• Journal of Korean Society on Water Environment
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• v.40 no.2
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• pp.89-100
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• 2024

Climate change has a broad impact on the entire water environment, and this impact is growing. Climate adaptation in water supply systems often involves quantity and quality control, but there has been a lack of research examining the impacts of climatic factors on water supply productivity and operation conditions. Therefore, the present study focused on, first, building a database of climatic factors and water purification operating conditions, and then identifying the correlations between factors to reveal their impacts. News big data was analyzed with keywords of climatic factors and water supply systems in either nationwide or region-wide analyses. Metropolitan area exhibited more issues with cold waves whereas there were more issues with drought in the Southern Chungcheong area. A survey was conducted to seek experts' opinions on the climatic impacts leading to these effects. Pre-chlorination due to drought, high-turbidity of intake water due to rainfall, an increase of toxins in intake water due to heat waves, and low water temperature due to cold waves were expected. Pearson correlation analysis was conducted based on meteorological data and the operating data of a water purification plant. Heavy rain resulted in 13 days of high turbidity, and the subsequent low turbidity conditions required 3 days of high coagulant dosage. This insight is expected to help inform the design of operation manuals for waterworks in response to climate change.

• Journal of Korean Society of Environmental Engineers
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• v.31 no.3
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• pp.203-207
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• 2009

The concern of seriousness and harmful effects of environmental pollution is rising by the various water pollutions, appearances of new micro-noxious substances and increase of sustainable pollutants. The method is suggested that can effectively increase the removal of organic substances and several pollutants using a coagulation process. The experiment for characteristics of $ZrSiO_4$ (zirconium silicate) as a coagulation-aid was carried out for application to coagulation process with domestic wastewater and lake water, and the removal rate of the organic substances depending on a dosage was evaluated by PDA (Photometric Dispersion Analyzer) in this study. Zeta-potential of zirconium silicate solution was -32.22 mv at pH 7 and the lower negative(-) charge was detected in the more acidic conditions. Absorbance on $UV_{254}$ presented higher when zirconium silicate was added than in a domestic wastewater itself. Besides, the results by PDA experiment represented that injection of zirconium silicate could promote growing of floc. Tests for coagulation process were conducted by three ways which are pre-injection, co-injection and post-injection of zirconium silicate with alum. Accordingly, removal efficiency of organic substances increased over 15% in co-injection than in using of alum as a sole reagent. When a 20 mg/L of alum was used with a 10 mg/L of zirconium silicate, the removal efficiency was high up to 90%. Removal efficiency of $COD_{Cr}$ was improved more than 15% in case of dosage of coagulant either PAC (Poly aluminium chloride) or PACS (Poly aluminium chloride Silicate) together with zirconium silicate. As a result, the removal efficiency of $COD_{Cr}$ were 5~10% higher in a co-injection of zirconium silicate with a coagulant than a pre-injection and a post-injection but it of soluble substances was lower in a co-injection.

• Journal of Korean Society of Environmental Engineers
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• v.35 no.3
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• pp.171-178
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• 2013

In this study, the sludge that occurs in the initial operation of coagulation system developed for the treatment of CSOs were returned to the flocculation reactor. The purposes of this study were to analyze the Characteristics of flocs that are generated through the recycling sludge and settling characteristics of sludge, and to evaluate the possibility that high concentrations of particulate matter in the initial inflow of CSOs could be used as an weighted coagulant additive. As a result, the concentration of treated CSOs pollutants at the beginning of the CSOs influent with a large amount of particulate matter over 20 ${\mu}m$ was low, after gradually increasing the concentrations of them. The flocs generated from the sludge return were similar in size compared to flocs generated through injection of micro sands, and settling velocity in case of return sludge injection was decreased from 55.1 cm/min to 21.5 cm/min. SVI value of the sludge accumulated at the bottom of the sedimentation tank was 72, and settled sludge volume decreased rapidly due to the consolidation of sludge to the time it takes to 10 minutes. these mean that sludge used for recycling has good settling characteristic. A condition of returned sludge which is 0.1% return of 0.3% extraction was formed in the balance of settlement and extraction. In this case, This condition was to be adequate to maintain the proper concentration such as 100~200 mg/L of TS and 50~100 mg/L of VS in the flocculation reactor. The usage of the return sludge containing particulate matters of CSOs as an weighted coagulant additive was able to secure a stable treated water quality despite the change of influent water quality dynamically. Furthermore, it can be expected to reduce the alum dosage along with the sludge production.

• Applied Chemistry for Engineering
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• v.10 no.5
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• pp.737-742
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• 1999

This study was conducted for the two purposes; one was removal of dissolved humic acid, the well-known precursor of trihalomethanes (THMs), by physicochemical treatment processes such as ozone oxidation, coagulation and activated carbon adsorption. The other was qualitative identification of by-products in chlorination of the dissolved humic acid. When ozone oxidation was applied to remove the dissolved humic acid, pH was abruptly decreased. It was indicated that humic acid was not perfectly converted to $CO_2$ and $H_2O$, but to low fatty acid. In coagulation process, the coagulant was polyaluminumchloride which was widely used for drinking water treatment in recent years. With the dosage of 160 mg/L, total organic carbon(TOC), $COD_{Cr}$ and color were removed with 23%, 24% and 5% respectively. Color was effectively removed by ozone oxidation process, which was the first order reaction, with the reaction rate constant of $0.067min^{-1}$. In activated carbon adsorption process, preozonation process could remove more effectively the dissolved humic acid than that without preozonation. When the dissolved humic acid and sodium hydrochloride were reacted with 1 mg-NaOCl/mg-TOC, only trihalomethanes were detected.

• Analytical Science and Technology
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• v.29 no.3
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• pp.126-135
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• 2016

In the present study, we evaluated the efficiency of the drinking water treatment unit processes controlled by targeting high pharmaceutical compounds that are likely to be released into the water supply. In the coagulation process, the removal rate of sulfonamide, an antibiotic, amounted to 22.6~42.1 %, that of naproxen to 28.2 %, and that of acetaminophen to 20 %. Trimethoprim has demonstrated a low removal rate (4.4 %), while the removal rate of erythromycin was 2.4 %; aspirin was not removed at all. When applying a mixture of chlorination and the coagulation process, the removal rate was increased with increasing the chlorine dosage. When the chlorine injection with the concentration of 3 mg/L was applied, sulfonamide antibiotics, acetaminophen and naproxen, were completely removed. Trimethoprim exhibited a high removal efficiency of ca. 98%, while the removal efficiency of erythromycin was about 55 %; at the same time, aspirin showed a lower removal ratio (ca. 10 %). When applying the powdered activated carbon adsorption process, the removal rate was increased with increase of the concentration of the powder activated carbon injection. Sulfonamide antibiotics showed about 18~50 % removal efficiency in the 1 mg/L, the removal rate was increased by at least 80 % in 25 mg/L. The evaluation results of the titration injection concentration of chlorine treatment and adsorption, coagulation process for the efficient processing of the remaining pharmaceutical compounds in the water treatment process, when applying the chlorine 3 mg/L, powdered activated carbon 10 mg/L and coagulant 15 mg/L were removed more than 90 %.

• Journal of Korean Society of Environmental Engineers
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• v.22 no.7
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• pp.1285-1294
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• 2000

In this study, we investigated the possibility of the elimination of suspended solid and the factors affecting effluent water quality, and the amount of treated water, using the SS removal equipment adapted capillary-syphon phenomenon. Treated water quantity decreased as the accumulation time and the increase of head of capillary syphon, whereas the effluent water quality was improved. At coagulant dosage 0, 0.45, $1.82mg/{\ell}$ (as $Al^{+3}$) and limiting flux $107{\ell}/m/day$. turbidity of treated water was 2, 1, 0.5 NTU in each case. During operating period 15~17 days, the amount of washing water was just used 0.5~0.7% of the amount of treating water. So it is expected that coagulation & sedimentation and rapid filtration process can be replaced with the SS removal equipment adapted capillary-syphon phenomenon in water purification process.

• Journal of the Korean Society of Food Science and Nutrition
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• v.39 no.10
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• pp.1565-1572
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• 2010

Onion (Allium cepa L.) production in Korea has increased gradually over the past 15 years, placing second in food consumption survey with 20.6 g daily intake in 2006. Onions, used as an ingredient in many dishes and accepted by almost all traditions and cultures, have been reported to have a range of health benefits which include anticarcinogenic, antiasthmatic, antibiotic, and antioxidative effects. These effects may be attributable to a powerful flavonoid pigment-containing compounds, such as quercetin and alk(en)yl cysteine sulphoxides (ACSOs). Although antiplatelet and antithrombotic activities of onion have been confirmed by many of in vitro or animal studies, only a few human intervention studies have been examined. The majority of human studies identified that onion improves some cardiovascular markers such as lipid profile and platelet coagulant. With regard to antioxidative effects, somewhat positive effects are confirmed through strengthening the resistance of oxidative DNA damage in lymphocyte and urine, while most studies failed to find inhibitory effects on LDL oxidation. The discrepancies among studies might be ascribed to producing area, processing methods of onion, dosage, subject characteristics, study duration, and measurement methods. In this review, we focused on the preventive effect of cardiovascular disease through onion consumption in human intervention studies.

• Journal of the Korean GEO-environmental Society
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• v.11 no.6
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• pp.69-75
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• 2010

Total suspendid solid (TSS) of non point source pollutants in construction site are in higher concentration than others (BOD, COD etc). Also, the TSS concentration is very sensitive to the rainfall intensity in early stage of construction. There are two methods for treatment of non point source pollutants, which are temporary treatment facility and filtering one. But they have disadvantages. Temporary facility system has very low efficiency and filtering system consumes high energy and takes up large footprint. This study shows how prefabricated flocculation/coagulation system is developped to cover the above weakness and evaluation of the system performance in construction site. The prefabricated flocculation/coagulation system has very high treatment efficiency comparing with temporary and filtering system and takes small footprint. Therefore, it expects that the system leads to prevention of pollution near construction site and reduction of public grievance. Proper coagulant dosage and sludge circulation facility application, controlling the height of sludge interfacial are necessary to maximize the system efficiency.

• Journal of Environmental Impact Assessment
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• v.28 no.3
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• pp.332-345
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• 2019

The purpose of the study is to evaluate the treatability of contaminated groundwater with TPH and (or) $Cr^{6+}$. Laboratory scale tests were performed for oil/water separation, dissolved air flotation (DAF), coagulation and precipitation, and filtration with sand and activated carbon respectively. Two times of oil/water separation tests for total 40 minutes of separation or separating time shows 90.2 % of TPH removal rate. In case of DAF test for high TPH sample, the TPH removal rates were not varied significantly by the variation of microbubble size. However, tests for low TPH samples show that TPH removal rate increases as microbubbles are smaller. When coagulant was added to sample for DAF test, TPH removal rate was increased 12.3 %. SS removal rate by DAF was 97.9 % at $16-40{\mu}m$ and it was increased as the size of microbubble is reduced. Tests for coagulation and precipitation were performed to evaluate the removal of $Cr^{6+}$ in groundwater. The increase of $FeSO_4$ dosage increased $Cr^{6+}$ removal rate in the coagulation and precipitation process. As the amount of activated carbon in the filter media increased TPH removal rate in the filtration process. SS removal rate by the filtration was 96.7 % similar to the results of DAF process tests. The filtration process treats TPH and SS. Best design parameters are determined as the size of sand is $425-850{\mu}m$ and the ratio of activated carbon and sand is 50:50.

• Journal of Korean Society of Water and Wastewater
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• v.28 no.6
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• pp.623-634
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• 2014

This study examined a feasibility of coagulation as post-treatment to remove sulfide and phosphorus for the effluent of anaerobic fluidized bed reactor (AFBR) treating domestic wastewater. Removal efficiencies of sulfide, phosphorus and COD by coagulation were not affected by pH in the range of 5.9 to 7.2. Alkalinity requirement could be estimated by the amount of $Fe^{3+}$ to form $Fe(OH)_{3(S)}$ and to remove sulfide and phosphorus. At coagulant aid dosage of 2 mg/L, anionic polymer showed best results regarding size and settleability of flocs. Sulfide removal for the AFBR effluent at the $Fe^{3+}/S^{2-}$ ratio of 0.64, close to the theoretical value of 0.67 found with a synthetic wastewater, was only 75.2%. One of the reasons for this high $Fe^{3+}/S^{2-}$ ratio requirement is that the AFBR effluent contains sulfide, phosphorus, hydroxide and bicarbonate which can react with $Fe^{3+}$ competitively. Concentrations of sulfide and phosphorous reduced to below 0.1 and 0.5 mg/L, respectively, at the $Fe^{3+}/S^{2-}$ ratio of 2.0. Average effluent COD of 80 mg/L, mostly soluble COD, was obtained at the dosage 50 mg $Fe^{3+}/L$ ($Fe^{3+}/S^{2-}$ ratio of 2.0) with corresponding COD removal of 55%. For better removal of COD, soluble COD removal at the AFBR should be enhanced. Coagulation with $Fe^{3+}$ removed sulfide, phosphorus and COD simultaneously in the AFBR effluent, and thus could be an alternative process for the conventional wastewater treatment processes where relatively high quality effluent is not required.