CAJ | 학술논문

为了研究纯氧气/液混合装置在循环水养殖系统中的实际使用效果，对闭合循环水产养殖系统中气/液混合装置的氧气吸收效率（absorption efficiency，AE）及运行效果进行了研究。结果表明，气/液混合比（gas to liquid ratio，G/L）变化在0.333%～3.333%（O2流量0.57～5.70 g/min）之间时，气/液混合装置的平均氧气吸收效率变化在94.001%～36.049%之间。当G/L=0.667%（O2流量1.141 g/min），在30.5℃、26.3℃、22.9℃和19.2℃水温条件下，气/液混合装置的氧气吸收效率别为87.833%、90.451%、93.606%和94.001%；其中，试验水温为19.2℃时， AE达到最大（94.001%），混合器出水溶解氧浓度达13.36 mg/L。当G/L大于或小于0.667%时，AE均随G/L的变化而降低；各温度组AE值的方差分析表明，温度对AE值有显著影响。
위료연구순양기/액혼합장치재순배수양식계통중적실제사용효과，대폐합순배수산양식계통중기/액혼합장치적양기흡수효솔（absorption efficiency，AE）급운행효과진행료연구。결과표명，기/액혼합비（gas to liquid ratio，G/L）변화재0.333%～3.333%（O2류량0.57～5.70 g/min）지간시，기/액혼합장치적평균양기흡수효솔변화재94.001%～36.049%지간。당G/L=0.667%（O2류량1.141 g/min），재30.5℃、26.3℃、22.9℃화19.2℃수온조건하，기/액혼합장치적양기흡수효솔별위87.833%、90.451%、93.606%화94.001%；기중，시험수온위19.2℃시， AE체도최대（94.001%），혼합기출수용해양농도체13.36 mg/L。당G/L대우혹소우0.667%시，AE균수G/L적변화이강저；각온도조AE치적방차분석표명，온도대AE치유현저영향。
Control of dissolved gases, especially oxygen and carbon dioxide, is an essential component of closed recirculating aquaculture systems. The use of oxygenation in closed recirculating aquaculture systems increases the mass of fish that can be supported in a given water flow by removing oxygen as a limiting factor to a system’s carrying capacity. In general, oxygenation technique in aquaculture is relatively mature with well established operational principles, techniques, and equipment. Since the 1970s, pure oxygen gas has been used as an economical means of providing supersaturated dissolved oxygen and thereby intensifying fish production in recirculating systems. Use of pure oxygen can lower fish production costs by supporting high fish and feed loading rates and reducing water flow requirements, which in turn reduces the size and cost of pumping, culture tanks, and water reuse equipment. Transferring pure oxygen rather than air into water can increase the mol fraction of gaseous oxygen and solubility of dissolved oxygen in water. The maximal dissolved oxygen concentration can be influenced by the ratio of gas to water flow rate within the gas transfer unit. When pure oxygen is in contact with water, the dissolved gases tend to come to equilibrium at saturation. If there is venting of off-gas from an oxygenation system, some of these other gases will be removed from the water. Choosing the appropriate oxygenation technology for recirculating systems depends on oxygen absorption efficiency (AE, mass of oxygen absorbed per mass of oxygen applied), oxygen transfer efficiency (mass of oxygen transferred per power required), ability to strip nitrogen and other gases, ability to treat flows containing suspended solids without plugging, system layout and intended location of the oxygenation process, and whether flow must be pumped through the unit or if gravity flow is adequate. The configuration of a recirculating system determines the appropriate type of oxygenation unit. Regulation of dissolved oxygen concentrations is typically carried out by means of gas transfer processes, and the gas transfer units commonly used to add pure oxygen within large recirculating aquaculture systems include U-tubes, oxygenation cones, and multi-staged low head oxygenators. The gas/liquid mixing device can inject pure oxygen into liquid, especially suited to applications in closed recirculating aquaculture systems with high carrying capacity, and it had recently been successfully used to provide supersaturate water with oxygen for increasing fish production in our pilot scale recirculating aquaculture system. In this study, AE of the gas/liquid mixing device was determined under conditions with different oxygen gas to liquid ratios (G/L) ranging from 0.333%to 3.333%(0.57-5.70 g/min) at different water temperatures from 30.5℃to 19.2℃) in order to assess application of pure oxygen in a closed recirculating aquaculture system. The AE of the gas/liquid mixing device averaged 94.00%-36.05%. Among conditions with different GL values, the AE under the condition with the G/L value of 0.667%(1.141 g/min) was highest with 87.833%at 30.5℃, 90.451%at 26.3℃, 93.606% at 22.9℃, and 94.001% at 19.2℃, respectively. It was obvious that AE value declined with decreasing temperatures at a given G/L value, suggesting that water temperature was a key factor affecting the AE of the gas/liquid mixing device. The highest value of AE (94.001%) was obtained when G/L equaled to 0.667%(1.141 g/min) and water temperature at 19.2℃. Under this condition, the corresponding dissolved oxygen entering fish ponds was 13.36 mg/L.