Before committing to large-scale installation of a PFAS filter technology, utilities and large facility operators typically conduct pilot studies — controlled, small-scale evaluations of candidate technologies using actual source water. Understanding pilot study design and interpretation is relevant both for water professionals and for informed consumers evaluating manufacturer performance claims.
Purpose of Pilot Studies
Pilot studies evaluate filter performance under site-specific conditions that standardized laboratory certification tests do not capture. Your source water’s specific PFAS mixture, organic carbon content, pH, hardness, temperature, and other characteristics all affect how a technology performs. A pilot study using actual water from your source provides the most reliable prediction of full-scale system performance at that location.
Key Design Elements
A rigorous pilot study specifies the empty bed contact time to be evaluated (typically multiple EBCT values to identify performance-cost trade-offs), the sampling frequency for influent and effluent PFAS analysis (typically weekly during the initial rapid-change period, then monthly), the statistical methods for analyzing breakthrough curves, and the performance target (e.g., maintain effluent below the MCL for at least 80% of rated service life).
Interpreting Pilot Results
Breakthrough curves — plots of effluent PFAS concentration over volume treated — are the central output of GAC pilot studies. A curve that rises steeply early in the study suggests poor adsorption affinity (common for short-chain PFAS on carbon); a curve that remains flat for extended operation then rises sharply indicates strong adsorption with predictable exhaustion. These curves directly predict how frequently media must be replaced to maintain target effluent concentrations and therefore drive life-cycle cost calculations for full-scale system planning.