FRS® -The solution of the future is here

– FRS stands for Fishsludge Recovery System. A sustainable waste management for land based aquaculture, developed by the Norwegian company Bioretur AS.

Fish sludge – a resource

Aquaculture is facing ever increasing pressure for sustainable waste management. Now fish producers can focus on delivering a high quality product, while the waste is handled by our fully automated FRS® technology. Drying of the fish sludge takes place on site, without the addition of polymers, which makes it suitable for further processing. A subscription to the Bioretur agreement enables full utilization of the dried sludge in a sustainable and environmentally friendly manner. 

International technology

It provides a compact, reliable and fully automated treatment plant that processes sludge from below 0.1% dry matter to 90% dry matter in a continuous system. A complete sludge solution without the need for manual operation and completely without the use of chemicals. 

In addition, the system has a very low energy consumption and the discharge water is sterilized and clean. See tables at the bottom of this page for details. 

sludge footprint


The ultra-compact facility enables the FRS to fit into most locations. 

flexible sludge treatment solutions


The modular system can easily be adapted to increases in production.

Reliable sludge treatment technology


Proven technology provided by reputable suppliers.

Efficient sludge treatment


Fully automated system without the need for manual labour or chemicals.

This is the FRS

Bioretur offers Fish Sludge Recovery System (FRS). All of out FRS-systems are modular and therefore adaptable to most locations and needs. We believe that sustainable solutions are increasingly an important part of both brand trustworthiness and positioning.

By taking part in our Bioretur value chain you also help create products such as Phosporous, Equus fertilizer and BiogasBoost. We are proud to say that we are the only provider of the complete value chain, from problem to product.

FRS® T – Fish sludge to fertilizer

The FTS-T is based on either hot air or frictional heat and will dry the sludge to the point of storage stable dry matter, before its transported for processing. The dry sludge will be used as material for sustainable and environmental friendly products such as Equus or BiogasBoost (a substrate in production of biogas).

The illustration is an example and visualize a 30 square feet FRS facility with a capacity of 40m³/h*. The size is adaptable to flow rate, quantity of fish sludge and will fulfill the regulations.

* With TS 0,5 %


Electrosonic flocculation

This process minimizes maintenance without the use of chemicals. The process sterilizes the waste water to prevent odour, growth of bacteria and viruses. The flocculation concentrates the effluent water from <0.1% to 5-8% dry matter. [/av_image_spot] [av_image_spot tooltip_pos='av-tt-pos-right av-tt-align-centered' tooltip_width='av-tt-xlarge-width' tooltip_style='main_color' link='' link_target='' hotspot_color='' custom_bg='' custom_font='' custom_pulse='' hotspot_pos='42.7,30.6' av_uid='av-1orro6p']


The decanter removes more of the water bringing the sludge up to between 25% and 40% dry matter


Drying and cooling

The drying is efficiently achieved by friction which heats the now pretreated sludge to between 100-105°C causing rapid evaporation of the remaining moisture. Following this drying process, the sludge is now approx. 95% dry matter and sterilized. Finally the dry sludge is run through a cooling screw conveyor to ensure that the material is stable for storage.



The steam created by the drying process is cleaned in the scrubber to remove any particles and eliminate any possible odour issues

Reduction of environmentally sensitive substances (through flocculation)


Reduction of
Organic waste


Reduction of
Total dissolved


Reduction of
in total


Reduction of
other phosphates


Reduction of

Contact us

Questions about Fish sludge, sludge management and FRS? Ask our engineer and sales team.

Managing Director

Steinar Wasmuth
Phone: +47 906 96 000

Jan Knudsen

Project Engineer

Jan Knudsen
Phone: +47 414 69 307