PURPOSE: To effectively remove the phosphorous compound in waste water and to sufficiently remove an iron ion by using a back pressure washable hollow yarn membrane as a membrane separation means which separates waste water into the separated concentrate of the phosphorous compound and treated water.
CONSTITUTION: Raw water containing a phosphorous compound as a solid phase component is transferred to a separation tank TK-302 to be separated into the solid phase component and supernatant water herein and the settled solid phase component is removed to the outside of the system as sludge. The raw water from which the solid phase component is settled and separated is transferred to neutralization tank TK-303 by natural falling to be neutralized to predetermined pH herein by caustic soda supplied from a caustic soda tank TK-307. A ferrous ion is precipitated as ferrous hydroxide by neutralization treatment. The neutralized raw water is sent to a hollow yarn membrane separator UF-307 through a pump P-3-1 and passed through a hollow yarn membrane to be separated into a concentrate containing a component with a fractionation mol.wt. or more and treated water. The treated water is transferred to a treated water tank TK-305 to be transferred to the outside of the system from the treated water tank TK-305.
SHIRAGE HIROKAZU
HAMA KOTARO
MITSUI PETROCHEMICAL IND