AWWA WQTC62431

The objective of thisstudy was to determine if the application of an alternative preoxidant would bebeneficial to water utilities treating water from the San Francisco Bay Delta area, which at timeshas elevated and highly variable TOC and bromide levels.The focus of this project was on determining which preoxidants had thegreatest potential to reduce subsequent chlorination disinfection byproduct (DBP) formation. Experimental conditionswere designed to enhance DBP formation in order to aid in this determination. Then thecombinations that showed evidence of synergistic capabilities by reducing DBP formation wereanalyzed more thoroughly and in conditions more representative of a traditional treatmentsystem, including preoxidation, alum coagulation, intermediate oxidation and filtration. Bench scale experiments were designed to compare the impact of alternative preoxidationon the subsequent formation of chlorination DBPs in natural waters. Raw water was used toenhance DBP formation and magnify any possible synergistic effects. Four primary disinfectantswere tested including 2.0 mg/L chlorine (Cl₂), 1.0 mg/L chlorine dioxide (ClO₂), 1.0 mg/L ozone(O₃), and 1.5 mg/L potassium permanganate (KMnO₄), followed by chlorine as a secondary disinfectant. Primary oxidant doses were selected to be representative of water treatment in theSan Francisco Bay area, and secondary chlorine doses were selected to ensure that there was atleast 1 mg/L chlorine residual after 24 hours based on preliminary demand tests. The potassiumpermanganate dose was larger than typically applied in the San Francisco Delta (1.5 mg/L),however the literature review suggested that such a high dose would be required to have an effecton THM formation. Includes 25 references, figure.

Product Details

Edition:

Vol. - No.

Published:

11/01/2005

Number of Pages:

7

File Size:

1 file , 200 KB