STRUCTURE OF WATER DISCHARGE MECHANISM INSTALLED ON UPPER LID OF TREATMENT TANK, STRUCTURE OF UPPER LID OF TREATMENT TANK, AND TREATMENT TANK

摘要

PROBLEM TO BE SOLVED: To provide a new structure of a water discharge mechanism for discharging treated water in a treatment tank for waste water using microorganisms immobilized on a carrier.SOLUTION: The structure of the water discharge mechanism 40 is installed on an upper lid 10b of the treatment tank 1 for purifying raw water 2 by microbial treatment. The water discharge mechanism 40 has an outflow portion 41 for making water in the treatment tank 1 flow out, a filter mechanism 42 mounted to the outflow portion 41 to prevent the outflow of at least the carrier for immobilizing the microorganisms, and a space forming portion 43 for forming an internal space 43a for accommodating the filter mechanism 42 therein. The space forming portion 43 is configured to have a part where a horizontal sectional area M (refer to a hatched part in Fig.3) in the internal space 43a becomes narrower toward the upper side.