New Orleans is turning discarded bottles into coastal sand. Crushed glass is now helping rebuild shrinking wetlands

New Orleans is finding an unusual way to tackle two environmental problems at once: mountains of discarded glass and a coastline that is steadily losing land. Instead of sending bottles to landfills, researchers and recycling groups are crushing them into sand and using the material to build experimental islands and strengthen wetlands. The idea is being tested in wetlands around New Orleans, where recycled glass is being mixed with natural sediment to create new ground for plants and eventually wildlife.

How a Louisiana-based company is building coastal ecosystems

Glass Half Full, a Louisiana-based recycling company founded by Tulane University students Franziska Trautmann and Max Steitz, supplies the crushed material. The partnership with Tulane researchers is exploring whether something normally treated as waste can become a useful building material for disappearing coastal ecosystems.

At Bayou Bienvenue, researchers have already constructed experimental islands using different combinations of Mississippi River sediment and recycled glass sand. Tulane said the project has expanded from two initial islands to a four-island system designed to compare how vegetation develops in the different substrates. The concept is strikingly simple: crush bottles, turn them into sand and put that sand where a vulnerable wetland needs more ground.

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Why Louisiana needs every grain of sand

Louisiana's coastal wetlands are under enormous pressure from erosion, rising seas, storms and changes to the natural flow of sediment. The U.S. Fish and Wildlife Service estimates that Louisiana currently loses about 10.9 square miles of coastal wetlands every year, equivalent to roughly 6,944 acres. The agency says the state has experienced more than 90% of the coastal wetland loss recorded across the lower 48 states.

Those wetlands are more than empty stretches of marsh. They provide habitat for wildlife and commercially important fish and shellfish while helping buffer inland areas from storms. That makes finding additional sources of restoration material increasingly important.

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Scientists are testing whether glass can actually support plants

The recycled glass is not simply being dumped into wetlands. Scientists are studying how plants respond to it and whether the material behaves differently from conventional dredged sediment. A 2025 study published in Restoration Ecology compared recycled glass sand with dredged river sediment. Researchers found that responses varied by plant species, but some trees grew equally well in coarse recycled glass, mixed material and conventional dredge. The researchers said glass sand could provide an additional supply of restoration material while keeping bottles out of landfills.

Science News reported that greenhouse experiments also produced encouraging results. Plants grown in a coarse glass-and-sediment mixture performed comparably to those grown in natural sediment in the experiments. Christine Whitcraft, a wetland ecologist at California State University, Long Beach, who was not involved in the research, told Science News: “They found success across a range of plants … so it does seem to hold a lot of promise.” She also cautioned that more field research is needed.

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A ‘ghost swamp’ gets another chance

One of the most striking projects is taking place at Bayou Bienvenue, an area where saltwater intrusion previously killed large numbers of cypress and tupelo trees. WWNO reported in 2024 that volunteers from Glass Half Full and Tulane began building new islands there using a mixture of river sand and crushed glass.

Trautmann described the degraded area as a “ghost swamp”, while explaining the project's ambition: “We're taking trash, we’re turning it into sediment that can breathe life and hopefully bring some cypress back to this swamp.” The aim is not simply to create artificial islands. Once vegetation establishes itself, roots can help hold material together and the developing ecosystem can begin functioning more like a natural wetland.

The experiment is bigger than New Orleans

The approach could eventually matter beyond Louisiana if researchers can demonstrate that recycled glass works safely and effectively in different coastal environments. Science News reported that researchers are monitoring the experimental islands for years, while additional studies have examined dune plants, salt-marsh grasses and mangroves. Results have generally been encouraging, although scientists stress that the best glass-to-sediment ratio and grain size may differ between ecosystems. Tulane's Bek Markel described the broader potential as “a blueprint for other coastal cities facing erosion.”