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Dynamics of the oxidant-induced particle destabilization phenomenon
In this study, the dynamic nature of oxidant/natural organic matter/particle interactions was investigated. For the purposes of this research, "dynamic" was defined as a significant variation in a measured parameter over a time scale of interest. The research objectives were to determine if oxidant-induced particle destabilization (OIPD) is a dynamic phenomenon and if this aspect of the phenomenon has an impact on subsequent treatment processes. Bench-scale experiments were conducted to study the effects of oxidant type and dose, coagulation pH, organic material and oxidant contact time on OIPD. The research was carried out in three phases. In Phase I, measurements of suspension properties were made following the addition of oxidants to model waters. In Phase II, the effect of oxidant contact time prior to coagulant addition on the treatment of model waters was evaluated. In Phase III, the effect of oxidant contact time prior to coagulation addition on the treatment of natural waters was investigated. The addition of ozone or PEROXONE induced time-dependent changes in the EPM of the suspension. No effects of oxidant addition on turbidity or DOC/TOC ratio were observed. When chlorine was used as the preoxidant, no effects on any measured properties were observed. When alum was used as a coagulant, removal of turbidity, TOC, and DOC decreased after the addition of preoxidants. The changes occurred rapidly following oxidant addition and achieved a steady state after 4 minutes of contact time. When a cationic polymer was used as a coagulant, removal of turbidity, TOC, and DOC increased following preozonation. These changes occurred rapidly following ozone addition and achieved a steady state after 4 minutes of contact time. Time-dependent changes in the suspension EPM did not occur when calcium was not present in the water matrix, and, the suspension EPM is significantly more negative without calcium present. It was concluded that calcium complexes NOM and acts as a charge neutralization species. It is likely that time-dependent changes in calcium-NOM complexation are responsible for the changes in EPM and this reduction in negative particle charge may be the cause of increased removals of turbidity and NOM by polymer coagulation.
Schneider, Orren David, "Dynamics of the oxidant-induced particle destabilization phenomenon" (1996). Doctoral Dissertations Available from Proquest. AAI9619433.