PREVENTION OF ADHESION OF ALGAE

PROBLEM TO BE SOLVED: To prevent the adhesion or growth of algae on the guttering surface of a sedimentation tank for drain treatment equipment over a long period of time and to facilitate the peeling of algae while preventing an environmentally harmful substances in treated water from flowing out by bonding the tiles to the guttering surface of the sedimentation tank discharging supernatant water. SOLUTION: In waste water treatment equipment, tiles are bonded to the guttering surface of a sedimentation tank discharging at least supernant water. The guttering surface of the sedimentation tank means the surface of the guttering taking out supernatant water from the sedimentation tank and the surface of the guttering guiding supernatant water to a discharge port. When tiles are bonded, they may be bonded to the entire guttering surface of the sedimentation tank or may be partially bonded to a surface receiving solar rays and facilitating the adhesion and growth of algae. It is desirable that glaze is applied to the surface of a tile material to make the tile surface glossy and the tile has a smooth surface. By this constitution, the adhesion and growth of algae on the guttering surface of the sedimentation tank can be prevented over a long period of time.