POND WATER PURIFICATION

PURPOSE:To effect a simple and efficient purification of pond water by producing an upward stream of air bubbles in a vertical passage of a cylindrical frame installed in the pond water to create the upward motion of the pond water, thereby inducing a flow of the pond water transverse to a decontamination contact layer provided in said frame. CONSTITUTION:A cylindrical frame 1 is installed at a suitable location in a pond 11, so that said frame will extend from slightly above the pond bed 5 to above the water surface 6 of the pond. The air is then sent from a nozzle 8A near the pond bed 5 into a vertical passage 2 of the frame 1 to produce an upward stream of air bubbles 9, which creates the upward motion of the pond water 4, thereby inducing a flow of the pond water 4 transverse to a decontamination contact layer 3 in the cylindrical frame 1. The pond water 4 is subjected to a biological treatment while passing through the decontamination contact layer 3 for digestion and removal of the polluted material from the pond water 4 by microorganisms retained in said contact layer 3. The pond water 4 thus purified is sent back into the pond through the cylindrical frame 1.