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ABSTRACT Recycled glass offers a promising, cost-effective alternative to silica sand for water filtration. This study evaluated its performance in a gravity-driven flow system using three particle sizes: gravel (G), coarse sand (CS), and fine sand (FS). As expected, a tradeoff was observed between turbidity reduction and permeability. FS achieved the greatest turbidity reduction (96.6% in particulate filtration and 93.1% in environmental water filtration) and Escherichia coli log removal of 1 ± 0.2, but low permeability. Higher permeability but poor turbidity and E. coli removal was achieved using G. To balance these tradeoffs, a layered filtration system was used to improve permeability with effective turbidity reduction (96.9% in particulate filtration and 93.5% in environmental water filtration). Without coagulant treatment, the E. coli log removal was 0.27 ± 0.15; with coagulant pre-treatment, it increased to 2.5 ± 0.4 for the layered filtration system. These findings demonstrate that crushed recycled glass can be used as an effective filtration medium and the filtration system can be configured with different particle sizes and/or layers to meet application-specific requirements. 

Sand made from recycled glass cullet could supplement limited dredged river sand (dredge) in coastal wetland restorations; however, its suitability for wetland plants is unknown. In two experiments, we compared the biomass of several wetland plants in recycled glass sand to growth in dredge. First, we grewSalix nigra,Zizaniopsis miliacea, andSporobolus alterniflorusin fine‐ and coarse‐glass sands, dredge, and a coarse‐glass/dredge mixture. Second, we grewTaxodium distichumandSchoenoplectus californicusin a revised coarse‐glass blend, dredge, and a mix. We characterized the substrate porosity, particle density, and bulk density for both experiments and tested how substrate nutrients, metals, and pH impactedS. californicusleaf contents. We found species‐specific responses to substrates: herbaceous species grew better in the mix and dredge than in glass alone, whereas trees grew equally well in the coarse glass, mix, and dredge. Glass sand was less dense than dredge. When saturated and compressed, finer‐grained glass sand and mixes had lower estimated porosities than coarser glass sand and dredge.S. californicusleaf chemistry resembled that of the plant's substrate. This study demonstrated that wetland plants can grow in glass sand, that mixtures of glass and dredge have species‐specific effects, and that substrate structure and chemistry could help explain these differences. Thus, it opens the door for broader field studies on how glass sand can best be used in coastal restoration efforts.