• Journal of Korean Society on Water Environment
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• v.31 no.4
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• pp.392-398
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• 2015

The aim of this study was to investigate the bio-adsorption using modified zeolite with Mg (Mg-zeolite) in the dyeing wastewater treatment. Mg-zeolite adsorbed successfully 100% of the color, suspended solid (SS). chemical oxygen demand (COD), biological oxygen demand (BOD), total nitrogen (TN) and total phosphorus (TP) in the dyeing wastewater at the following optimal Mg-zeolite loading: 20 mg/L for colour, SS, TN and TP, 30 mg/L for BOD and COD. These results indicated that the amount of 1 mg/L Mg-zeolite adsorbed 11.6 mg/L for color, 9.5 mg/L for SS, 45.0 mg/L for COD, 12.7 mg/L for BOD, 0.91 mg/L for TP and 2.25 mg/L for TN. The bio-adsorbent, Mg-zeolite, can be a promising adsorption due to its high efficiency and low dose requirements.

• Journal of Environmental Health Sciences
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• v.42 no.4
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• pp.280-292
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• 2016

Objectives: The objective of this study was to build COD regression models for the Han River and evaluate water quality. Methods: Water quality data sets for the dry season (as of January) during a four-year period (2012-2015) were collected from the database of the Han River automatic water quality monitoring stations. Statistical techniques, including combined genetic algorithm-multiple linear regression (GA-MLR) were used to build five-descriptor COD models. Multivariate statistical techniques such as principal component analysis (PCA) and cluster analysis (CA) are useful tools for extracting meaningful information. Results: The $r^2$ of the best COD models provided significant high values (> 0.8) between 2012 and 2015. Total organic carbon (TOC) was a surrogate indicator for COD (as COD/TOC) with high reliability ($r^2=0.63$ in 2012, $r^2=0.75$ for 2013, $r^2=0.79$ for 2014 and $r^2=0.85$ for 2015). The ratios of COD/TOC were calculated as 2.08 in 2012, 1.79 in 2013, 1.52 and 1.45 in 2015, indicating that biodegradability in the water body of the Han River was being sustained, thereby further improving water quality. The BOD/COD ratio supported these findings. The cluster analysis revealed higher annual levels of microorganisms and phosphorous at stations along the Hangang-Seoul and Hantangang areas. Nevertheless, the overall water quality over the last four years showed an observable trend toward continuous improvement. These findings also suggest that non-point pollution control strategies should consider the influence of upstreams and downstreams to protect water quality in the Han River. Conclusion: This data analysis procedure provided an efficient and comprehensive tool to interpret complex water quality data matrices. Results from a trend analysis provided much important information about sources and parameters for Han River water quality management.

• Korean Journal of Soil Science and Fertilizer
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• v.46 no.4
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• pp.296-302
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• 2013

This study was carried out to investigate the effect of organic content level on ultimate methane potential and anaerobic biodegradability of substrate by biochemical methane potential assay. Three organic matters (whole sludge and liquid and solid fraction of sludge) of the same origin, which had different organic contents, were fermented at the batch anaerobic reactor for 70 days. Ultimate methane potential and anaerobic biodegradability were determined by the terms of volatile solid (VS) and chemical oxygen demand (COD). Volatile solid contents of whole sludge and solid and liquid fraction of sludge were 2.4, 18.8, and 0.2% and COD were 5.3, 30.4, and 0.5%, respectively. Ultimate methane potentials ($B_u$-COD) and anaerobic biodegradability ($D_{VS}$) determined by VS content were $0.5Nm^3kg^{-1}-VS_{added}$, 76.3% for whole sludge, $0.5Nm^3kg^{-1}-VS_{added}$, 76.3% for the liquid fraction of sludge, and $0.6Nm^3kg^{-1}-VS_{added}$, 77.0% for the solid fraction of sludge. Ultimate methane potentials ($B_u$-COD) and anaerobic biodegradability ($D_{COD}$) determined by COD were $0.2Nm^3kg^{-1}-COD_{added}$, 73.4% for whole sludge, $0.2Nm^3kg^{-1}-VS_{added}$, 74.0% for the liquid fraction of sludge, and $0.33Nm^3kg^{-1}-COD_{added}$, 99.1% for the solid fraction of sludge. In conclusion, ultimate methane potential and anaerobic biodegradability given by the VS term showed more reasonable results because COD might be underestimated by the interference of $NH_4{^+}$ in the case of highly concentrated organic material.

• Journal of the Korean Chemical Society
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• v.58 no.1
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• pp.76-79
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• 2014

Petroleum refinery effluents are waste originating from industries primarily engaged in refining crude oil. It is a very complex compound of various oily wastes, water, heavy metals and so on. Conventional processes are unable to effectively remove the chemical oxygen demand (COD) of petroleum refinery effluents. Supercritical water oxidation (SCWO) was proposed to treat petroleum refinery effluents. In this paper, methanol was used to investigate co-oxidative effect of methanol on petroleum refinery effluents treatment. The results indicated that supercritical water oxidation is an effective process for petroleum refinery effluents treatment. Adding methanol caused an increase in COD removal. When reaction temperature is $440^{\circ}C$, residence time is 20 min, OE is 0.5 and initial COD is 40000 mg/L, and COD removal increases 8.5%.

• Journal of Korea Technical Association of The Pulp and Paper Industry
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• v.41 no.5
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• pp.44-49
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• 2009

Old newspaper was deinked using commercial cellulolytic enzymes and a surfactant complex at low alkalinity. The properties of the deinked pulp(DIP) were evaluated and the suspended solids content, cationic demand, turbidity, and chemical oxygen demand(COD) of the process water were measured. The results can summarized as follows, 1. The brightness and yield of the DIP were improved using enzymatic surfactant complex deinking. 2. The amount of foaming during deinking with the enzyme surfactant complex was higher than that with synthetic surfactant deinking. However, it was not sufficient to cause process problem. 3. The pH and turbidity of the white water from deinking with the enzyme surfactant complex were similar to those of the white water from surfactant deinking. 4. The suspended solids content, cationic demand, and COD of the white water from deinking with the enzyme surfactant complex were improved compared to those of the white water from surfactant deinking.

• Ocean and Polar Research
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• v.43 no.2
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• pp.65-72
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• 2021

In order to evaluate the dissolved organic carbon (DOC) and fluorescent dissolved organic matter (FDOM), as indicators of organic matter in the coastal environments, we measured the concentrations of DOC, FDOM, and chemical oxygen demand (COD) in saline groundwater (Woljeong, Pyoseon, and Hwasun beaches) and coastal seawater (Haengwon, Gwideok, Pyoseon, and Yeongnak) in Jeju, Korea. The highest concentrations of DOC and COD in groundwater were found in Woljeong and Pyoseon, and those in coastal water were observed in Haengwon and Pyoseon, indicating that the higher concentrations of DOC and COD seem to be associated with saline groundwater-driven dissolved organic matter (DOM) and/or biogeochemical processes. According to origin and optical properties of DOM using FDOM as a tracer, proportion of humic-like FDOM, more refractory DOM, was relatively greater in the groundwater than in the coastal water. With regard to this result, there was no relationship between DOC and COD in groundwater, while DOC showed a good positive correlation (r² = 0.66) with COD in coastal water. This result indicates that COD as an indicator of assessment of DOM has a limitation in which it is difficult to quantify refractory DOM. Although DOC is a potential alternative to COD in the coastal environments, particulate organic carbon cannot be negligible due to relatively higher concentration compared to the open ocean. Therefore, the use of total organic carbon (TOC) as a replacement of COD in the coastal ocean is important, and the evaluation criterion of the TOC is necessary in order to evaluate of organic matter indicator in the various coastal environments.

• Journal of Korean Society on Water Environment
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• v.22 no.4
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• pp.720-726
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• 2006

Long-term monitoring results of water qualities at major lakes in Korea showed COD (chemical oxygen demand) concentrations have been increasing while BOD (biochemical oxygen demand) concentrations have been decreasing during last decades. This was mainly due to refractory organic matters have been accumulated in the water body. In this study, the possible causes of COD concentration increase were evaluated. From the statistics, it can be understood that potent pollutant sources including fertilizer consumption, population, livestock, and carbon uptake have increased. Leaching tests were carried out with soils and biomasses sampled at agricultural-forestry area. From the leaching experiments, leachate qualities as a ratio of $COD_{Cr}/BOD$ were in the range of 2.5-5.0, implying that NOM (natural organic matters) discharged from the forestry area was mainly responsible for the COD accumulation. It can be understood from this research that diffuse pollutants from forestry areas should be controlled properly to reduce COD accumulation in the lakes.

• Korean Journal of Environmental Biology
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• v.18 no.2
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• pp.227-235
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• 2000

As a part of basic investigation to Fishery Purge Project for the Special Administrative in Chollanamdo Province, the sedimentary environmental characteristics of Yoja Bay at 15 stations were studied. The analysis was carried out in July, 1998, through studies of Loss On Ignition (LOI) by depth, Total Sulfide (T-5), Chemical Oxygen Demand (COD) concentrations and Grain-size distribution. The LOI value was found to be 6.20-12.20% (mean of 8.89%), with the neighboring Sunhakri and Haksanri areas showing slightly higher values. These values were similar to the LOI values observed in the Hansan-Koje Bay and Jinju Bay areas on the southern coast of Korea. T-S and COD concentrations were found to be, respectively, 0.060-0.104 mg/gㆍd (mean of 0.052 mg/gㆍd) and 5.53-29.71 mg/gㆍd(mean of 13.24 mg/gㆍd), not exceeding eutrophication limits. T-S concentration was especially high at stations close to the central areas of the bay and inland areas, which caused by organic matter input from the nearby agricultural areas. COD concentration was very high at stations nearby the bay entrance and Doonbyungdo, but the mean value was lower than that of Hansan-Koje Bay. This leads us to believe that the level of pollution in Yoja Bay is not significant. The prevailing sediment composition was mud, consisting of 61.38% silt and 34.87% clay. [Sediments in Yoja Bay, Loss On Ignition, Total Sulfide, Chemical Oxygen Demand, Grain-Size Distribution].

• Korean Chemical Engineering Research
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• v.47 no.3
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• pp.292-302
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• 2009

The wet oxidation of phenol has been investigated at temperatures from 150 to $250^{\circ}C$ and oxygen partial pressures from 25.8 to 75.0 bar with initial pH of 1.0 to 12.0 and initial phenol concentration of 10 g/l. Chemical Oxygen Demand COD has bee measured to estimate the oxidation rate. Reaction intermediates have been identified and their concentration profiles have been determined using liquid chromatography. The destruction rate of phenol have shown the first-order kinetics with respect to phenol and the changes in COD during wet oxidation have been described well with the lumped model. The impact of various homogeneous catalysts, such as $Cu^{2+}$, $Fe^{2+}$, $Zn^{2+}$, $Co^{2+}$ and $Ce^{3+}$ ions, on the destruction rate of phenol and COD has also been studied. The homogeneous catalyst of $CuSO_4$ has been found to be the most effective for the destruction of phenol and COD during wet oxidations. The destruction rate of formic acid formed during wet oxidations of phenol have increased as increasing temperature and $CuSO_4$ concentration. The final concentrations of acetic acid which has been formed during wet oxidations and difficult to oxidize have increased with reaction temperature and with decrease in the catalyst load.

• Journal of Environmental Science International
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• v.28 no.5
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• pp.465-474
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• 2019

Herein, we analyzed the spatial and temporal variation of DO (dissolved oxygen), BOD (biochemical oxygen demand), and COD (Chemical Oxygen Demand) with the monthly mean observed data for 10 years (2008~2017) in the main stream of the Nakdong River. The water quality of the stations declined in a downstream direction, with the BOD and COD showing their highest values at the ST5 station. From the analysis of the correlation of water quality components at 10 stations, the correlation coefficient between the DO and water temperature was more than -0.90, and that between BOD and Chl-a was 0.48~0.85, and that between COD and TOC was more than 0.65 except for the ST5 and ST10 stations. From the regression analysis using data collected from all stations, the water temperature and DO decreased linearly with a coefficient of determination of 0.90, and the Chl-a and BOD could be described by increasing power functions with a coefficient of determination of 0.83. The TOC and COD followed increasing logarithm functions with a coefficient of determination of 0.58. The TOC efficiency at the 10 stations was estimated and the average efficiencies of BOD and COD were 15.5~36.3% and 57.4~89.6%, respectively.