Occurrence of Disinfection By-Products (DBPs) in Finished Water and Formation of Emerging DBPs from Polluted Source Water in Taiwan
Date Issued
2011
Date
2011
Author(s)
Chang, Hui-Hsien
Abstract
Disinfectants used in water treatments can react with the organic materials to form various disinfection by-products (DBPs). The carbonated DBPs (C-DBPs), which mainly include trihalomethanes (THMs) and haloacetic acids (HAAs) in drinking water, have been shown to possess different kinds of toxicities, mutagenicities and carcinogenicities. Due to the analytical limitation and lack of regulation for HAAs in drinking water, the database for distribution of HAAs in drinking water has been not available in Taiwan. Nitrosamines are a class of emerging nitrogenated DBPs (N-DBPs), which are mainly formed with treatments of chloramination, and far more carcinogenic than traditional C-DBPs. Among nitrosamines, N-nitrosodimethylamine (NDMA) is the dominant species in drinking water. Besides chloramines, dissolved organic nitrogen (DON) compounds have been recognized as important precursors of nitrosamines and many of them have not been identified.
This study included three objectives: (1) to establish the preliminary database of HAAs and THMs in Taiwan based on water samples collected from 141 water treatment plants (WTPs) between 2007 and 2009. (2) Nine representative nitrogenous organic compounds with different DON characteristics and structures were selected to react with free chlorine, chlorine dioxide and monochloramine for their DBP formation characteristics (nitrosamines, THMs and HAAs). (3) A modified DON fractionation method (DAX-8, XAD-4 and MSC-1H resins) was used to fractionate the seasonal effluents of Neihu wastewater treatment plant in Taipei City (TN) and source waters of Tai Lake WTP in Kinmen (KT).
The concentrations of HAAs were distributed from 0.5 to 84.4 μg/L and those of THMs were from ND to 133.2 μg/L. Due to the various raw water qualities, the C-DBP concentrations showed the seasonal and geographical variations in different parts of Taiwan, and a higher portions of brominated species was observed in the off-shore island WTPs. Moreover, statistically significant (P<0.005) logarithmic linear regression models were also proposed to describe the correlations between the total THMs (TTHM) and HAAs (HAA5=1.219×TTHM0.754; HAA9=1.824×TTHM0.735).
In the DBPs formation tests of surrogate compounds, dimethylamine (DMA), benzyldimethyltetradecylamine (benzalkonium chloride, BKC) and 3-(N,N-dimethyloctyl-ammonio)propanesulfonate (3-N,N-DAPSIS) inner salt were identified as potent precursors for C-DBPs (up to 2700 μg/L of THMs) and N-DBPs (up to 2×105 ng/L of NDMA). Then, further studies of DMA, 3-N,N-DAPSIS and BKC were performed to determine the impact of pH, reaction temperature and bromide concentration on DBP formations. The DBP yields apparently increased with rising temperature, however, no consistent correlations were observed between DBPs yields and pH. Bromide shifted the DBP species into brominated DBPs, and this phenomenon was more apparent when BKC was treated with chloramine.
For the survey of DON distributions and compositions, both TN and KT samples had similar compositions of DON fractions except for AMPB/N isolate to show the general trend: HPOA > HPIA/N > HPIB > AMPA > HPOB/N > AA. Finally, seasonal isolate samples were mixed to perform the DBPFPs with the three disinfectants mentioned previously. It was found that the AA fraction formed the highest amounts of C-DBPs (up to 1258.2 μg/L of THMs), and the AMPB/N fraction could form as high as 9238.0 ng/L of NDMA at 10 mg/L of NPDOC.
Subjects
Disinfection by-products
Dissolved organic nitrogenous
Distribution
Formation potential
Haloacetic acids
Nitrosamines
Trihalomethanes
SDGs
Type
thesis
File(s)![Thumbnail Image]()
Loading...
Name
ntu-100-D95844002-1.pdf
Size
23.32 KB
Format
Adobe PDF
Checksum
(MD5):83e71740a12ac54493ccf217efb852cb