• 한국물환경학회지
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• 제23권6호
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• pp.843-849
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• 2007

Monitoring of NOM characteristics is important for improving removal efficiency of natural organic matter (NOM) in water treatment processes. In this study, several NOM characteristics, which include specific UV absorbance (SUVA), total carbonate content, molecular weight distribution, and fluorescence properties, were measured using samples collected from a pilot-scale water treatment plant consisting of coagulation/flocculation (C/F), filtration, ozonation and granular activated carbon (GAC) processes. The highest removal of NOM was observed in C/F and filtration processes as demonstrated by the reduction of dissolved organic carbon (DOC) by 25% and 21%, respectively. Despite nearly no change in DOC, however, the lowest SUVA value and the highest total carbohydrate content were observed in the sample from ozonation process. This indicates that non-degradable aromatic compounds become depleted and biodegradable organic compounds are enriched during the process. Comparison of synchronous fluorescence spectra of the samples showed that ozoation process increased protein-like fluorescence while it decreased fulvic-like and terrestrial humic-like fluorescence. Consistently, a slight peak of protein-like fluorescence was observed in the sample from ozonation process. The greatest change in molecular weight distributions of the samples was observed in C/F process. Comparison of size exclusion chromatogram of the samples revealed that NOM fractions with the molecular weight greater than 2000 Da were reduced by over 90% after C/F process. SUVA values and total carbohydrate content of the samples were well correlated with a ratio of protein-like fluorescence and terrestrial humic-like fluorescence intensities with the correlation coefficients of 0.99 and 0.91, respectively. This suggests that synchronous fluorescence properties of NOM could be used as useful tolls for monitoring changes of some NOM characteristics during water treatment processes.

• 농약과학회지
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• 제3권2호
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• pp.29-36
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• 1999

물리화학적 성질이 상이한 두 종류의 토양으로 충전된 유리 column (5 cm I.D. ${\times}$ 30 cm H.)을 이용하여 bipyridylium계 제초제 paraquat의 용탈을 조사하였다. 토양 A (양토)의 벼 재배구와 무재배구에서 117 일 동안 토양 column으로부터 용탈된 $^{14}C$은 각각 총 처리량의 0.42%와 0.54%이었고, 토양 B (사양토)의 경우에는 각각 0.21%와 0.31%이었다. 벼에 흡수된 $^{14}C$은 토양 A와 B에서 각각 3.87%와 2.79%이었고 대부분이 뿌리에 분포하였다. 두 토양 모두에서 총 처리량의 96% 이상이 토양중에 남아 있었고, 특히 $0{\sim}5$ cm 부위에 대부분 존재하였다. Paraquat 토양잔류물의 물에 의한 추출율은 $6.10{\sim}9.10%$이었고 추출불가 토양잔류물의 분포비율은 humin>humic acid>fulvic acid 순이었다. 벼 무재배구의 토양 pH는 담수의 혐기적 조건때문에 용탈실험 후 증가하였으나 벼 재배구에서의 토양 pH는 벼 뿌리로부터 분비되는 삼출물에 의한 상쇄효과로 증가되지 않았다. 토양중 paraquat의 낮은 이동성은 논에 잔류되어 있는 paraquat에 의한 지하수의 오염가능성이 매우 희박함을 시사해 준다.

• 한국지하수토양환경학회:학술대회논문집
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• 한국지하수토양환경학회 2006년도 총회 및 춘계학술발표회
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• pp.49-53
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• 2006

The possibility of removal of PCBs (Polychlorinated Biphenyls) in soil was studied using biological method. The effects of soil and co-substrate on both PCBs reduction rate and chloride ion concentration in soil were investigated. It was shown that PCBs concentration of all the soils used in this study were reduced from 5ppm to below 1ppm after 60days, also chloride ion concentration in slurry increased, Results showed that leaf mold and humic acid as co-substrate do not seem to be effective for biological treatment of PCBs in soil,

• 상하수도학회지
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• 제7권2호
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• pp.34-38
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• 1993

An experimental study was conducted to investigate the effects of chlorine dioxide and ozone on reduction of THM(trihalomethane) formation. Precursor concentration, chlorine concentration, reaction time, pH, and temperature were governing compornents of THM formation. When other conditions are constant, THM formation increased linearly with precursor concentration increased. THM formation increased when pH increased from 5 to 9. In combined treatment with chlorine and chlorine dioxide, chlorine treatment after chlorine dioxide treatment made less THM than any other case does. Ozonation reduced THMFP(THM formation potential) of THM precursor. THMFP decreased exponentially with reaction time increased. Also biodegradability of humic acid was enhanced by ozonation.

• 미생물학회지
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• 제38권2호
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• pp.133-138
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• 2002

금속 이온 환훤 세균에 의한 철(III)환원은 생물지구화학적 물질순환(biogeochemical cycle)에 무척 중요하다. 이는 크롬(Ⅵ)이나 우라늄(Ⅵ)과 같은 독성 중금속 물질의 환원과 유기물질의 산화에 모텔이 되기 때문이다. 총 37균주의 Fe (III)환원 세균을 소양호와 천호지의 저질토에서 각각 분리하였다. 두 정점 중 초기 Fe (II)의 함유량이 가장 높았던 것은 소양호의 저질토였으나 Fe (III)환훤능은 반대로 가장 낮은 Fe (II)함유량을 보여 주었던 천호지가 높게 나타났다. 또한 분리한 균주 중 천호지에서 분리한 균주 C2와 C3가 가장 높은 Fe (III) 환훤능을 보여 주었으며 이 균주를 이용하여 다양한 전자 공여체의 이용 여부를 실험하였다. Glucose, yeast extract, acetate, ethanol, toluene등을 이용하여 실험한 결과 두 균주 모두 glucose와 yeast extract만을 전자 공여체로 이용하였다. 또한 전자 수용체로 토양에 광범위하게 존재하는 humid acid와 nitrate를 이용하였으며 수율이 높은 nitrate reduction에 의해 환원되었던 humic acid가 다시 재 산화되는 것을 관촬할수 있었다. 활성능이 우수한 균주 C2와C3의 165S rRNA유전자 분석 결과에 의하면 Aeromonas hydrophila와 95%의 유사성을 보여주었다.

• 한국지하수토양환경학회:학술대회논문집
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• 한국지하수토양환경학회 2003년도 International Symposium
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• pp.111-124
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• 2003

기존의 오염물질을 제거하는 많은 화학적-물리적 정화 방법은 고비용과 오랜 시간을 요구하는 처리 과정 등의 단점을 갖고 있는 경우가 많았다. 따라서 흙과 수(水)환경내로 유입된 오염물질을 빠른 시간 내에 제거 할 수 있는 대안이 요구 되었다. 흙에 유출된 화합 물질 중 상당양은 흙에 의해 격리, 구속되고 이로 인해 일단 구속된 오염물질은 물과 유기 용매에 의해서도 잘 추출되지 않는 것으로 보고 되고 있다. 이러한 흙에 의한 오염물질의 비유동성(immobilization) 과정은 오염물질의 제거 기술의 대안으로 평가 될 수 있다. 기존 연구자들의 연구 결과, 화학적 혹은 물리적 반응 작용을 통해 오염물질을 흙을 구성하는 물질에 구속할 수 있음이 증명되었다. 이러한 과정 중 환경적 측면에서 볼 때, 화학적 반응이 더 우수하다 할 수 있다. 이는 강한 공유결합(covalent bonds)으로 연결될 경우 미생물의 활동이나 화학 처리로도 이를 분리하기 어렵기 때문이다. 리그닌(lignin) 분해에서 발생하는 휴믹(humic) 물질 등이 안정 된 화학적 연결을 통해 흙 매질 내에 오염물질과 결합하는 대표적 물질이다. 인위적으로 제조된 많은 화학물질은 자연적에서 발생하는 휴민산 발생원(humic acid precursors)과 닮았다. 따라서 화학물은 부식 과정(humifications process)동안 부식토(humus) 내로 병합(incorporate)되어 진다. 일단 이렇게 구성된 결합체는 생물체와 오염물질과의 반응을 방지하여 오염물질로 인한 생물체로의 독성을 감소시키는 역할을 하게 된다. 본 논문에서는 이러한 흙의 유기물(organic matter)와 오염물질과의 결합체에 대한 평가로서 다음의 항목에 대한 고찰이 이루어져야 함을 강조하였다. (a)결합체에서 생물체(biota)와의 반응에 의해 오염물질은 감소되는가\ulcorner (b) 모(parent) 화합물과 비교하여 복합체 생성물(complexed products)이 얼마나 덜 유독한가\ulcorner 그리고 (c)지하수 오염이 오염물질의 유동성 구속에 의해 얼마나 감소되는지\ulcorner

• Membrane and Water Treatment
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• 제13권2호
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• pp.97-104
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• 2022

With a small particle size, specific surface area and chemical nature, Pd/Cu-Fe nanocomposites can efficiently remove the organic compounds. In order to understand the applicability for in situ remediation of contaminated groundwater, the degradation of p-nitrophenol by Pd/Cu-Fe nanoparticles was investigated. The degradation results demonstrated that these nanoparticles could effectively degrade p-nitrophenol and near 90% of degradation efficiency was achieved by Pd/Cu-Fe nanocomposites for 120 min treatment. The efficiency of degradation increased significantly when the Pd content increased from 0.05 wt.% and 0.10 wt.% to 0.20 wt.%. Meanwhile, the removal percentage of p-nitrophenol increased from 75.4% and 81.7% to 89.2% within 120 min. Studies on the kinetics of p-nitrophenol that reacts with Pd/Cu-Fe nanocomposites implied that their behaviors followed the pseudo-first-order kinetics. Furthermore, the batch experiment data suggested that some factors, including Pd/Cu-Fe availability, temperature, pH, different ions (SO42-, PO43-, NO3-) and humic acid content in water, also have significant impacts on p-nitrophenol degradation efficiency. The recyclability of the material was evaluated. The results showed that the Pd/Cu-Fe nanoparticles have good recycle performance, and after three cycles, the removal rate of p-nitrophenol is still more than 83%.

• Advances in environmental research
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• 제10권1호
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• pp.59-86
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• 2021

Landfilling is the most commonly adopted method for a large quantity of waste disposal. But, the main concern related to landfills is the generation of leachate. The leachate is high strength wastewater that is usually characterized by the presence of high molecular recalcitrant organics. Several conventional methods are adopted for leachate treatment. However, these methods are only suitable for young leachate, having high biodegradability and low toxicity levels. The mature and stabilized leachate needs advanced technologies for its effective treatment. Advanced oxidation processes (AOPs) are very suitable for such complex wastewater treatment as reported in the literature. After going through the literature survey, it can be concluded that Fenton-based approaches are effective for the treatment of various high/low strength wastewaters treatment. The applications of the Fenton-based approaches are widely adopted and well recognized due to their simplicity, cost-effectiveness, and reliability for the reduction of high chemical oxygen demand (COD) as reported in several studies. Besides, the process is relatively economical due to fewer chemical, non-sophisticated instruments, and low energy requirements. In this review, the conventional and advanced Fenton's approaches are explained with their detailed reaction mechanisms and applications for landfill leachate treatment. The effect of influencing factors like pH, the dosage of chemicals, nature of reaction matrix, and reagent ratio on the treatment efficiencies are also emphasized. Furthermore, the discussion regarding the reduction of chemical oxygen demand (COD) and color, increase in biodegradability, removal of humic acids from leachate, combined processes, and the pre/post-treatment options are highlighted. The scope of future studies is summarized to attain sustainable solutions for restrictions associated with these methods for effective leachate treatment.

• 한국물환경학회지
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• 제24권1호
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• pp.123-128
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• 2008

The Dissolved Organic Carbon (DOC) existing in a water includes both hydrophobic and hydrophilic substances however, most of the discussion focuses on hydrophobic substances. The hydrophobic fraction was easily removed by absorption or coagulation more than hydrophilic fraction. Therefore, control of the hydrophilic fraction is very important in water treatment process. This study is to determine the variation of DOC, the removal efficiency of DOC, and Trihalomethane formation potential (THMFP) after each stage of water treatment process by fractionating Natural Organic Matters (NOM) into hydrophobic and hydrophilic substance. DOC from raw water was fractionated at acidic pH (pH<2) using XAD 8 resin column, into two fraction : hydrophobic substance (i.e. humic substance) adsorbed on XAD 8 and hydrophilic substance which represent the organics contained in the final effluent. THMFP was carried out according to the following set condition: Cl2/DOC=4 mg/mg, incubation at $25^{\circ}C$ in darkness, pH 7 adjust with HCl or NaOH as necessary, and 72hour-contact time. THMs analyzed in this study were chloroform, bromodichloromethane, dibromochloromethan, and bromoform. Sewage was almost evenly split between the hydrophobic (56%) and hydrophilic fraction (44%). But, Aldrich humic substance (AHS) was found to contain less hydrophilics (14%) than hydrophobics (86%). The formation of THMs may depend on the source which is characterized by the composition of organic matters such as AHS and sewage. The THMFP yield of sewage and AHS were assessed as follows. The value of the THMFP reaction yield, AHS $172.65{\mu}g/mg$, is much higher than that of sewage $41.68{\mu}g/mg$. This illustrates possible significant difference in THMFP according to the component type and the proportion of organic matter existing in water source. Apparently AHS react with chlorine to produce more THMFP than do the smaller molecules found in sewage. Water treatment process may reduce THMFP, nevertheless residual DOC (the more hydrophilic substance) has significant THMFP. Further reduction in organic halide precursors requires application of alternative treatment techniques.

• 상하수도학회지
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• 제18권5호
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• pp.588-597
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• 2004

In this research, we investigated the variation of transmembrane pressure and permeate water quality with pre coagulation and sedimentation with iron based coagulant and chlorination of feed water for PVDF (polyvinylidene fluoride) based MF membrane filtration. NaCIO was fed to the membrane module with dosage of 0.5mg/L and maintained during filtration. To observe the effect of raw water, three types of raw and processed waters, including river surface water, coagulated water and coagulated-settled water, were applied. In case of river surface water, the transmembrane pressure increased drastically in 500 hours of operation. On the contrary, no significant increase in transmembrane pressure was observed for 1,200 hours of operation for coagulated water and coagulated-settled waters. The turbidity of permeate was lower than a detection limit of equipment for all raw waters. The removal efficiency of humic substances of coagulated water and coagulated-settled water was approximate ten times of that of surface river water. And, the removal efficiency of TOC and DOC was approximate two times of that of surface river water. From the results of plant operation, stable operation was maintained at $0.9m^3/m^2{\cdot}day$ filtration flux through the combination of pre-coagulation and pre-chlorination. However, the water quality of permeate was the best when pre-coagulation-sedimentation process was combined with pre-chlorination.