AWWA ACE63222

The objectives of this study on the impacts of sludge volume and age on the formation of disinfection byproducts were to: determine whether settled sludge contributes to disinfection byproduct (DBP) formation; determine how water quality affects DBP levels; and, suggest DBP control strategy for Blacksburg/Christiansburg/VPI (BCVPI) Water Authority. Experimental approach included sampling sedimentation basins for: TTHM and HAA5 in sludge water and overlying water, in µg/L; total organic carbon (TOC), in mg/L; total chlorine, in mg/L; water temperature, in ºC; UV254, cm-1; and, pH. Sludge volume calculation included: sludge depth recorded at nine points along length of basin; plotted in Excel and area under curve was calculated; and, area x width of basin. Conclusions included: when operating under normal conditions, and not applying ClO₂, the "overall" TTHM and HAA5 models may be used to predict DBP levels formed in the sedimentation basins; sludge was not found to contribute to DBP formation and therefore, basin cleaning is not mandatory; when treating with ClO₂ in summer months, predictive models suggested that sludge is influential in DBP formation; and, sedimentation basins should be cleaned frequently. Includes tables, figures.