Aquaculture of captive-pond mode has higher sewage treatment efficiency and breeding den-sity,which is due to the benefit of frequent removals of aquaculture waste in the captive tank.However,dissolved oxygen in high density aquaculture water is a concern for farmers.When the water temperature is high in summer,air aeration is inefficient,and the bubble-based aeration method cannot meet the require-ments of oxygen supply.Gas-liquid mixed pump has a great performance on increasing dissolved oxygen in sewage aeration treatment.To explore whether gas-liquid mixed pump is suitable for the oxygen enhance-ment in the captive-pond mode,it is necessary to explore the optimal process parameters through experi-ments.In this study,the performances of the pump were tested under different water temperatures,outlet pressures and gas-water volume ratios,and the field tests were carried out in the pond captive tank(diame-ter 4 m,height 2 m,aquaculture water volume 20 m3).The results showed that,under the conditions of outlet pressure of 0.25 MPa and gas-water volume ratio of 0.01 to 0.05,the dissolved oxygen in outlet wa-ter was inversely proportional to the water temperature(5.6℃,13.5℃and 30.3℃),and the dissolved ox-ygen varied from 47.93 mg/L to 20.60 mg/L.The oxygen absorption efficiency was inversely proportional to the gas-liquid volume ratio,and the oxygen absorption efficiency varied from 91%to 33.7%.The dy-namic efficiency was proportional to volumetric gas-liquid ratio and varied from 22.32 kg/(kW·h)to 55.12 kg/(kW·h).Field test showed that,under the condition of fish oxygen consumption density of about 13.19 to16.49 kg/m3,when the pump's working power was about 3 kW,the dissolved oxygen of each captive tank can reach 11 mg/L in the daytime and keep above 8 mg/L at night.The fluctuation of dis-solved oxygen in the captive tank was within 0.2 mg/L,and the uniformity was good.The pump system is simple in structure and can work efficiently under high water temperature conditions.
aquaculturedissolved oxygengas-liquid mixingoxygen aerationround tank aquacul-ture in pond
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