Treatment of surface water supplies by conventional methods is becoming increasingly complex
as utilities must comply with increasingly stringent current and future water quality regulations.
In-depth knowledge of chemical process options is necessary to produce a high-quality water that
meets both aesthetic and health-related criteria. Consequently, a bench-scale study was
undertaken to assess the impact of a variety of different chemical treatment options on a surface
water for which a new water treatment plant is currently being planned. A 100-gallon water
sample was collected from the Savannah River, a typical flashy surface water that is low in
alkalinity (median 14 mg/L, maximum 20 mg/L as CaCO3), low in organic content (median TOC
2.9 mg/L, maximum 4.5 mg/L) and low in turbidity but subject to run-off related excursions
(annual median 2 NTU, maximum 130 NTU). The major water quality issues affecting design of
the new treatment plant are common to many water utilities around the United States: chlorinated
disinfection byproducts (DBPs), particularly total trihalomethanes (TTHMs) and haloacetic acids
(HAAs), and taste and odor episodes associated with algal activity in upstream river
impoundments. Control of seasonal iron and manganese episodes occurring in the raw water,
associated with turnover in upstream impoundments, is also a concern. A wide range of strategies
was evaluated for the common water quality problems of DBPs, taste and odor, and iron and
manganese. Of all the treatment scenarios tested, ozone was the most effective for addressing all
of these concerns. Chlorine dioxide did not produce beneficial effects at doses acceptable with
respect to chlorite formation. When cost and operational complexity were considered, the
inclusion of KMnO4 and PAC addition in a conventional process train was the most effective for
DBP control, as well as providing the flexibility to address seasonal taste, odor, iron and
manganese episodes. Includes 6 references, tables, figures.
| Edition : | Vol. - No. |
| File Size : | 1
file
, 370 KB |
| Note : | This product is unavailable in Ukraine, Russia, Belarus |
| Number of Pages : | 18 |
| Published : | 11/01/2002 |
