Determining GAC bed life

This study developed a way to rapidly and effectively evaluate the remainin g life of a granular activated carbon (GAC) bed used to mitigate taste and odor episodes. The maximum attenuation of a 2-methylisoborneol (MIB) episod e, a representative taste and odor compound, can rapidly be determined usin g laboratory-scale columns packed with partially spent GAC taken from full- scale operating adsorbers. These laboratory-scale columns closely simulated the performance of pilot-scale columns. The percent of a transient MIB loa d removed by GAC did not depend on the influent MIB concentration but did d epend on the amount of natural organic matter adsorbed on the GAC surface. This approach can be used to determine GAC's potential percentage removal o f taste- and odor-causing compounds as a function of GAC service time. It a llows GAC to be tested to estimate its readiness for summer taste and odor episodes. Adsorption alone in GAC adsorbers that used < 10 min of empty bed contact lime was insufficient to fully protect against typical MIB episode s.