Andfjord Salmon:
Sustainable Sludge Treatment for
Land-Based Salmon Farming
The Challenge: Managing Sludge in a Flow-Through System
Andfjord Salmon has developed one of the world’s most innovative fish farming concepts – a flow-through system that combines the advantages of both sea-based and land-based operations. Here, the fish have access to clean, oxygen-rich seawater with a stable temperature year-round.
However, a flow-through system of this scale places high demands on sludge and wastewater management. The volume of sludge produced is substantial, and it must be handled efficiently, hygienically, and in compliance with strict environmental standards.
Andfjord therefore needed a scalable and reliable sludge treatment system that could operate safely throughout all production phases — without affecting fish welfare or daily operations.
From idea to finished solution – Sterner equipment produced in collaboration with our partners, ready for delivery.
The Solution: Sterner’s Complete System for Sludge Treatment and Water Purification
Sterner delivered a complete, integrated system for sludge treatment, tailored to Andfjord Salmon’s unique flow-through concept and designed with the goal of producing biogas from clean fish sludge.
The system covers the entire process chain – from intake to fully treated sludge and purified water:
- Sludge collection and pumping: Sludge is collected using cleaning robots (ROVs) from each tank and pumped into a buffer tank. This ensures consistent input and stable operation of the process plant.
- Thickening and dewatering: Sterner supplied in-house developed lamella thickeners with a purification rate above 90%, as well as energy-efficient dewatering equipment that increases the dry matter content of the sludge to 20–25%. This reduces water volume, simplifies handling, and significantly cuts transport costs. A custom solution for pumping high dry matter sludge to storage tanks is also integrated.
- Salinity management: Sludge with high salinity is a well-known challenge in dewatering. Sterner has developed a solution that handles salt content efficiently and easily.
- Purification efficiency: At least 80% of suspended solids are removed from the incoming sludge to the treatment system, along with a significant reduction in nitrogen, phosphorus, and organic carbon.
- Automation and control: The system is fully automated and integrated with Andfjord Salmon’s operational control system, enabling continuous monitoring and data sharing.
The solution is built as a modular system, allowing new tanks and production phases to be added without interrupting ongoing operations – a key requirement in Andfjord’s expansion plan.
The Result: Clean Water, Stable Operations, and a Future-Proof Solution
Sterner’s system provides Andfjord Salmon with a robust and sustainable sludge treatment solution, adapted to both current operations and future expansions.
Key results:
- Stable and predictable sludge treatment with high dry matter levels
- Reduced environmental footprint and controlled discharge of organic material
- Significant transport cost savings through efficient water removal
- User-friendly operation and maintenance
- Scalability for future tanks and process lines
Through this project, Sterner helps turn sludge into a controlled resource – an important step toward circular, sustainable aquaculture production.
