Ozone has a special application in aquatic breeding ponds due to its wide benefits. Ozone is a very strong disinfectant and oxidizing agent and plays a significant role in preventing and eliminating fish diseases in aquaculture facilities. In addition to increasing the level of dissolved oxygen in water, it also oxidizes organic pollutants. By using the ozone generator, ozone can be injected into the system in a certain amount automatically.
This substance causes disinfection and oxidation of pollutants in water, the destruction of viruses, bacteria, fungi and protozoa. This substance has a very favorable effect against streptococci in the breeding environment. The use of ozone increases fish growth and reduces the use of drugs and antibiotics in aquaculture.
What you read in this article:
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Objectives of using ozone in water treatment for aquaculture
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Methods of using ozone in aquaculture ponds
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The benefits of using ozone in the aquatic breeding pond
Objectives of using ozone in water treatment for aquaculture
Removal of fine and colloidal solids
Fine and colloidal solids consist of particles of 1-30 microns and 0.001 microns, respectively. The small size of the particles allows the solids to remain in suspension and avoid most mechanical separation methods. The accumulation of fine and colloidal solids can lead to a decrease in the nitrification efficiency of biological filters and harm to aquatic life. Ozone destroys solids and colloidal substances through concentration of solids (microflocculation). This substance facilitates this process by breaking the foam, filtration and sedimentation.
Removal of dissolved organic compounds
Soluble organic compounds or refractory organics give a stain like tea color to water. Soluble organic compounds are non-degradable and accumulate according to feed input, water exchange rate and solids removal rate. High amounts of dissolved organic compounds can stress the fish and reduce the nitrification efficiency of the biological filter. Ozone destroys dissolved organic compounds through oxidation to products that are more rapidly converted to nitrates.
nitrite removal
As production intensifies and organic loads increase, nitrite can accumulate. Bacteria that process ammonia into nitrite are more subject to organic loads than bacteria that process nitrite into nitrate (Nitrobacter) and increase nitrite levels. High amounts of nitrite are toxic and dangerous for fish. Available data for silver flake show nitrite levels as low as 2.8 parts per million (ppm) which can reduce the growth of salmon by 5%.
disinfection
An important measure in reducing the risk of disease outbreak in the fish breeding pond is the use of standard quarantine methods for each fish. Disinfecting the point of entry of wastewater into the environment is very important to prevent the transmission of various diseases. Ozone can usefully inactivate a wide range of bacterial, viral, fungal and protozoan fish pathogens. The purifying effect of ozone depends on the concentration of ozone, length of exposure to ozone (contact time), pathogenic loads and the amount of organic matter. In the presence of large amounts of organic matter, the demand created through oxidation of the organic matter can make it difficult to maintain sufficient residual ozone for effective disinfection.
Methods of using ozone in aquaculture ponds
Aquatic washing
If fish or shrimp are washed with ozonized water after catching or harvesting, its shelf life is increased due to the reduction of microbial load. Violle has reported this time increase of 5 days. According to the same report, he changed the microbial quality of sea water, which included bacteria such as Bacillus Typhus and Bacillus Coli, to the microbial quality of drinking water using ozone. Violet observed that the contact of water containing ozone with marine crustaceans had no effect on their taste or appearance. Therefore, he suggested to use chilled water containing ozone to reduce the pollution load of marine crustaceans.
Using ice containing ozone to cool fish
Using ice made from ozonated water, while reducing the microbial load, prolongs the storage time of fish and shrimp. The study conducted in this regard shows that the use of ice containing ozone has a significant effect in reducing the overall count of microbes. In this study, the total number of bacteria after 12 days of keeping fish with normal ice and ice containing ozone was counted as 2,800,000 and 90,000, respectively.
A study by Salmon & Gall in this field indicates that if fresh fish is kept under ice containing ozone, it will maintain its edible quality for 12-16 days. Also, the quality of fresh fish that was stored in ice produced from chlorinated water was reported to be inedible after 8 days. According to the report of Graham and colleagues (Graham, et all), the use of ozone in cooling and storing white fish can increase its shelf life by 50%.
Disinfection of surfaces and processing equipment
Studies have shown that ozone is 52% stronger than chlorine in destroying microorganisms, and its destruction rate is more than 3 times that of chlorine. The use of ozone increases the immunity level of the product against pathogenic bacteria. When using ozone in cleaning and disinfection of aquatic processing units, the following measures should be taken:
- Cleaning surfaces and equipment from fish and shrimp residues
- Spraying ozone water on surfaces and equipment without using other disinfectant chemicals
Wastewater treatment of fishing industry units
Wastewater from fishing industry units, especially units that use large amounts of water in product processing (such as surimi and canned fish factories), has a large amount of blood, fat, protein, etc. The BOD and COD of the wastewater of these factories are very high and appropriate measures should be taken to reduce them. Ozone, together with other physical and chemical methods, can easily purify the wastewater of fishing industry units.
The benefits of using ozone in the aquatic breeding pond
In order to achieve the highest level of survival in fish and shrimp breeding centers, the incoming water must be clean and free of microorganisms and other contaminants. Ozone disinfects the water entering the ponds and increases the percentage of survival and removes chemicals for water preparation. It can also increase the amount of dissolved oxygen in the water, and compared to chlorine, which is problematic for fish life, it does not contain any danger. In shrimp farming, ozone removes vibrios (which are the cause of disease in shrimp farming). Ozone added to the sea water keeps farmed shrimp healthy.
- Replacing ozone instead of any other disinfectant
- Complete elimination of parasites, viruses, fungi, moss and algae eggs and all micro-organisms
- Disinfection and water purification of aquatic breeding ponds (fish, shrimp, algae, leeches, etc.)
- Use in closed circuit systems instead of using UV
- Optimal use of pool water in case of water circulation
- Improving water quality and increasing the amount of aquatic life
- Reducing diseases and eliminating chemicals and drugs
- Being safe for living organisms
- Increasing dissolved oxygen in water and ORP (Oxygen Reduction Potential)
- Coagulation of colloidal bodies 1-30 microns and their separation in biofilters
- Help to remove ammonia and increase the efficiency of the biofilter
- Separation of nitrite in closed systems by its oxidation
- Reduction of fish diseases and CIP of pools
- Washing aquatic products and increasing its shelf life due to the reduction of microbial load
- Using ice containing ozone to cool water in a sterilized way
- Removing the unpleasant smell of water in processing plants
- Disinfection of fillets, processing surfaces and equipment from all pathogens
- Spraying water containing ozone to surfaces and equipment without using other chemicals/disinfectants
- Wastewater treatment of processing units and reduction of BOD and COD