To enable an efficient treatment of sludge, which is a secondary problem in a wetland type water purification system.
A water channel having a lot of zigzag turns is formed from the inflow port of an artificial wetland 1 to the discharge port thereof. While polluted water flows in the zigzag water channel, horizontal infiltration and vertical infiltration are repeated, thereby purifying the polluted water. In at least a part of the artificial wetland 1, a middle bottom 17 passing water and the sludge is installed over a bottom 3 to form a double bottom structure, and a space between the bottom 3 and the middle bottom 17 is made to be a sludge storage space 18. A sludge discharge pipe 20 is inserted into the sludge storage space 18 beforehand, which forms a structure where the sludge accumulating in the sludge storage space 18 can be discharged outside from the bottom of the artificial wetland 1 by negative pressure suction power.
OGURA YUJIRO
ISHIHAMA KENICHI
Hiromichi Kobayashi