Chlorine

Abstract: Chlorine: History, Manufacture, Properties, Hazards, and Uses Hypochlorination On-Site Generation of Chlorine Chemistry of Chlorination Determination of Chlorine Residuals in Water and Wastewater Treatment Chlorination of Potable Water Chlorination of Wastewater Disinfection of Wastewater Chlorine Facilities Design Dechlorination Operation and Maintenance of Chlorination and Dechlorination Equipment Chlorine Dioxide Ozone Ozone, Peroxone, and AO x Ps Ozone Facility Design Bromine, Bromine Chloride, and Iodine Ultraviolet Radiation and AO x Ps Appendices Index.

Abstract: The UV/free chlorine process forms reactive species such as hydroxyl radicals (HO•), chlorine atoms (Cl•), Cl2•–, and O•–. The specific roles of these reactive species in aqueous micropollutant degradation in the UV/chlorine process under different conditions were investigated using a steady-state kinetic model. Benzoic acid (BA) was chosen as the model micropollutant. The steady-state kinetic model developed fitted the experimental data well. The results showed that HO• and Cl• contributed substantially to BA degradation, while the roles of the other reactive species such as Cl2•– and O•– were negligible. The overall degradation rate of BA decreased as the pH increased from 6 to 9. In particular, the relative contributions of HO• and Cl• to the degradation changed from 34.7% and 65.3% respectively at pH 6 to 37.9% and 62% respectively at pH 9 under the conditions evaluated. Their relative contributions also changed slightly with variations in chlorine dosage, BA concentration and chloride concentration. ...