Artificial mixing of lake water by bubble plume and effects of bubbling operations on algal bloom

In order to develop a method of predicting and assessing lake eutrophication, which is a serious environmental problem, and to propose effective measures for improvement of water quality, this paper presents a composite model of the mixing of lake water by air bubble plume and lake phytoplankton model. The equations of heat aid mass transfer in the lake were solved together with equations governing physical and biological processes under real atmospheric conditions coupled with an integrated model of bubble plume. The verification of the model was conducted using data of Lake Calhoun (USA). Using the developed model, numerical experiments were carried out far an imaginary lake in the Hiroshima region of Japan with different gas flow rates of bubble plume, different numbers of bubble ports, different starting dates of bubbler and different bubbler depths. The optimization of the improvement of water quality in the lake can be obtained by using the appropriate gas flow rate and number of bubble ports, and applying it at an appropriate period of the year. (C) 2000 Elsevier Science Ltd. All rights reserved.