1. Seminar on Smolt Production March 1st 2000 - Campbell River, BC
Why use recirculation
Recirculation vs. single pass flow through systems
In-tank BIOFISH type of recirculation
History of BIOFISH development - Testing BIOFISH for the production of:
Rainbow trout
Atlantic salmon smolt (1st and 3rd generation of BIOFISH)
Arctic char
Brown trout for restocking
(Turbot and halibut in sea water)
Effluent discharge from smolt production in BIOFISH
Conclusions
BIOFISH:
Use feed with a low dust content
Avoid overfeeding
Research Director B. Eikebrokk, SINTEF/NTNU

2. Traditional recirculation systems
Fish tanks
Particle
removal
Biofiltra-
tion
Aeration/
Oxygen
Particle rem
Heating
Water treatment volume % of fish tank volume
Complex, high risk of disease transfer from tank to tank

3. Traditional flow through systems
Fish tanks
Particle
removal
Water flow: liters per minute per kg of fish
Frequent tank flushing

4. Tank - Internal Recirculation systems
Particle
removal
Discharge
Water consumption and discharge L/min/kg
Water treatment volume % of fish tank volume
Less complex, less risk of disease transfer from tank to tank

5. Background - BIOFISH development:
The need for a simple and production-effective fish farming
technology with
low water consumption rates (compared to flow through)
low discharge rates
advanced effluent treatment (optional)
to meet the strict regulations regarding discharge to fresh water
recipients in Norway
Development of:
simplified water reuse technology (BIOFISH)
dual outlet with efficient particle removal from effluent
disinfection of effluent water (not described here)

6. The BIOFISH recirculation system
(“2nd generation” )
From Eikebrokk et al (1995) Aq. Res 26:

7. The BIOFISH recirculation system
(“3rd generation” )

8. The KMT moving bed biofilter
Material: poly ethylene
Sp. Density: 0,96
Sp. Biofilm Growth Area: 500m2/m3

9. The dual outlet with particle removal
Whirl separator
Treated
effluent
Tower screen pipe
Fish tank bottom
Particle effluent
to whirl separator
Bottom screen
Recirculated water
to bioreactor
Uneaten feed
can be observed
feeding control!

10. Water Sampling - Smolt experiments
Make up water S
Screened
effluent(40 µm) S S S
Particle effluent
12 L/min
Recirculated water
250 L/min

11. Biomass and feeding Species : Atlantic salmon (Salmo salar)
Average fish weight : 190 g
Stocking density : 62 kg/m3
Spec water consumption : 0,025 L/min*kg
Temperature : 13,6 oC
Oxygen conc. : 9 mg/L
Feed type : Tess Edel 2,5 mm pellets
Feed supply : 5,27 kg /d
Total dry matter (DM) : 94,7 %
COD : 1162 g/kg
Tot-P : 9,9 mg/kg
Tot-N : 96,2 mg/kg

12. Analyses Water samples : SS COD tot-P tot-N
Sludge : TDS (total dry solids)
Ash

13. Mass balance calculation from sampling and feeding data
Mass flow
Feed supply
Effluent
Mass balance calculation from sampling and feeding data
FISH AND
BIOFILTER
WIRL SEPARATOR
SLUDGE
SCREEN
EFFLUENT
FEED
(100%)

14. SS in mixed samples (4hrs)

15. Suspended solids (SS)
Feed supply
Effluent
Sludge
100 82 16
0,6
1,2

16. Organic matter (COD)
Feed supply
Effluent
Sludge
100 86 9
0,6
4,2

17. Phosphorous (tot-P)
Feed supply
Effluent
Sludge
100 33 55 2
9,5

18. Nitrogen (tot-N)
Feed supply
Effluent
Sludge
100 49 9
0,5 42

19. Calculated mass flows
(whirl separation only)

20. Calculated mass flows
(whirl separation + screening 40 µm)

21. Calculated removal efficiencies by particle removal from effluent water (%)

22. Calculated total discharges (g/kg feed supplied)

23. Characterization of sludge from whirl separator
Sludge production: 1.59 L /kg feed supplied

24. Screening combined with sludge thickening (Bergheim et al, 1993) *)
UNIK rotary screen
( 150/60 µm )
Effluent from
flow through
tanks (sea wtr.)
Step 1
RECIPIENT
60 µm
Step 2
RECIPIENT
0.2 m/h
Step 3
RECIPIENT
Sludge
*) Aq. Eng. 12 (1993)

25. This study
BIOFISH
recirculation tank
16,5 m/h
Sludge
RECIPIENT
Step 1

26. Comparing total removal efficiencies

27. Conclusions
A simplified full scale recirculation system (BIOFISH) with dual outlet and
whirl separation was applied successfully for salmon smolt production
Sampling and mass balance calculations showed low effluent discharge
rates (17, 55 and 1.2 g/kg feed of SS, COD and tot-P respectively)
High removal efficiencies were obtained by whirl separation
(SS: 90 % ,COD: 66 % , and tot-P: 82 % )
Nitrogen compounds are mostly dissolved and can not be removed as
particles
Visual observation of uneaten feed contributes to an effective feeding
control, low fcr and low discharge rates
The whirl separator produces a concentrated sludge ( > 9 % TDS ), well
suited for further treatment and disposal

28. History of BIOFISH development
Idea/Predesign ( )
Calculations on tank hydraulics, aeration and nitrification capacities
Building of first prototype tank (1986)
Experimental testing/verification of idea
Rainbow trout (data on production, water quality, capacities)
Modified tank design/testing (1st generation, 1988)
Atlantic salmon smolt (data on production, water quality, capacities)
Arctic char (data on production, water quality, capacities)
Modified design/testing (2nd generation, 1990)
Brown trout for restocking (production, water quality, capacity data)
Modified design and testing (3rd generation, 1995)
Atlantic salmon smolt (production, incl. effluent discharge data)
Turbot and halibut (saline water - not presented here)