Improving GAC performance by optimized coagulation

The effect of optimized coagulation on granular activated carbon (GAC) performance for removal of natural organic matter and control of disinfection by-products was investigated. Coagulation optimized for total organic carbon (TOC) removal increased GAC run times by a factor of 2-3 over run times observed for GAC receiving conventionally treated water. The improved performance was mainly a result of reductions in influent TOC and pH after optimized coagulation, as compared with conventional pretreatment. Conventional coagulation prior to GAC was more cost-effective than optimized coagulation, because of increased costs associated with the high alum dosages used in this study.