• Journal of Korean Society of Water and Wastewater
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• v.30 no.1
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• pp.69-75
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• 2016

This study was conducted to examine the byproducts formation characteristics at the water treatment plants which applying electrolysis as a disinfection process in Gangwondo, Korea. Total of forty plants located in Gangwon Province, Korea were selected for the study. Correlation between dissolved organic carbon(DOC) and $SUVA_{254}$ was not clear. Among the species of the disinfection byproducts(DBPs), chlorate and trihalomethanes(THMs) accounted for 76% and 14% of DBPs, respectively. The effect of DOC or $SUVA_{254}$ on DBPs formation was not clearly demonstrated. The increased amount of THMs due to the raw water bromide content was found primarily in the form of chloroform, and the percent fraction of BDCM(bromodichloromethane) and DBCM(Dibromochloromethnae) was relatively insignificant. When the value of $SUVA_{254}$ was greater than $2L/mg{\cdot}m$, the percent fraction of BDCM and DBCM decreased while percent fraction of CF(chloroform) increased.

• Journal of Korean Society of Water and Wastewater
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• v.36 no.5
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• pp.249-260
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• 2022

The effect of permanganate oxidation was investigated as water treatment strategy with a focus on comparing the reaction characteristics of NaOCl and sodium permanganate (NaMnO₄) in algae (Monoraphidium sp., Micractinium inermum, Microcystis aeruginosa)-contained water. Flow cytometry explained that chlorine exposure easily damaged algae cells. Damaged algae cells release intracellular organic matter, which increases the concentration of organic matter in the water, which is higher than by NaMnO₄. The oxidation reaction resulted in the release of toxin (microcystin-LR, MC-LR) in water, and the reaction of algal organic matter with NaOCl resulted in trihalomethanes (THMs) concentration increase. The oxidation results by NaMnO₄ significantly improved the concentration reduction of THMs and MC-LR. Therefore, this study suggests that NaMnO₄ is effective as a pre-oxidant for reducing algae damage and byproducts in water treatment process.

• Journal of Korean Society on Water Environment
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• v.26 no.3
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• pp.406-412
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• 2010

Concentrations and speciations of Trihalomethanes (THMs) and Haloacetic acids ($HAA_5$) that can be formed during chlorine disinfection by-product (DBPs) in full-scale drinking water treatment plants were investigated. Jeon-ju D water treatment plant that adopted conventional water treatment processes was chosen for investigation. SUVA values according to water treatment process changes were observed from 1.3 to 2.1. The process average concentrations of THMs was 7.4 ppb, 9.0 ppb and 14.7 ppb respectively, while the average concentrations of $HAA_5$ by each process which are precipitation water, filterater water, treated water, were 15.5 ppb, 14.9 ppb and 25.8 ppb respectively. DBPs concentrations was lower in the winter than summer. The major species of THMs was chloroform and the second highest was bromodichloromethane (BDCM) and the third highest was dibromochloromethane (DBCM). In case of $HAA_5$, the rate of trichloroacetic acid (TCAA) was detected. The species disribution of THMs is related to the change of SUVA and species disribution of $HAA_5$ is related to the concentrations of bromine and injection position of chlorine and injection quantity.

• Journal of Korean Society of Environmental Engineers
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• v.39 no.9
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• pp.513-518
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• 2017

In this paper, the removal efficiency of THMs (Trihalomethanes) and DOC (Disolved organic carbon) was compared under different GAC (Granual activated carbon) filling methods. One method is "full filling method" in which column is fully filled with GAC at once and the other is "periodic cumulative method" in which column is partially filled with GAC (10, 20, 33 and 50% of total column volume) and added each ratio during 300 days. The effluent concentration of both THMs and DOC under full filling method was low during the initial period, however, steadily increased with operating time. In the contrast, with periodic cumulative method, it maintained (relatively) evenly during the operating period. Periodic cumulative method was more efficient for removing THMs than full filling method. However, when the ratio of chlorodibromomethane or bromoform among THMs was significantly higher than chloroform and bromodichloromethane, full filling method was more efficient than periodic cumulative method. Full filling method had benefit to total DOC removal and control of average DOC concentration in effluent. Overall, periodic cumulative method is more efficient to equalize the removal efficiency of THMs and DOC, so the more frequent refilling of column with small amount of GAC is more advantageous.

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

• Analytical Science and Technology
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• v.13 no.1
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• pp.55-65
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• 2000

In this study, we collected the tap water that treated from water plant in Seoul, Incheon, Taejon, Kwangju, Taeku and Pusan and supplied each house. The sampling period was June and September, 1997. The concentration of THMs formed by chlorination in drinking water was determined with the purge and trap method with GC/MSD recommended by the us EPA 542.2 method. Chloroform is the most of THMs (47.43%~93.11%) and the content order is bromodichloromethane > chlorodibromomethane > bromoform. In Incheon, Taejon, Kwangju, Taeku and Pusan, the content of bromodichloromethane, chlorodibromomethane and bromoform was higher than Seoul. But, in June and September, the concentration of THMs in six cities is not over Korea Drinking Water Regulation $100{\mu}g/L$. The calculated human exposure for each substances were chloroform $6.14{\times}10^{-4}mg/kg/day$, bromodichloromethane $1.01{\times}10^{-4}mg/kg/day$, chlorodibromomethane $0.29{\times}10^{-4}mg/kg/day$, bromoform $0.01{\times}10^{-4}mg/kg/day$ and THMs $7.98{\times}10^{-4}mg/kg/day$.

• Journal of Korean Society on Water Environment
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• v.24 no.4
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• pp.415-422
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• 2008

Drinking water treatment is enhanced by coagulant dosages and chlorine injection because of pH increase in raw water in droughty seasons such as spring and fall. But water quality deterioration is occurred by increase in residual aluminium and disinfection by-products. Coagulation process can be used to control natural organic matter (NOM) during water treatment. The effect of coagulation process appeared to depend on the pH of water rather than coagulant dosages. In this study, for water treatment in high pH season $H_2SO_4$ was applied for pH adjustment at full scale. Before and after pH adjustment by $H_2SO_4$ injection, water quality of drinking water was evaluate. In the result of investigation of total organic carbon (TOC) removal in high pH season, TOC was removed approximately 30~40%, which showed decrease in water treatment efficiency. Also, it is increased both particle numbers and residual Al concentration in the water. After $H_2SO_4$ injection for adjustment to pH<7.5 in settled water, treated water turbidity decreased in 0.047 NTU from 0.059 NTU, and particle numbers of filtered water decreased in 20/mL from 90/mL. On the other side, TOC removal efficiency increased in approximately 10% after adjustment of pH. In the result of decrease in pH in raw water through more coagulants and prechlorine without $H_2SO_4$ injection, trihalomethanes (THMs) concentration increased in $16{\mu}g/L$ from $8{\mu}g/L$.

• Journal of Environmental Science International
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• v.15 no.8
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• pp.785-797
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• 2006

The formation characteristics of trihalomethanes (THMs) and haloacetic acids (HAAs) were investigated in chlorination of raw water of different organic mallet characteristics. The samples used in this study were hydrophobic (N-HPO) and hydrophilic fraction (N-HPI) (which were concentrated and separated from Nakdong river water), and humic acid (HA) (which is known as a strong hydrophobic acid) as a reference organic matter, the specific UV absorbance (SUVA) of which was 2.19, 1.15 and 7.92, respectively. With increasing chlorine contact time, THMFP and HAAFP (the formation potential of THMs and HAAs) increased, but their increase was different depending on the organic mallet characteristics (i.e., for N-HPI, THMFP was higher than HAAFP, but the inverse result was obtained for N-HPO and HA and the ratio between them was greater for HA), and the mainly formed chemical species were CHCI$_3$ in case of THMs and dichloroacetic acid (DCAA) and trichloroacetic acid (TCAA) in case of HAAs for N-HPO and HA (and the ratios of CHCI$_3$ to total THMs and DCAA and TCAA to total HAAs for HA were higher than those for N-HPO), but for N-HPI, the ratio of brominated THMs was a little higher than that of CHCI$_3$ and the ratio of DCAA and TCAA to total HAAs was lower than that of N-HPO, although they are main chemical species in case of HAAs. Comparing THMFP and HAAFP with the increase in bromide concentration added with those in not adding it, the former increased greatly and its increase was higher for the organic mallet with stronger hydrophobicity, but the latter was lower for N-HPO and N-HPI and was similar for HA. The main chemical species with increasing bromide concentration were CHBt$_3$ in case of THMs regardless of organic matter characteristics, and dibromoacetic acid (DBAA) for N-HPO and N-HPI, DBAA and tribromoacetic acid (TBAA) for HA in case of HAAs. With increasing reaction temperature and pH, THMFP and HAAFP increased for the former, but for the latter, THMFP increased and HAAFP decreased, although the rate of increase or decrease was different with organic mallet characteristics.

• Journal of Korean Society of Environmental Engineers
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• v.30 no.3
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• pp.286-292
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• 2008

This study was conducted to analyze and determine the formation potential of chlorination DBPs from seven urinary compounds with or without Br$^-$. Three of seven components were kynurenine, indole and uracil that were relatively shown high the formation potential of chlorination DBPs concentrations. The reported results of THMs/DOC with or without Br$^-$ in kynurenine showed that THMs/DOC was detected 86.9 $\mu$g/mg when Br$^-$ was not added, and THMs/DOC was detected 100.8 $\mu$g/mg when Br$^-$ was presented. In indole, THMs/DOC was increased from 6.58 $\mu$g/mg to 31.4 $\mu$g/mg when Br$^-$ was added. Moreover, among them, the highest, second-highest and third-highest HAAs/DOC were shown in kynurenine, uracil and indole respectively. Specially, HAAs/DOC was significantly deceased in kynurenine and indole when Br$^-$ was presented. This was a totally different phenomenon for THMs/DOC. TCAA was dominated in HAAs for kynurenine and indole, and DCAA was also dominated in HAAs for uracil. The highest formation of HANs/DOC was shown in kynurenine whether or not Br$^-$ presented, and DCAN was predominant in HANs. HANs was not formed by chlorination in uracil. In addition, the formation of CH/DOC was relatively low in kynurenine and indole. The formation of CH/DOC was specially high(1,270 $\mu$g/mg) in uracil when Br$^-$ was not added. The formation of CH/DOC was 1,027 $\mu$g/mg in uracil when Br$^-$ was added. The formations of THMs and HAAs were also investigated in kynurenine, indole and uracil when Br$^-$ was presented or not. The formation of THMs/DOC was higher in kynurenine and indole when Br$^-$ was presented. The formation of HAAs/DOC was reduced in kynurenine when Br$^-$ was added. The result could be attributed to higher formation of THMs/DOC in kynurenine when Br$^-$ was added. The formation of HAAs/DOC was also reduced in indole when Br$^-$ was added. To the contrary, this result was not attributed to higher formation of THMs/DOC in indole when Br$^-$ was added.

• Journal of Korean Society of Environmental Engineers
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• v.39 no.3
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• pp.105-111
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• 2017

This study was conducted to evaluate the effects of pH control and ozonation, coagulation on trihalomethanes (THMs) formation during prechlorination of the Nakdong river water. The results showed that lower pH was reduced THMs formation during prechlorination. THMs formation of water lowered pH 9.5 to 9.0, was reduced 18.3% and lowered pH 9.0 to 8.0 was reduced 14%, lowered pH 8.0 to 7.0 was reduced 7%, lowered pH 9.5 to 8.0 was reduced 29%. A low ozone dose ($0.11{\sim}0.48mg{\cdot}O_3/DOC$) before chlorination reduced the yields of THMs (reduced 6~24% in chlorination) compared with no preozonation. Thus the low ozone dose pretreatment is relatively effective plan to reduce THMs formation during chlorination. When ozone 1.0 mg/L, Alum 40 mg/L and sulfuric acid 6 mg/L dosed, The yields of THMs formation was reduced 42% compared with only chlorination. Input of chlorine after preozonation (followed coagulation, pH control) is more effective than only decline pH at a intake station to control THMs formation in a water treatment process. When chlorine 2.5 mg/L was added before coagulation (alum 40 mg/L), THMs formation was reduced 19% by lower pH and decreased 18% by a natural organic matter (NOM) removal compared with only chlorine 2.5 mg/L addition. Because coagulation could induce simultaneously lower pH and NOM removal, THM formation concentration is more effectively lowed than decreasing pH in the Nakdong river water.