Abstract: In this bench-scale test, a membrane bioreactor (MBR) was investigated for the removal of trace 2,4-dichlorophenol (2,4-DCP) from surface water with slight pollution.Sixty four days of continuous test proved that when the concentration of 2,4-DCP in the raw water fluctuated between 2—200 μg·L-1, averaged removal efficiency reached 936%And the averaged 2,4-DCP concentration in the treated water was 428 μg·L-1, which could meet the Sanitary Standard for Drinking Water Quality issued by the Ministry of HealthAt the same time, intermittent tests were carried out to study the 2,4-DCP removal mechanisms in MBRIt was concluded that biological degradation played a major role in 2,4-DCP removal by MBR It was found that biodegradation of 2,4-DCP followed zero-order kinetics with a rate constant of 106 μg·L-1·min-1Besides, it was confirmed that secondary substrate utilization was the mechanism that allowed effective biodegradation of 2,4-DCP by MBR, however dosing glucose into the raw water could not improve the biodegradation.