Ozone, with its efficient and broad-spectrum sterilization, water purification, and disease prevention and control capabilities, has become a core green, safe and efficient water treatment technology in the field of aquaculture. It is widely used in various aquaculture scenarios including industrial recirculating aquaculture, nursery workshops, high-position pond aquaculture, and live fish temporary rearing, and is a key technical means to promote the green transformation, quality improvement and efficiency increase of aquaculture.
Core Mechanisms of Ozone in Aquaculture
The application value of ozone in aquaculture mainly relies on its strong oxidation characteristics. Through multiple reaction pathways, it simultaneously achieves multiple effects including sterilization, harmful substance degradation, water quality improvement and dissolved oxygen enhancement, which fits the core needs of aquaculture.
Broad-Spectrum Sterilization and Disinfection Mechanism
Ozone has an oxidation-reduction potential (ORP) of 2.07 V, with an extremely strong inactivation effect on pathogenic bacteria, viruses, fungi, spores and other harmful microorganisms in aquaculture.
It can directly destroy the cell membrane and cell wall structure of microorganisms, penetrate into the interior of cells, and damage nucleic acid and enzyme systems.
It causes irreversible inactivation of microorganisms, and fundamentally cuts off the pathogen transmission route in aquaculture water.
It has an efficient killing effect on common harmful organisms in aquaculture, such as Vibrio, Edwardsiella, Saprolegnia, and white spot syndrome virus (WSSV).
The sterilization process is fast, with strong broad spectrum, and it is not easy to cause drug resistance, which is different from traditional antibiotics and disinfectants.
Degradation Mechanism of Harmful Substances in Aquaculture Water
Toxic and harmful substances such as ammonia nitrogen, nitrite and hydrogen sulfide are easy to accumulate in aquaculture water.
Ozone can directly decompose these toxic substances through oxidation reaction, reducing their toxic harm to cultured organisms.
For nitrite, ozone can quickly oxidize it into non-toxic nitrate, solving the problems of stress and poisoning of cultured organisms caused by excessive nitrite.
For hydrogen sulfide, ozone can oxidize it into sulfate, completely eliminating the black odor and toxicity of water and sediment.
For ammonia nitrogen, ozone can oxidize and decompose it under catalytic conditions, reduce the concentration of ammonia nitrogen in water, and alleviate water eutrophication.
Water Purification and Improvement Mechanism
Aquaculture water often contains macromolecular organic matter and colloidal substances produced by the decomposition of residual bait and feces, which easily cause water turbidity and reduced transparency.
Ozone can oxidize and decompose macromolecular organic matter in water, break them into small-molecule degradable substances, and provide nutrients for beneficial microorganisms in water.
It can destroy the stability of colloidal particles in water, promote colloidal flocculation and sedimentation, improve water transparency, and optimize water appearance.
It can oxidize and decompose odor-causing substances in water, eliminate the fishy odor of water, and improve the aquaculture water environment.
The final decomposition product of ozone is oxygen, which can directly increase the dissolved oxygen content of aquaculture water, improve the dissolved oxygen environment of water, and avoid anoxia in the bottom water body.
Core Application Scenarios of Ozone in Aquaculture
Ozone technology has strong adaptability, and can cover the whole process of aquaculture from seed breeding, adult culture, temporary rearing and transportation to tail water treatment. It is the core supporting technology for intensive and green aquaculture.
Water Treatment for Industrial Recirculating Aquaculture System (RAS)
Industrial recirculating aquaculture is the most widely used and mature scenario for ozone technology application.
The closed water circulation in RAS is prone to pathogen accumulation and water quality deterioration, and ozone is the core water treatment unit of the system.
In the recirculating water treatment process, ozone can simultaneously complete multiple functions of sterilization, harmful substance degradation and water purification.
It can effectively control the concentration of pathogenic bacteria such as Vibrio in aquaculture water, and greatly reduce the incidence of aquaculture diseases.
It can stabilize the water quality indicators of the circulating water body, reduce the water exchange rate, and lower the aquaculture energy consumption and water resource consumption.
When used with protein skimmers and biofilters, it can further improve water treatment efficiency and ensure water quality safety of high-density culture.
At present, it has been widely used in industrial high-density culture of fish, shrimp, crab, shellfish and other species.
Water Treatment for Aquatic Seed Nursery Workshops
In the aquatic seedling stage, the seedling physique is fragile, highly sensitive to water quality and pathogens, and diseases can easily cause large-scale death.
Ozone technology can provide a stable, clean and safe water environment for seedling breeding, and improve the survival rate of seedlings.
It can efficiently kill pathogenic bacteria, viruses and protozoa in the nursery water, and eliminate the risk of pathogens from vertical and horizontal transmission.
It can precisely regulate the water quality indicators of the nursery water, degrade harmful substances such as ammonia nitrogen and nitrite, and reduce the stress response of seedlings.
It can increase the dissolved oxygen content of water, optimize the micro-ecological environment of nursery water, and promote the growth and development of seedlings.
In the breeding of fish, shrimp, crab, sea cucumber, shellfish and other aquatic seedlings, ozone water treatment has become the mainstream technology for quality and efficiency improvement.
Water Treatment for Intensive High-Position Pond Aquaculture
High-position pond culture is the mainstream mode of intensive mariculture and freshwater fish and shrimp culture, and high-density culture easily leads to water quality deterioration and frequent diseases.
Ozone can be applied to water quality regulation and disease prevention and control of high-position pond culture through mobile or fixed dosing systems.
In the early stage of culture, ozone can be used to disinfect the whole aquaculture water body, completely kill pathogens in the water, and prepare for seedling release.
In the middle stage of culture, ozone can be used regularly to treat aquaculture water, degrade harmful substances such as nitrite and ammonia nitrogen, and control the number of pathogenic bacteria.
It can improve water transparency, stabilize algae phase, and reduce the risk of outbreak of harmful algae such as cyanobacteria and dinoflagellate.
Compared with traditional disinfectant spraying, ozone has no drug residue, does not damage the beneficial bacterial phase of water, and is less irritating to cultured organisms.
Temporary Rearing and Live Preservation Transportation of Finished Aquatic Products
In the link of temporary rearing and transportation of aquatic products, problems such as high density, rapid water quality deterioration, cross infection of pathogens, and high mortality rate are prone to occur.
Ozone technology can effectively solve the water quality and survival problems in the temporary rearing and transportation links, and improve the survival rate and quality of aquatic products.
In temporary rearing ponds and tanks, ozone can continuously purify water, degrade harmful substances produced by the metabolism of aquatic products, and kill pathogenic microorganisms.
It can increase dissolved oxygen in water, reduce the frequency of water change during temporary rearing, and maintain a stable temporary rearing environment.
In the live fish transportation link, supporting small ozone generators can improve the quality of transportation water, reduce transportation mortality, and extend the live preservation time.
It is widely used in aquatic product wholesale markets, supermarket temporary rearing, cold chain live fresh transportation and other scenarios.
Aquaculture Tail Water Treatment
With the tightening of environmental protection requirements, aquaculture tail water needs to meet the discharge standard for discharge or recycling. Ozone is one of the core technologies for tail water treatment.
Aquaculture tail water contains residual organic matter, ammonia nitrogen, phosphorus, pathogenic bacteria and other pollutants, which are difficult to meet the standard stably by conventional treatment.
Ozone can oxidize and decompose refractory organic matter in tail water, and degrade pollutants such as ammonia nitrogen and nitrite.
It can kill pathogenic bacteria and harmful microorganisms in tail water, and avoid biological pollution to the surrounding water environment caused by discharge.
It can remove the chromaticity and odor of tail water, improve the tail water treatment effect, and meet the different requirements of farmland irrigation, recycling for aquaculture, and standard discharge.
It can be matched with sedimentation tank, biochemical tank, constructed wetland and other processes to build a low-cost and high-efficiency tail water treatment system.
Core Advantages of Ozone Application in Aquaculture
Compared with traditional disinfectants, antibiotics and water quality improvers used in aquaculture, ozone technology has multiple advantages such as green safety, comprehensive functions, high efficiency and stability, which is in line with the industry direction of green and high-quality development of aquaculture.
Green and Safe, No Residue and Secondary Pollution
The final decomposition product of ozone is oxygen, without any toxic and harmful residues in the water body.
It will not generate carcinogenic disinfection by-products (DBPs) such as trihalomethanes like chlorine preparations, and will not pollute aquaculture water and cultured products.
It will not produce drug residues in aquatic products, which meets the production standards of green food and organic food for aquaculture.
It will not damage the ecological environment of aquaculture water, and has no negative impact on the subsequent biological treatment and bacterial phase cultivation.
Broad-Spectrum and High Efficiency, No Drug Resistance in Sterilization
Ozone has an extremely strong inactivation effect on all kinds of pathogenic microorganisms including bacteria, viruses, fungi and spores.
The sterilization speed is far faster than traditional disinfectants, it can complete the inactivation of pathogenic bacteria within a few minutes, with high action efficiency.
The sterilization process is a physical and chemical oxidation effect, which will not make microorganisms produce drug resistance, and can be used stably for a long time.
It can solve the industry pain points such as drug-resistant bacteria and drug residues caused by the abuse of traditional antibiotics.
Multi-Functional Coordination, Comprehensive Improvement of Breeding Environment
Ozone can simultaneously achieve four core functions: sterilization, harmful substance degradation, water purification and oxygenation.
One set of ozone system can replace a variety of disinfectants, water quality improvers and sediment modifiers, simplifying the aquaculture management process.
It can optimize the aquaculture ecology and reduce aquaculture risks from multiple dimensions such as water environment, pathogen prevention and control, and dissolved oxygen guarantee.
It can reduce the frequency of water change in the breeding process, save water resources, and adapt to the high-density intensive aquaculture mode.
Strong Adaptability, Covering the Whole Aquaculture Scenario Application
Ozone technology can adapt to the application needs of different breeding species, different breeding modes and different water body scales.
It can be used for continuous water treatment in industrial recirculating water, and also for regular water quality regulation in high-position ponds.
It can adapt to different water quality environments such as seawater, fresh water and brackish water, with flexible application scenarios.
The equipment can be large or small, which can be adapted from the centralized system of large breeding bases to the small equipment for supermarket temporary rearing.
Key Technical Specifications and Operation Points of Ozone Application in Aquaculture
The strong oxidation characteristics of ozone have both effects and risks. In aquaculture application, we must strictly follow the technical specifications and accurately control the operating parameters, so as to avoid aquaculture safety risks while ensuring the treatment effect.
Precise Control of Ozone Concentration in Water
Ozone concentration control is the core of aquaculture application, which is directly related to use safety and treatment effect.
Excessive residual ozone concentration in aquaculture water will damage the gills and body surface mucosa of cultured organisms, causing stress, poisoning and even death.
Different breeding species and different growth stages have significant differences in ozone tolerance.
In adult fish culture water, the residual ozone concentration must be strictly controlled below 0.1 mg/L.
In the water body of the seedling stage, the residual ozone concentration must be controlled below 0.05 mg/L.
Crustacean aquatic products such as shrimps, crabs and shellfish have lower tolerance to ozone, so the threshold of residual concentration needs to be further reduced.
It is necessary to support on-line ozone concentration monitoring equipment to control the ozone concentration in water in real time and ensure the safety of aquaculture.
Scientific Dosing and Contact Reaction Mode
Ozone dosing should adopt a reasonable way to improve ozone utilization rate and avoid direct contact between ozone and cultured organisms.
It is strictly forbidden to dose ozone directly into the culture pond. Side-stream treatment should be adopted, and the reaction between ozone and water should be completed in a special contact reaction tank.
The contact reaction tank must ensure sufficient reaction time, usually controlled at 5-10 minutes, to ensure full reaction and decomposition of ozone.
Support gas-liquid mixing devices, such as ejectors and micro-nano aerators, to improve the solubility and utilization rate of ozone in water.
After the reaction, the water body must undergo residual ozone elimination and aeration treatment to ensure that the ozone in the water is completely decomposed before flowing back to the culture pond.
Off-Gas Treatment and Safety Control
Ozone off-gas that is not dissolved in water has strong irritation. Direct discharge will harm human health and pollute the surrounding environment.
The ozone system must be equipped with an off-gas destruction device, which decomposes ozone in the off-gas into oxygen before discharge through activated carbon adsorption, catalytic decomposition and other methods.
Ozone leakage monitoring and alarm devices must be installed in the breeding workshop, linked with the ventilation system, to ensure that the ozone concentration in the workshop meets the safety standards.
The equipment room must maintain good ventilation, and operators must take personal protection to avoid direct contact with high-concentration ozone.
A complete equipment operation and maintenance and emergency disposal plan must be formulated to eliminate safety risks such as ozone leakage and excessive concentration.
Supporting Coordination with Other Water Treatment Processes
Ozone technology must be used in conjunction with other water treatment processes to achieve the best treatment effect and economy.
In the recirculating aquaculture system, ozone should first be matched with a protein skimmer to remove most of the organic matter in the water and reduce ozone consumption.
After ozone treatment, it is necessary to support a biofilter to further degrade small-molecule organic matter produced by ozone oxidation with microorganisms and stabilize water quality.
Avoid using ozone at the same time with live bacteria preparations and probiotics. Ozone will kill beneficial microorganisms, and sufficient time interval is required.
In aquaculture tail water treatment, ozone should be matched with sedimentation tank and biochemical treatment unit to reduce treatment cost and ensure effluent up to standard.
Existing Bottlenecks and Precautions for Ozone Application in Aquaculture
Existing Technical and Application Bottlenecks
High difficulty in precise control. The water quality of aquaculture water fluctuates greatly, and the ozone demand changes dynamically. It is difficult for conventional systems to achieve accurate dynamic dosing, which is prone to excessive concentration or insufficient treatment effect.
High operating energy consumption. Ozone production requires electric energy consumption. For large-scale open-air breeding modes, the energy consumption and cost of full water treatment are relatively high, which limits the popularization and application.
High threshold for equipment operation and maintenance. Ozone generation equipment, monitoring system and dosing device require professional personnel for installation, commissioning, operation and maintenance, and small and medium-sized farmers lack professional technical capabilities.
Great difference in adaptability to different water quality. In mariculture, ozone oxidation will produce a small amount of by-products such as bromate. It is necessary to strictly control the dosage and reaction conditions to avoid the risk of by-products.
Core Application Precautions
It is strictly forbidden to dose ozone directly in the culture pond. Side-stream treatment must be adopted to avoid direct contact between ozone and cultured organisms, causing irreversible damage.
It is forbidden to use ozone during the sensitive period of cultured organisms such as stress, disease onset and molting, so as to avoid aggravating the stress response and causing death.
Before the new system is put into use, sufficient commissioning and concentration testing must be carried out to determine the adapted dosage and operating parameters before formal operation.
It is necessary to calibrate the ozone concentration monitoring equipment regularly, maintain the ozone generator and off-gas destruction device regularly, to ensure the stable operation of the equipment.
For mariculture scenarios, the ozone dosage must be strictly controlled to avoid the generation of harmful by-products such as bromate, and ensure the safety of cultured products.
Development Trend of Ozone in Aquaculture Field
With the transformation of aquaculture to intensive, industrialized and green mode, the application scenarios of ozone technology continue to expand, and the technical system is also constantly upgraded and optimized. The core development trends are concentrated in the following directions.
Upgrading of low-energy ozone production equipment. The industry is accelerating the research and development of miniaturized, low-energy and high-efficiency ozone generators, reducing the power consumption and equipment cost of ozone production, and broadening the application of small and medium-scale breeding scenarios.
Research and development of intelligent precise control system. Combined with online water quality monitoring, Internet of Things and AI algorithm, it can realize real-time dynamic adjustment of ozone dosage, adapt to changes in water quality and breeding density, eliminate the risk of excessive concentration while ensuring treatment effect, and reduce operating energy consumption.
Specialized process and equipment optimization. For different scenarios such as seedling breeding, temporary rearing, recirculating aquaculture and tail water treatment, research and develop special ozone water treatment systems, optimize process parameters, and improve scenario adaptability and treatment efficiency.
Optimization of by-product prevention and control technology. Aiming at the problem of bromate formation in ozone application in mariculture, research and develop ozone catalytic oxidation process and dosing method with low by-products, to avoid the risk of by-products from the source.
Construction of multi-technology coupling integrated system. Promote the deep coupling of ozone technology with protein separation, biological filtration, micro-nano bubbles, ultraviolet disinfection and other technologies, build an integrated aquaculture water treatment system, simplify operation and maintenance, and improve the comprehensive treatment effect.
Improvement of supporting green breeding standards. With the continuous tightening of the control of aquaculture inputs, ozone and other green and residue-free water treatment technologies will gradually replace traditional disinfectants and antibiotics, become the standard technology for green aquaculture, and the relevant application specifications and industry standards will continue to be improved.
