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 eutrophicatio n, which is a serious environmental problem, and to propose effective measu res for improvement of water quality, this paper presents a composite model of the mixing of lake water by air bubble plume and lake phytoplankton mod el. The equations of heat aid mass transfer in the lake were solved togethe r with equations governing physical and biological processes under real atm ospheric conditions coupled with an integrated model of bubble plume. The v erification of the model was conducted using data of Lake Calhoun (USA). Us ing the developed model, numerical experiments were carried out far an imag inary lake in the Hiroshima region of Japan with different gas flow rates o f bubble plume, different numbers of bubble ports, different starting dates of bubbler and different bubbler depths. The optimization of the improveme nt of water quality in the lake can be obtained by using the appropriate ga s flow rate and number of bubble ports, and applying it at an appropriate p eriod of the year. (C) 2000 Elsevier Science Ltd. All rights reserved.