The removal of selected PPCPs by backwashed slow sand filters and the influence on the bacterial community of the filter media - Supplementary Materials - QIIME2 .qzv files

This study examined the removal of N,N-Diethyl-m-toluamide (DEET), caffeine (CAF) and triclosan (TCS) using backwashed slow sand filters (SSFs). Two systems, each comprising a mixture reservoir and a sand filter column, were evaluated, with one spiked with selected pharmaceuticals and personal care products (PPCPs) in methanol. Backwashing, used as an alternative to scraping to simplify filter maintenance, was assessed for its influence on contaminant removal and bacterial community composition over time. Average PPCP removals within the filter were 20.3% (DEET), 56.3% (CAF) and 32.8% (TCS), increasing with time. Combined removal across the reservoir and filter reached 97.3% (DEET), 97.2% (CAF) and 88.0% (TCS). Proteobacteria dominated the bacterial community (60–83%), with Methylophilus (3-49%) prevailing in the contaminated filter and Sphingopyxis (7-41%) in the control. Principal coordinates analysis showed that PPCP contamination primarily explained bacterial variation, while backwashing and time had minor effects. PERMANOVA confirmed significant differences between contaminated and non-contaminated filters (pseudo-F = 10.49; p = 0.001). The presence of Methylophilus, Sphingopyxis and Pseudomonas, genera associated with PPCP biotransformation and methanol utilisation, suggests functional bacterial adaptation driving compound attenuation. SEM analysis revealed particle size stratification in the sand column after backwashing, without compromising performance. Overall, backwashed SSFs provided biologically mediated attenuation of PPCPs while maintaining filtration efficiency, highlighting their potential as a low-cost, sustainable treatment option for trace organic contaminant removal.

The data are presented as .qzv files generated in QIIME 2 for visualization.