EFFECT OF MICROBUBBLE GENERATOR OPERATING PARAMETERS ON OXYGEN TRANSFER EFFICIENCY IN WATER

摘要

Dissolved oxygen (DO) is a fundamental requirement for a healthy aquatic ecosystem and it specifies the capability of waterbody to support a balanced ecosystem. It is probably the single state variable that provides maximum information about water quality conditions in natural waters. In this study, dissolved oxygen formation was investigated at laboratory scale by using micro-bubble generator, in which saturator pressure, water supply and gas flow rates and type of gas were the main operating factors considered. The effect of changing the operating parameters was described in terms of dissolution performance using volumetric mass transfer rate, which is very important element for aerator design and scale-up. Pressure values from 1 to 6 atm were taken for the analysis. The volumetric mass transfer coefficient was limited below 0.01 per min for air; however, the value varied from 0.10 to 0.13 per min for oxygen at 4.5 L/min flow rate, showing increasing pattern with pressure. Corresponding system operating cost-benefit using pure oxygen at 4.5 atm pressure was found to be better than that of air. Thus, for improvement of natural water bottom area environment, use of pure oxygen microbubbles results in higher DO and system transfer efficiency. Even though the use of air to produce microbubbles seems more economical, considering the excessive dissolution of gas with the bubbles, use of pure oxygen is appropriate.