Turning Windmill Blades Feed Oxygen to the Lake Bottom
|
A device that uses wind power to purify water was introduced for testing last month at Lake Biwa. This is the first time this type of device has been used in Japan. The device was developed in Finland, the Scandinavian country of lakes. Large blades turn to feed oxygen to the bottom of the lake, a process that is expected to prove beneficial to lake water purification efforts.
A trading company has arranged for the device to be lent, free of charge, to the Omi Environmental Protection Foundation of Shiga Prefecture. The device was installed 750 meters off the shore of Yabase Kihanto in the city of Kusatsu. The device was developed in 1993 by Finnish engineer Kalevi Koponen. Three bowl-shaped blades approximately 2.1 meters in diameter are installed on a floating body. As the blades rotate, oxygen rich water near the surface is pumped through a pipe to the lake bottom, circulating the water in the lake. This system uses wind, a natural source of power, so it does not pollute the environment. The device is already in use at Lake Hankavesi, 350 kilometers north of Helsinki. Once the device went into operation at the oxygen-depleted lake, oxygen density was restored to 60%. While visiting Lake Biwa for the installation of the device, Mr. Koponen commented that the beautiful lake must be protected, and that he has high expectations that the device will be effective. |
