Investigating the Effect of Operational Strategies and the Role of Microbial Biomass for Extending the Lifetime of Granular Activated Carbon

Drinking water utilities must adapt treatment operations to meet new PFAS regulations while managing other contaminants of emerging concern (CECs), such as nitrogenous disinfection byproducts (n-DBPs). Granular activated carbon (GAC) filtration is widely used for PFAS removal, yet utilities lack clarity on how operational strategies affect both PFAS and n-DBP control, particularly regarding microbial biomass on GAC. While biomass accumulation was once thought to hinder PFAS removal by blocking adsorption sites, recent findings suggest it may also enhance retention through biosorption. Additionally, microbial activity on GAC can influence organic matter degradation, impacting n-DBP formation and overall contaminant removal.

This study evaluates how operational strategies impact GAC performance at full-scale utilities and a pilot-scale system. Researchers will assess biomass levels and bioactivity in relation to PFAS and n-DBP removal across four utilities using different pre-treatment and backwashing strategies. Pilot-scale experiments at Ann Arbor Water will examine ozone (O3) versus ozone with hydrogen peroxide (H2O2) pretreatment and compare chloraminated vs. disinfectant-free backwash water effects on microbial activity and contaminant breakthrough. Findings will provide utilities with actionable strategies to optimize GAC filter performance for PFAS and n-DBP control, potentially extending GAC lifespan and improving regulatory compliance.

This project will enhance understanding of the role of microbial biomass in PFAS removal, helping utilities balance contaminant control with sustainable operations.