RAS Technologies

Water treatment for land-based aquaculture

Krüger Kaldnes provides the most advanced recirculating aquaculture systems (RAS) technology and support to the land-based aquaculture sector. Our technologies optimise the growth, health and welfare of fish, and allow for sustainable aquaculture operations with lower carbon footprint.


Jack Tucker

Sales Manager Aquaculture 

[email protected]
+47 489 56 629

Krüger Kaldnes delivers water treatment systems for land-based aquaculture farms. Our core competence within RAS and our innovative solutions contribute to a reduction in the amount of water required to produce seafood.


Healthy fish = happy farmer

At Krüger Kaldnes, the welfare and health of the fish is always our number one priority. By providing the right technology, tools and support, we are responsible for enabling our customers to succeed within RAS operations.

In the wild, it takes 2-5 years before salmon smolt can live in saltwater. Modern day RAS facilities have maximised production by reducing the development time from fry to smolt to six months. Krüger Kaldnes designs optimal RAS facilities that offer the benefit of increased production and reduced consumption of natural resources, in this case water among others, and thus carbon footprint.


Complete solutions

Krüger Kaldnes has been a leading player within the RAS sector for more than 20 years. Together with Veolia Water Technologies, we offer complete solutions for cleaning and recycling of wastewater for land-based aquaculture. Our Kaldnes™RAS solutions are designed by multidisciplinary experts from the fields of engineering and biology.

Our goal is to utilise our wide and unique set of competencies, technologies and solid solutions to assist our customers in producing healthy and robust fish. We design RAS solutions according to our customers production needs. Our solutions also improve resource management, better quality monitoring and more sustainable operations.


See our references here.


Research & Innovation

Krüger Kaldnes research and innovation department works closely with academic institutions, world-leading researchers, internal resources and suppliers to create value for our customers and the industry. 

In the picture above, you can see our process engineer Ms. Sharada Navada, who is currently performing her PhD thesis on water quality in RAS at the University of Trondheim. The work is performed under the CtrlAqua research programme, where Krüger Kaldnes is an active partner and member of the board.

Pushing boundaries to create value

Our technologies are the foundation of our expertise. We take a structured approach to innovation, aiming to find new solutions that meet the needs of our customers while preparing our company for the years to come.      

Innovation is in our DNA. Our solutions have been used to create more than twenty successful RAS facilities, including the world's two largest fish farms, Lerøy Sjøtroll and Helgeland Smolt in Norway. We continue to learn by experimenting as well as collecting vital live data to enable optimal production of robust fish, always with fish welfare in mind.

Land-based fish farming has evolved at a rapid pace in the last decade. We expect this trend to continue. We believe that in the near future, even more sustainable fish farms will be developed in surprising locations. This pushes us to discover, test and design solutions to meet future demands and remain at the forefront of the industry.



Frode Eriksen
Business Development and Innovation Director

[email protected]    |     +47 979 77 905


Project Management

Our project management department has a multidisciplinary team with expertise to execute land-based aquaculture projects globally.

We are constantly developing our technical competence, leadership and strategy skills. Value creation, setting ambitious goals and establishing the highest standards for our customers is always at the forefront.
Multidisciplinary teams
The project management department is the driving force in our organisation. We manage all stakeholders and multiple contract strategies in executable projects. We strive to achieve the customers and our own goals on every project.
Krüger Kaldnes has the competence and experience needed to deliver successful projects. Our project management department is supported by a multidisciplinary team of experts within the areas of installation management, engineering, purchase, process and automation. Our approach ensures projects are completed successfully.  We prioritise customer profitability, staying within budget, and project execution and make decisions based on the customer's overall goals.


Tom Haslum
Project Director

[email protected]     |     +47 909 69 014

Process & fish health

Nothing is left to chance when planning a new RAS facility. The location is always the starting point, as well as these three priorities:

1. The health and biology of the fish
2. The needs of the operating personnel
3. The limitations of technology and logistics


It's all about fish welfare
The main processes within RAS facilities include mechanical and biological cleaning, oxygenation, sludge treatment and the circulation of water through the facility. The areas and rooms within the RAS facilities are strategically laid out for easy access, ensuring optimal working conditions for operations and maintenance. Our designs take into account the safety of the operating personnel, the overall working environment and any logistical challenge.

In addition, we have a strong focus in fish welfare. Necessary handling of the fish is reduced to a minimum, and all transport routes are carefully designed to reduce the possibility of spreading disease. 


Christian Rønning
Department Manager Process 

[email protected]    |    +47 959 35 903


We listen to our customers to understand their challenges and needs. At Krüger Kaldnes, the automation department works in close collaboration with other departments.

In this way, our customers benefit from the state of the art technologies customised to suit their needs.

Customised and efficient 
The scope and size of the operation increases the need for automation. In our automation department, we make sure that processes run smoothly and by themselves. We create cost-saving results by reducing operational costs and the carbon footprint, all without compromising the quality of the facility and related services. As a result, their employees operating the RAS facility can focus their time and efforts on important tasks which cannot be automated. This way operations are more efficient and profitable because fish farmers can focus even more on fish welfare. 

Krüger Kaldnes has always been a driving force in pushing the use of automation and digitisation in the industry. We believe this is only the beginning. In the future, we will see an increase in digitisation and artificial intelligence within land-based aquaculture.


Espen Karlsen
Department Manager Electro/B.Sc.Automation

[email protected]     |     +47 922 81 681


Our mechanical department is responsible for the water circulation. We focus on pumps, pipes, valves and all equipment needed to make the water circulate for the fish to thrive and grow.

Cutting-edge solutions
The department consists of dedicated engineers who design our RAS facilities. We develop and provide the technical specifications in close collaboration with our process and automation departments to find optimal solutions for our customers. Together with our subcontractors, we provide cutting-edge expertise to constantly develop and improve our design and solutions.

We focus on details and the overall picture. Our 3D modelling demonstrates how components and subsystems connect into a complete land-based fish farm. Together with our customers we have a unique possibility to find the best solutions on the digital drawing board, before we start to build.


Sverre Lous
Department Manager Mechanical / Senior Project Manager

[email protected]     |     +47 957 59 832

Services & after-sales

At Krüger Kaldnes, our service department is dedicated to training our customers' operational personnel. We also provide support and service to the facility.

Due to the challenging environment within a RAS facility, ongoing maintenance is crucial. To achieve a long equipment lifespan, it requires a well-trained and competent staff. At Krüger Kaldnes, we train our customers' operational personnel to inspect and maintain their RAS facility. 

We recommend regular onsite visits to inspect, follow-up and provide expert services. We then prepare a report with our observations and recommended measures. Our service department can also perform risk and vulnerability analysis of the system, and suggest a list of spare parts. 

We can be a customer's single point of contact when it comes to spare parts for the whole facility. Read more about our Services here.




Mike Halmer
Service Manager

[email protected]    |     +47 954 17 400

RAS: what it is and its benefits

What is RAS?

RAS stands for recirculating aquaculture systems that refers to a method land-based fish farms use to recycle their water. RAS facilities are characterised by having pipe systems connected to various technical installations for mechanical, biological and chemical treatment of the wastewater from the fish tanks. Up to 99% of the treated water is returned into the system. The remaining 1% is intake water which can be freshwater, seawater or a mixture of both.



RAS systems encourage the growth of beneficial bacteria, unlike flow-through systems (FTS). One of the benefits of a RAS facility over FTS is that it creates a symbiosis between the bacteria and the fish, so that the bacteria cleans the water and the fish have an optimal water quality.

Where the fish in flow-through facilities are kept in water where the number of microorganisms are reduced to a minimum, in RAS fish are kept in "living water" where the number of microorganisms is high. In a RAS facility, we not only care about the fish, but also the bacteria living in the system. The bacteria must be well-cared for in order to do their job of removing pollutants from the wastewater.

RAS is not chosen because it is simple, but to improve control of the fish's environment down to the smallest detail. Good RAS facilities perform better on a number of parameters for operation including lower mortality, water consumption, pre-quantity and environmental footprint. At the same time, RAS provides optimal biological conditions that improve fish health and ensure increased growth.



Our KaldnesRAS solution helps our customers reap the benefits of the technology. We provide good design, correct dimensioning, well-functioning equipment components, and a solid control and monitoring system. 

KaldnesRAS Illustration (657.38 KB)