Sodium dodecylbenzenesulfonate removal from water and wastewater.: 2.: Kinetics of the integrated ozone-activated sludge system

A batch-activated sludge process (AS) has been applied to eliminate sodium dodecylbenzenesulfonate (NaDBS), a linear alkylbenzenesulfonate (LAS) compound, from synthetic and real domestic wastewater. The kinetics of surfactant biodegradation was best described by first-order kinetics with rate constants of 1.28 and 1.15 L.(g VSS.day)(-1) for synthetic and real domestic wastewater, respectively. The effect of preozonation on the overall surfactant and COD removal rates was also studied. The results indicated that treatment by combined ozone-AS leads to negligible foam ability and low residual surfactant concentration and COD in the treated effluent. Acclimation of a mixed culture to ozonated products was beneficial to highly improve biodegradation rates after preozonation. Thus, when applying ozone at a dose of 100 mg.L-1, the first-order surfactant biodegradation rate constant increased up to 1.79 and 3.09 L (g VSS day)(-1) for synthetic and real wastewater, respectively. Continuous experiments of ozonation followed by activated sludge of synthetic wastewater were also carried out, and the reactor performances were compared to those obtained from the application of the available kinetic data (derived from batch experiments) to the operating conditions. Good agreement between experimental and calculated data confirmed the reliability of the model.