Navigation List

Design and Benefits of Recirculating Aquaculture System (RAS)

The recirculating aquaculture system (RAS) is basically what it sounds like it is a water system that recirculates the water. RAS represent a new and unique way to farm fish.You can combine fish and plant or produce culture in one system. And Recirculating systems filter and clean the water for recycling back through fish culture tanks, and also provide nutrients to both the fish and the plants. There are completely closed system. So it's a very little use of water which is really important these days. There are a lot of problems associated with ocean fish farming, pollution of the waters, escapement of the fish that intermix with or overtake wild fish populations, damage to the habitats on the ocean bottom. recirculating aquaculture systems on the other hand because they're completely closed and contained can grow just about anything anywhere there's no risk of escapement of the fish or a problem with the plants. They can be as small as a personal system in someone's backyard or front porch or as large as a commercial operation. Some systems are as little as $6,000 dollars.

Recirculating aquaculture systems can provide protein and produce to communities that otherwise wouldn't have access to them year-round. This is truly a green technology. It's lower energy usage lower, water usage, completely bio-secure it uses less or no chemicals or antibiotics. And it requires people to run the farm.

The RAS Design

We really needed to share the basic design of recirculating aquaculture system (RAS) and aslo discuss different topics, work together to promote recirculating aquaculture in the modern farming.

The basic parts of a RAS include a: (1) growing tank, (2) sump of particulate removal device, (3) biofilter, (4) oxygen injection with U-tube aeration and, (5) water circulation pump. Depending on the water temperature and fish species selected, a water heating system may be necessary. Ozone and ultraviolet sterilization also may be advantageous to reduce organic and bacteria loads.

Recirculating Aquaculture System (RAS) using Oxygenated Ultra Fine Bubbles

Benefits of Recirculating Aquaculture System (RAS)

In traditional Recirculation Aquaculture System (RAS) the environmental condition of rearing tank can be controlled in a facility. Therefore, the system has some advantages that it is less susceptible to external factors such as red tides, fish diseases, heavy weather and it is also high yielding. However, traditional RAS also has disadvantages of high initial cost, high running costs, and thus low profitability.

RAS offer fish producers a variety of important advantages over open pond culture.
  • These include a method to maximize production on a limited supply of water and land;
  • Nearly complete environmental control to maximize fish growth year-round;
  • The flexibility to locate production facilities near large markets, complete and convenient harvesting, and quick and effective disease control. 

For RAS attempts to reduce costs while maintaining productivity have been made for a long time. Ultra fine bubbles that are making innovations in various fields has been found to be a key to solve the problem. A closed recirculating aquaculture system (CRAS) using oxygenated ultra fine bubbles. Now, we will introduce the innovative system that we have evolved.

This figure shows the system flow diagram, in this CRAS, rearing water is reusing by recirculating filtration and additional water will be supplemented as needed to compensate for water evaporation. The definite characteristic of the system is using Aqua Nanox and oxygenated ultra fine bubble generator for controlling DO level in the whole CRAS.

Rearing water once passed through Aqua Nanox becomes highly oxygenated water containing oxygenated ultra fine bubbles with 20 mg/L DO.

Rearing water brought to a biofilter with Effects of high concentration of oxygen and ultra fine bubbles activates nitrifying bacteria, maximizing the performance of the biofilter. Though a bio filter requires a large amount of DO, Aqua Nanox maintains dissolved oxygen content of rearing water even after passing through the bio filter of above 10 mg/L.

Accordingly, it becomes possible to control the oxygen content throughout the system using only one oxygen supply source, not requiring oxygen supply to each rearing tank.

Aqua Nanox makes it possible to control the oxygen content throughout the whole system using only one oxygen supply source. It also easily keeps high dissolved oxygen condition so fishes suffer no stress and accelerate their growth.

Bactericidal effect of ultra fine bubbles inhibits the growth of bacteria and rearing water, without any treatment for sterilization. Sterilization using electrolyzed water or ozone common sterilization methods, involves risks. After sterilization using electrolyzed water, residual chlorine and oxidant that are toxic to fishes remain in water. Ozone sterilization also involves a risk of residual oxidant. Sterilization with ultra fine bubbles that uses only oxygen is a safe method is free from these risks. Ultra fine bubbles have cleaning effect making rearing tanks, channels and piping resistant to dirt.

Cleaning effect of ultra fine bubbles are also appreciated for example in pipe cleaning and food industrial plants. This effect reduces the frequency of large-scale cleaning operations for rearing tanks. Accordingly, it is possible to reduce stress to fishes and the number of workers.

Ultra fine bubbles also have bacteriostatic effect to retard excess feed and dead fishes and breeding water tanks. Bacteriostatic effect of ultra fine bubbles prevents deterioration of water quality and bad odor.