The performance of packed beds using dual media for removing particles is examined using both predictive mathematical modeling and experimental column studies. Models for the effectiveness of clean filter beds were used to simulate the effects of chemical pretreatment and filtration rate on particle removal at the onset of filtration runs. Experimental studies were conducted over complete filtration runs and were evaluated using measurements of head loss development and removals of turbidity, UV254 absorbance, and particles. The results indicate that dual media beds have significant advantages over monomedia beds during both filter ripening and filter breakthrough; they are particularly helpful at high filtration rates and during periods of inadequate chemical pretreatment. Finally, particle counts provide an earlier indicator of deteriorating filter performance than turbidity measurements at the end of a run.

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