Role of biological granular activated carbon in contaminant removal and ultrafiltration membrane performance in a full-scale system

This study evaluated a long-term impact of biological activated carbon (BAC) filter that was employed in a full-scale drinking water treatment plant to enhance the removal of contaminants by the ultrafiltration (UF) process. The results showed that BAC enhanced UF performance by increasing the flux by 18.5% and extending the filtration run by 45%. The presence of BAC improved the removal of primary contaminants, including dissolved organic carbon (4–40%), UV254 (10–57.7%), geosmin and 2-methylisoborneol (80%). BAC was also effective in decreasing the concentration of biopolymers, humic substances, (semi-)volatile organics, chlorite and halonitromethanes, thereby lowering contaminant load on the UF unit. The changes in primary water quality parameters in the combined process showed that the humic substances in dissolved organic nitrogen, low molecular weight substances in UV254, and fluorescence protein-like substances could be useful indicators for DBPs as these organic fractions had strong correlation with DBPs. Obvious spatio-temporal characteristics of GAC grain and microbial communities in BAC filter were observed with operation time and filter depth. The bacterial community in BAC filter was highly diverse and was less influenced by influent quality with an increase in filter depth, while the communities in UF cake layer correlated with organic removal in the UF system.