CHLORINE DIOXIDE DISINFECTION OF DRINKING WATER: INSTALLATIONS AND PRACTICES IN RUSSIA

Low drinking water quality standards may be explained by inefficient water treatment technology, the use of outdated chemicals as disinfectants and secondary water pollution during its transportation to the ultimate consumer via the poor quality water supply systems. The paper describes chlorine dioxide disinfection technology with the help of DCh-100 at drinking water treatment plant with capacity of 45600 m(3)/day. DCh-100 type automated unit is made in Russia. The DCh-100 local automated plant producing a highly efficient and economical "Chlorine Dioxide and Chlorine" Compound Disinfectant from readily-available raw materials (sodium chlorate, sodium chloride, and sulfuric acid) for drinking water treatment and disinfection. The optimal chlorine dioxide dosing was identified: 1) During primary chlorination at the stage of pretreatment oxidation (chlorine was used for secondary disinfection). The dose of chlorine dioxide was 0.43-0.85 mg/l at the research season. 2) During two-stage scheme of water disinfection. Chlorine dioxide was used for pretreatment oxidation and secondary disinfection. The dose of chlorine dioxide was 0.30-0.40 mg/l for pretreatment oxidation and 0.15-0.20 mg/l for secondary disinfection process. 3) During one-stage disinfection. The dose of chlorine dioxide 0.26-0.33 mg/l was chosen. For the given disinfecting modes the optimal dosing of coagulants and flocculants was identified.