• Journal of Korean Society of Environmental Engineers
• /
• v.33 no.12
• /
• pp.893-899
• /
• 2011

The occurrence of THMs, the characteristics of THMs formation and removal of THMs were investigated. The treatment train of M plant consists of prechlorination, flocculation, sedimentation, filtration, ozonation, activated carbon and postchlorination. The study of THM formation indicated that about 92% of the THMs were formed in the flocculation/sedimentation/filtration process which affected by prechlorination. The formation of THMs was highly correlated to $KMnO_4$ consumption and water temperature in raw water. The regression model had showed 0.72~0.80 of determination coefficient so it could be used to predict the amount of THMs formation in finished water. Compared to the prechlorination process, the THMs formation was reduced in interchlorination process. With the addition of PAC, fewer THMs were formed in PAC-chlorination process than in chlorination-PAC process. Our results showed that air stripping could be used to remove the existing THMs.

• Journal of Environmental Health Sciences
• /
• v.23 no.2
• /
• pp.28-34
• /
• 1997

This study was carried out to investigate the effects of prechlorination and algae growth on THMs generation. The sample water obtained from Paldang Dam which is a main source of raw water for the Seoul metropolitan area. THMs concentration in the sample water was investigated in water treatment process prechlorifiation, chemical coagulation, and sand filtration. And also, THMs concentration were analyzed in the water which cultured algae in laboratory. The results were as follows 1. The THMs concentration produced by prechlorination unit process were increased in control (not purified) but decreased in process of purification. 2. The THMs concertration can reduce by increasing the number of cleaning filters. 3. The main precursor in raw water for the THMs generation was supplied by algae growth. So as to reduce the THMs concentration in water supplying system, it is the best method to manage algae growth in water body of Paldang reservoir.

• Journal of Environmental Health Sciences
• /
• v.25 no.3
• /
• pp.1-6
• /
• 1999

This study was conducted to survey trihalomethane(THMs) levels in finished water of J water treatment plant and examine its reduction by powder activated carbon(PAC) treatment. Samples were collected weekly based and head-space technique was employed to determine THMs levels by G.C-ECD. THMs levels in finished waters were highest in August and showed close relationship with water temperature. All the samples satisfied the drinking water limit(100 ${\mu}$g/l) for THMs. The individual formation rates of THMs were 64.8% for CHCl$_3$, 28.4% for CHCl$_2$BR, 6.5% for CHClBr$_2$ and 0.3% for CHBr$_3$, respectively and showed little monthly difference. The reduction efficiency of THMs formation by PAC treatment was 67% during July and August. Bromine substituents were more efficiently reduced than CHCl$_3$ by PAC.

• Journal of environmental and Sanitary engineering
• /
• v.14 no.1
• /
• pp.11-16
• /
• 1999

This study was performed to investigate THMs formation by chloramination as a secondary disinfection in drinking water distribution system. As the $Cl_2/NH_3-N$ ratio increased from 1:1 to 4:1, the THMs concentration had actually no change in the breakpoint curve of pH 6, 7. At pH 8, THMs level was not augmented at between 1:1 and 5:1. In the $Cl_2/NH_3-N$ ratio of more than 5:1 and 6:1 respectively, THMs level was raised. Only the chloroform of THMs was insignificantly detected by both preformed chloramine and preammoniation applications, which was probably attributed to the stoichiometrically unstable equilibrium in the preparation of chloramine, whereas $CHCl_3$, $CHCl_2Br$ and $CHClBr_2$ of THMs were found in the application of free chlorine. However it turned out that the THMs levels by chloramine was incomparably inferior to that of free chlorine.

• Journal of Environmental Science International
• /
• v.13 no.7
• /
• pp.627-635
• /
• 2004

Evaluated were household THMs exposure associated with the use of municipal tap water treated with chlorine and with ozone-chlorine. The current study measured the THMs concentrations in the tap water and indoor and outdoor air in the two types of household, along with an estimation of THMs exposure from water ingestion, showering, and the inhalation of indoor air. Chloroform was the most abundant THMs in all three media, yet no bromoform was detected in any sample. Contrary to previous findings, the fall water THMs concentrations exhibited no significant difference between the chlorine and ozone-chlorine treated water. However, the spring median chloroform concentration in the tap water treated with chlorine (17.6 ppb) was 1.3 times higher than that in the tap water treated with ozone-chlorine (13.4 ppb). It is suggested that the effects of the water parameters should be considered when evaluating the advantage of ozone-chlorine disinfection for THMs formation over chlorine disinfection. The indoor air THMs concentration trend was also consistent with the water concentration trend, yet the outdoor air THMs concentrations did not differ significantly between the two types of household. The indoor to outdoor air concentration ratios were comparable with previous studies. The THMs exposure estimates from water ingestion, showering, and the inhalation of indoor air suggested that, for the residents living in the surveyed households, their exposure to THMs in the home was mostly associated with their household water use, rather than the indoor air. The THMs exposure estimates from tap water ingestion were similar to those from showering.

• Journal of Korean Society of Environmental Engineers
• /
• v.30 no.7
• /
• pp.721-728
• /
• 2008

DBPs(Disinfection By-Products) are most formed through the reactions between chlorine and NOM(Natural Organic Matter) in water treatment. In this study, occurrence of DBPs including THMs(Trihalomethanes) is evaluated. Also, influencing factors by the seasons and raw water quality were investigated for correlation among them and the characteristics of THMs formation by prechlorination process. This study investigated the operation condition for THMs removal depending on raw water quality. Water treatment plant from intake station to gauging well flows for about 10 hours in Y Water Supply Office. It is limited to control of THMs formation because of excessive reaction time between chlorine and THMs precursors in the intake station. Therefore, as multi-points prechlorination from intake station to gauging well, THMs formation was decreased in the water treatment, and it was willing to prevent overdosage of chlorine. The concentration of THMs was 0.021 mg/L in the summer, 0.015 mg/L in the winter, respectively. Also, THMs formation showed that 0.013 mg/L in the water of gauging well after prechlorination, 0.014 mg/L in the flocculation/sedimentation/filtration, 0.016 mg/L in the water after postchlorination, respectively. THMFP(Trihalomethane Formation Potential) removed 42.7% and 50% through the flocculation/sedimentation and filtration, respectively, and it is similar TOC removal efficiency. In this study, multi-points prechlorination from intake station to gauging well decreases in contact time and concencrations of NOM and chlorine. Also, it decreases in THMs and amount of chlorine uesd. In the result of multi-points prechlorination in the summer, the concentration of THMs was 0.013mg/L in the treated water. In view of these facts, THMs formation can be decreased approximately 50%.

• Journal of Korean Society of Environmental Engineers
• /
• v.36 no.1
• /
• pp.35-41
• /
• 2014

Trihalomethanes (THMs) are formed as a results of the reaction of residual chlorine, used as a disinfectant in drinking water, with the organic matter in raw water. Although chlorinated and brominated THMs are the most common disinfection byproducts (DBPs) reported, iodinated THMs (I-THMs) can be formed when iodide is present in raw water. I-THMs have been usually associated with several medicinal or pharmaceutical taste and odor problems and is a potential health concern since they have been reported to be more toxic than their brominated and chlorinated analogs. Currently, there is no published standard analytical method for I-THMs in water. An automated headspace-gas chromatography/electron capture detector (GC/ECD) technique was developed for routine analysis of 10 THMs including 6 I-THMs in water samples. The optimization of the method is discussed. The limits of detection (LOD) and limits of quantification (LOQ) range from 12 ng/L to 56 ng/L and from 38 ng/L to 178 ng/L for 10 THMs, respectively. Matrix effects in river water, sea water and wastewater treatment plant (WWTP) final effluent water were investigated and it was shown that the method is suitable for the analysis of trace levels of I-THMs, in a wide range of waters. The method developed in the present study has the advantage of being rapid, simple and sensitive.

• Journal of Environmental Health Sciences
• /
• v.27 no.4
• /
• pp.41-46
• /
• 2001

Trihalomethane(THMs) levels in drinking tap water, indoor swimming pool water and industrial effluent in Kunsan area were surveyed in this study. During experimental period, the monthly averages of THMs in drinking tap water from Keumkang wide-area supply ranged from 15$\mu\textrm{g}$/ι/to 50 $\mu\textrm{g}$ showing the highest level in summer. 3 indoor swimming pools showed the monthly average levels of THMs formation ranging from 8$\mu\textrm{g}$/ι/to 20$\mu\textrm{g}$/ι and the pool under public management seemed to maintain its water quality more stable than those under private management THMs concentrations in the effluents. discharged from 10 manufacturing companies, ranged from N.D. to 95$\mu\textrm{g}$/ι and it was estimated that the overall THMs level discharged front those manufacturing companies is not high, reflecting the traces recorded for most effluents. The composition ratios of individual THMs for industrial effluents showed a difference from those for drinking water and swimming pool water, along with their wide variations according to the company and relatively high composition ratios of Br substituents.

• Journal of Environmental Health Sciences
• /
• v.39 no.3
• /
• pp.223-229
• /
• 2013

Objectives: In an effort to examine the distribution of THMs (Trihalomethane) generated from chlorine disinfection by the drinking water treatment plants located on the east coast region of Gangwon-do, this study surveyed the distribution and concentrations of each component of THMs twice per month for 5 years from 2008 to 2012. Fluctuation pattern in the seasonal generation amount was identified. In addition, the correlation between the concentration of organic substances in water and THMs was assessed, along with stability of purified water quality supplied by the water treatment plants on the east coast by analyzing the composition ratio of each component that constitutes THMs and the detection frequency. Method: The research was done on purified water supplied by 29 water treatment plants in 7 cities and counties (Goseong-gun, Sokcho-si, Yangyang-gun, Gangneung-si, Donghae-si, Samcheok-si, Taebaek-si) located in Gangwon-do on the east coast. Water samples were collected twice a month from 2008 to 2012 and were investigate for chloroform, bromodichloromethane (BDCM), dibromochloromethane (DBCM), and bromoform, based on analysis through Purge-Trap (Tekmar 3000) devices using FID-attached GC (HP 6890, Hewlett Packard). Result: THMs concentration detected at Gangneung-si was 0.0086mg/L, Goseong-gun 0.0019mg/L, Donghae-si 0.0099 mg/L, Samcheok-si 0.0016 mg/L, Sokcho-si 0.0057 mg/L, Yangyang-gun 0.0027 mg/L and Taebaek-si 0.0038 mg/L. As the THMs composition rate, chloroform constitutes 51.4% followed bybromodichloromethane 22.3%, bromoform 15.2% and dibromochloromethane 11.1% respectively. Conclusion: Throughout the entire THMs survey areas and period, the maximum concentration was 0.072mg/L, which did not exceed the water quality standards (0.1 mg/L), and the overall average concentration was very low at 0.0044 mg/L.

• Applied Biological Chemistry
• /
• v.37 no.6
• /
• pp.472-479
• /
• 1994

This study was conducted to determine the effective removal method of THMs and humic material in drinking water when the doses of oxidants, coagulants, and activated carbon, and the points of oxidants treatment were changed in the drinking water treatment process. The inhibition of THMs formation and the removal of humic matter were more effectively achieved by $ClO_2$ than by other oxidants, $Cl_2,\;NH_2Cl,\;KMnO_4\;and\;O_3$. By changing the point of oxidant treatment, the formation of THMs was reduced by about 36.7 to 8.2% on treatment after coagulation, but the content of humic matter was not affected. The coagulation efficiency of alum and ferric sulfate to coagulate organic materials in water was affected by the molecular weight of humic matter in drinking water. The treatment of activated carbon after filtration was found to be more effective than that before oxidation in inhibiting THMs formation and removing THMs.