Pumping performance of a modified commercial paddlewheel aerator for split-pond aquaculture systems

Authors: Brown, Travis; Tucker, Craig

Submitted to: North American Journal of Aquaculture
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: 10/18/2013
Publication Date: 1/9/2014
Citation: Brown, T.W., Tucker, C.S. 2014. Pumping performance of a modified commercial paddlewheel aerator for split-pond aquaculture systems. North American Journal of Aquaculture. 76(1):72-78.

Interpretive Summary: The split-pond aquaculture system consists of a small fish-holding basin connected to a waste-treatment lagoon by two conduits. Split ponds require large water volumes circulated between the two basins (10,000 to 20,000 gal/min for 5- to 10-ac ponds) to remove fish waste and provide oxygenated water to the fish. Catfish farmers in the United States have rapidly adopted this new technology to improve production efficiency. Pumping performance was evaluated at a range of rotational speeds and paddle depths. Water flow rates ranged from 8,240 to 25,069 gal/min. Flows increased with increasing rotational speed and paddle depth. Power input varied directly with flow rate and water discharge per unit power input (a measure of pumping efficiency) decreased as water flow rate increased and paddle depth was reduced. Placing the paddlewheel at the channel inlet where water is pushed through the channel produced flow rates three times greater than placement at the outlet where the pump pulled water through the channel. This study demonstrated that commercial paddlewheel aerators can be modified, operated, and located to provide water flows needed in commercial-sized split ponds. Long-term studies are underway to compare operational issues and costs associated with the use of various pump types, including paddlewheel aerators, in split-pond aquaculture.

Technical Abstract: The split-pond aquaculture system consists of a small fish-holding basin connected to a waste-treatment lagoon by two conduits. Split ponds require large water volumes circulated between the two basins (10,000 to 20,000 gal/min for 5- to 10-ac ponds) to remove fish waste and provide oxygenated water to the fish. Farmers producing ictalurid catfish in the United States have rapidly adopted this new technology to improve production efficiency. The original split-pond design used large, slow-turning paddlewheels to circulate water; in this study we evaluate paddlewheel aerators as pumps for split ponds. Pumping performance was evaluated at rotational speeds of 24.75-66.00 rpm and paddle depths of 4.00, 6.75, and 9.50-in. Water flow rates ranged from 8,240 to 25,069 gal/min. Flows increased with increasing rotational speed and paddle depth. Power input varied directly with flow rate and ranged from 1.08 to 8.28 hp. Water discharge per unit power input (a measure of pumping efficiency) ranged from 3,026 to 10,824 gal·min-1·hp-1. Pump efficiency decreased as water flow rate increased and paddle depth decreased. Placing the paddlewheel at the channel inlet where water is pushed through the channel produced flow rates three times greater than placement at the outlet where the pump pulled water through the channel. This study demonstrated that commercial paddlewheel aerators can be modified, operated, and located to provide water flows needed in commercial-sized split ponds. Although more expensive to operate than slow-turning paddlewheels that are specifically designed as water pumps, paddlewheel aerators offer the advantages of lower investment cost, availability, and easy maintenance. Long-term studies are underway to compare operational issues and costs associated with the use of various pump types, including paddlewheel aerators, in split-pond aquaculture.