AWWA ACE95063

Utilities are currently facing the challenge of controlling disinfection byproducts (DBPs) to low levels. In the proposed D/DBP rule the maximum contaminant level (MCL) for total trihalomethanes (TTHM) is reduced to 80 ug/L for Stage 1 requirements and 40 ug/L for Stage 2 requirements. In addition, the sum of five haloacetic acids (HAA5) will be regulated at 60 ug/L and 30 ug/L for Stage 1 and Stage 2 requirements, respectively. Most utilities will be able to meet Stage 1 requirements with existing treatment processes. However, it is anticipated that many utilities will have to implement advanced treatment processes such as granular activated carbon (GAC) or membranes to comply with Stage 2 requirements. An effective means of DBP control is the removal of natural organic matter (NOM) which serves as the precursor material. GAC has the potential of being an economical means for NOM removal and DBP control. GAC evaluation at the full- or pilot-scale can be costly and time consuming. Also, NOM characteristics and the impact on adsorption is not well understood. To date, there has been no systematic evaluation of the use of GAC for DBP precursor removal for a range of water sources that examines DBP precursor characteristics, the mechanism for DBP precursor removal and the relationship between DBP precursor removal and the formation of DBPs.