In consideration of the inhibition effects of 4-chlorophenol (4-cp) on phenol degradation and the substrate inhibition of phenol at high concentrations in the cometabolic transformation of 4-cp, an integrated bioreactor system incorporating adsorption on granular activated carbon and hollow fiber membrane cell immobilization was fabricated and investigated. Polysulfone hollow fiber membranes were used to immobilize the cells (Pseudomonas putida ATCC 49451) within the sponge-like porous regions, while activated carbon was provided to reduce the solution concentrations of the two substrates. Under batch operation of the bioreactor, simultaneous transformation of 1600mg/L phenol and 200mg/L 4-cp could be achieved. At these concentrations, the cells were not able to grow (let alone degrade) in free suspension. By immobilizing the cells in the hollow fiber membranes, the cells could tolerate much higher concentrations of both phenol and 4-cp. Subsequently, the integrated bioreactor system was operated under semi-continuous mode at various feed rates to demonstrate its efficiency and long-term sustainable operation. The experimental results show that the bioreactor system could effectively remove 1000mg/L phenol and 400mg/L 4-cp at feed rates up to 40mL/h in the semi-continuous feed mode.