Wastewater Solutions for Compliance and Reuse Recirculating Aquaculture System - RAS - Agriculture - Aquaculture
Aquaculture is a rapidly developing industry. Intensive fish ponds and hatcheries are challenged to achieve high levels of water reuse, requiring unique and efficient treatment for ammonia, COD and solids separation.MBBR Biological treatment can offer tailor-made biological processes and clarification solutions allowing this industry to meet these challenges at a sustainable manner. Recirculating aquaculture systems (RAS) represent an exciting, eco-friendly and unique way to farm fish. Instead of the traditional method of growing fish outdoors in open ponds, net cages or tanks, this system rears fish at high densities within an operator controllable rearing environment inside a building. Recirculating systems filter and clean the water for recycling back through the fish culture tanks. New water is added to the tanks only to make up for water loss due to splash out and evaporation and to replace that used to flush out fish waste materials to storage tanks.
RAS designs have several system process technologies all of which work together to ensure minimum loss of water, heat and of course fish stocks, while constantly cleaning and re-using the fish tank water. RAS farms can be designed to various levels of complexity, however all true water recirculation designs involve the use of equipment to remove and safely store wastes, clean and re-use water and maintain rearing conditions at or near optimum for the species of fish being raised.
In contrast, many older style tank farming systems that have been used to grow fish are termed 'open' or 'flow through' systems because the water makes only one pass through the tank and then is discarded. Although several improvements can be added to older designs to reduce water usage and create hy-bird types of operations, these are not exactly true water recirculation farms
Low water Requirements:
Because RAS farms recycle most of their water, they consume considerable less than other types of culture systems and are especially well suited to areas with limited water supplies. A properly designed and operated recirculating system requires a minimum daily input of water, just enough to clean the waste from the filters and to replace water lost to evaporation.
Less Land Requirements:
Since fish in a recirculating system are reared in tanks, with oxygen being supplied and their metabolic wastes removed by constantly recirculate water, fish can be safely stocked and grown at high densities.
Control of Water Temperature:
The low water requirement of recirculating systems opens up the possibility of economically controlling temperature which, next to the lower water amounts need, controlling water temperature (and the resulting stock growth rates) is one the greatest benefits of these systems.
Protection from the Elements and Potential Predators:
By rearing the fish indoors, the farmer is no longer limited by weather conditions where a sudden cold spell can wipe out a year's production by killing the larval fish or disrupting the normal spawning of the brood fish.
Control of Water Quality:
With recirculating systems, the aqua culturist has the opportunity to control water quality, to the benefit of the live fish stock to the final product and the environment.
Reduced labour requirements:
A typical 100 metric ton per year RAS can be run by as few as two people, which is at least a fivefold reduction in labor usage versus traditional fish farming methods.
Lower risk of negative impact from adverse weather conditions:
The risk of crop loss from a natural disaster can be eliminated in a properly sited and constructed RAS. The traditional fish farmer is more vulnerable to natural disasters and the effects of natural weather patterns.
Lower risk of creating adverse environmental impacts:
If left untreated, the discharge plume from traditional fish and shrimp farms is essentially a source of pollution of local water bodies. Recirculating systems treat and reuse the water and there is zero discharge to the local environment. RAS should be selected when an environmentally friendly solution to the growing demand for seafood is required.
A properly designed and managed RAS has complete control over biosecurity concerns, whereas a traditional open system is open to attack.