AWWA ACE65310

The City of Chicago, Department of Water Management owns and operates two largeconventional water treatment plants. In order to optimize treatment processes at these plants withoutaffecting full-scale operations, a pilot plant was built. The pilot plant consisted of two side-by-sidetreatment trains and was carefully designed to simulate Jardine Water Purification Plant operationswhile allowing for flexibility in source waters, additional treatment processes, chemical applicationpoints, and filter media. After successful calibration of the pilot plant to JWPP operations, researchwas conducted into ozonation of taste- and odor-causing compounds as well as bromate control.Because the pilot plant used sodium hypochlorite instead of chlorine gas, the coagulation pH levels inthe pilot plant were slightly higher than those in full-scale operations. Both alum and sulfuric acidaddition were effective at reducing the pilot plant pH to produce similar settled water turbidity levels tothose in full-scale operations. Pilot plant ozonation resulted in significant removal of MIB andgeosmin. At an ozone dose of 3.0 mg/L, MIB and geosmin removal occurred much faster than at adose of 1.5 mg/L. At a contact time of 10 min. and a dose of 3.0 mg/L, ozone was found to reduceMIB and geosmin by 95.8 and 73.7%, respectively, to below 5 ng/L. At the same dose, however,bromate in the pilot plant was found to exceed the Stage 2 D/DPBR MCL of 10 µg/L. Successfulbromate control strategies included reducing the ozone dose to 1.5 mg/L with a contact time of 13minutes or less, lowering the pH to 7.3 or lower, and addition of 0.065 mg/L ammonia-nitrogen. Includes 4 references, tables, figures.

Product Details

Edition:

Vol. - No.

Published:

06/01/2007

Number of Pages:

54

File Size:

1 file , 2 MB