Possibilities to Use Fish Waste for Energy

Abstract

Most of the fish caught is used in the food industry. About 40% of the fish weight comprises fish fillet, and secondary raw materials, such as the fish head, tail, fins, guts and bones can comprise up to 60% of the fish weigt. The secondary raw materials can be used in food industry, agriculture, for pharmaceutical purposes, etc. Other, no less important way for usage of secondary raw fish, dead fish and fish farming sludge is the utilization of mentioned feedstocks for energy purposes, i.e. biofuels production. The aim of this study is to investigate the use possibilities of fish oil, which being in the secondary fish materials is unsuitable for the usage in the pharmaceutical industry, for biodiesel production, and biomass left after oil extraction or non de-oiled fish biomass for biogas production. Besides, fish farming slugde as fraction of composite feedstock substratum was used in this study. The investigation of energy production from fish waste were performed using dried and wet feedstock. The estimated oil content in fish biomass reached 40.4%. The results of study of fatty acids composition showed that fish oil contains high content of monounsaturated fatty acids. The major part of saturated fatty acids is palmitic acid (8.8%), monounsaturated and polyunsaturated are oleic (49.6%) and linoleic acids (9.42%). During analysis of biogas production was estimated that from 1 g volatile solids of fish waste it is possible to get more than 1000 ml of biogas, containing more than 65% of methane and from fish farming sludge amount of biogas is app. 600 ml/gVS.Compared with biomass of fish waste, fish farming sludge has a significantly lower dry matter content (app.0.3-4%).[...]