Biosecurity measures are key factors in land-based fish farming in order to prevent the spread of pathogenic bacteria, fungi and viruses at both intake water and effluent water. Pathogens can create enormous problems in land-based fish farms, decimate fish stocks and decrease economic value. Disinfection is vital to secure good water quality and can be accomplished by a number of methods, including filtration, ozonation, chemical application, mechanical separation, chlorination, heat treatment, and ultraviolet (UV) radiation. UV radiation inactivates pathogens by damaging their DNA, a process called dimerization.
Disinfection by means of UV radiation is ideally suited for treating incoming and recirculated water in land-based fish farms and hatcheries as it uses no chemicals and does not create by-products which would harm the fish stock, or other aquatic life, on discharge. Another advantage is that the pH level is not altered by the UV radiation.
In order for the UV sterilizer to work effectively, the water passing through the UV sterilizer must be mechanically filtered to remove larger aquatic animals and debris. The Bernoulli Filter is an excellent pre-filter before the UV sterilizer, achieving filtration down to 100 micron.
Case story: EWOS
EWOS Group is one of the world’s largest suppliers of feed and nutrition for farmed fish. The company, headquartered in Bergen, Norway, was founded in 1931 and has operation in Canada, Chile, Norway, Scotland and Vietnam.
Ewos Innovation is the R&D Company of Ewos Group, focusing on research activities in developing new fish diets for the farming industry, through processing, raw material and nutritional improvements and breakthroughs. In Dirdal, the Norwegian R&D station is located and holds tank and sea cage trials and a technology center to make and test new materials and diets.
Standardizing and optimization of water quality, in addition to routine operational and sampling procedures are essential in order to conduct high quality fish trials. Precise control of feeding and continuous collection of uneaten pellets gives us a true indication of feed conversion ratio for all the feeds being tested. In order to secure good water quality to the fish tanks a combined system consisting of Bernoulli Filter, UV-sterilizer and flow meter do the job. The two Bernoulli Filters, BSG 300, act as a pre-filter before UV-sterilizers. In this installation the BSG 300 is tailor-made with an outlet nozzle size of DN 350 in order to fit pipe diameter of flow meter and UV-sterilizer, which are in DN350.
Facts and figures
Customer: Ewos Innovation AS Location: Dirdal, Norway
Application: Pre-filter before UV-sterilizer
Filter model: 2 x BSG 300
Filtration: 0,2 mm
Operating flow: 600 m3/h
Operating pressure: 1,5 bar g
Design pressure: 6,0 bar g