In-depth Demand Report | Disassembling Small Scale Recirculating Aquaculture System

Recirculating Aquaculture Disinfection SystemIn recirculating aquaculture systems, the hazards of bacteria and viruses cannot be underestimated. Bacteria consume a large amount of dissolved oxygen in water, leading to oxygen deficiency in farmed organisms, slow growth, and even death. Pathogenic bacteria such as Flavobacterium columnare and Aeromonas hydrophila can cause diseases like gill rot and septicemia in farmed organisms, leading to large-scale mortality and significant economic losses for aquaculturists. Viral infections are characterized by fast transmission and difficulty in control, which can infect a large number of farmed individuals in a short time, disrupt their physiological functions, and severely impact aquaculture efficiency.Ultraviolet (UV) and ozone are highly effective in killing bacteria and viruses. UV radiation penetrates the cell membrane of microorganisms through strong radiative light waves, reaches the nucleus, and breaks the DNA double helix structure, preventing bacteria from reproducing and leading to their death. It is particularly effective against suspended bacterial microorganisms in water. Ozone, with strong oxidizing properties, reacts rapidly with bacteria and viruses, destroying their organelles, DNA, and RNA, and altering cell permeability, leading to cell lysis and death. It can kill a variety of microorganisms, including bacterial vegetative cells, spores, viruses, and fungi. Due to its good diffusibility, ozone can disinfect the entire aquaculture water without dead angles.UV Sterilization1. Classification by Installation MethodUV sterilization lamps can be classified into two types based on installation method: pipe-mounted and channel-mounted: 1. Pipe-mounted UV sterilization lamps are usually installed inside the water delivery pipelines of recirculating aquaculture systems. Water flows directly through the pipe section with the sterilization lamp, ensuring full contact between water and UV light, thus efficiently sterilizing the flowing water. Their advantages include a compact structure that integrates well with the pipeline system, making them suitable for water sterilization in scenarios with relatively low flow rates. 2. Channel-mounted UV sterilization lamps are generally installed above or on the sides of open water channels with a certain width and depth, irradiating and sterilizing the water flowing through the channel. They can cover a large area of water, making them suitable for handling large flow rates and open water bodies, ensuring that a large area of water is effectively irradiated by UV light to guarantee sterilization performance.2. Classification by Voltage IntensityUV sterilization lamps are divided into two types based on voltage intensity: low-pressure and medium-pressure: Low-pressure (LP) UV sterilization lamps operate at relatively low voltages and typically generate single-wavelength UV light, mostly around 254 nanometers. This wavelength has a significant germicidal effect, low energy consumption, and good stability. However, their power is relatively limited, making them suitable for small-scale applications or places where extremely high sterilization intensity is not required. Medium-pressure (MP) UV sterilization lamps operate at higher voltages, generating multi-wavelength UV light with a wider coverage and stronger germicidal capability. They have higher power, allowing rapid treatment of large-flow and highly polluted water bodies. However, they consume more energy and have higher equipment costs, making them commonly used in large-scale recirculating aquaculture systems with high requirements for sterilization efficiency and treatment capacity.3. Principles and Influencing Factors of UV SterilizationUV light is a type of electromagnetic radiation, divided into multiple wavelength bands. The primary band used for sterilization is the UVC band (200-280 nanometers), with around 254 nanometers being the most effective wavelength for germicidal purposes. When recirculating water carrying microorganisms such as bacteria flows through the irradiation area of a UV sterilization lamp, the energy of UV photons is absorbed by the genetic material (such as DNA or RNA) inside the microbial cells. The chemical bonds in these genetic materials break after absorbing sufficient UV energy—for example, hydrogen bonds in the DNA double helix structure are destroyed—thereby disrupting genetic information processes such as replication and transcription. This prevents microorganisms like bacteria from reproducing, leading to their death and thus sterilizing and purifying the recirculating water, ensuring water quality safety and creating a healthy growth environment for farmed organisms. The main factors influencing the effectiveness of UV sterilization in recirculating aquaculture are as follows:1.UV DosageUV dosage, determined by UV intensity and irradiation time, is critical for sterilization effectiveness. Insufficient dosage cannot break the DNA or RNA structure of microorganisms like bacteria and viruses, leading to ineffective sterilization. Only when the specific dosage required by the target microorganisms is achieved can a good sterilization rate be ensured.2.Water TurbiditySuspended solids and organic particles in water increase turbidity. These impurities scatter and absorb UV light, preventing it from penetrating the water and reducing the actual UV exposure of microorganisms, thus decreasing sterilization efficiency. The higher the turbidity, the more UV light is attenuated, and the poorer the sterilization capability.1. Water Flow RateToo fast a water flow rate shortens the residence time of microorganisms in the UV irradiation area, preventing them from receiving sufficient UV dosage and leading to incomplete sterilization. Too slow a flow rate, while ensuring irradiation time, may affect the overall efficiency of the recirculating water system.2. Microbial SpeciesDifferent microorganisms have varying tolerances to UV light. For example, bacterial spores, due to their special structure, are more resistant to UV irradiation than ordinary bacterial cells. Viruses, lacking a cellular structure, also differ in their UV sensitivity from bacteria. Therefore, the types of microorganisms present affect sterilization efficacy.3. Lamp Aging DegreeAs usage time increases, the luminous efficiency of UV lamps gradually decreases, reducing the output UV intensity and the effective sterilization dosage provided. This leads to a decline in sterilization performance compared to when the lamps were newly installed.

Recirculating Water Quality Parameters

In fish farming production, feed cost is the largest part of the whole cost, basically accounting for about 60% to 70%. Therefore, saving feed cost is also a way to improve farming efficiency, but it must be based on reasonable and scientific methods. .1. Choose feed with reasonable and balanced nutrientsThe quality of the feed is directly related to the cost of breeding. If the quality of the feed is good, the digestible and absorbable part of the fish after eating is high, the growth rate of the fish is fast, and the feed coefficient is low. Conversely, raising fish with poor-quality feed will greatly increase the cost of farming.2. Scientific and reasonable feeding is an effective way to reduce feed waste and control feed costFeeding should be based on the principles of "four determinations" timing, fixed point, qualitative and quantitative, so as to achieve a uniform and appropriate amount, and avoid sudden more and less, resulting in oversatisfaction, hunger, indigestion, and affecting the normal digestion and absorption of fish.The feeding amount should be determined according to water quality, weather, fish activity and feeding status.In terms of feeding amount, the fish are generally controlled to eat "80% full", that is, 80% of the fish are full, and 20% of the fish are not very full; after 2 hours of feeding, the feed is basically eaten, and there is a little leftover, or There are also a few schools of fish swimming around in search of food. This maintains the fish school's appetite and reduces feed loss.Reasonable determination of feeding times should be determined according to the feeding habits, growth status and feeding strength of fish. Reasonable feeding amount and frequency are beneficial to improve the digestibility of fish to feed, reduce the loss of feed in water, and reduce the feed coefficient.Properly grasp the feeding time and choose the feeding place. The feed table should be placed on the leeward side of the pond where the water is deeper, the bottom is harder, less leakage, and more open.The time and frequency of feeding are determined according to the species of fish, feeding habits and size.Generally, adult fish are fed twice in the morning and evening, preferably at 8-9 o'clock in the morning and 5-6 o'clock in the afternoon.3. Healthy water quality managementWater quality management is very important, as the saying goes: 'Three minutes of species, seven minutes of management. ’ Pipe refers to water quality management. Pond water quality conditions have an important impact on fish feed coefficient.Generally speaking, in water bodies with no pollution, fresh water, and sufficient dissolved oxygen, fish have a large food intake, strong appetite, high feed utilization rate, fast growth rate, and small feed coefficient.Among the various physical and chemical factors of pond water quality, the amount of dissolved oxygen in the water body is the biggest factor affecting the feed. If the dissolved oxygen in the water body is sufficient, the growth and metabolism of the fish body will be vigorous, the digestion time for the feed will be greatly shortened, and the growth rate index of the fish will increase. coefficient is negative.According to experiments by aquaculture experts, when the dissolved oxygen in water drops from 7.6 mg/ton to 3.1 mg/ton, the feed factor increases by 5.6 times, while the growth rate decreases by 9 to 10 times.In addition, within a certain water temperature range, the consumption of fish feed is directly proportional to the increase in water temperature. Within a certain range of water temperature, for every 1°C increase, the feeding rate of fish with the same body weight will increase by 0.1% to 0.5%.Therefore, the same fish size has different feeding rates at different water temperatures.