EFFECTS OF NOM SOURCE VARIATIONS AND CALCIUM COMPLEXATION CAPACITY ONOZONE-INDUCED PARTICLE DESTABILIZATION

Laboratory bench-scale experiments were conducted to elucidate the eff ect of ozone on the colloidal stability of particles coated with natur al organic matter (NOM) derived from different sources. Four types of NOM (three surface water and one groundwater) were studied. Experiment s were conducted in the absence and presence of calcium. The results r evealed that flocculation benefits from ozonation are dependent on the specific NOM being studied. For some NOM sources, flocculation benefi ts can be attributed to a significant increase in association with cal cium after ozonation. The magnitude of the increase in calcium associa tion is dependent on the type of NOM being studied and its reactivity to ozonation. Calcium association with NOM can be expected to increase after ozonation only if ozone affects the number of functional groups that specifically complex calcium. The results also indicated that ca lcium-NOM association can be related to the oxygen content of NOM. (C) 1998 Elsevier Science Ltd. All rights reserved.