AWWA QTC98322

Bench-scale experiments were performed in which chlorine dioxide doses of 1.5 and 3.0 mg/L were applied to a raw surface water. Samples were taken over time and chlorine dioxide residuals were measured to develop decay curves for all the experimental conditions. The effect of three independent variables - TOC concentration, pH, and temperature - on decay rates was examined. Chlorine dioxide CT requirements for 0.5, 1, and 2-log Cryptosporidium inactivation were obtained from the literature. Using the decay data, chlorine dioxide doses needed to achieve the CT requirements for each level of inactivation were calculated. For an assumed detention time of 60 minutes, chlorine dioxide appears to be a feasible alternative for 0.5 and 1-log Cryptosporidium inactivation if a chlorite ion removal method is used. It does not appear to be practical for 2-log Cryptosporidium inactivation because of the very high doses and/or detention time required. Temperature, pH, and TOC concentration all significantly influenced chlorine dioxide decay. TOC concentration appeared to have the most significant impact on initial oxidant demand and decay rates. The application of ferrous ion proved to be a more efficient chlorite ion removal process than the addition of sulfite ion.

Product Details

Published:

01/01/1998

ISBN(s):

0898679796

Number of Pages:

11

File Size:

1 file , 110 KB