ARS | Publication request: Processes to improve energy efficiency during pumping and aeration of recirculating water in circular tank systems

Submitted to: Book of Abstracts Aquaculture America
Publication Type: Abstract
Publication Acceptance Date: October 30, 2008
Publication Date: March 15, 2009
Citation: Colt, J., Summerfelt, S.T., Pfeiffer, T.J., Fivelstad, S., Rust, M. 2009. Processes to improve energy efficiency during pumping and aeration of recirculating water in circular tank systems [abstract]. Book of Abstracts Aquaculture America. p.344.

Technical Abstract: Conventional gas transfer technologies for aquaculture systems occupy a large amount of space, require considerable capital investment, and can contribute to high electricity demand. In addition, diffused aeration in a circular tank can interfere with the hydrodynamics of water rotation and the speed and efficiency of solids fractionation to the center drain on the tank bottom. To improve the energy efficiency of pumping and aerating water in a circular tank-based recirculating system while maintaining tank hydrodynamics for optimum solids removal, two processes were evaluated to provide high water flow and low lift gas exchange. One process incorporates a sidewall airlift pump with snap cap diffusers and the other process utilized Aero-Tubing. The first process generated 1.7 m3 /min of water flow at an air to water volume ratio of approximately 0.06. Air in this unit was provided by a 0.25 kW blower through three coarse snap-cap diffusers at a submergence depth of 0.086 m. The diffusers were changes to 2.2 m of Aero-Tubing, placed at a depth of 0.94 m, and supplied with air by a 0.38 kW blower. This airlift apparatus moved water a flow of 1.9 m3/min with an air to water volume ratio of 0.02. Oxygen addition across the first airlift device was 0.45 mg/L and across the second device it was 1.79 mg/L. These trials were run at 13C and dissolved oxygen concentration of approximately 7.0 mg/L. The sidewall box airlift technology provided relatively efficient gas exchange and water movement in circular tanks.