Sludge and residue from salmon farming contains useful resources which commonly disappears into the blue. What if we collected it instead?

Contains valuable nutrients

Filled with nutrients such as phosphorus and nitrogen, sludge from fish farming has a big potential if collected and reused.

In fact, the two nutrients are important ingredients in fertilizers in modern agriculture[1]. While nitrogen is easier to produce, that is not the case with phosphorus.

When about 70 percent of the phosphorus from fish feed goes, easily said, right through the fish it is clear that this could be a good source of the nutrient[2]. Recycling sludge from salmon farming would therefore be valuable both economically and for the environment since build-up of these nutrients have a negative impact on the environment surrounding the fish farm.

Biogas resource

Our member Ragn-Sells Havbruk, is part of an exciting project involving sludge. On behalf of Ragn-Sells Havbruk and other actors PwC has made a report showing that sludge from fish farms could replace Russian gas and phosphorus.

In other words, sludge also shows promising potential as a resource for biogas. Ragn-Sells writes that it could give power to 600 000 households.

Benefits and barriers

Summed up, here are some of the pros of collecting fish feces and residue from salmon farms:

  • Prevent pollution of fjords
  • Resource in biogas production
  • A valuable source of phosphorus
  • Good source of nitrogen

There are some barriers as well. For example, costs connected to equipment and maintenance, as well as an immaturity in the marked.

Despite the obstacles the future of fish feces shows great promise.

About the sludge project

The four aquaculture actors Framo Aquaculture, Ragn-Sells Havbruk, Aquapro, and AMOF Fjell Process Technology are working on a solution to generate renewable projects from sludge collected at Norwegian fish farms through a project called ARAL. All of the ARAL project’s actors, along with PwC and the Cluster, are members of the project group in the report, which will be released soon.