To explore alternatives to mineral fertilizers, a pilot facility producing fertilizer from Adriatic fish and mollusk sidestreams was developed. It involves different production stages: the mechanical treatment of raw materials, a subsequent hydrolysis and a concentration step (Figure 1). A life cycle assessment (LCA) identified the main environmental hotspots of this fertilizer production regarding climate change, acidification and eutrophication: production of enzymes for hydrolysis, energy use during the concentration step and packaging.
To reduce freshwater eutrophication, the input of enzymes should be minimized as much as possible. Greenhouse gas emissions can be lowered by using optimized concentration or drying technologies, e.g. with heat recovery. The corresponding emissions can be further lowered by the use of renewable energy sources such as biogas. In addition, the amount of packaging for the final fertilizer needs to be reduced to a minimum.
Figure 1: Fertilizer production scheme with sidestreams (grey), process stages (blue), co-products (yellow) and enzyme input (orange).
Further information:
Andreola et al. (2023), Techno-economic assessment of biorefinery scenarios based on mollusc and fish residuals. Waste Management, 166, 294-304, doi.org/10.1016/j.wasman.2023.05.014
Landert et al. (2023), Life cycle assessment (LCA) of bio-based fertilizers from fisheries and aquaculture sidestreams. Presentation at ESPP WARM Research Meeting.