Recycled Oyster Shells Make Eco-Friendly Ingredient For Cement

Researcher James Morris is rethinking what happens to the enormous number of mollusk shells that end up in landfills every year, according to Popular Science. Morris's team Calcium in a Changing Environment or CACHE, wants to recycle the waste produced by seafood lovers. Oysters on the half shell may seem like a special treat, but enough people eat them for the deterioration of oyster beds and waste management to be have become a serious issue. CACHE is proposing that the shells be recycled, by either being restored to oyster reef systems or crushed for their potential as bio material.

“Reusing shell waste is a perfect example of a circular economy, particularly as shells are a valuable biomaterial,” Morris told Popular Science. “Not only does it improve the sustainability of the aquaculture industry moving forwards, but it can also provide secondary economic benefits to shellfish growers and processors as well.”

The shells of mollusks serve an important purpose in the aquatic eco-system. Climate change has been a blow to oyster reefs, as the water heats and pollution rises. Oyster larvae needs a hard place to settle in order to grow, and the disposed shells could be the perfect place—if they're not destroyed.

“For oysters, particularly, overfishing and disease have reduced the amount of living and dead shells present, and subsequently the amount of hard surfaces available for the young to settle on,” Morris explained.

'If done properly, these structures quickly get covered in living oysters, which in turn attracts other species," he added, meaning that supporting healthy oyster reefs will lead to diversity of species and ocean health generally.

The other value in an oyster shell is the material calcium carbonate, which is generally found through the unsustainable practice of limestone mining. Calcium carbonate is used for lots of things, like in cement mix or even as a dietary supplement for hens.

“In Galicia, Northern Spain, where the biggest mussel farming industry in the European Union is, shells are cleaned and used to treat acid soils in the local area,” Morris said. “This practice has been going on for a long time. There are also examples of shells being used in basic aggregate mixes: oyster shells in France, for instance. But these applications represent a small portion of the shells produced.”

These possibilities may be well-known in some places, but one of CACHE's most challenging works is just connecting engineers and industries that rely on calcium carbonate with venues that produce oysters, or mollusk shell waste. And they're not the only ones struggling with getting the word out. Earlier this summer, Fast Company reported on an organization called the Alabama Coastal Foundation, which had also launched an oyster shell recycling program.

The group had connected with almost 30 restaurants, diverting their oyster shells to repair oyster beds in the Gulf Coast. They in turn had been inspired by a similar program run by the Coalition to Restore Coastal Louisiana, which has been in place since 2014. A great idea will always catch on, and hopefully grown into a firm foundation for saving marine life, and a tasty appetizer.