Paddlewheel aerator oxygen transfer efficiencies at three salinities

Oxygen transfer rates, or standard aeration efficiencies (SAE) were measure d using seven paddlewheel impellers at three salinities (0, 11 and 22 parts per thousand) and with two aeration devices (0.37 and 0.75 kW) in clean wa ter tests. Oxygen transfer rates increased significantly at higher saliniti es. With the 0.37-kW aerator, mean SAE values increased 67% at 11 parts per thousand compared with freshwater (0 parts per thousand), while SAE increa sed 46% at 11 parts per thousand with the 0.75-kW aerator. SAE values incre ased further at 22 parts per thousand, but the increases were much less. Th ese findings clearly demonstrated a significant salinity affect on oxygen t ransfer efficiencies with paddlewheel aerators. (C) 1999 Elsevier Science B .V. All rights reserved.