Haloacetic acids (HAAs) are a group of
disinfection byproducts (DBPs) resulting
from chlorination of natural
organic matter in drinking water.
Concerns over the carcinogenic effects of
HAAs prompted the US Environmental Protection
Agency to regulate them through the
Stage 1 Disinfectants/DBP Rule. The stability
of HAAs in distribution systems and during
sample storage is not well understood, but
their control in finished water is important to
water utilities.
The objectives of this study were to investigate
the stability and biodegradation of
HAAs in the presence of suspended bacteria
or biologically active carbon (BAC) in water
and evaluate the carbon adsorption capacities
of HAAs through experiments. HAAs
were not found to be stable in the presence of
biological activity, BAC effectively removed
milligram-per-litre, level HAAs spiked in
dechlorinated drinking water. The degradation
of HAAs coincided with an increase in
heterotrophic bacteria growth, indicating
that a certain portion of common
heterotrophic bacteria in treated water was
able to degrade HAAs. Granulated activated
carbon (GAC) also removed HAAs, through
a combination of carbon adsorption and
biodegradation.
Zhou and Xie suggest that the carbon
adsorption of HAAs could supplement biological
HAA removal - when new GAC filter
media are installed in water treatment systems,
carbon adsorption could remove HAAs
before bioactivity is fully developed. By the
time the carbon adsorption capacity is
exhausted, biodegradation will be dominant
in removing HAAs. This study provides
water professionals with a better understanding
of the stability of HAAs in the distribution
system and the importance of sample
preservation during HAA monitoring and
analysis. Includes 19 references, table, figures.
| Edition : | Vol. 94 - No. 4 |
| File Size : | 1
file
, 450 KB |
| Note : | This product is unavailable in Ukraine, Russia, Belarus |
| Number of Pages : | 7 |
| Published : | 04/01/2002 |
