Investigation of surfactant-modified activated carbon for recycled water disinfection

This study investigated the effectiveness of surfactant-loaded granular activated carbon (GAC) to deactivate total coliform, E. coli, and enterococci found in tertiary effluent under various experimental conditions, i.e. varying surfactant dose, GAC dose, and contact time. The results indicate that GAC loaded with 100 mg/g of hexadecyltrimethylammonium bromide (CTAB) and didodecyldimethylammonium bromide (DDAB), achieved log reductions as high as 1.02 and 1.86 of total coliform, respectively. At varying GAC doses and contact times, 200 mg/g of DDAB dose achieved 99.9 to 100% reduction in total coliform at initial concentrations as high as 38,000 MPN/100 mL. Complete deactivation of E. coli and enterococci were observed for CTAB and DDAB at 200 mg/g dose for varying GAC doses and contact times used in this study. DDAB was more effective than CTAB at deactivating total coliform and E. coli, both Gram-negative bacteria, while both surfactants were shown to have similar disinfection capabilities against enterococci. Surfactant dose and GAC dose were shown to enhance bacteria deactivation; however, surfactant dose was found to be the most important parameter. For contact times evaluated in this research, bacterial deactivation remained the same or slightly decreased with contact time. In conclusion, surfactant-modified GAC can be used as an effective disinfection technique for recycled water.