Aquaculture vs decarbonization through industrial symbiosis: The role of bivalve shell recycling

Recycling mussel shells offers environmental and industrial benefits. As a by-product of aquaculture and food processing, shells are often discarded, contributing to waste management challenges and costs. Recent studies highlight their potential as a sustainable source of high-purity calcium carbonate (CaCO₃), which can be extracted through processes involving washing, grinding, and calcination. This valorization reduces waste volumes, lowers disposal expenses for producers and introduces low-cost raw material to the CaCO₃ market. Notably, calcium derived from mussel shells can be utilized in emerging technologies such as calcium looping (CaL) for CO₂ capture, where calcium oxide (CaO) acts as a regenerable sorbent. Using shell-derived calcium in such applications supports circular economy principles and enhances the environmental performance of carbon capture. The MATSHELL project explores the potential of recycling bivalve shells to produce biogenic CaCO₃ and reuse for high-value applications. Findings show that biologically sourced precipitated CaCO₃ offers a competitive alternative to conventional sources, with rising market demand in high-value sectors. However, key barriers exist, including supply chain integration, regulatory complexity, and limited industrial adoption. The results of our analysis, conducted by interviewing a panel of experts, identified potential actions to address the challenges in accordance with industrial symbiosis models. The potential of the developed model was enhanced by integrating appropriate activities to optimize its implementation.