BATCH-SCALE SCREENING OF ENGINEERED MEDIA FOR NATURE-BASED TREATMENT OF ALTERNATIVE WATER MATRICES

Abstract

Nature-based solutions (NbS) are increasingly applied to improve urban water quality fromalternative water sources, though the specific treatment approach varies by source: bioretention systems are established for stormwater (SW) management, while graywater (GW) and recycled wastewater (RW) are more commonly treated through engineered wetlands and other constructed treatment systems. The amendment of these systems with sorptive media is an emerging concept that has shown promise for enhanced contaminant removal, yet remains largely untested at scale and is not yet standard practice. A barrier to wider adoption is the lack of matrix-relevant performance data: sorption capacities determined in deionized (DI) or synthetic water frequently misrepresent performance in complex real-water matrices, where dissolved organic matter (DOM), suspended solids, competing ions, and residual treatment chemicals (e.g., coagulant or disinfectant byproducts carried over in RW) can substantially suppress removal. Most published studies are conducted in clean or synthetic waters, leaving a fundamental gap in how real matrix composition governs sorptive removal of contaminants of concern under field-relevant conditions. ii This work addresses that gap by developing a controlled, comparative batch-scale screening program that evaluates commercially available engineered media across spiked DI-water and three alternative water matrices (GW, RW, and SW) to produce a comparative, cross-matrix dataset linking media performance to water quality conditions. While the results directly inform media down-selection for subsequent column- and pilot-scale validation within the broader project, the batch-scale findings independently advance mechanistic understanding of how matrix chemistry governs sorption across media types and contaminant classes. Batch-scale sorption-experiments were conducted under standardized contact conditions (24 hours, 150 rpm, approximately 25 °C) using triplicate amended reactors and paired no-sorbent controls, with dissolved-phase analytes. Media evaluated included two proprietary per- and polyfluoroalkyl substances (PFAS) targeted amendments (CM-1 and CM-2), granular activated carbon (GAC), clinoptilolite zeolite, aluminum-based water treatment residuals (WTRs), and oak-feedstock biochar, tested against PFAS (6:2 FTS, PFOA, and PFOS), ammonium (NH4+), orthophosphate (PO43-), and dissolved metals (copper (Cu) and lead (Pb)) across graywater, recycled wastewater, and stormwater relative to a DI-water baseline. No-sorbent controls revealed matrix-specific background losses for selected nutrients and PFAS constituents, underscoring the necessity of control-corrected reporting for defensible cross-matrix comparison. Performance was strongly dependent on both sorbent class and water-matrix chemistry. CM-1 sustained high PFAS removal in RW (~81–94%) and SW (~61–87%), while CM-2 exhibited selective suppression for PFOA and 6:2 FTS and GAC showed consistently low removal across all complex matrices despite intermediate DI-water performance. Clinoptilolite zeolite achieved high NH4+ removal across DI-water, GW, and SW (mean 68–85%), with bounded matrix dependence attributable to co-ion competition. WTRs provided moderate-to-elevated phosphate iii removal in DI-water, GW, and SW but yielded negligible net sorption in RW, where background treatment residuals dominated orthophosphate behavior independently of WTR amendment. Biochar achieved robust dissolved Pb removal across matrices (61–87%), where Cu removal was more matrix-sensitive (24–75%), with strongest suppression in high-TOC GW. Zn was excluded from dissolved-phase evaluation after total metals screening revealed negligible sorptive removal by biochar. Collectively, these findings confirm that clean-water screening can misrepresent field-relevant performance and provide a ranked, empirically grounded basis for column-scale experimental design targeting multi-contaminant NbS treatment of alternative waters.