable reuse systems. Without a clear regulatory pathway to approve higher LRVs for MBRs, potable reuse agencies are faced with installing additional treatment and/or costly monitoring systems to improve pathogen credits for other processes. The Australian WaterVal program describes three tiers of validation to obtain LRV credits for viruses, Cryptosporidium, and Giardia. This project evaluated the Tier 3 WaterVal MBR validation protocol for test cases in the United States, identified modifications needed to adapt the Tier 3 protocol for the United States, and developed implementation recommendations for a Tier 3 style regulatory approach for increased operational flexibility in reuse facilities. Research partner: California State Water Resources Control Board. Published in 2023.