PAC membrane bioreactor as an alternative to biological activated carbon filters for drinking water treatment

A high concentration powdered activated carbon (PAC) membrane bioreactor (MBR) was fed by clarified-ozonated surface water. As a control, a MBR without PAC was run in parallel. Water quality was also compared with a full-scale biological activated carbon (BAC) filter. Biological PAC inside the MBR caused a higher fouling rate as compared to the MBR without PAC, although it was still possible to maintain operation for about 3 months at 25 L m � 2 h � 1 before a chemical cleaning was needed. The fouling rate inside the MBR with PAC increased as the PAC age increased from 0 to 60 d. Full nitrification was achieved in the PAC-MBR down to 7 W C. Preozonation had no significant impact on dissolved organic carbon removal. Although the PAC-MBR globally provided superior removal of natural organic matter, haloacetic acid precursors and UV absorption at 254 nm (UVA254), its removal of trihalomethane (THM) precursors was inferior compared to the BAC filter. This effect was shown to be caused by the accumulation of suspended solids inside the bioreactor.