JP2592341B

PURPOSE:To bring COD in waste water to a discharge tolerant value by bringing the water-containing waste solution discharged from an esterifying reaction process and/or a glycol recovery process into contact with a strong acidic ion exchange resin to apply activated sludge treatment thereto. CONSTITUTION:The waste water discharged from the esterifying reaction process and/or glycol recovery process of a process for preparing polyester from difunctional carboxylic acid based on terephthalic acid and glycol based on ethylene glycol by a direct polymerization method is brought into contact with a strong acidic ion exchange resin and subsequently subjected to activated sludge treatment. As embodiments of the strong acid group of the aforementioned strong acidic ion exchange resin, there are a sulfate group, a phosphate group and a sulfonate group. By performing the above-mentioned treatment, COD in the waste water is lowered so as to be within the dischargeable standard at a low cost and the treated water can be discharged to rivers.