Comparisons of devices for aerating inflow of pipes

Eleven different devices for aerating water discharged from pipes were evaluated for effectiveness in increasing dissolved oxygen (DO) and decreasing carbon dioxide (CO₂) concentrations. All devices were more effective than a straight pipe in oxygenating water and provided DO concentrations above 4 mg/l. DO concentrations above 6 mg/l resulted with Tee and Ell aspirators and with a half-open gate valve. The gate valve had the greatest oxygen transfer rate. Although the aerators removed as much or more CO₂ than they added O₂, none was efficient in removing CO₂. Water was highly supersaturated with CO₂, and concentrations were only reduced by 3.7 to 13.4 mg/l - 2.2 to 8.6% of the initial vaiues.