PURPOSE: To prevent the contamination of yeast bacteria with general bacteria and to exceedingly prolong microbial cell life as well as to produce good-quality treated water by forming a fermentation tank into a batchwise air permeation and agitation system and adding a disinfector thereto and to facilitate the maintenance and management of an activated sludge treating device and culture and to make the yeast treatment practicable by temp. control and pH adjustment of disinfection.

CONSTITUTION: The hermetic type yeast fermentation tank 1 having vent pipes is formed of the temp. controller composed of a hermetic type cooling column 20 and a boiler with a heat exchanger 21, the disinfector consisting of a blower 5 having a disinfecting filter 4, a general bacteria extraction pipe 6, a general bacteria extraction pump 7, a bactericidal liquid tank 10, etc., the bath treatment system having a discharge port 25 for the supernatant liquid of the batch treatment, etc.