Marine Harvest Dalsfjord

Marine Harvests location at Dalsfjord near Volda in Møre og Romsdal- Norway, produces salmon smolt. Krüger Kaldnes AS has between 2009 and 2012 planned and delivered two plants to Dalsfjord for the production of more than 4 million salmon smolts per year. On-groing 1 and on-growing 2 each has its own separate water treatment system (RAS1 and RAS2), where fish from the start feeding is introduced into on-growing 1, before being transferred to on-growing 2, from which it is introduced to the sea.


Main Components

The water treatment plants, Kaldnes®RAS, consists of four main components:

Mechanical Cleaning

Hydrotech™ drumfilters remove particular matter like excess feed and fish feces from the water.

Biological Treatment

Dissolved waste products are decomposed by bacteria and microorganisms in a two-stage Kaldnes®MBBR (moving bed bio-reactor).


Carbon dioxide from the fish respiration is removed in the sentralized CO2-degasser.


The plants are monitored and controlled by Veolia’s own control system - VA-Operator.


Both Kaldnes®RAS plants have a very small foot print.

  • RAS1 has a capacity of 3.000 kg per day feeding, with a total hydraulic capacity of 4.275 m3/hour. It is an extremely compact plant with a foot print of less than 200 m2 including deepshaft oxygen cones.
  • RAS2 has a capacity of 2.000 kg per day feeding, with a total hydraulic capacity of 2.400 m3/hour and a foot print of less than 250 m2.


Key Parameters

Parameter RAS 1 RAS 2
Total fish tank volume 2.850 m3 1.400 m3
Maximum biomass 142.500 kg 70.000 kg
Maximum feeding 3.000 kg/d 2.000 kg/d
Dilution water 300 l/kg feed 300 l/kg feed










Table: Basis of design


Parameter Testverdier
CO2 out of fish tank 12-13 mg/l
NH4-N + NH3-N 0,6 mg/l
NO2-N <0,16 mg/l
Nitrogen saturation <101 %









Table: Water quality at 900 kg/day feeding and 45-60 kg/m3 biomass.


Facing the challenge of very limited available area, RAS1 was designed as an extremely compact plant. Less than 200 m2 is used to treat 2.850 m3 water. Kaldnes®RAS is located in a separate building, while the fish tanks are placed outside.

RAS2 is an operator-friendly indoor water treatment plant with good access to the equipment, well arranged and with compact design. The plants are characterized by extended use of automation and by material of high quality.

Commissioned: 2010/2012

Design and build of two separate low footprint RAS-plants, outdoor and indoor.

Kaldnes® RAS, comprising of Hydrotech™ drumfilters, Kaldnes®MBBR, centralized CO2 degasser and circulation pumps. The two plants are fully managed and monitored via the control
program VA-Operatör.

Design capacity:

Maximal feeding:
3.000 + 2.000 kg pr. day

Fish tank volume:
2.850 + 1.400 m3

Operational data:
CO2 out of fish tank: 12-13 mg/l
NH4-N + NH3-N: 0,6 mg/l
NO2-N: < 0,16 mg/l
Nitrogen saturation: < 101 %