• Environmental Engineering Research
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• 제10권3호
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• pp.105-111
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• 2005

The applicability of the USEPA's (United States Environmental Protection Agency) three criteria of enhanced coagulation (criterion 1-TOC level less than 2 mg/l. before chlorination; criterion II-% requirement of TOC removal; criterion III-point of diminishing return) for Korean waters was evaluated in this study. This study also investigated an effect of enhanced coagulation on turbidity removal, and attempted to identify the best coagulant for enhanced coagulation. Three different waters were used in this study: one river water and two lake waters. five different coagulants were used: alum, liquid alum, PACl, ferric chloride with and without water. Results of this study showed that all three criteria were achievable for the tested waters. For these waters, controlling criterion was found to be different depending upon raw water characteristics. When initial Toe level was low(< 4 mg/L), criterion I (< 2 mg/L) could be the controlling criterion. As TOC level increased, criterion II (% TOC removal) became the controlling criteria. It was possible to achieve different goals of turbidity and TOC removals. Although the optimum region of TOC removal was more acidic than that of turbidity removal, there was no conflict between these two removals. The best coagulant was found to be different depending upon the evaluation tool: maximum and optimum removal. ferric chloride was more effective than alum in terms of the maximum TOC removal, while Al-based coagulant such as alum or PACl was the best coagulant in terms of the optimum TOC removal.

• 분석과학
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• 제13권2호
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• pp.234-240
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• 2000

수질계의 부식산을 화학적 산화처리하기 위한 방법의 하나로 광산화공정을 도입하여 부식산의 특성 변화를 조사하였다. 광산화공정은 UV단독, UV/$TiO_2$ 및 UV/$H_2O_2$ 시스템을 실험하였다. UV 단독 조사시 TOC 제거율은 pH 7-9에서 가장 높았으며, 흡광도는 강알카리성 영역에서 감소율이 향상된 결과를 보였다. 각 시스템별로 처리도를 보면, UV/$TiO_2$ 시스템의 경우 $TiO_2$ 의 농도가 50ppm 일때 TOC 제거와 흡광도 감소의 효율이 높았으며 50ppm 이상을 투입해도 처리율에 변화가 없었다. UV/$H_2O_2$ 시스템에서는 과산화수소의 농도가 20mM이 최적의 주입농도로 조사되었으며, 그 이상 투입할 경우 TOC와 흡광도의 처리율이 저하되었다. 탄산이온을 첨가할 경우, TOC 제거율 및 UV 흡광도의 감소율 모두 감소하며, TOC 제거율이 흡광도 감소율에 비해 상대적으로 더 크게 나타났다.

• 한국환경과학회지
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• 제11권9호
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• pp.955-960
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• 2002

The recycled washwater, which has different water quality and is produced about 5 to 20% of the total water volume treated, affects the unit operation of water treatment, especially coagulation process. However, the effects of recycled washwater on unit operation of water treatment have not been fully investigated. In this study, effects of recycled washwater on coagulation process were investigated to find the optimum coagulation condition by analyzing turbidity, $UV_{254}$, TOC removal efficiencies. In addition, effects of recycled washwater on residual Al after coagulation were studied by analyzing soluble and particulate Al. The size distribution and fractal dimension of coagulated also analyzed. The recycled washwater was lower pH than the raw water. And the recycled washwater had higher $UV_{254}$, TOC and residual Al concentration than the raw water. Residual Al concentration of recycled washwater was about 50 times higher than that of raw water. Optimum coagulant dosages on the blending recycled washwater and the raw water for turbidity, $UV_{254}$ and Al removal were lower than that on the raw water. However, TOC removal increased by increasing coagulant dosage. The size and fractal dimension of coagulated particle produced in the blending recycled washwater were larger, which imply faster settling velocity, than those produced in the raw water only.

• 한국환경보건학회지
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• 제28권3호
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• pp.49-54
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• 2002

Poly acrylamide(PAA)와 활성슬러지를 포괄법 에 의하여 고정화 담체를 제조하였다. 이 고정 화 담체를 이용하여 폐수처리에서의 적용 가능성과 특성을 조사하였다. 본 연구에서는 실제 폐수처리 공정에 적합한 12% acrylamide농도의 담체를 구하였다. 그리고 sequencing batch reactor(SBR)에서 30일 동안 운전한 결과, TOC와 인의 제거효율이 각각 95%와 70%를 나타내었다. 또한 이 연구 결과로부터 반복적인 혐기와 호기 조건의 사이클 운전이 TOC와 인의 제거효율을 향상시킴을 알 수 있었으며, 운전기간 중에 PAA고정화 담체는 깨짐이 없이 사용되었다.

• Journal of Electrochemical Science and Technology
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• 제3권1호
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• pp.44-49
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• 2012

Electrochemical and photochemical techniques have been proved to be effective for the removal of organic pollutants in textile wastewater. The present study deals with degradation of synthetic textile effluents containing reactive dyes and assisting chemicals, using electro oxidation and photo catalytic treatment. The influence of various operating parameters such as dye concentration, current density, supporting electrolyte concentration and lamp intensity on TOC removal has been determined. From the present investigation it has been observed that nearly 70% of TOC removal has been recorded for electrooxidation treatment with current density 5 mA/$dm^2$, supporting electrolyte concentration of 3 g/L and in photocatalytic treatment with 250 V as optimum lamp intensity nearly 67% of TOC removal was observed. The result indicates that electro oxidation treatment is more efficient than photocatalytic treatment for dye degradation.

• 한국환경보건학회지
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• 제26권4호
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• pp.29-37
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• 2000

Fenton’s oxidation process is one of the most commonly applied processes to the wastewater which cannot be treated by conventional biological treatment processes. However, it is necessary to minimize the cost of Fenton’s oxidation treatment by modifying the treatment processes or other means of chemical treatment. So, as a method for the chemical oxidation of biorefractory or nonbiodegradable organic pollutants, the Photo-Fenton-Reaction which utilizes iron(11)salt. $H_2O$$_2$ and UV-light simultaneously has been proprosed. Therfore, the purpose of this study is to test a removal efficiency of dye-wastewater and treatment cost with Fenton’s and Photo-Fenton’s oxidation process. The Fe(11)/$H_2O$$_2$ reagent is referred to as the fenton’s reagent. which produces hydroxy radicals by the interaction of Fe(11) with $H_2O$$_2$. In this exoeriment, the main results are as followed; 1. The Fenton oxidation was most efficient in the pH range of 3-5. The optimal condition for initial reaction pH was 3.5 for the high CO $D_{Cr}$ & TOC-removal efficiency. 2. The removal efficiency of TOC and CO $D_{Cr}$ increased up to the molar ration between ferrate and hydrogen peroxide 0.2:1, but above that ratio removal efficiency hardly increased. 3. The highest removal efficiency of TOC and CO $D_{Cr}$ were showed when the mole ration of ferrate to hydrogen peroxide was 0.2:3.4. 4. Without pretreatment process, photo-fenton oxidation which was not absorbed UV light was not different to fenton oxidation. 5. And Fenton oxidtion with pretreatment process was similar to Fenton oxidation in the absence of coagulation, the proper dosage of F $e^{2+}$: $H_2O$$_2$ was 0.2:1 for the optimal removal efficiency of TOC or CO $D_{Cr}$ .6. Also, TOC & CO $D_{Cr}$ removal efficiency in the photo-fenton oxidation with pretreatment was increased when UV light intensity enhanced.7. Optimum light intensity in the range from 0 to 1200 W/$m^2$ showed that UV-intensity with 1200W/$m^2$ was the optimum condition, when F $e_{2+}$:$H_2O$$_2$ ratio for the highest decomposition was 0.2:2.5.EX>$_2$ ratio for the highest decomposition was 0.2:2.5.

• 한국환경보건학회지
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• 제29권2호
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• pp.1-6
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• 2003

This paper reports on a pilot scale comparison of PACS coagulation with and without pH preadjustment. The pH of the water was adjusted with carbon dioxide and sulfuric acid. Process performance was assessed on the basis of total organic carbon(TOC), UV absorbance, turbidity and disinfection by-product(DBP) precursors. Coagulation pH appeared to be a determining factor for maximum NOM removal. The optimum coagulation pH in order to decrease TOC and turbidity were pH 7. Preadjustment of pH 7 increased TOC removal to as much as 43, 47 percent with sulfuric acid and carbon dioxide. Moreover, coagulation at pH 7 caused a reduction in UV$_{254}$, THMFP and HAAFP compared to the baseline coagulation. For preadjustment of pH 7 with carbon dioxide, the percentage of TOC, UV$_{254}$, THMFP and HAAFP shows the reduction rate of 3.8, 0.5, 4.8, 9.4％ comparing to the coagulation rendition using sulfuric acid. Acid addition to depress pH during coagulation decrease Langelier Saturation Index(LSI), potentially causing increase corrosion in water distribution systems. LSI for carbon dioxide and sulfuric acid at pH 6 was -2.3, -3.3. Therefore, carbon dioxide was more effective at controlling corrosion than sulfuric acid.

• 한국환경보건학회지
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• 제31권5호
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• pp.404-410
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• 2005

The pH efforts on the removal of 1,4-dioxane and the biodegradobility enhancement of dioxane contaminated water were investigated using $O_3/H_2O_2$ baled advanced oxidation process. Experiments were conducted using a bubble column reactor under different initial pH. The $O_3/H_2O_2$ process effectively converted 1,4-dioxane to more biodegradable intermediates which had a maximum $BOD_5$ enhancement at pH 11 within the experimental range, precisely, when the initial pH increased, $BOD_5$ enhanced. However, in case of removal efficiencies of 1,4-dioxane during $O_3/H_2O_2$ oxidation the optimum condition was shown at pH 9 compared with pH 6 and 11. TOC and COD values were not largely changed for all reaction time. From the results of 1,4-dioxane removal efficiency, TOC, COD, and $BOD_5$ enhancement with reaction time, it was surely observed that 1,4-dioxane was just converted to biodegradable materials, not completely oxidized to carbon dioxide.

• Environmental Engineering Research
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• 제25권4호
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• pp.488-497
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• 2020

The present study investigates the feasibility of nitrogenous heterocyclic compounds (NHCs) (Pyridine-Quinoline) degradation by catalytic wet peroxidation (CWPO) in the presence of nanoscale zerovalent iron supported on granular activated carbon (nFe⁰/GAC) using statistical optimization technique. Response surface methodology (RSM) in combination with Box-Behnken design (BBD) was used to optimize the process parameters of CWPO process such as initial pH, catalyst dose, hydrogen peroxide dose, initial concentration of pyridine (Py) and quinolone (Qn) were chosen as the main variables, and total organic carbon (TOC) removal and total Fe leaching were selected as the investigated response. The optimization of process parameters by desirability function showed the ~85% of TOC removal with process condition of initial solution pH 3.5, catalyst dose of 0.55 g/L, hydrogen peroxide concentration of 0.34 mmol, initial concentration of Py 200 mg/L and initial concentration of Qn 200 mg/L. Further, for TOC removal the analysis of variance results of the RSM revealed that all parameter i.e. initial pH, catalyst dose, hydrogen peroxide dose, initial concentration of Py and initial concentration of Qn were highly significant according to the p values (p < 0.05). The quadratic model was found to be the best fit for experimental data. The present study revealed that BBD was reliable and effective for the determination of the optimum conditions for CWPO of NHCs (Py-Qn).

• 대한환경공학회지
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• 제30권12호
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• pp.1273-1280
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• 2008

본 연구에서는 섬유가공공정 중 머서화공정으로부터 가성소다액를 회수하기 위한 최적의 운전조건을 확립하고자 하였다. 주요 인자들로는 NF/RO막의 적용을 위해 세라믹 막을 이용하여 파울링 지수를 평가, 고분자 막의 적용을 위해 가성소다액의 회수율을 측정, 막의 재생율 향상, 화학세정 조건, 유기물부하, 탁도 및 색도의 최적 제거조건, 그리고 세라믹 막과 고분자막의 복합공정에서의 투과플럭스를 조사하였다. 결과에 따르면, 1단계 공정의 세라믹 한외여과막과 2단계 공정의 나노여과막은 총부유고형물, 잔류유기물, 색도를 포함한 탁도의 제거 그리고 가성소다 용액의 회수에 적합한 공정구성임을 확인하였다. 한외여과막만을 단독으로 사용했을 경우, 총 부유물질과 탁도를 99.0%이상 제거하였고, 색도와 TOC는 각각 74.7%와 49.2%의 제거효율을 얻을 수 있었다. 반면에 세라믹 UF+NF 복합막 공정에서는 총 부유물질과 탁도를 99.9%이상 제거할 수 있었고, 색도는 87.7%, TOC는 78.2%의 제거효율을 얻을 수 있었다. 특히, 복합막 공정에서는 83.7%의 부피회수율일 때 91.3% 가성소다를 성공적으로 회수 할 수 있었다. 이러한 측면에서 복합공정을 통해 가성소다 폐수로부터 순도 높은 가성소다액을 회수할 수 있었으며, 회수된 가성소다액은 공정 내에 재사용이 가능하여 경제적인 이득을 기대할 수 있다.