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Converting sludge into a valuable resource


Fjell Technology Group (FTG) recycles sludge from fish farms and municipal waste water plants. The sludge is used as an additive in fertiliser or other agricultural products.

Land-based fish farming and closed- & semi-closed fish farming cages in sea is an expanding industry. With more fish farms of this type being established, wastewater management becomes an increasing concern.

These fish farms must clean their wastewater before letting it out into the recipient. The origin of the organic material in the wastewater is faeces and fish feed residues.

If we focus upon a land-based fish farm there are typically two sources of wastewater that needs to be treated. The first and primary are mechanical filters of type disk filters or drum filters. All water circulating in a Recirculating Aquaculture System (RAS) or going through a Flow Through fish farm goes through these mechanical filters. The suspended solids are collected by filters and through a backwash system removed from the filters.

The second main source, fixed bed biofilters, are only relevant for RAS fish farms. These bioreactors convert ammonia (NH3) and ammonium (NH4+) to NO3- (Nitrate) by use of nitrifying bacteria living on fixed structures with large surface. All wastewater fractions are transported typically to a buffer tank prior to the wastewater treatment plant.

Fjell Technology Group offer 3 main types of solutions for treatment aquaculture wastewater:

- Low-Cost Capture System: low investment cost and moderate capture rate

- Fjell P&W ECO Capture System: environmentally friendly solution with high capture rate

- High Capture Separation System: highest possible capture rate

The 3 different solutions are 100% scalable to any amount of wastewater and organic load that needs to be treated. Typically, the first step is to build structure in the wastewater before the wastewater enters a separation/thickening process stage. The second step is dewatering before the sludge is either put into storage/transport tanks, or enter a Fjell FRS Sludge Dryer System. Fjell Sludge Dryer System are robust and scalable to need.

Wastewater is also an ongoing concern for many municipalities and waste management authorities, who must manage public sewage and waste streams from growing populations.

FTG's dryer design is patented and market leading. Fjell's Turbo Disc Dryers are the most reliable and energy-efficient dryer available on the market. It is common to transport wet sludge, with typical dry matter content between 15-25% with trucks or train to processing plants that can utilize it further. By drying the sludge locally, it becomes more storage stabile and as much as 75% of the water can be removed, thus saving significant cost of transportation.

The dried sludge could be repurposed as an additive for producing fertiliser, or in other agricultural products that rely on nutrients such as nitrogen and phosphorus.


FTG’s technology contributes to a circular economy by recycling sludge to fertilizer.

The solution helps fish farmers and municipal wastewater plants to minimize waste management and transport. Our solution cuts both costs and emissions from production, treatment processes and transport.

FTG has delivered its biowaste handling equipment worldwide, including Germany, Holland, Iceland, Italy, Japan, Norway, and Saudi Arabia.

At a glance:

- 3 different wastewater treatment solutions tailor made for customer needs

- Recycling of fish sludge and wastewater for fertiliser

- Complete process taking organic material from wastewater concentrations below 0,1% up to

stabilized fine-grained powder with dry matter content above 90%.

- Reduces the need for sludge transport

Please check our references for more info.

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