Eva Brod
Research Scientist
Attachments
CV 2026Biography
Education:
PhD in Soil Science from Norwegian University of Life Sciences (NMBU) in 2016
Areas of expertise:
- Fish sludge as fertiliser
- Plant-available phosphorus and nitrogen in bio-based fertiliser
- Characterisation of inorganic phosphorus compounds
- Soil analysis (phosphorus)
Authors
Eva BrodAbstract
No abstract has been registered
Abstract
Smolt production in freshwater is an essential component of the salmonid aquaculture production chain. But it generates sludge (feed waste and fish feces) that must be managed to meet environmental regulations. While sludge can be reused as a resource, there are limited empirical results about cost structures, market conditions, and energy implications in industrial aquaculture. This study analyzes sludge collection, processing, and utilization based on a single-case study of a Norwegian smolt producer (Sisomar AS). The analysis combines company-level production data, accounting information, and process descriptions. In 2023, the company produced approximately 9.2 million smolt (1184 tons of biomass), generating 140 tons of dried sludge. Sisomar’s value creation from production of bio-based fertilizer from sludge is relatively close to that of comparable mineral fertilizers, but a direct comparison here is difficult because of large variations in the prices of mineral fertilizers. The energy consumption is significantly lower for organic fertilizer from Sisomar compared to standard technology for mineral fertilizer production. Bio-based fertilizers are looked at as an important contribution to dealing with environmental challenges, and this study discusses the characteristics of how market structures have importance for this.
Abstract
Fish sludge (faeces and fish residues from farmed fish) is currently not permitted as an ingredient in CE-marked fertilising products under the EU Fertilising Product Regulation No. 2019/2009 (FPR). This report provides the scientific basis for a potential proposal to include fish sludge in the FPR by 1) summarising existing knowledge on contaminant levels and the agronomic efficiency, and 2) identifying knowledge gaps. The legal status of fish sludge under the Animal by-products regulation (EU) No. 1069/2009 (ABP) has to be clarified first but is outside the scope of the report. Most available data on fish sludge originate from land-based Atlantic salmon production in Norway. A major knowledge gap is therefore the lack of data on contaminant levels and the agronomic efficiency of fish sludge from sea-based systems, as well as from other countries and aquaculture species. With respect to contaminant levels in fish sludge from land-based smolt systems in Norway, additional data are required for hexavalent chromium, inorganic arsenic, pharmaceuticals, and certain pesticides. The agronomic efficiency of fish sludge from land-based smolt systems in Norway is relatively well documented.