Natural organic matter (NOM) is important in drinking water treatment because of its
potential to react with chlorine to form disinfection byproducts (DBPs), which may have adverse
health effects. Enhanced softening might be able to remove natural organic matter (NOM) and decrease DBP formation;
however, it has received inadequate research attention.
The objective of this research was to evaluate the impact of
different conditions of softening on NOM removal and subsequent DBP formation.
Jar tests were performed on five source waters (Austin, TX; St. Louis, MO; Ft. Lauderdale,
FL; Sioux Falls, SD; and Omaha, NB), using covered jars to prevent CO2 transfer. Sioux Falls
water was collected twice, in December and again in May during the spring snow melt when the
dissolved organic carbon (DOC) is high. These waters represent a broad spectrum of hardness and
NOM conditions among waters that are softened. A variety of operating scenarios were tested,
including lime softening alone, lime softening with various chemical additions, and lime softening
with sludge recycle. Softening, NOM, and DBP parameters were measured. Softening parameters
included pH, Ca+2, Mg+2, and alkalinity. NOM parameters included DOC, ultraviolet absorbance at
254 nm (UV254), and SUVA (UV254 normalized by the DOC concentration). Samples were
chlorinated using softening uniform formation conditions (SUFC), a standardized chlorination
procedure identical to UFC5 but at pH 9 instead of pH 8, as appropriate for softening plant effluents.
DBP parameters included dissolved organic halides (DOX) and 21 specific DBPs: four
trihalomethanes (THMs), nine haloacetic acids (HAAs), four haloacetonitriles (HANs), two
haloketones (HKs), chloropicrin (CP), and chloral hydrate (CH).
Includes 5 references, figures.
| Edition : | Vol. - No. |
| File Size : | 1
file
, 430 KB |
| Note : | This product is unavailable in Ukraine, Russia, Belarus |
| Number of Pages : | 9 |
| Published : | 06/16/2002 |
