Improvement of Membrane Filtration Performance for Surface Water Treatment by Combining GAC with Both Adsorption and Antimicrobial Function

The combined use of silver-loaded granular activated carbon (Ag/AC) and Microfiltration (MF) was evaluated for surface-water treatment to improve permeate quality and mitigate membrane fouling. Ag/AC was prepared by AgNO3 impregnation and thermal stabilization, resulting in strong and durable antimicrobial activity (≥99% bacterial inactivation) while maintaining high adsorption capacity for Dissolved Organic Matter (DOM). By suppressing microbial growth and reducing biofilm precursor formation within the carbon bed, Ag/AC pretreatment decreased biodegradable organics and delivered cleaner feedwater to the MF unit. Increasing the Empty Bed Contact Time (EBCT) from 10 to 30 min significantly enhanced DOM and aromatic compound removal, lowering DOC from 1.35 to 0.50 mg/L and reducing UV260. When coupled with MF, Ag/AC pretreatment effectively reduced membrane resistance-related substances and stabilized permeate flux compared with direct filtration of raw water. Although slight localized resistance increases were observed relative to unmodified GAC, possibly due to silver-associated deposits, the overall improvement in permeate quality and membrane operational stability was substantial. These results demonstrate that integrating Ag/AC with MF provides a practical and efficient strategy for surface-water purification, offering synergistic benefits of adsorption and antimicrobial effects for long-term fouling control in drinking water treatment systems.