Fish farming and Recirculating Aquaculture Systems (RAS)

Land-based and sea-based fish farming play an important role in the global fish and shellfish production. Today, there is much focus on developing more environmentally friendly, recirculating land-based fish farming, so-called Recirculating Aquaculture Systems (RAS). We have a wide range of products used in fish farming and different types of Recirculating Aquaculture Systems (RAS).

Here are some products and solutions that we deliver:

  • Tank cleaning equipment for various types of tanks, basins and ponds
  • Spray nozzles to control or eliminate foam in tanks and basins
  • Biofilter - biocarriers and structured biofilter media
  • Random packings and structured packings for CO2-degassing and stripping
  • Spray nozzles for various cleaning and washing processes

We deliver products and solutions focusing on process efficiency, sustainability and productivity.

Fiskodling med lax kan vara både landbaserad (Recirculating Aquaculture Systems, RAS) eller havsbaserad. Fiskodling är viktigt för den globala produktionen av fisk och skaldjur.

Land-based vs sea-based fish farming

Landbaserad fiskodling, även kallad Recircultating Aquaculture Systems (RAS), Denna metod ger fiskodlarna möjlighet att noggrant övervaka och kontrollera olika miljöfaktorer så som vattenkvalitet, temperatur och utfodring. Landbaserad fiskodling anses ofta vara mer hållbar och miljövänlig jämfört med havsbaserad fiskodling eftersom den minimerar risken för vattenföroreningar och möjliggör en effektiv avfallshantering.

Land-based fish farming and Recirculating Aquaculture Systems (RAS), involves growing fish in controlled environments such as tanks, basins and ponds on land. This method allows fish farmers to closely monitor and control various environmental factors such as water quality, temperature and feeding. Land-based fish farming is often considered more sustainable and environmentally friendly compared to sea-based fish farming as it minimises the risk of water pollution and allows for efficient waste management.

Sea-based salmon fish farming in Bergen, Norway. The picture shows six circular open net cages linked to each other.

Sea-based fish farming means that the facility is located in coastal areas, offshore or in lakes and the fish are confined in open net cages. This method is cost-effective and takes advantage of surrounding marine conditions. Sea-based seafood farming requires careful consideration of its environmental impact, disease control and sustainable practices to maintain the well-being of both the farmed fish and the surrounding ecosystem.

Recirculating Aquaculture Systems (RAS)

Recirculating aquaculture systems (RAS) are advanced fish farming systems designed to efficiently and sustainably grow fish and other aquatic organisms in tanks, basins and ponds in a controlled environment. The system includes various filtration and water treatment processes to remove waste products and maintain optimal water quality. The basic water treatment system consists of the removal of waste products by mechanical filtration, degradation of organic matter and ammonia in a biological treatment step, and the control of CO2, N2 and H2S by using degassing and stripping. In some recirculating aquaculture systems UV disinfection and oxygen control are also part of the process.

Illustration av ett Recirculating Aquaculture System (RAS). Systemet. Systemet innehåller olika filtrerings- och vattenbehandlingsprocesser för att avlägsna avfallsprodukter och upprätthålla en optimal kvalitet på vattnet. Det grundläggande vattenbehandlingssystemet består av borttagning av avfallsprodukter genom mekanisk filtrering, nedbrytning av organiskt material och ammoniak i ett biologiskt behandlingssteg, samt kontroll av CO2, N2 och H2S med hjälp av avgasning/strippning. Ibland behövs ytterligare processteg så som UV-desinfektion och kontroll av syrenivåer.

Our products and solutions for optimising the RAS process

Biofilter - biocarriers and structured biofilter media

The first treatment step in a RAS plant is a mechanical filter where larger particles of organic matter are filtered out. After the mechanical filter, finer particles together with dissolved pollutants such as nitrogen go to the next treatment stage, which is a biofilter. Nitrogen in the form of free ammonia (NH3) is toxic and must be transformed in the biofilter to harmless nitrate. The breakdown of organic matter and ammonia is a biological process carried out by bacteria in the biofilter.

The biological water treatment step often uses some form of biofilter media, which can be a moving bed bio-carrier (MBBR) or a bed of structured biofilter media. Biocarriers and structured biofilter media both have a large surface area on which bacteria can grow. The large surface area optimises the contact between ammonia and bacteria, thus creating an effective biological water treatment.

We supply different types of biocarriers and structured biofilter media for the biological water treatment process. For each product, there are several different options to choose from (surface area, material, etc.) depending on each system's specific process requirements.

Degassing with stripping

High CO2– och kvävgasnivåer i vattnet är skadligt för fiskarnas välbefinnande och tillväxt. För att ta bort de skadliga gaserna i systemet går vattnet igenom en avgasningsprocess som kallas stripping. I den här processen avlägsnas oönskade gaser genom att vattnet blandas med luft i en bädd med fyllkroppar eller strukturerade packningar i en kolonn. Vattnet som innehåller de oönskade gaserna fördelas i toppen av kolonnen över den packade bädden. Luften strömmar motströms till vätskeflödet från botten till toppen av kolonnen. Packningarna optimerar kontaktytan mellan luft och vatten och den processen leder till att den oönskade gasen följer med luftströmmen ut ur kolonnen.

Read more about CO2-stripping >>

We have extensive experience and knowledge about stripping processes and we can supply complete stripping columns and solutions. We also supply a wide range of different types of random and structured packings that enable specific process requirements to be met.

Cleaning tanks, basins and ponds

We have a complete range of different types of tank cleaning nozzles and tank cleaning machines to effectively clean tanks and basins with a diameter from 1 up to 50 meters. We deliver very efficient tank cleaning solutions, focusing on cleaning results, short washing cycles, optimisation of water, chemical and energy consumption, and easy maintenance of the products and the system.

Läs mer om rengöring av tankar

Spray nozzles to control or eliminate foam in tanks and basins

In some RAS facilities, there is a need to control or eliminate the amount of foam in tanks and basins. Unwanted foam is removed by spraying liquid over the surface of the water. The spray droplets hit the foam bubbles, breaking them up and thus removing the foam. It is important to choose the right type of nozzle for this type of spray process. Depending on the amount and type of foam, droplets of a certain size range and flow rate/m² are required to achieve the most effective foam elimination.

Läs mer om skumkontroll

Spray nozzles for cleaning, washing and rinsing

RAS facilities and other types of fish farms are often in need of spray nozzles for different cleaning processes. To make the cleaning process as effective as possible, it is important to choose a spray nozzle that creates a spray with the right droplet size and sufficient impact force to remove the contamination, and to use as little washing liquid as possible. We are happy to help you find the right spray nozzle for your specific cleaning process.

Läs mer om Rengöring, tvättning och spolning

Droplet separation

In the RAS facility, there may be a need for droplet separation, i.e. reducing humidity and removing droplets from an air or gas flow. This may be, for example, at an air intake or to protect moisture-sensitive equipment. We have a lot of experience in droplet separation and are happy to help with technical advice. We have a complete range of products and solutions in order to deliver an effective solution for your facility.

Läs mer om droppavskiljning

Project review and proposed solution

AB Hansa Engineering AB
Alexander Bergman Droplet separation, Column internals, Spray nozzles & systems, Tank cleaning I look forward to providing product advice and solutions! Let's meet via a video call or a site visit. You can also phone or email us, of course.
LC Hansa Engineering AB
Linda Caporicci Column internals, Droplet separation, Spray nozzles & systems, Other products I look forward to providing product advice and solutions! Let's meet via a video call or a site visit. You can also phone or email us, of course.
HL Hansa Engineering AB
Hans Linder Spray nozzles & systems, Tank cleaning, Safety showers, Tank storage equipment I look forward to providing product advice and solutions! Let's meet via a video call or a site visit. You can also phone or email us, of course.

A start-up meeting is important to find out about various factors that will affect choice of equipment and solution in order to achieve the most efficient and sustainable solution. We are happy to set up the start-up meeting as a web meeting or a site visit, depending on your preference. All details and information from the start-up meeting we will summarise and go through with you to make sure we agree on project scope and objective.

Next step, we present a proposed solution, focusing on function, lifespan, quality, choice of material, operating and maintenance costs, and environmental impact. Our goal is to deliver a sustainable solution that creates added value to your company,