Experimental study on the dissipation performance of supersaturated total dissolved gas in microbubble treatment

Abstract

The production of total dissolved gas (TDG) supersaturation resulting from dam discharges has been identified as a causative factor for gas bubble disease (GBD) or mass mortality in fish. In this study, the mitigation solution for fish refuge in supersaturated TDG water was explored by using microbubbles generated by aeration to enhance supersaturated TDG dissipation. The effects of various aeration factors (aeration intensity, water depth, and aerator size) on the dissipation processes of supersaturated TDG were quantitatively investigated through a series of tests conducted in a static aeration column. The results indicated that the dissipation rates of supersaturated TDG increased as a power function with the factors of aeration intensity and aerator size and decreased as a power function with increasing water depth. A universal prediction model for the dissipation rate of supersaturated TDG in the aeration system was developed based on the dimensional analysis of the comprehensive elements, and the parameters in the model were determined using experimental data. The outcomes of this study can furnish an important theoretical foundation and scientific guidance for the utilization of aeration as a measure to alleviate the adverse impacts of supersaturated TDG on fish. HIGHLIGHTS Conducting the supersaturated TDG dissipation experiment in a fine-bubble aeration column.; Investigating the impact of different aeration conditions on supersaturated TDG dissipation behavior.; Establishing a correction between the dissipation coefficients and different aeration conditions.; Developing a dissipation coefficient prediction model for universal aeration systems.; Fish biodiversity preservation in river systems.;

Keywords

• aeration conditions
• dissipation coefficient
• mitigation measure
• prediction model
• total dissolved gas supersaturation