Concepts and profitability forutilisation of fish-industry side-stream

Abstract

This study evaluates the possibility of increasing the oil and protein utilisation of the fish-processing side-streams and also of applying these side-streamsfor the co-generation of biogas and fertilisers on a farm. The study introduces three concepts: 1) processing of the fish side-stream at a farm biogas plant; 2) the fish protein concentrate (FPC) process, wherein oil is thermally extracted and protein concentrate and meal are used as a feed; and 3) a two-stage process for producing high-quality oil and protein-rich hydrolysate and meal. The possibility of utilising meal at a farm biogas plant is also considered, for concepts 2 and 3. Production costs and revenues associated with the processes are evaluated, and the uncertainty of the process parameters is analysed. The results shows that the fish side-stream examined here is too expensive for direct utilisation at a farm biogas plant, but with a lower-cost side-stream the process could be profitable.The processes producing concentrate and hydrolysateare both profitable;in addition, thehydrolysate concept, with value-added more expensive products,shows advantages over the concentrate concept.