01/06/2020

UV-C in Aquaculture

Harmful pathogens are a scourge within the aquaculture industry and are often controlled with antibiotics. This has a negative impact on the water quality and thus also on the quality of the fish. As the aquaculture sector is growing every year, it becomes more important to reduce these pathogens in a sustainable way.

The answer for this is UV-C disinfection. UV-C disinfection is safe to use and protects against fish diseases without formation of any disinfection by products (DBPs) and ensures a higher survival rate. VGE Pro UV-C systems are therefore very cost-effective for the inactivation of many types of bacteria, viruses and parasites and provide healthy, clear and safe water. This results in a pure, untainted product: better and healthier fish without residual medications. In addition, VGE Pro UV-C systems are suited to combat bacteriological and microbiological hazards and bring water to the quality level the sector is required to meet.

Typically UV systems are installed in recirculation aquaculture systems (RAS) as well as intake and discharge water applications. For intake water, the main purpose is to ensure no external pathogens will enter the facility. In circulation systems UV-C enhances permeability of the water and most important reduce microorganisms from replicating. In a closed system with a high density of fish this is extremely important as it is quite easy for a disease to spread if no proper measures are taken.

 

Inactivating common bacteria

There are no microorganisms known on the planet that are resistant to UV-C radiation. Depending on the type of microorganism a different UV dose is advised. Common bacteria such as Aeromonas Salmonicida, Aeromonas Hydrophila, Vibrio Salmonicida and Vibrio Anquillarum are quite easily inactivated and need a UV-C dose below 15 mJ/cm². Viruses however, often need a higher UV-C dose. For instance the Infectious Pancreatic Necrosis Virus (IPNV) needs a dosage of about 250 mJ/cm² and some viruses even more! The UV dose (mJ/cm²) is calculated as a multiplication of the irradiance (intensity) and irradiation time.

Aquaculture Vissen Vge Pro Site

Ozone

Besides just disinfection, UV-C radiation can also destroy ozone when this is being used as part of the water treatment installation. Ozone is extremely toxic to the fish and needs to be removed before it flows back to the tanks. UV-C can destroy ozone in the water very quickly and makes sure no residual ozone will enter the fish tanks. UV-C radiation can also be used to oxidise organic matter in the water. Some contaminants can be oxidised directly with UV light, this is called photolysis. Others can be oxidised by adding an oxidant (such as H2O2 or O3) to the water, in combination with UV light so called hydroxyl radicals will be produced, this is called AOP (Advanced Oxidation Process). Hydroxyl radicals are the strongest in water available oxidant. AOP and/or photolysis can be used to reduce or eliminate off-flavour compounds such as geosmin and 2-MIB.

For correctly sizing the UV system at least three factors need to be known; flow rate, transmittance of the water (which tells us how strong the water absorbs the UV light) and required UV dose (or which pathogens should be reduced by how much). Through this model our team can correctly size and select the system according to your specifications. More can be found in our Aquaculture leaflet below.

Download our aquaculture leaflet

Want to know more about the usage of VGE Pro UV-C disinfection systems in aquaculture? Read our leaflet below!

Ruud
Ruud van de Ven
International Sales Engineer