• Title, Summary, Keyword: NOM

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The Effects of Reaction Conditions and NOM on Persulfate Oxidation of RDX (Persulfate에 의한 RDX 산화시 반응조건과 NOM의 영향)

  • Wu, Dabo;Bae, Bum-Han
    • Journal of Korean Society of Environmental Engineers
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    • v.33 no.10
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    • pp.723-730
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    • 2011
  • In this experiment, persulfate, a strong oxidant for ISCO (In-Situ Chemical Oxidation) was used to degraded RDX in artificial ground water at ambient temperature. Results of RDX degradation by persulfate in a batch reactor showed that the oxidation reaction was pseudo first order with estimated Ea (activation energy) of $1.14{\times}10^2kJ/mol$ and the rate was increased with the increase of reaction temperature. The oxidation of RDX by persulfate increased slightly with the increase of initial solution pH from 4 to 8. The RDX oxidation rate increased 13 times at pH 10 compared with that at pH 4, however, alkaline hydrolysis was found to be the main reaction of RDX degradation rather than oxidation. The study also showed that the oxidation rate of RDX by persulfate was linearly dependent upon the molar ratios of persulfate to RDX from 5 : 1 up to 100 : 1, with a proportion constant of $4{\times}10^{-4}$ ($min^{-1}$/molar ratio) at $70^{\circ}C$. While NOM (Natural Organic Matter) exerted negative effects on the oxidation rate of RDX by persulfate, with a proportion constant of $1.21{\times}10^{-4}$ ($min^{-1}{\cdot}L/mg-NOM$) at $70^{\circ}C$ and persulfate/NOM molar ratio of 10/1. The decrease in RDX oxidation rate was linearly dependent upon the added NOM concentration. However, the estimated activation energy in the presence of 20 mg-NOM/L was within 3.3% error compared to that without NOM, which implies the addition of NOM does not alter intrinsic oxidation reaction.

Formation of Organic Chloramines during Monochloramination of Natural Organic Matters (천연유기물과 모노클로라민의 반응시 유기성 클로라민 생성)

  • Lee, Wontae
    • Journal of Korean Society of Environmental Engineers
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    • v.36 no.9
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    • pp.604-608
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    • 2014
  • This study investigated influence of dissolved organic nitrogen (DON) in natural organic matter (NOM) on the formation of organic chloramines upon monochloramination. Ratios of dissolved organic carbon (DOC) to DON of the 16 NOM isolates ranged from 7 to 47 mg-C/mg-N. Levels of organic chloramines maxed in 24 hours at $0.16mg-Cl_2/mg-N$ in average. The yields were relatively lower, but decay of organic chloramines were slower than those upon chlorination. Organic chloramines formed upon monochloramination decreased by 56% in average in 120 h. NOM with lower DOC/DON ratios formed more organic chloramines. NOM fractions such as hydrophobic, hydrophilic, transphilic, and colloidal did not significantly impact formation of organic chloramines. As the monochloramine doses increased, more organic chloramines were produced ($R^2=0.91$). Overestimation of disinfection capacity due to the formation of organic chloramines may not be concerns for monochloramine systems since only 6% of monochloramine could be converted to organic chloramines upon monochloramination of NOM.

A Quantitative Analysis of the Cyclomatic Complexity of the Web Software (웹 소프트웨어의 순환복잡도에 대한 정량적 분석)

  • Kim, JeeHyun
    • Journal of the Korea Society of Computer and Information
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    • v.19 no.2
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    • pp.183-191
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    • 2014
  • In this study Cyclomatic Complexity of Web Software has been analyzed quantitatively by correlation between complexity and Number of Classes(NOC), and Number of Methods(NOM) which are object oriented programming measures. Based on the frequency distribution of complexity, NOC and NOM of software at the Web environment, correlation between complexity threshold and NOC threshold, and NOM threshold has been measured and more than 4,000 ASP files of 10 Web real projects have been used as the sample. The empirical result shows that NOC threshold is 21, NOM threshold is 40 and complexity threshold is 68 as high value, and 8 projects among of 10 except 2 projects with especially high frequency distribution shows that NOC threshold is 12, NOM threshold is 21 and complexity threshold is 52 with relatively low value, so correlation has been found out as exists. And also 8 projects with low threshold of complexity, NOC and NOM were internal management software, and the other 2 projects were external sales service software, Number of Classes and Number of Methods can be defined at the design stage according to business properties, and also the complexity can be estimated in order to improve the software quality.

Characterization of Organic Matters Removed by Biological Activated Carbon (생물활성탄처리에서 제거된 유기물 특성)

  • Kim, Woo-Hang;Mitsumasa, Okada
    • Journal of Environmental Science International
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    • v.16 no.6
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    • pp.671-675
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    • 2007
  • The objective of this study was to clarify the characteristics of the removed micropollutant since the breakthrough of adsorption ability was occurred in biological activated carbon(BAC) process. The removal efficiency of DOC (Dissolved Organic Carbon) was 36 % in the breakthrough of BAC occurred by NOM (Natural Organic Matter). The most of removal DOC was found out the adsorbable and biodegradable DOC (A&BDOC). But it was not clear to remove by any mechanism because A&BDOC have simultaneously the adsorption of activated carbon and biodegradation by microorganism in BAC. The removal of bromophenol was examined with BAC and rapid sand filter, for investigation of DOC removal mechanism in the breakthrough of BAC. In this experiment, BAC filter has been operated for 20 months for the treatment of reservoir water. The BAC filter was already exhausted by NOM. Bromophenol, adsorbable and refractory matter, was completely removed by BAC filter. Therefore, it might be removed by the adsorption in BAC. Adsorption isotherms of bromophenol were compared to two BACs which was preloaded with 500 daltons and 3,000 daltons of NOM. BAC preloaded with 3,000 daltons of NOM was not decreased to the adsorbability of bromophenol but BAC preloaded with 500 daltons of NOM was greatly decreased to it. These result indicated that NOM of low molecular weight can be removed by adsorption after a long period of operation and the breakthrough by NOM in BAC. Therefore, micropollutants might be removed through adsorption by saturated BAC.

Behavior of Natural Organic Matter(NOM), Chlorine Residual, and Disinfection By-Products(DBPs) Formation in Pulsed UV Treated Water (Pulsed UV 처리수에서의 자연유기물질, 잔류염소 및 소독부산물 생성 거동)

  • Sohn, Jinsik;Han, Jihee
    • Journal of Korean Society of Water and Wastewater
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    • v.26 no.5
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    • pp.685-692
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    • 2012
  • UV technology is widely used in water and wastewater treatment. Many researches have been conducted on microbial disinfection and micro pollutant reduction with UV treatment. However, the study on NOM with UV has limited because low/medium pressure UV lamp is not sufficient to affect refractory organics such as NOM. Pulsed UV treatment using UV flash lamp can be operated in the pulsed mode with much greater peak intensity. The pulse duration is typically in microseconds, whereas the interval between pulses is in the order of milliseconds. The high intensity of pulsed UV would mineralize NOM itself as well as change the characteristics of NOM. Chlorine demand and DBPs formation is affected on the changed amounts and properties of NOM. The objective of this study is to investigate the effect on NOM, chlorine residual, and chlorinated DBPs formation with pulsed UV treatment.

Variation of Natural Organic Matter Characteristics through Water Treatment Processes (정수공정별 천연유기물질의 특성 변화)

  • Hwang, Jeong-Eun;Kang, Lim-Seok;Kim, Seung-Hyun;Yoon, Cho-Hee
    • Journal of Korean Society of Environmental Engineers
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    • v.22 no.7
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    • pp.1253-1261
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    • 2000
  • Natural organic matter (NOM) which occurs ubiquitously in both surface and ground waters, consists of both humic (i.e., humic and fulvic acids) and nonhumic components. NOM in general as well as certain constituents are problematic in water treatment. From a regulatory perspective, concerns focus upon the role of NOM constituents as disinfection byproduct (DBP) precursors. The fractionation of NOM through water treatment processes can provide insight into treatment process selection and applicability. Problematic NOM fractions can be targeted for removal or transformation. Significant source-related differences in NOM were observed among various source waters. This study found that bulk Dissolved Organic Carbon (DOC) concentration was hardly removed by oxidation process. Oxidation transformed high Molecular Weight (MW) hydrophobic fraction into low MW hydrophilic fraction. Ozone reduced s-pecific Ultraviolet Absorbance (SUVA) value more than chlorine. High MW hydrophobic fraction was effectively removed by coagulation process. About 50% of Trihalomethane Formation Potential (THMFP) was removed by coagulation process.

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A Study of Risk Analysis Model on Web Software (웹 소프트웨어의 위험분석 모델에 관한 연구)

  • Kim, Jee-Hyun;Oh, Sung-Kyun
    • Journal of the Korea Society of Computer and Information
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    • v.11 no.3
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    • pp.281-289
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    • 2006
  • Even though software developing environment has been changing to Web basis very fast, there are just few studies of quality metric or estimation model for Web software. In this study after analyzing the correlation between the risk level and property of objects using linear regression, six middle sized industrial system has been used to propose the correlation model of size and Number of Classes(NOC), size and Number of Methods(NOM), complexity and NOC, and complexity and NOM. Among of six systems 5 systems(except S06) have high correlation between size(LOC) and NOM, and four systems(except S04 & S06) have high correlation between complexity and NOC / NOM. As Web software architecture with three sides of Server, Client and HTML, complexity of each sides has been compared, two system(S04, S06) has big differences of each sides compleity values and one system(S06) has very higher complexity value of HTML, So the risk level could be estimated through NOM to improve maintenance in case of that the system has no big differences of each sides complexity.

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Ion Exchange Processes: A Potential Approach for the Removal of Natural Organic Matter from Water

  • Khan, Mohd Danish;Ahn, Ji Whan
    • Journal of Energy Engineering
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    • v.27 no.2
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    • pp.70-80
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    • 2018
  • Natural organic matter (NOM) is among the most common pollutant in underground and surface waters. It comprises of humic substances which contains anionic macromolecules such as aliphatic and aromatic compounds of a wide range of molecular weights along with carboxylic, phenolic functional groups. Although the concentration of NOM in potable water usually lies in the range of 1-10 ppm. Conventional treatment technologies are facing challenge in removing NOM effectively. The main issues are concentrated to low efficiency, membrane fouling, and harmful by-product formation. Ion-exchangers can be considered as an efficient and economic pretreatment technology for the removal of NOM. It not only consumes less time for pretreatment but also resist formation of trihalomethanes (THMs), an unwanted harmful by-product. This article provides a comprehensive review of ion exchange processes for the removal of NOM.

Effect of pore characteristics of activated carbon on adsorption of natural organic matter (활성탄의 세공이 자연유기물질의 흡착에 미치는 영향)

  • Pak, Jung-Sun;Hong, Seong-Ho
    • Journal of Korean Society of Water and Wastewater
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    • v.25 no.2
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    • pp.249-255
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    • 2011
  • It is complicate problem to optimize removing natural organic matter (NOM) by activated carbon in drinking water treatment because the activated carbon has heterogeneous surface area and pore structure. Seven different coals based activated carbons which have different pore structures were used in the study. Sand filtered effluents which normally used as GAC adsorber influent were used. The molecular weight distribution showed that most of the NOM was bigger than 10,000Da. In this study, systematical approaches such as characteristics of surface area and pore volume were evaluated on NOM adsorption. Especially, the adsorption capacities for NOM were evaluated by effect of micro-pores and meso-pores in surface area and pore structure. The results show that the higher ratio of meso-pore compare to the micro-pore has not only the better adsorption capacities for NOM but also the higher strongly-adsorbable fraction. Therefore, the overall adsorption capacity is increased with higher meso-pore ratio with existing of reasonable micro-pore surface area and volume.

Molecular size distribution of NOM after ozonation and its effect on adsorption with activated carbon (NOM의 오존처리에 따른 분자크기분포변화가 활성탄 흡착에 미치는 영향)

  • Lee, Hyung-Jik;Hong, Seong-Ho
    • Journal of Korean Society of Water and Wastewater
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    • v.27 no.6
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    • pp.805-813
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    • 2013
  • In this study, molecular size distribution of natural organic matter (NOM) after ozonation was measured and its effect on adsorption capacity of activated carbon was investigated. According to the results, the molecular size of NOM was limitedly changed. Specifically, the molecular size of NOM between 5,000 to 10,000 Da were slightly decreased with increasing ozone doses. The adsorption capacity after ozonation was evaluated using Freundlich isotherm with ideal adsorbed solution theory (IAST) which simulated the multi components adsorption. Further, mini-column test was conducted. The Freundlich constant, K was reduced after ozonation and the non-adsorbable fraction was increased with ozonation. However, no correlation between K and ozone doses was found. The present study also agreed with the correlation between adsorption capacity and pore size characteristics of activated carbon.