Abstract：A series of continuous flow biological activated carbon (BAC) columns were operated for removing benzene, toluene, ethylbenzene and xylene (BTEX) from water to evaluate the effect of high loading and carbon type on the BAC treatment performance. The inoculated granular activated carbon (GAC) columns (EBCT =3.2min) became stable BAC systems quickly; with the exception of benzene, the TEX were totally removed from the 6mg/L single compound influent during the 40d study. The BAC treatment performance was affected for a few days after the increase in loading (8.68~12.9 kg TOC/(m3·d), BTEX =19~32mg/L, EBCT = 1.2min); the benzene column effluent was affected the most with a peak concentration of > 10mg/L before declining to the base level of 5~10mg/L while TEX in effluents from the other columns remained at < 5mg/L. Both coal and coconut GAC samples of the respective BAC columns treating the toluene feed exhibited much higher residual toluene capacities relative to the same type GAC of the non-bioactive columns due to bio-regeneration. The BAC function resulted in a more complete recovery of the toluene capacity of the coal GAC than the coconut GAC (53.6% vs. 26.6%) because of its more abundant macropores and large mesopores.
