Communications: Comparison of Two Methods of Oxygen Supplementation for Enhancing Water Quality in Fish Culture

Abstract

Abstract In this study, we compared sealed column oxygen supplementation with a pipeline oxygenation system at gas-to-liquid flow ratios of 0.7, 1.5, and 2.2%. The sealed columns receiving oxygen at a gas-to-liquid ratio of 2.2% increased dissolved oxygen by 73.5% (to 149.3% oxygen saturation) while decreasing nitrogen saturation and total dissolved gas saturation to 93.1 and 105.0%, respectively. Oxygen added at a gas-to-liquid ratio of 2.2% through the pipeline manifold increased raceway dissolved oxygen by 53.7% (to 134.6% oxygen saturation) and reduced nitrogen and total dissolved gas saturations to 99.0 and 106.1%, respectively. Sealed column oxygen supplementation was most efficient, having an oxygen transfer efficiency of 82.3% when a 0.7% gasto-liquid ratio was used. Oxygen added through the pipeline manifold resulted in a 54.1–62.7% variation from mean column effluent dissolved oxygen. The pipeline manifold also caused column water flow fluctuations that varied by as much as 21%. We recommend oxygen injection directly into sealed columns over use of a pipeline manifold system for adding supplemental oxygen to fish-rearing water.