Fish discard valorisation into low carbon biochar-compost composite

Fish discard (FD) production is increasing continuously due to the higher demand for seafood worldwide. These by-products mostly consist of viscera, head, fin, etc. highly putrescible, and require proper stabilisation strategies to avoid environmental impacts. Normally, a discarding fee is paid by fish processing companies for disposing of these by-products. In the case of a company based in Ancona (Italy), whose annual discards account for 26 t.y-1 , they imply management costs amounting to 5720 €. y -1 (220 €. ton-1 ). Alternatively, these by-products are rich in valuable nutrients and can be recovered using sustainable circular economy approach, like composting to recover nutrients for agricultural purposes. The environmental impacts of aerobic composting can be reduced by adding biochar, which is novel approach. This study aimed to recover composite biochar compost as a low-carbon, sustainable soil improver. Results showed that biochar addition resulted in low GHG emissions during composting process and preserved high nitrogen content in the final product compared to control compost.