Oxygen Transfer Efficiency Evaluation of Underwater Bubbles
AUTHORS
Yong-Du Jun,Professor, Division of Mechanical and Automotive Engineering, Kongju National University, Chungnam, Korea
Jong-Soo Lee,Adjunct Professor, Division of Mechanical and Automotive Eningeering, Kongju National University, Chungnam, Korea
ABSTRACT
This paper presents the study results on the dissolved oxygen concentration behavior in water body with underwater bubbling. The rage of algae in dams and reservoirs around the country, especially during the summer season, is threatening the habitat environment of these water resources by significantly lowering the dissolved oxygen concentration level. Different aeration devices based on underwater bubbling are widely applied in order to remedy this problem, however, fundamental study results on the performance of these devices in terms of dissolved oxygen level improvement are rarely reported in literature. In the present study, we focus on the quantitative evaluation of oxygen transfer performance of bubble diffusion process, which is the underlying physical model of aeration devices. For this purpose, related physical laws such as Henry’s law of solubility, Fick’s law of diffusion along with water quality standards are reviewed and a new test apparatus is established for this study, with which both the degassing and aeration can be systematically simulated. The test apparatus is composed of a closed water tank (stainless steel; 0.65m×0.65m×1.0m) with depressurization and degassing feature, underwater bubbler and measurement system for temperature, pressure and oxygen level. This system is capable of maintaining minimum pressure level of 0.1 atm and the dissolved oxygen concentration level down to 2 mg/L. According to the test results for a commercially available bubbler at three different air flow rates (10, 20, and 30 slpm) and at two bubbling depths of 0.4m and 0.8m, the oxygen transfer efficiency of 1.3-2.5% are confirmed and the best performing conditions could be successfully identified.
KEYWORDS
Dissolved oxygen, Bubble diffusion, Oxygen concentration, Oxygen transfer efficiency, Solubility
REFERENCES
[1] B. Cheng, R. Xia, Y. Zhang, Z. Yang, S. Hu, F. Guo, and S. Ma, “Characterization and causes analysis for algae blooms in large river system,” Sustainable Cities and Society, vol.51, 101707, (2019)
[2] J. Navisa, T. Sravya, and M. Venkatesan, “Effect of bubble size on aeration process,” Asian Journal of Scientific Research, vol.7, pp.482-487, (2014)
[3] D. F. McGinnis and J. C. Little, “Predicting diffused-bubble oxygen transfer rate using the discrete-bubble model,” Water Research 36, pp.4627-4635, (2002)
[4] Wikipedia, the free encyclopedia, https://en.wikipedia.org/wiki/Solubility, (2020)
[5] Y. A. Cengel, M. A. Boles, and M. Kanoglu, “Thermodynamics-An Engineering Approach,” McGrawHill (2019)
[6] Environmental Standard of Water Quality, ME, Korea, http://www.me.go.kr/home/web/policy_data/read.do? menuId=10263&seq=2, (2020)
[7] Y. D. Jun et al., “Dissolved gas discharging apparatus and dissolved gas discharging method using the same,” Korean Patent 10-2020-0002833 (pending), (2020)