Optimization of Aeration Tube Configuration Considering the Efficiency of Waste Collection and Water Mixing in Aquaculture Tanks

Proper configuration of aeration tubes is crucial for improving water quality and promoting the welfare and growth of cultured organisms in Recirculating Aquaculture Systems (RASs). To investigate the effects of aeration tube shapes (arc-shaped, disc-shaped, and linear-shaped) and positions (d = r, 1/2r) on performance, this study conducted experiments in a circular RAS tank. Methodologically, feed pellets were used to simulate solid waste, while ink was added to visualize the flow field, and mixing performance was quantitatively assessed using the spatial distribution uniformity. The results indicated that without aeration, the physical presence of the tubes affected waste collection but had minimal impact on water mixing. Under aeration conditions, placing tubes at d = 1/2r instead of d = r resulted in more efficient waste collection and improved water mixing. Waste collection performance was ranked as arc-shaped > disc-shaped > linear-shaped, whereas water mixing performance ranked linear-shaped > arc-shaped > disc-shaped. It is therefore recommended to place arc-shaped aeration tubes at d = 1/2r to achieve optimal overall performance. These findings provide valuable baseline insights into the selection and placement of aeration devices, offering preliminary practical guidance for aquaculture engineering.