Abstract: A water treatment technique using biological activated carbon fiber (BACF) instead of granular activated carbon (GAC) was studied. First, the possibility of microbe immobilization on ACF was confirmed by means of raw water flowing through the ACF column. The microbe growth on ACF was investigated by SEM. Then, sludge liquor (SL) incubation and microbe liquor (ML) incubation were used to plant microbes on BACF to form SL-BACF and ML-BACF. The resultant BACFs were subjected to standard water treatment testing for raw water containing small amounts of pollutants. The ability of the BACF process for organic pollutant removal was better than that of BAC. The remaining chemical oxygen demand in the outflow meets the Chinese sanitary standard for drinking water quality. Comparing the two BACFs, it was found that ML-BACF was superior to SL-BACF in terms of treatment efficiency and flow capacity, although the amount of microbes immobilized on the former was less than that of the latter.