Number of holes and blades to control the performance of aquaculture aerator

Abstract

Water quality determines the success of inland aquaculture. The factor determining water quality is the concentration of dissolved oxygen (DO). To find effective paddlewheel aerators to enhance DO concentration, nine model aerators were examined: aerator 4 blades, 6 blades and 8 blades with variations of 12 holes per blade, 16 holes per blade and 20 holes per blade. They were rotated at 80 RPM, 100 RPM, 120 RPM and 140 RPM. The results show the higher the rotation speed is, the bigger the increment of DO concentration is, but their relationship is not linier. There is a condition when increasing rotation does not affect the DO concentration meaningly. The results also indicate the greater number of blades increase more DO concentration. The results also suggest the greater number of holes per blade initially increase DO concentration increment, but after 16 holes the increment tends to reduce. It is predicted owing to that widening surface interaction due to the holes in the blade is taken over by reducing the volume of splashed water. In this research, likely the aerator with 8 blades, 16 holes per blade and rotated at 120 RPM is the optimum one to increase DO concentration. However, if the energy consumption is also the concern, the aerator with 6 blades and 16 holes per blade likely is the better choice.