Optimizing tilapia biofloc technology systems, part 1

Published on: 07/31/2018
Author/s : Ramon M. Kourie / Chief Technical Officer, SustAqua Fish Farm.

Engineering design at Chambo Fisheries, the world’s largest biofloc tank farm for tilapia Battery of eight multi-cohort sequential continuous culture BFT tanks at Chambo Fisheries.   Experience raising tilapia in biofloc technology (BFT), where aerial feeding rates are at least four to five orders of magnitude greater than in shrimp BFT systems, is limited. Areas that are particula...

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July 31, 2018

Good Day Ray

I am finding this concept fascinating. The multicohort, leading to partial harvesting, was something that I modeled for our Dusky Kob and it makes economic sense.

I am intrigued to find out in practice how the screens, that are used to divide the tank for the different GSs, impact on the flow rate and subsequent solids removal.


Do you also have any metrics to share on the percentage oxygen saturation that these systems run at under optimal stocking and Biofloc levels?

Regards
Neil

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July 31, 2018

Hi Neil

The only way to maximize throughput production relative to maximum carrying capacity is via the management of a single tank system as a multi-cohort sequential stock management system. This we call the Production: Capacity Ratio (P:C ratio). Apart from reduced CAPEX per unit fish production, the benefits filter down to energy costs for aeration, carbon dioxide stripping and horizontal water movement where power costs are basically halved when compared to a batch production system.
As far as water velocities are concerned there are two aspects that require hydraulic calculations 1) the frictional drag forces of the moving water mass which occurs at the wetted surface area (walls and floor) and 2) the frictional drag forces which occur through the screened compartments. The sum of which is called the system hydraulic gradient against which horizontal water movement needs to be balanced to achieve the design water velocity.
Screen selection, number of screens, % open area are all important affecting the final hydraulic gradient. An offset bottom bar raised three inches from the tank floor and the use of a round bar or cable to achieve complete closure of the screen are the tricks of the trade preventing solids collecting at the floor-bottom bar of the screens.

At velocities of 25-30cm/sec, the movement of heavier solids (dead material, fibrous material) the heavier material drifts on the tank floor at velocities around 15-20% slower than the water column velocities - movement is still achieved. Industrial aquaculture involves a significant amount of engineering design, hydraulics, fluid mechanics, thermodynamics, heat transfer etc. The objective being to produce fish sustainably at the lowest possible cost capitalizing on the benefits of scale economies. At 1130m above sea level we opted to run at 4.5mg/L while the added cost to take dO2 levels to 5mg/L was not great but not essential - calls for added floor diffusers. The combination of paddlewheels and floor diffusers greatly improved the driving gradient in R-ended tank systems increasing oxygen transfer efficiencies under field conditions. Our next project using sea-water BFT for O. mossambicus will, in addition, carry a nano-bubble aeration system to pick dO2 levels up into the 75-85% saturation range. Hope the above is satisfactory for now.

Best, Ray.

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August 1, 2018
Thanks Ray for a detailed reply, greatly appreciated.
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September 24, 2019

Hello Ray could you do the experiment with Nano bubble generator what was the result?

Reply
September 24, 2019
Hi Harish. The problem with nano-bubble aeration is that it does little to remove other gases (gas stripping) such as carbon dioxide in the water mass in BFT. Also when the nano-bubbles collapse they release allot of energy due to the internal pressure within the nano-bubble. This concerns me as this could impact on the bacteria. One study in Japan confirmed my fears on this. I think the safest application for nano-bubble technology is in an aquaponics environment where the plants could benefit from higher oxygen levels around the root zone. Apart from in an aquaponics set-up I've abandoned all further work on nano-bubble technology due to the reasons shared here. Best, Ray
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September 25, 2019
Ramon Kourie
Could you please share the Japanese study you referred to? Best, Kolbjorn
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September 25, 2019
Hello ramon, We have been using our systems in Aeration tanks of ETP’s and lagoons with fantastic results and savings of energy....Flocs were more stable...Very curious to hear about the Japan project as something seems to be missing....
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September 25, 2019
https://m.english.vietnamnet.vn/fms/society/195633/hi-tech-methods-raise-production-value-of-farm-produce--hcm-city.html#ui=mobile


50 tons/ ha/ cycle using Biofloc and Nanobubble technology....
Reply
Ramon Kourie Ramon Kourie
Agro Engineer Zootechnist
September 26, 2019
Hi Kolbjorn.I wll look for the Japanese study hen revert.
Best, Ray
Reply
Ramon Kourie Ramon Kourie
Agro Engineer Zootechnist
September 26, 2019
Hi Harish
If you can get 50t/Ha/crop of shrimp using nano-bubble aeration technology then I've got to hop onto a an airplane to see your set-up. I'll be bale to promote your initiatives.
Reply
Pannita Seareaw Pannita Seareaw
Student
September 4, 2018

Nice forum! I will share it with all of my friends.

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November 18, 2018
need some help

need small production capacity project report for fish culture using BFT
Reply
November 18, 2018
RAJENDRAKUMAR SHINGALA, SUPRINTENDENT OF FISHERIES, GUJARAT FISHERIES, GUJARAT, INDIA

Please mail me with the particulars of the request to .
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Vijayakumar Patibandla Vijayakumar Patibandla
Marketing Manager
December 5, 2018

Please give complete practices of farming as some of the farmers are interested to go for Tilapia (TBT) on low salinity areas of shrimp ponds proposal of conversion.
Regards.

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March 14, 2019

What is the costing in Bioflock system project?
And what is the cost of production and yield?

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July 3, 2019
Plz.give me information about bioflok fish farming cost of production and profit and duration of production

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August 13, 2019

Kindly need project report on farming gift tilapia in 65000ltr using BFT

Reply
September 19, 2019

Sir
I have around 35 cent land with 2500 sqft shed. I want to do Biofloc system first on trail basis before going into 100% commercial. As trail I want to go for 3 tank with 13 to 15000 liters tank. I am thinking of doing three varieties of fish ie.pearl spot, Mono sex tilapia and rohu, pls advice if it's ok or should I change my plan. I want a project report for the same, will it be possible for you to get me a report to present the same to the bank? My e-mail is sunnyamarpi03@gmail.com. regards

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September 20, 2019
Would like to know more on optimising tilapia Biofloc.
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September 24, 2019
Yes would like to know more. Also advice how much density I can go in a 10000 ltrs tank in case of tilapia and what density for Anabas.
Reply
Ramon Kourie Ramon Kourie
Agro Engineer Zootechnist
September 26, 2019
To all interested Engormix list members.

I'm afraid I'm always under pressure and cannot always answer your questions. I am busy writing a book to be called, "A Guide to Tilapia Production in Biofloc Technology (BFT) Systems". I wont be covering shrimp BFT production as there is already a good publication available through the World Aquaculture Society (WAS). My mission is promote tilapia production using sustainable intensification systems, BFT is one of them, as means to produce tilapia at a cost of US$0.90/kg - by 2050 there will be over 9 billion people sharing the planet...BFT could be one of the answers.
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