• Journal of environmental and Sanitary engineering
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• v.19 no.3 s.53
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• pp.13-21
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• 2004

This study was focused on the evaluation of Nanjido landfill site by leachate analysis. Several parameters, for example pH, BOD, $COD_{Mn},\;COD_{Cr}$, SS, TP, $NH_3-N$, Color, were selected as major leachate quality parameters. $BOD/COD_{Cr}$. was used to estimate the biodegradable portion in organic matter. Samples were collected at the leachate storage wells and leachate treatment facility inflow in each quarter of 2003. The results were as follows : 1. Inflow quality of treatment plant in 2003 was analysed as $pH\;7.3\~8.0,\;BOD\;12.4\~30.0mg/L,\;COD_{Mn}\;101.2\~130.3mg/L,\;COD_{Cr}\;122.5\~238.0mg/L,\;SS\;16.1\~115.3mg/L$, $T-P\;0.27\~0.80mg/L,\;NH_3-N\;208.0\~~354.0mg/L$, Color $110.3\~129.0$ unit. 2. $BOD/COD_{Cr}$ of inflow ranged between $0.07\~0.16$ indicating that the landfill had the properties of old-fill and organic portion in leachate was mostly persistent organic matter. 3. Though concentrations of BOD, COD, $NH_3-N$, Color in leachate storage wells were mostly higher in first landfill than in second landfill, $BOD/COD_{Cr}$ ranging from 0.03 to 0.20, showed reversely. 4. Correlation coefficient$(R^2)$ between color and other parameters related to organic matter showed mostly above 0.7 and especially highest value with $COD_{Mn}$ of 0.7985.

• Journal of environmental and Sanitary engineering
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• v.12 no.3
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• pp.19-29
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• 1997

The Chemical Oxygen Demand(COD) by potassium permanganate and potassium dichromate is used as a measure of the organic matter content of a sample. Newly proposed $K_{2}Cr_{2}O_{7}$ analysis method to be list at Korean Official Method was made from analysis and comparison of the experimental process on Japanese Industrial Standard(JIS), American Open Reflux and Closed Reflux Methods. New $K_{2}Cr_{2}O_{7}$ method had better the qualitative and reproducible COD results than another methods as a result of the tested four times repeatedly by using Lakes water Plant wastewater. The COD data ratio by $KMnO_{4}$ and $K_{2}Cr_{2}O_{7}$ methods was 2-3, 3, 2-17 and 3-4 times respectively when its data had compared with the lakes water and treated water of domestic and experimental wastewater, and raw wastewater which is generated at the manufacturing process of 6 steps and treated wastewater of chemistry source. Its ratio indicated to 2-4 and 2-3 times respectively on raw wastewater and plant wastewater of Chemistry, rubber and plastic, fiber, metal molding source. Oxidation ratio of benzene and ethyl benzene by $KMnO_{4}$ method was nearly zero, but the oxidation ratio by $K$_{2}Cr_{2}O_{7}$ method was 50%, 70% respectively. Also, Oxidation ratio of phenol by $KMnO_{4}$ and $K_{2}Cr_{2}O_{7}$ methods was 80%, 100% respectively, and trichloroethylene and tetrachloroethylene were not nearly oxidizd by $KMnO_{4}$ and $K_{2}Cr_{2}O_{7}$ methods. As the above contents, oxidation ratio and COD results by $KMnO_{4}$ and $K_{2}Cr_{2}O_{7}$ were different from various from various compounds and samples respectively.

• Journal of Environmental Science International
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• v.13 no.11
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• pp.987-991
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• 2004

The purpose of this research is to evaluate the removal efficiencies of COD$\_$Cr/ and color for the dyeing wastewater by the different dosages of ferrous solution and H$_2$O$_2$ in Fenton process. In the case of H$_2$O$_2$ divided dosage for the Fenton's reagent 7:3 of H$_2$O$_2$ was more effective than 3:7 to remove COD$\_$Cr/ and color. The results showed that COD$\_$Cr/ was mainly removed by Fenton coagulation, where the ferric ions are formed in the initial step of Fenton reaction. On the other hand color was removed by Fenton oxidation rather than Fenton coagulation. The removal mechanism of COD$\_$Cr/ and color was mainly coagulation by ferrous ion, ferric ion and Fenton oxidation. The removal efficiencies were dependent on the ferric ion amount at the beginning of the reaction. However, the final removal efficiency of COD$\_$Cr/ and color was in the order of Fenton oxidation, ferric ion coagulation and ferrous ion coagulation. The reason of the highest removal efficiency by Fenton oxidation can be explained by the chain reactions with ferrous solution, ferric ion and hydrogen peroxide.

• Journal of Environmental Impact Assessment
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• v.8 no.1
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• pp.81-92
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• 1999

This study discussed the appropriateness of organic matter indexes such as biochemical oxygen demand(BOD) and chemical oxygen demand with potassium permanganate($COD_{Mn}$) in water quality environmental standard of streams and lakes and the applicability of the items to water quality environmental standard to add or substitute COD with potassium dichromate ($COD_{Cr}$) and total organic carbon(TOC) being used as index of organic matter. And indexes of organic matter content and organic carbon concentration were distinguished between dissolved and particulate component in water sample to estimate their effect on pollutants loading in lake and stream. The ratio of $COD_{Cr}$/BOD was 5.1 under BOD concentration 3mg/L in river water quality environmental standard II, and 2.67 above it. This ratio was diminished to 2.04 when BOD concentration was more than 8mg/L, in river quality environmental standard IV. Also the ratio of $COD_{Mn}$/BOD showed 2.16 under 3mg/L(BOD), and 1.1 above it. This ratio is also diminished to 0.84 over 8mg/L(BOD). Accordingly, we should apply this ratio depending on the concentration level to add and change organic matter index of water quality environmental standard newly. The ratio $COD_{Cr}/COD_{Mn}$ both in lake and stream shows 2.37(r=0.986, p<0.001). But the ratios showed range of 2.34~2.50, which is no much difference of this ratio according to $COD_{Mn}$ concentration.

• Journal of Korean Society of Environmental Engineers
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• v.34 no.8
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• pp.517-522
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• 2012

In this study, not only making an effort to find a solution for sewage and wastewater treatment, but also demonstrating a feasibility of wastewater disposal process which is treated with the cohesion and adsorption mechanism of sewage and wastewater using quartz porphyry and zeolite, which is a domestic natural resource. By using a jar test, we evaluated removal efficiency of $COD_{Cr}$ after reation. According to the result of experiment, when we injected 400~1,200 g/L of quartz porphyry and zeolite into a sewage as a coagulant, there was no difference of the rejection rates of $COD_{Cr}$, however, when quartz porphyry and zeolite, which were sintered at $600^{\circ}C$, were treated into urban sewage, removal efficiency of $COD_{Cr}$ had increased by about 15%, 3% respectively. In addition, we applied into a cosmetic tissue wastewater by using mixture of quartz porphyry and natural zeolite in order to analyze the applicability of other wastewater as well as Municipal Sewage.

• Applied Chemistry for Engineering
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• v.21 no.6
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• pp.610-615
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• 2010

In this study ozonation of bis(2-chloroethyl) ether (BCEE) in aqueous solution was performed in a laboratory scale batch reacter. The ozonation process of BCEE was carried out by bubbling ozone at the bottom of reactor containing the BCEE solution. Ozonation was almost complete after 80 min with an ozone concentration of $50{\pm}10mg/L$. Ozonation treatment efficiencies of BCEE were evaluated in terms of $BOD_5$, $COD_{Cr}$, and TOC. In the ozonation of BCEE a 62.79% decrease of the $COD_{Cr}$ and a 57.25% decrease of the TOC lead to biodegradable by-products ($BOD_5/COD_{Cr}$ = 0.39). The results of this research show that wastewaters containing non-biodegradable compounds, such as BCEE can be successfully treated by ozonation followed by bio-treatment. The pseudo first-order rate constants of the ozonation was $2.00{\times}10^{-4}sec^{-1}$ and the activation energy was $10.02kcal{\cdot}mol^{-1}$ at $30^{\circ}C$.

• Journal of Korean Society of Environmental Engineers
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• v.35 no.10
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• pp.703-709
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• 2013

Ozonation was performed under various experimental conditions that $Al_2O_3$ catalysts dosage and temperature for removal of DMP in laboratory scale batch reactor. Flow rate of ozone $1.0Lmin^{-1}$ and ozone concentration of $300{\pm}10mgL^{-1}$ were maintained constantly, and the pH, $COD_{Cr}$ and TOC was measured in 10 min intervals during the 60 min at oxidation processes. As a result, the presence of the $Al_2O_3$ than only ozonation increased the removal efficiency of both $COD_{Cr}$ and TOC in solution. The pseudo first-order rate constants for the elimination of $COD_{Cr}$ and TOC were $3.65{\times}10^{-4}sec^{-1}$, $2.52{\times}10^{-4}sec^{-1}$, and activation energy was $0.75kcal{\cdot}mol^{-1}$ and $0.70kcal{\cdot}mol^{-1}$ at $20^{\circ}C$, respectively.

• Microbiology and Biotechnology Letters
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• v.24 no.5
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• pp.597-603
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• 1996

This study was carried out to examine degradation characteristics of microalgae Chlorella vulgaris in methane fermentation. We measured COD and VS reduction, gas and methane productivity, VFA (volatile fatty acid), respectively. Then we calculated material balance and hydrolysis rates in soluble and solid material. The substrate concentration was controlled from 14 gCOD$_{cr}$/l to 64 gCOD$_{cr}$/l in batch cultures, and HRT (hydraulic retention time) controlled from 2 days to 30 days in continuous experi- ments. The results were as follows. In batch culture, accumulated gas productivity increased with the increase of the substrate concentration. The SS and VSS was removed all about 30% increase of substrate concentration and the most of the degradable material removed during the first 10 days. The curve of gas and methane production rate straightly increased until substrate concentration is 26 gCOD$_{cr}$/l. In continuous culture experiments, the removal rates at HRT 10days were 20% for total COD and TOC, respectively. At longer HRT, there was no increase in the removal efficiency. At HRT 15 days, the removal rates were 30% for SS and VSS, respectively. Soluble organic materials were rapidly degraded, and so there was no accumulated. Soluble COD concentration was not increase regardless of HRT-increasing. That meaned the hydrolysis was one of the rate-limiting stage of methane fermentation. The first-order rate constants of hydrolysis were 0.23-0.28 day$^{-1}$ for VSS, and 0.07-0.08 day$^{-1}$ for COD.

• Journal of Korean Society on Water Environment
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• v.31 no.1
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• pp.29-34
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• 2015

The aim of this study is to understand the limitation of organic pollutant indexes ($BOD_5$, $COD_{Mn}$, $COD_{Cr}$) and estimate to set the TOC standard by comparing oxidation rates of $BOD_5$, $COD_{Mn}$, $COD_{Cr}$ and TOC based on the 487 organic compounds and 11 effluents from industrial wastewater containing various and unknown organic compounds. The range of ratio of theoretical oxygen demand (ThOD) to theoretical organic carbon (TOCt) was 0.00~5.33 and average ratio of classes of organic compounds was 2.68~3.70. According to classes of organic compounds, the average ratio of $O_2/C$ was 1.2 (range : 1.02~1.39). The order of oxidation rate for 15 organic compounds was TOC (90.7%) > $COD_{Cr}$ (88.8%) > $BOD_5$ (54.4%) > $COD_{Mn}$ (30.8%) indicating the lower oxidation rate of $BOD_5$ and COD compared with TOC. The ranking for average oxidation rate was $COD_{Cr}$ > $COD_{Mn}$ > $BOD_5$ indicating that $BOD_5$, $COD_{Mn}$ could be underestimated comparing with ThOD of organic compounds in case of industrial wastewater containing high concentration of refractory organic compounds. Most of the relationships between organic pollutant indexes and TOC were higher than 0.9. The ratio of TOC to organic compound indexes decreased in the order : $COD_{Cr}$ (3.4) > $COD_{Mn}$ > (1.9) > $BOD_5$ (0.7).

• Journal of Environmental Science International
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• v.7 no.1
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• pp.81-88
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• 1998

This study was conducted to assess the characteristics of plgment wastewater and the removal rates of appropriate treatment by physical, chemical and biological Process, and the possibility of reuse for effluent. Based on the results, the wastewater qualities of pigment were pH 5.1$\pm$3.4, temperature 43.0$\pm$ 15.$0^{\circ}C$, BOD 1,431.4$\pm$589.6mg/l, COD 2,282.8$\pm$466.5mg/l, turbidity 1,340$\pm$820NTU, color 243.0$\pm$147.0unit, Pb 36.5$\pm$9.5mg/l and $Cr^+6$ 10.3$\pm$ 1.3mg/l, respectively. The removal rates of adsorption by activated carbon and filter process were BOD 40.6% , COD 57.0% , turbidity 89.6%, color 87.2%, Pb 86.0% and $Cr^+6$ 10.6%, respectively. And the removal rates of reduction, neutralization, coagulation and aP floatation process were BOD 18.2%, COD 24.3%, turbidity 74.3%, color 56.7%, Pb 68.6% and $Cr^+6$ 97.8%, respectively. The removal rates of activated sludge process were BOD 95.9%, COD 86.0%, turbidity 27.8%, color 25. 2%. Pb 26.9% and $Cr^+6$ 50.0% , respectively. The total removal rates of treatment by physical, chemical and biological process were BOD 98.0% , COD 95.4%, turbidity 98.1%, color 95.8%, Pb 97.0% and $Cr^+6$ 99.0%, respectively. According to the test results for possibility of reuse with coagulation-adsorption by activated carbon process of effluent, COD was higher than that of raw water and others were similar to that of raw water thus, it Is considered to be reused.