Sodium dodecylbenzenesulfonate removal from water and wastewater.: 1.: Kinetics of decomposition by ozonation

Ozonation experiments were conducted to investigate the sodium dodecylbenzenesulfonate (NaDBS) removal from aqueous solution and domestic wastewater. The influence of pH and tert-butyl alcohol concentration, a known scavenger of hydroxyl radicals, on the ozonation rate was observed. The degradation rate was especially fast at pH 10 in the absence of hydroxyl radical scavengers. The rate constants of the reactions NaDBS-ozone and NaDBS-hydroxyl radical were found to be 3.68 and 1.16 x 10(10) M-1.s(-1), respectively. Organic matter in wastewater competes with NaDBS for both dissolved ozone and hydroxyl radical, resulting in a decrease in the overall removal rate of the surfactant. COD and TOC were not completely removed from the wastewater due to an ozone-resistant fraction which remained after the treatment. Nevertheless, the ability of ozone to cause alteration in the molecular structures of dissolved compounds resulted in an increase of the wastewater biodegradability, demonstrated by the increase of the BOD5/COD ratio. The contributions of the direct and free radical reactions to the oxidation of NaDBS were evaluated in percentages of pollutant removal.