(188c) Applying Process Design Principles to Glass Recycling for Coastal Restoration

The US recycles less glass than other countries due mainly to government policies, lower consumer engagement, and cost. Successful glass recycling facilities are often co-located with bottle manufacturers that recycle old glass into new. However, many communities, particularly those in rural areas and along the coast, lack this infrastructure. Furthermore, recycled glass sand has many potential benefits over natural sand for many applications; for example, it can be made coarser, does not compact as much, and is more resistant to erosion, making it an excellent – and underutilized – material for coastal protection and restoration.

This talk will describe research initiated by two chemical engineering professors and a chemical engineering alumna of their department now being conducted with funding from the National Science Foundation Convergence Accelerator Program, Track E: the Networked Blue Economy. The overarching vision of the ReCoast Team, founded in 2021 in response to the NSF’s request for proposals, is to create coastal community recycling programs to keep glass out of landfills and instead use it for glass sand products that support coastal restoration, preservation, and resiliency. Through extensive regional economic, social, cultural, and environmental research, the team is ensuring ecological safety and mitigation of land loss.

The focus of the talk will be on correlations between the physical and chemical properties of recycled glass sand with how the glass recycling process is carried out, from glass collection to final product. Key findings include: (1) for small-to-mid-size operations, limiting collection to food and beverage bottles (soda-lime glass) to avoid contaminants like lead (e.g., leaded crystal) and minimize wear-and-tear on machinery from reinforced glasses (e.g., borosilicate) is important; (2) for food and beverage bottles, the parts-per-million presence of various metals that give the bottles color or clarity do not leach based on TCLP analysis by a certified lab; (3) size and angularity of the crushed glass products both increase with wear on the machinery, so operations intending to produce coarse sand for restoration may need to change wearable parts more frequently than manufacturer recommendations or compared to operations selling to different markets. A brief discussion of research demonstrating ecological safety in marsh environments and technoeconomic feasibility will also be presented to provide context for these results.

*Funding: NSF 2137730, 2230769