Comparison of PAC and GAC Bed Pretreatment Coupled with a Membrane Filtration System for Treating Polluted Lake Water

Modified membrane filtration (MF), when combined with activated carbon-powdered activated carbon (PAC) and granular activated carbon (GAC)-has been proven to be an efficient process for improving the water quality of rivers and lakes. However, MF alone does not remove color, natural organic matter, or synthetic organic chemicals. Therefore, the MF process must be integrated with other conventional technologies, such as activated carbon adsorption, to meet stringent drinking water regulations. This study evaluated the water purification efficiency and membrane fouling behavior of PAC and GAC prior to the MF process in removing natural organic matter and turbidity from lake water. The PAC and GAC processes, each with a dosage of 50 mg/L, were applied as adsorption steps followed by membrane filtration using a stirred dead-end filter. Under a contact time of 30 minutes for the PAC and GAC beds, the PAC/MF and GAC/MF systems achieved 33% and 30% efficiency, respectively, in removing dissolved organic carbon (DOC). This indicates that PAC adsorption was slightly more effective than GAC in reducing DOC. The remaining permeate flux (J/Jo) in the membrane process declined with increasing driving pressure and decreasing activated carbon particle size, such as with PAC. This suggests that the appropriate size of activated carbon particles is crucial in determining the effectiveness of the MF process when coupled with activated carbon.