2007 Annual Report 1a.Objectives (from AD-416) The objective of this project is to develop/test a powered u-tube (Power Tube) aerator for use in commercial channel catfish ponds. Target performance parameters would be: 1)One 10-hp Power Tube using a 5-hp motor to move water and a 5-hp blower to inject air) should be capable of supporting 33,000 lbs. of catfish with a pond dissolved oxygen(D.O) concentration of 0 mg/L. 2)The Power Tube must be capable of increasing the D.O. concentration in the worst possible water (0 mg/L) by 4 mg/L. 3)Assuming a catfish respiratory rate of 225 mg 02/lb/hr, water velocity through the 3' diameter inner tube must be approximately 3.3 ft/second to meet the estimated respiratory demand. 1b.Approach (from AD-416) A motor-powered u-tube aerator ("Power Tube"), scaled to commercial catfish ponds will be constructed and tested. The initial unit will have a 36" diameter tube. A 5-hp three-phase electric motor will power the impeller, which will draw water down and discharge it through a 90 EL. A 5-hp blower, with a capacity to produce up to a 20% air/water mix will inject air into the water before it is drawn down to the bottom of the tube. Measurements will be conducted using a YSI Model 55 dissolved oxygen meter and a General Oceanic Model 2035 MKIV flow meter with a Model 2031H remote digital acquisition readout. The performance parameters to be determined include: water velocity and volume flow in the tube; increase in D.O. concentration at various inlet (environmental) D.O. concentrations; the effect of the air/water mix (determined from 0-20%) on the increase in oxygen saturation. These data will be used to develop the final design recommendations. 3.Progress Report This report documents research conducted under Non-Funded Cooperative Agreement between ARS and Southern Machine Welding, Inc. Additional details can be found in the report for the in-house project 6402-13320-003-00D, “Optimizing catfish/water quality interactions to increase catfish production.” The purpose of this agreement is to develop and test a novel aerator design for use in commercial fish ponds. A prototype u-tube has been constructed and installed in a 0.4 ha pond at the MSU Delta Branch Experiment Station. The tube was fabricated from a 36” diameter corrugated culvert and was buried to a depth of 20 ft below the pond bottom. The motor, gear box, impeller and open loop vector AC drive were all installed as planned. This initial prototype shows promise. With an impeller speed of 150 RPM, the motor draws 12.7 amps (5.36 hp) and has an output of 8,300 gpm. A variety of diffuser types have been tested. Oxygen transfer efficiency tests have been conducted. A 2’ diameter “down” tube insert was installed to increase the downflow water speed to increase air intake, while maintaining a similar upflow speed, to maintain oxygen transfer, It is expected that both the technical (improving efficiency) and practical (reducing cost and producing a unit that can operate reliably in a commercial environment) recommendations will be incorporated into a Phase II design for continued testing in future years. The ADODR monitors this project through telephone calls and e-mails to the collaborator, and through annual meetings with the collaborator.