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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. 

Abstract IntroductionWe rely on coastal resources for food, water, and energy. However, over 75% of U.S. coastlines are eroding. Concurrently, the U.S. recycles less glass than other developed countries, landfilling hundreds of millions of tons every year. Recycled glass sand has many potential benefits over natural sand for combatting land loss; for example, it can be produced with controlled particle size to better resist erosion, making it an excellent—and underutilized—material for environmental restoration. ObjectivesThis research compares the physical and chemical properties of recycled glass sand to natural sands (beach and dredge) from the U.S. Gulf Coast to assess environmental safety. MethodsParticle size distribution, angularity, particle and bulk density, compaction, and permeability were evaluated using standard methods. Elemental composition and leaching were analyzed using x‐ray fluorescence and toxicity characteristic leaching procedure (TCLP), respectively. ResultsRecycled glass sand is not “sharp,” although it is less well‐rounded than natural sand. Porosity, compaction, and water permeability depend on particle size, and glass sand can be size‐separated to match or complement natural sand. Recycled glass sand is mostly silica. Additional elements used in glass processing are present at acceptable levels, and no leaching of harmful elements is detectable by TCLP. Thermally decomposable residues (e.g. label and adhesive) reliably comprised less than 1% of the material. ConclusionsThe characteristics of recycled glass sand make it a good resource for environmental restoration. 

Abstract AimsThe goal of this study was to explore the suitability of recycled glass sand for the growth of beach-adapted plant species given the potential environmental benefits of utilizing glass sand for beach and dune restoration in the face of dwindling natural sand resources. MethodsWe grew three species native to US Gulf of Mexico beaches (Ipomoea imperati(Vahl) Griseb.,I. pes-caprae(L.) R.Br., andUniola paniculata(L.)) in three greenhouse experiments in glass sand, beach sand, or mixtures. First, we investigated nutrient and microbial effects by growing each species in pure glass sand, beach sand, and 80%/20% mixtures of glass sand/beach sand. Second, we comparedU. paniculatagrowth in glass sand mixed with 100%, 75%, 50%, 25%, or 0% beach sand. These experiments included fertilizer and microbial sterilization treatments. Third, we investigated soil permeability effects by comparing growth of all species using different grain sizes of glass sand. ResultsOverall, plants produced significantly more biomass in beach sand than in glass sand, and the effect was more pronounced with the fertilizer treatment. There were significant effects of substrate mixtures and interactions with fertilizer treatments onUniolabiomass. Further, when glass sand grain sizes were manipulated, plant biomass was equal or higher in the coarsest glass sand compared to beach sand. ConclusionsOur results demonstrate that beach-adapted plants can grow in glass sand and suggest that recycled glass sand is a potential resource for ecological restoration with incorporation of soil amendments such as fertilizer and utilization of selected grain sizes. 

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.