Aquaculture cement tank design

#1

Greetings,

I am about to start my Aquaponics journey, which requires some aquaculture design. Admittingly I have no experience in aquaculture design but I read/watched a lot to come with a solution that I would like to ask communities opinion.

In order to increase the efficiency of swirl filter I am going to have an overflow from 4 , 2000 gallon the cement tanks into a up/under filter then to an another biofilter and then to the sump.
The Swirl Filter will be dealing with the heavily loaded eta 20 % flow from the fish tanks, while overflow from the tanks will be recycled once they are treated.

This is a simplified version of dual drain tank design with radial flow settler, and I cant see any drawbacks other then cleaning the up/under filter occasionally.

I would really like to hear the opinion of the community on this matter.

Best Regards

Murat

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#2

Hi Murat, welcome to the community!

Not sure what you mean by cement tank. Also the rest of the description does not generate a clear picture in my mind of what kind of setup you have in mind.

Regarding swirl filters vs. radial flow settlers it is said that the latter have a higher efficiency and less variability wrt flow and TSS load. See:

Davidson, John, und Steven T. Summerfelt. „Solids removal from a coldwater recirculating system—comparison of a swirl separator and a radial-flow settler“. Aquacultural Engineering 33, Nr. 1 (Juni 2005): 47–61. Redirecting.

The 80%/20% ratio between draining to mechanical filtration and biofiltration seems just about in a good ballpark.

Best regards!

-rolf

#3

Hi Rolf,

Thanx for the reply,

By cement tank I mean concrete tank for fish rearing. In this part of the world people use the term cement tank/concrete tank interchangeably.

The rest of your comment, I wholeheartedly agree and I have read some of Summerfelts papers regarding both fish rearing and aquaponics.

What I am lacking here is someone with the knowledge of RAS system. When I ask agriculture firms that I am looking for a contractor to establish an Aquaponics Farm, they drag their feet. For this reason I decided to design my own.

This design involves 2500 gal rearing tanks immersed into the ground, thus concrete would fit the bill better. At least this is what I am thinking. With a SLO line(1-20%) to a clarifier/settler and side flow (80-99%) to a possible up/down filter and then to a bio filter is the design atm. I am just curios if this kind of a set up is good enough to ensure good water quality for a not high density rearing system.

#4

Thank you for the clarification!

The only second hand piece of experience regarding cement tanks I can share is that the rebar used for fortification should be buried a bit deeper in the concrete than one yould usually do with normal concrete. Anecdotally one operator of an aquaculture farm told me that in the first design the rebar was placed too shallow beneath the surface and even though they used water proof coating on the concrete the concrete got wet underneath and the rebar started to rust and subsequently destroyed the fish tank walls. That is all I know about cement tanks.

Regarding the validity of your design I would recommend to have a RAS design company go over your specs and recalculate the validity of the dimensions. Probably this is at a lower price than ordering a fresh design from scratch. Confidentiality for those companies to not circulate the details of your design should be taken for granted.

I can wholeheartedly recommend aquaponik manufaktur GmbH. Alternatively Wolf Aqua or Landing Aquaculture might also be suitable service companies.

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#5

Once again thanks for the reply.

I just wrote an email to some of the aforementioned firms. Now all I have to do is wait …

MM

#6

Hi Murat,

The project foundation needs to researched prior to any installation.

Find out how deep is the water table and the soil composition before proceeding any further.

Also, where in the world are you planning such a venture in order to determine whether or not the climate and other factors could impede on your project.

Just to inspire your design, have you ever considered a holding/rearing tank that provides an artificial river environment but also allows you to transfer fish to other tanks and allows fast harvesting of the fish without any manual handling, product damage and unnecessary stress?

#7

Hi pniu,

I have been told by a civil engineer that the water table is below 2 meters at the proposed farm site which is in Turkey in a subtropical climate.

Regarding the artificial river environment I have only heard about it, but haven’t seen any applications in any video or book/article. I know for sure an AP Farm in Spain (NerBreen) has their fish rearing layout in such fashion but that’s it. If you have any reference for such kind of a design I would really like to learn more about it.

PS Swiss Lachs also have such a design but they are too fancy and also its only aquaculture.

#8

The design is like a narrow running track for athletes but in this case fish.

The track line is basically the holding/rearing tank and the centre is used for all the filters and pumps that swirl the water around the track.

The artificial river environment helps to improve the fish health and quality.

Gates are used to divert the fish to other rearing tanks including isolation quarantine tanks and premarket tanks.

Premarket tanks contain salt and has a separate high filtration system including UV.

The salt doesn’t harm the fish but rids it of any missed parasites, ingested food and that AP water taste that can taint the fish flesh…You’ll notice after this process the fish tastes much better.

The premarket tank empties into deeper harvesting tank that is also used as a sump. The harvester has a an adjustable stainless steel grill platform that is about 10-15cm below the water line. When the fish are diverted to this tank, 95% of the previous tanks water is below the grill, this allows the fish to be funneled to transportation vehicles and live packaging or filleting tables in a controlled flow.

The use of air lift pumps are used as they are easy to maintain outside the water and they also oxygenated the water like a venturi.

#9

Hi Murat,

Is the AP system being built within an existing structure like a warehouse/greenhouse or a purpose built structure?

I need a more precise location to determine what would be the best and cheapest method to control temperature and ventilation.

Also how do you intend to power the setup?

Lastly, what are you planning to do with your food waste i.e. dead fish and organic matter?

#10

Hi pniu,

So far the plan is to build a brand new greenhouse and attach a fishhouse with PV at the top. Pretty generic I assume.

There will be couple of bioreactors to digest any or collected waste to convert to liquid fertilizer.

I am planning a decoupled AP thus to manage the nutrient concentration and water quality issues I am planning to build relatively but not too small rearing volume the the required volume. I will be adding additional nutrients to get the optimum system health/production. I am hoping that I don’t have to buy too much additional fertilizers.

#11

Ideally to provide free ventilation and cooling with little or no electricity, would be to design the greenhouse with a windcatcher system that passes over the rearing tanks. Furthermore, water evaporating cooling walls with a header tank supplied by an airlift pump can further cool and control the greenhouse humidity.

Fly curtains can be used to quarantine sections of the greenhouse but also be used to create wind tunnels to manage airflow.

Fresnel lens are used to increase temperatures, including the use of livestock, compost and anaerobic methane digesters can also increase temperatures.

Organic waste from the AP fuels the fish/livestock (pigs/cows) and anaerobic methane digesters on site…in return you get methane gas, electricity, fertiliser, heat and meat/dairy products, plus extra revenue.

Any dead fish is use to make a maggot farm to provide protein for the fish. Ideally use black soldier flies.

The holding/rearing tanks will benefit from base thermal insulation to help manage water temperatures better.

I had frozen bottles of water on standby as an emergency backup to help decrease water temperatures.

Are you planning to use oxygen on site to create intensive fish farming?

#12

The plan is to start as simple as possible but design the facility at least on paper with every possible option available for AP. I am not sure how I could achieve passive cooling within the greenhouse but the plan is to have a very large sump deep within the ground (ave Temp 15.6°C ) and let the air flow over/through the water surfaces for cooling. It will also enable gas exchange.

Intensive fish farming is probably the last possible step in all production steps, while the plan is to have a decoupled AP with minimum supplement addition. The higher the fish load, the higher the fish water must be directed to the hydroponics part, which may lead to too much water usage or even discharge of water/nutrients. I am not favoring this.

#13

https://www.researchgate.net/publication/342042036_Design_of_a_Passive_Downdraught_Evaporative_Cooling_Windcatcher_PDEC-WC_System_for_Greenhouses_in_Hot_Climates

The link below is very informative

https://www.mdpi.com/1996-1073/13/11/2934/htm

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#14

Cheapest and fastest way to create a holding/rearing tank system would be to dig a trench with a mechanical excavator and dozer, lay thermal insulation and cover with a EPDM lake liner or similar product.