• Journal of Korean Society of Water and Wastewater
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• v.29 no.4
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• pp.469-479
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• 2015

This study have been conducted to analyze the feasibility of establishing Contamination Warning System(CWS) that is capable of monitoring early natural or intentional water quality accidents, and providing active and quick responses for domestic C_water supply system. In order to evaluate the water quality data set, pH, turbidity and free residual chlorine concentration data were collected and each statistical value(mean, variation, range) was calculated, then the seasonal variability of those were analyzed using the independent t-test. From the results of analyzing the distribution of outliers in the measurement data using a high-pass filter, it could be confirmed that a lot of lower outliers appeared due to data missing. In addition, linear filter model based on autoregressive model(AR(1) and AR(2)) was applied for the state estimation of each water quality data set. From the results of analyzing the variability of the autocorrelation coefficient structure according to the change of window size(6hours~48hours), at least the window size longer than 12hours should be necessary for estimating the state of water quality data satisfactorily.

• Journal of Korean Society of Environmental Engineers
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• v.32 no.3
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• pp.296-308
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• 2010

The peroxone process overcomes many of the limitations associated with conventional and advanced water treatment systems using chlorine disinfection and ozone oxidation processes. Ozone and hydrogen peroxide generate highly reactive hydroxyl free radical which oxidize various organic compounds and has highly removal efficiency. The key issue to operate peroxone process is developing the method to achieve high process effectiveness when scavengers that inhibit generation of OH radicals or consume OH radicals are co-existing in the process. Also many studies, to minimize inorganic oxidative by-products such as bromate and to reduce disinfection by-products after chlorination behind peroxone process, are needed. And we should consider the excess residual hydrogen peroxide in the water. On-line instruments and control strategies need to be developed to ensure effective and robust operation under conditions of varying load. If problems above mentioned are solved, peroxone process will be applied diversely for water treatment.

• Journal of Korean Society of Water and Wastewater
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• v.22 no.3
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• pp.379-387
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• 2008

The pH & alkalinity adjustment method by lime and carbon dioxide($CO_2$) for corrosion control in water distribution system was investigated to evaluate the corrosion characteristics of metal pipes, such as galvanized iron, copper, stainless steel, and carbon steel. When the pH in sand filtered and ozone+GAC treated water was increased with lime and $CO_2$ from 7.5 to 8.0, the concentration of residual chlorine decreased at higher pH and longer reaction time; the concentration of trihalomethane increased. The corrosion rate of coupons with corrosion control using lime and carbon dioxide was showed much smaller than those without corrosion control using pilot-scale simulated distribution system. The galvanized iron was corroded much faster than carbon steel, copper, and stainless steel. Especially, copper and stainless steel coupons were hardly corroded. The galvanized iron and carbon steel coupons with corrosion control were produced the corrosion products less than those without corrosion control by the results of environmental scanning electron microscope(ESEM) and energy dispersive x-ray spectroscopy(EDS) analyses. The galvanized iron coupon with pH and alkalinity adjustment by lime and carbon dioxide was detected about 30 percent of zinc, when the carbon steel was detected about 30 percent of calcium by calcium carbonate products formation. For the results of X-ray diffraction(XRD) analyses, the goethite(${\alpha}$-FeOOH) was identified as primary corrosion product of galvanized iron without corrosion control, while the Zinc oxide(ZnO) was found on corrosion products of galvanized iron coupon with corrosion control as the results of EDS analyses. However, the carbon steel corrosion products regardless of corrosion control were composed predominantly of maghemite(${\gamma}-Fe_2O_3$) and hematite(${\alpha}-Fe_2O_3$).

• Journal of Environmental Science International
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• v.17 no.8
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• pp.899-905
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• 2008

Quality test for activated carbon(AC) filter used for drinking water purifier is now an obligatory test and the standard material for valid purifying amount in water purifier performance test has been changed from residual chlorine to chloroform according to the notice of Ministry of Environment in 2006. Therefore, this study aimed to compare the ingredients of AC filters by confirming chloroform removal rate of AC filter and conducting 4 adsorption tests (Iodine, methylene blue decolorization, phenol value, ADS value) for AC filters provided by manufacturers. With water pressure of $1kgf/cm^2$, 1,500 liters of prepared inflow went through to check chloroform removal rate. As a result, product with removal rate of below 60% from all products. On the other hand, 4 adsorption tests were conducted for filters in the market and filters from manufacturers. None of the products satisfied all 4 tests. In particular, they showed great shortage to the standard in phenol value and ADS value test. However, manufacturers' filter showed much better performance than filters in the market. Also, the result of valid purifying amount test for each of five products of appropriate product and inappropriate product based on filter quality test showed average 4,440 liters for appropriate product and average 2,620 liters for inappropriate product. According to the result, it is shown that the filter with good adsorption also had good chloroform removal efficiency and adsorption efficiency. Therefore, it is expected that customers can screen good quality product through obligatory conduct of filter quality test. However, it is considered that complementation in system is required for future inspection.

• Journal of Korean Society on Water Environment
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• v.20 no.5
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• pp.409-414
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• 2004

Pilot-scale experiments were performed for the treatment of bank filtrate contammg high manganese concentration around 2mg/L using rapid manganese sand filtration to investigate effects of oxidant dose and pH control on the removal efficiency of manganese. For theoretical dose ranges of oxidant (sodium hypochlorite) between 3 and 4mg/L, the manganese concentration of effluent was 0.57 mg/L, which corresponded to 72.5% removal and was higher than drinking water quality standards of 0.3mg/L. For excess dose ranges of oxidant between 4 and 8mg/L, the manganese concentration of effluent was reduced to 0.14mg/L, which corresponded to 94.5% removal, but the residual chlorine concentration was over 1.0mg/L. On the other hand, manganese removal efficiency drastically increased up to the value of 98.0%, which is equivalent to the effluent concentration of 0.03mg/L by controling pH to the range between 7 and 8 for the theoretical dose of oxidant. Consequently, these results indicated that appropriate dose of chemicals, such as oxidant and alkali, and continuous monitoring of manganese should be necessary to obtain efficient removal of manganese and to optimize the maintenance of treatment facilities for the treatment of bank filtrate with high concentration of manganese.

• Journal of Korean Society of Environmental Engineers
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• v.28 no.5
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• pp.558-562
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• 2006

Filtration experiments were conducted to determine the characteristics of manganese removal in filtration using 4 different filter media including sand and manganese sand(MS). Filtration velocity was 123 m/d and the flow rate was $3.9m^3/d$ per column. Duration of these experiments was about one year, and manganese dioxide accumulation, turbidity removal, manganese removal, and organic material removal were examined depending on filter media. When filter influent(residual chlorine 1.0 mg/L) with an average manganese concentration of 0.208 mg/L was fed through a filter column, the sand+MS and MS columns removed 98.9% and 99.2% of manganese respectively on an annual basis. When there is need to replace the sand filters with a MS filter to remove manganese, it was shown that the replacement of a partial sand filter with MS had adequate manganese removal.

• Proceedings of KOSOMES biannual meeting
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• 2017.11a
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• pp.236-236
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• 2017

Effluent treated by an NaDCC injection method in Ballast water management system (BWMS) contains reactive chlorine species and disinfection by-products (DBPs). In this study, we conducted whole effluent toxicity (WET) testing and ecological risk assessment (ERA) to investigate its ecotoxicological effects on marine environment. WET testing was carried out for four marine pelagic and freshwater organisms, i.e., diatom Skeletonema costatum, Navicula pellicuosa, chlorophyta Dunaliella tertiolecta, Pseudokirchneriella subcapitata, rotifer Brachionus plicatilis, Brachionus calyciflorus and fish Cyprinodon variegatus, Pimephales promelas. The biological toxicity test revealed that algae was the only biota that showed apparent toxicity to the effluent; it showed no observed effect concentration (NOEC), lowest observable effect concentration (LOEC) and effect concentration of 50% (EC50) values of 25-50%, 50-100% and >100%, respectively, at three water condition, but did not show any significant toxicities on other biota. Meanwhile, chemical analysis revealed that the BWMS effluent contained total residual oxidants (TROs) below $0.03{\mu}g/L$ and a total of 25 DBPs such as bromate, volatile halogenated organic compounds (VOCs), halogenated acetonitriles (HANs), halogenated acetic acids (HAAs), chloropicrin and Isocyanuric acid. Based on ERA, the 25 DBPs were not considered to have persistency, bioaccumulation and toxicity (PBT) properties. The ratio of predicted environmental concentration (PEC) to predicted no effect concentration (PNEC) of the other DBPs did not exceed 1 for General harbor environment. However, four substances (Isocyanuric acid, Tribromomethane, Chloropicrin and Monochloroacetic acid) were exceed 1 for Nearship environment. But observed toxicity in the test water on algal growth inhibition would be mitigated by normal dilution factor of 5 applied for nearship exposure. Thus, our results of WET testing and ERA showed that the BWMS effluent treated by NaDCC injection method would have no adverse impacts on marine environment.

• Journal of Environmental Science International
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• v.23 no.4
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• pp.737-742
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• 2014

This study aimed for evaluating the applicability of the two stage dual media filtration system in field water treatment plant. The field plant of two stage and dual media filtration system was operated for 2 months. Average iron concentrations of the settled water, existing filtered water and second stage filtered water was 0.041 mg/L, 0.007 mg/L and 0.005 mg/L, respectively. Removal efficiency of iron concentration in the second stage is appropriately 35% more than in existing filtered water. Also removal efficiency of residual chlorine in the dual media filtration system is relatively 42.3% more than in existing filtered water due to adsorption of activated carbon, but the removal of ammonia nitrogen by adsorption is insufficient. Average concentrations of THM and chloroform in the settled water are 0.033 mg/L, 0.026 mg/L, respectively and in existing filtered water are 0.023 mg/L and 0.023 mg/L. Average concentrations of THM and chloroform in the dual media filtration system are 0.008 mg/L and 0.013 mg/L. Therefore removal efficiency of THM concentration in second stage is more than 66.4% in existing filtrated water. Also removal efficiency of chloroform in the dual media filtration system is more than 50.0% in existing filtered water because of the adsorption of activated carbon. In this case backwashing period in dual stage system is 4~5 days, but in existing filtration system is 1~2 days.

• Journal of Korea Water Resources Association
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• v.39 no.1 s.162
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• pp.35-46
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• 2006

In this study, we proposed a layout of the integrated decision support system in order to prevent the contamination and to manage risk in water supply networks for safe and smooth water supply. We evaluated the priority of risk factors to detect anomaly in water supply networks using PROMETHEE and ANP techniques, which are applied to various Multi-Criteria Decision Making area in Europe and America. To develop the model, we selected pH, residual chlorine concentration, discharge, hydraulic pressure, electrical conductivity, turbidity, block leakage and water temperature as the key data item. We also chose pipe corrosion, pipe burst and water pollution in pipe as the criteria and then we present the results of PROMETHEE and ANP analysis. The evaluation results of the priority of risk factors in water supply networks will provide basic data to establish a contingency plan for accidents so that we can establish the specific emergency response procedures.

• Korean journal of food and cookery science
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• v.24 no.2
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• pp.228-235
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• 2008

In this study, vinegar disinfection was evaluated as a novel method for the preparation of raw food ingredients used in foodservice operations. The test materials were washed and disinfected using three different methods, and were then stored at temperatures of $3^{\circ}C\;and\;10^{\circ}$ for 7 days; Following storage, physicochemical and sensory characteristic comparisons were performed. Temperature for all test materials ranged between 15.2-20. $9^{\circ}C$, water activity was maintained near 0.96, and the pH levels of the samples were 6.44, 6.29, and 6.35, respectively. Residual chlorine levels were generally low, ranging between 0.01 and 0.02. The physicochemical qualities of the samples were evaluated according to the storage method and temperature. Brightness(L value), redness(a value), and yellowness(b value) tended to increase with increasing storage time. The evaluated sensory characteristics included appearance, color, smell, taste, texture, and overall acceptance. With regard to storage temperature the vinegar-treated samples were evaluated as superior, receiving a score of 7.00, and the ingredients stored at $3^{\circ}C$ were evaluated as significantly (p< 0.001) superior to those stored at $10^{\circ}C$. Overall, vinegar is an effective disinfectant to apply in the preparation of raw vegetables that are typically served without heating, and which can cause serious food safety issues when contaminated.