The recycling of oyster shells: an environmental analysis using Life Cycle Assessment

Abstract

Oysters represent a substantial fraction of the world's overall intensive aquaculture production. In Brazil, oyster aquaculture is still in the deployment phase but has the potential for growth and, likewise other aquaculture products, generate environmental impacts over their life cycle. Special attention should be devoted to the disposal or processing of the oyster shells, whose high calcium carbonate content (80-95%) gives them the potential for use as raw material for several other products. The objective of this study was to conduct a cradle-to-grave Life Cycle Assessment (LCA) of 1 kg of oysters produced in southern Brazil, incorporating the recycling of the oyster shells on the LCA. Two scenarios were considered. The first scenario (termed scenario A) assumed that the oyster shells were deposited in a landfill, whereas the second scenario (scenario B) assumed that the shells were processed to make them available as raw material as a source of CaCO(3). We used Eco-indicator 99 H/A to perform the impact assessment. Scenario A had an overall impact of 93.71 mPt, whereas scenario B had an overall impact of 58.97 mPt. The latter scenario had lower environmental impacts, however they were depended strongly on the distance between the source of the shells (restaurant) and the shell-processing facility. This distance must not be greater than 323 km to yield overall environmental benefits. Moreover, it is hypothesized that the environmental benefits would be even higher than predicted because there is no evidence that all post-consumer shell residues would receive proper waste management, as assumed for scenario A (landfill).