A novel method of powdered activated carbon (PAC) pre-coated microfiltration (MF) hollow fiber hybrid membrane for domestic wastewater treatment

Powdered activated carbons (PAC) have long been used in combination with membrane processes for the removal of pollutants from water and wastewater. PAC is considered as an effective adsorbent and is generally used in the pretreatment step, prior to membrane operation or in combination with membrane in the same tank. However, membrane fouling remains to be a major concern, especially while using porous membranes. In this study, powdered activated carbon was pre-coated on the microfiltration (MF) hollow fiber membrane, before the membrane was used to treat the secondary treated domestic wastewater. Three types of PACs, namely wood-based (WB), coal-based (CB) and coconut shell-based (HA) were studied. The experimental results indicated that by pre-coating the membrane surface with PAC, the membrane fouling was effectively minimized, as the rates of decline of permeate flux was significantly reduced. The type of PAC coated on the membrane and the amount coated could be the key factors in deciding the performance of the system. Further, when using the pre-coated membrane, addition of small amounts of PAC in the tank enhanced organic removal efficiency and maintained the permeate flux. The membrane hybrid system, without membrane pre-coating was also evaluated for comparison.