From salmon sludge and manure to fertiliser: a circular economy around land-based salmon farming

The human population is expected to increase by more than 30% by 2050 according to United Nations forecasts. This translates to a major challenge: to significantly increase food production in a sustainable manner. To meet this challenge, fish production must increase, but sea-pen aquaculture is facing numerous challenges including pollution, disease and water eutrophication. Animal manure is the primary source of ammonia emissions and nitrate leaching.  

In addition, fertilisers are needed to ensure food security. However, raw materials imports are limited, fertiliser production processes are energy intensive (2% of the world’s energy), and phosphate scarcity has raised fertiliser prices by 80% in the last year. 

This project has been built on the findings of a recent study, published in March 2022 by the Icelandic R&D company Matís, showing that sludge resulting from aquaculture has great potential as a fertiliser. 

To date, the consortium has invested over € 4,000,000 (own funds, private investment and national grants) in developing the first phase of an aquaculture farm, the mechanical and electrical engineering studies, and design of the dewatering process (tested in two Norwegian companies), and the preliminary studies on the soil, air, and water contamination of Iceland by fertilisers. Overall, the consortium considers the development of the Terraforming model to be at a technology readiness level (TRL) of 6/7. 

The Terraforming LIFE project will design and develop new technologies and methods to create an Integrated Agriculture Aquaculture (IAA) system in which aquaculture, agriculture farmers and agriculturists are at the heart of a circular economy. This project will optimise a new water recycling technology (Sideflow), complementary to the “Flow-Through System with Reuse” (FTS-R) aquaculture system. The Terraforming LIFE project aims to establish IAA associations in Iceland and Europe to promote circular economy, reduce pollution and energy consumption, while fostering farmers' economic growth. 

To achieve these objectives, the new technology must be optimised to develop land-based aquafarming to recover fish sludge (richer in phosphorous (P) than animal manure) and the animal manure from different farms (richer in nitrogen (N) than fish sludge) and combine them through a fermentation process. The combination of processed sludge and animal manure will be transported by a mobile treatment unit to a bio-fertiliser plant. It will be boosted with digestate from any dead fish that perish during rearing, and eventually dried to create a powerful natural fertiliser and biogas (which will power the plant thereby drastically reducing energy consumption).  

The project will consist of analysing all the different variables that determine the technology's efficiency and environmental impact. The existing fertiliser production line prototype will be extensively tested in a 48-month project. 

The following results are expected: 

-              Development of an integrated agriculture aquaculture (IAA) system by establishing a circular economy integrating aquaculture and agriculture.

-              Optimization of water recycling technology by implementing and enhancing Sideflow water recycling system.

-              Enhancement of aquaculture system by improving the FTS-R system with total gas control (TGC) and lava filtering.

-              Achieve lower capital and operational expenditures compared to other high-tech systems.

-              Maximization of nutrient utilization by optimizing the use of nutrients from fish manure.

-              Process fish and animal manure in a bio-fertilizer plant, boosted with digestate from dead fish and guts.

-              Generation of Valuable Products by producing bio-fertilizer biogas, and CO2 equivalents.