PURPOSE: To perfectly separate activated sludge from treated water, by contacting a liquid to be treated with a pellet wherein bacteria or activated sludge is immobilized in a polymer carrier before performing membrane treatment.
CONSTITUTION: Raw water is introduced into an immobilized bacteria treatment apparatus 15 to be contacted with immobilized bacteria. After a suspended substance such as diatomaceous earth is added to the treated water if necessary, said treated water is gathered to a storage tank 16. When a definite amount of water was gathered, a valve 1 is opened and a valve 2 is further opened to introduce treated water into an ultrafiltration module 17 to perform membrane treatment while treated water transmitted through a membrane is stored in a treated water tank 18 through a valve 9. Conc. water not transmitted through the membrane is again treated through valves 3, 4, 5. The conc. water flowing through the valve 5 is supplied to a microstrainer 20 to collect SS and returned to a biological treatment area from a valve 6 along with raw water.
NAKAJIMA ICHIRO
MORI NAOMICHI
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