Aquaculture infer the farming of aquatic organisms. These can be fish, molluscs, crustaceans, algae and more. Within these different areas, sludge or another highwater content material can be obtained. From fish farms this comes from the material gathered at bottom of the farming cages and with cultivation of algae, the algae itself.



With Freeze Dry Unit in the process the results are:

  • Greatly reduces the need for sludge transports
  • Opens up more areas of use for the final product
  • Turns waste in to a valuable new product and an income
  • Safe and polymer free final product
  • Recycling of reject water

The process with and without the Freeze Dry Unit

The process with and without the Freeze Dry Unit

On the bottom of the fishfarming cage leftover food, feces and dead fish i gathered and form a sludge


The sludge is dewatered and dried to a dry solids content of 95 % and can handle all the incomming volume


The sludge is normally dewatered using a mechanical method such as centrifuge or screw press


The water can be recirculated in system, cleaned or taken care of after the wishes of the customer. The volume of the sludge is now reduced and as well as the weight which results in effective transports


The sludge is transportetd to the area of disposal. As the sludge is still wet many transports are required


Different ways to dispose of the sludge are now available. For example it can be used as fertilizer i agriculture but is also dry enough to be incinerated or be used as fodder for animals.


Not many ways to dispose of the sludge are available. it can be used as a fertilizer i agriculture but as it is still wet there is a risk for decay

This is how Freeze Dry Unit makes a difference in aquaculture

Fish farming

As mentioned above the sludge from fish farms often consists of material gathered at the bottom of the farming cages. This consists of leftover food, feces and dead fish. This sludge contains a lot of valuable nutrients that, if not retrieved, are lost. If the sludge is not treated it starts to decay and cannot further be used.

If Freeze Dry Unit is used, the sludge can fast be dried to prevent rapid decay and the loss of the product. This makes the final dried product suitable within many different areas of use and turns the sludge from a waste into a valuable new product.


A dry final product can be spread on farmlands with a tractor, incinerated or reused as a new product within the aquaculture industry.


The Freeze Dry Unit is an optimal solution to be used for Recirculating Aquaculture Systems (RAS), Fish Farming Plants using fresh water, marine water or brackish water. The Freeze Dry Unit works for farming of different types of fish and other aquatic organisms like salmon, carps, crustaceans, mackerel, milkfish, mollusks, sea brass, sea bream, trout and others.


The sludge from smolt is rich in nitrogen and phosphorus. With Freeze Dry Unit the sludge is dried slowly, in low temperature which helps to keep the nutritional value high. The Freeze Dry Unit will dry the sludge from less than 0.1 % to over 95 % Dry Solids. This is also achieved with an energy requirement less than any other solution on the market. With this high dry solid content, the sludge can easily be stored and transports away from the plant can be optimized.




Micro algae or spirulina can be used in a variety of areas, for example animal feed, fuel, health food, cosmetics and pharmaceuticals. The algae also have an efficiency in fixating carbon as they grow using phototropic metabolism. To be able to use the algae further, the biomass must be concentrated as the biomass is very low when cultivated. This is done through different techniques of dewatering and drying.

The Freeze Dry Unit can be part of the dewatering and drying process of the algae as a single step of receiving a dry final product.


As spirulina is more and more used in health food and the Freeze Dry Unit is, if necessary, delivered in accordance with the specific requirements set out in the ISO 22000 of ISO 9001. Elajo has a rigid and long experience with working with high quality demands from the nuclear energy sector. A Freeze Dry Unit for food applications is produced according to documented food safety management system to manage the processes throughout the facility. As well as programs to ensure a sanitary environment.


According to the standards, Elajo also reassures that the suppliers used is in accordance with international quality, safety and reliability standards. Making sure that all products along their supply chain are manufactured in safe environments and meet the standard’s requirements.