Applications of industrial eggshell as a valuable anthropogenic resource

Nowadays the European guidelines boost the concept of “circular economy” which is focused on catalysing sustainable development. “Closing the loop” is particularly important for improving the recycling rates, and thus waste and by-products can be turned into a resource with benefits to the economy and environment. Within this scope, this work reviews and updates the potential of valorisation and legal framework of an anthropogenic biomineral with high content of calcium carbonate. Namely, the waste under consideration is the industrial eggshell waste (ES) resulting from egg breakage. This is considered an animal by-product (ABP) and thus some constraints may limit ES applications. The flux of this ABP mainly within the European region is also indicated and the estimated data highlight that significant amount of this biomineral is being produced. Despite legal restrictions, countries such as the UK, Spain and Portugal have been able to find practical application for ES, avoiding landfilling. The literature shows that applications for industrial eggshell may be grouped into two categories: raw material and operating supply. In the first case, the options are food additive, soil amendment, purified calcium carbonate, cosmetics and biomaterial composite. As operating supply, ES may be used as catalyst and sorbent. Although the economic profit should be evaluated in each case, the environmental benefit of those potential applications is in general high. Considering ES properties and the soil properties in large areas of Europe (acidic pH and low topsoil organic carbon content) the production of Ca-rich compost obtained through composting seems to be a particularly interesting approach toward “circular economy”.