This study was carried out to investigate the characteristics of disinfection by-products (DBPs-trihalomethanes (THMs), haloacetic acids (HAAs) and haloacetonitriles (HANs) formation in chlorination of principal raw waters used for drinking water on Jeju Island, Korea. The domestic water supply of o...
This study was carried out to investigate the characteristics of disinfection by-products (DBPs-trihalomethanes (THMs), haloacetic acids (HAAs) and haloacetonitriles (HANs) formation in chlorination of principal raw waters used for drinking water on Jeju Island, Korea. The domestic water supply of other area and humic acid solution (HA) were used as a reference point. The effects of chlorine contact time, solution temperature and pH on DBPs formation potential (DBPFP) were investigated for raw waters. In addition, the effect of $Br^-$ was studied for HA. The DBPFP (THMFP, HAAFP and HANFP) were increased with increasing chlorine contact time. Comparing the individual DBPFPs for raw waters, they decreased in the order of HAAFP > THMFP ${\geq}$ HANFP. As the solution temperature was increased, the THMFP, HAAFP and HANFP increased. With increasing the solution pH, the THMFP was increased, but HAAFP and HANFP were decreased. With the addition of 0.3 mg/L $Br^-$ for HA, the DBPFP was increased and the major chemical species changed: from trichloromethane to dibromochloromethane and tribromomethane for THMs; from dichloroacetic acid and trichloroacetic acid to tribromoacetic acid for HAAs; and from dichloroacetonitrile to dibromoacetonitrile for HANs.
This study was carried out to investigate the characteristics of disinfection by-products (DBPs-trihalomethanes (THMs), haloacetic acids (HAAs) and haloacetonitriles (HANs) formation in chlorination of principal raw waters used for drinking water on Jeju Island, Korea. The domestic water supply of other area and humic acid solution (HA) were used as a reference point. The effects of chlorine contact time, solution temperature and pH on DBPs formation potential (DBPFP) were investigated for raw waters. In addition, the effect of $Br^-$ was studied for HA. The DBPFP (THMFP, HAAFP and HANFP) were increased with increasing chlorine contact time. Comparing the individual DBPFPs for raw waters, they decreased in the order of HAAFP > THMFP ${\geq}$ HANFP. As the solution temperature was increased, the THMFP, HAAFP and HANFP increased. With increasing the solution pH, the THMFP was increased, but HAAFP and HANFP were decreased. With the addition of 0.3 mg/L $Br^-$ for HA, the DBPFP was increased and the major chemical species changed: from trichloromethane to dibromochloromethane and tribromomethane for THMs; from dichloroacetic acid and trichloroacetic acid to tribromoacetic acid for HAAs; and from dichloroacetonitrile to dibromoacetonitrile for HANs.
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문제 정의
The purpose of this study was to investigate the characteristics of DBPs (THMs, HAAs and HANs) formation in chlorination of principal raw waters for drinking water of Jeju Island, Korea.
1. DBPFP and DBPFP/DOC with chlorine contact time for the raw waters used in this study.
제안 방법
It is found that the DBPs formation potential (DBPFP) upon the reaction of raw water and chlorine depends on the organic matter characteristics and chlorine contact time (Huang and Yeh, 1997). In order to investigate the DBPFP (THMFP, HAAFP and HANFP) with chlorine contact time, a chlorine concentration of about ten times the DOC content of raw waters was added to water samples used in this study and they were incubated at 20℃ for 0.5, 1, 3, 6, 18, 24, 48, 72, 96, 120, 144, 168, 192 h, the results of which are shown in Fig. 1.
, 1980). In order to investigate the effect of solution temperature on the DBPFP, a chlorine concentration of about ten times the DOC content of raw water, was added to the samples (I-SW, G-SW, N-RW and HA), the waters were incubated at 5℃, 15℃ and 25℃ for 24 h, and the results are shown in Fig. 2. The THMFP, HAAFP and HANFP at 25℃, as compared with those at 5℃ were 2.
대상 데이터
The raw water samples of Jeju Island used in this study were as follows: Iho springwater (I-SW), Oedo springwater (O-SW) and Wolsan groundwater (W-GW), supplying Wolsan Water Treatment Plant (WTP), Jeju City; Samyang 3 springwater (S-SW), supplying Doryeon WTP, Jeju City and used after being mixed with other raw water; Eoseungsaeng springwater (E-SW), supplying Eoseungsaeng WTP, Jeju City; Gangjeong springwater supplying Gangjeong WTP, Seogwipo City; Topyeong groundwater (T-GW) supplying Topyeong WTP, Seogwipo City. As the reference water samples, Nakdong river water (N-RW) and humic acid solution (HA) were used.
THM content of water sample was performed according to Standard Method 6232C (APHA, AWWA and WEF, 2005). The instrument was a gas chromatograph (Varian CP 3800)/mass spectrometer (Varian Saturn 2200) (GC-MS), Tekmar Dohrmann 3100 purge trap and concentrator and Varian Archon purge trap autosampler. HAAs were analyzed by USEPA 552 (USEPA, 1995) (liquid-liquid extraction with methyl tertiary butyl ether (MTBE), esterification with diazomethane and gas chromatography with electron capture detection).
이론/모형
For organic halides analysis, H3PO4 (1+10) and ascorbic acid for THMs, and NH4Cl and 6 N HCl for HAAs and HANs were added to prevent the additional DBPs formation. THM content of water sample was performed according to Standard Method 6232C (APHA, AWWA and WEF, 2005). The instrument was a gas chromatograph (Varian CP 3800)/mass spectrometer (Varian Saturn 2200) (GC-MS), Tekmar Dohrmann 3100 purge trap and concentrator and Varian Archon purge trap autosampler.
성능/효과
The maximum HANFP per unit of DOC was 7.8~64 μg/mgC for the raw waters of Jeju Island, 60 μg/mgC for N-RW and 26 μg/mgC for HA, indicating that that for N-RW was 0.9~7.7 times higher than those for the raw waters of Jeju Island and 2.3 times higher than that for HA, and that for HA was the lowest, compared with THMFP/DOC and HAAFP/DOC.
3 mg/L Br- addition changed greatly, compared with those in the absence of Br- addition. For THMs, 100% of TCM in its absence changed to 4% of TCM, 12~14% BDCM, 38~40% of DBCM and 42~46% of TBM in the presence of Bradditions, indicating that the major chemical species in its presence changed from TCM to DBCM and TBM. For HAAs, 56~64% of DCAA and 36~44% of TCAA in its absence changed to 10~4% of DCAA, 3~1% of TCAA, 3~6% BCAA, 13~10% BDCAA, 10~12% CDBAA and 54~62% of TBAA in its presence, indicating that the major chemical species in its presence changed from DCAA and TCAA to TBAA.
For THMs, 100% of TCM in its absence changed to 4% of TCM, 12~14% BDCM, 38~40% of DBCM and 42~46% of TBM in the presence of Bradditions, indicating that the major chemical species in its presence changed from TCM to DBCM and TBM. For HAAs, 56~64% of DCAA and 36~44% of TCAA in its absence changed to 10~4% of DCAA, 3~1% of TCAA, 3~6% BCAA, 13~10% BDCAA, 10~12% CDBAA and 54~62% of TBAA in its presence, indicating that the major chemical species in its presence changed from DCAA and TCAA to TBAA. For HANs, 100% of DCAN in its absence changed to 17~6% of DCAN, 15~10% of BCAN and 68~84% of DBAN in its presence, indicating that the major chemical species changed from DCAN to DBAN.
For HAAs, 56~64% of DCAA and 36~44% of TCAA in its absence changed to 10~4% of DCAA, 3~1% of TCAA, 3~6% BCAA, 13~10% BDCAA, 10~12% CDBAA and 54~62% of TBAA in its presence, indicating that the major chemical species in its presence changed from DCAA and TCAA to TBAA. For HANs, 100% of DCAN in its absence changed to 17~6% of DCAN, 15~10% of BCAN and 68~84% of DBAN in its presence, indicating that the major chemical species changed from DCAN to DBAN.
39. It was considered that the DOCs of O-SW, I-SW, N-RW and G-SW were composed of largely aquatic humics, and that they were relatively hydrophobic, aromatic and of high molecular weight, whereas those of S-SW and T-GW were composed largely of non-humic materials which were relatively hydrophilic, less aromatic and of lower molecular weight, and those of W-GW and E-SW were composed of weak hydrophobic acids or hydrophilic neutrals.
The THMFP, HAAFP and HANFP were increased with increasing chlorine contact time, although they differed depending on the characteristics of raw water. Comparing the maximum DBPFP and DBPFP/ DOC among the raw waters, the maximum THMFP, HAAFP and HANFP were obtained from N-RW, but the maximum THMFP/DOC, HAAFP/DOC and HANFP/DOC were obtained for HA, HA and N-RW, indicating that the highest DBPFP was formed for N-RW with the highest DOC content, but the highest THMFP/DOC and HAAFP/DOC, lower HANFP and HANFP/DOC were formed for HA. Comparing the DBPFP for raw waters, it decreased in the order of HAAFP > THMFP ≥ HANFP, which is thought to be due to complex factors involving several water quality parameters, such as the concentration and characteristics of DOC, pH, Br- concentration, etc.
Each of THMFP/DOC, HAAFP/DOC and HANFP/ DOC in the presence of 0.3 mg/L Br- addition for HA, was 2.6~3.9 times, 1.4~1.8 times and 2.5~4.1 times higher than each of those in the absence of Braddition, respectively (indicating that DBPFP increased in the presence of Br-), and the major chemical species changed from TCM to DBCM and TBM for THMs, from DCAA and TCAA to TBAA for HAAs, and from DCAN to DBAN for HANs.
참고문헌 (14)
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