Ultrafiltration(UF) and powdered activated carbon(PAC) adsorption were combined to treat wastewater contaminated with refractory organic compounds. It was determined from batch test results that a contact time of 2 hours and a PAC dose of 450㎎/l would be used in the experiments. Backwashing was accomplished by forcing the permeates back ward with pressure of 2.5kgf/㎡ for 90 seconds. It was shown that refractory organics removal by the PAC-UF process was more efficient than UF process without PAC pretreatments. As backwashing frequency was decreased from four times to one time in an hour, the removal efficiency was significantly increased. The addition of PAC to the UF process mitigated the fluctuation of filtrate quality which was increased in UF process without PAC treatment as transmembrane pressure was increased.