PROBLEM TO BE SOLVED: To provide an artificial marsh which is capable of efficiently purifying polluted water and allows inexpensively reclamation. ;SOLUTION: This artificial marsh consists of a soil layer 11 where aquatic plants 12 are grown in banks, a drain layer 13 which is laid over the entire area on the rear surface of this soil layer 11 and is raised at one end 13a and an impervious material 14 which regulates the flow of the water through the packed region of the soil layer 11 and the drain layer 12 and the ground G of the circumference and delineates a pooling region P of a suitable depth on the soil layer 11. Piping 16 extending from water collection pipes 15 embedded in the one end 13a of the drain layer 13 is led out to the outside of the impervious material 14. Polluted water Wd supplied to the artificial marsh stagnates at a pooling depth 5 to 15 cm in the pooling region P and the org. floating suspended solids, etc., are predated and decomposed by microorganisms during this time. Nitrogen and phosphorus are removed by nitrifying and denitrifying bacteria and the adsorption effect of clay minerals during the course that the polluted water successively penetrates into the soil layer 11 mainly in a perpendicular direction therefrom.;COPYRIGHT: (C)2000,JPO
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