The objective of this
study was to determine if the application of an alternative preoxidant would be
beneficial to water utilities treating water from the San Francisco Bay Delta area, which at times
has elevated and highly variable TOC and bromide levels.
The focus of this project was on determining which preoxidants had the
greatest potential to reduce subsequent chlorination disinfection byproduct (DBP) formation. Experimental conditions
were designed to enhance DBP formation in order to aid in this determination. Then the
combinations that showed evidence of synergistic capabilities by reducing DBP formation were
analyzed more thoroughly and in conditions more representative of a traditional treatment
system, including preoxidation, alum coagulation, intermediate oxidation and filtration. Bench scale experiments were designed to compare the impact of alternative preoxidation
on the subsequent formation of chlorination DBPs in natural waters. Raw water was used to
enhance DBP formation and magnify any possible synergistic effects. Four primary disinfectants
were tested including 2.0 mg/L chlorine (Cl<sub>2</sub>), 1.0 mg/L chlorine dioxide (ClO<sub>2</sub>), 1.0 mg/L ozone
(O<sub>3</sub>), and 1.5 mg/L potassium permanganate (KMnO<sub>4</sub>), followed by chlorine as a secondary disinfectant. Primary oxidant doses were selected to be representative of water treatment in the
San Francisco Bay area, and secondary chlorine doses were selected to ensure that there was at
least 1 mg/L chlorine residual after 24 hours based on preliminary demand tests. The potassium
permanganate 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 effect
on THM formation. Includes 25 references, figure.
| Edition : | Vol. - No. |
| File Size : | 1
file
, 200 KB |
| Note : | This product is unavailable in Ukraine, Russia, Belarus |
| Number of Pages : | 7 |
| Published : | 11/01/2005 |
