• 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.

• Journal of Korean Society of Coastal and Ocean Engineers
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• v.18 no.3
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• pp.211-224
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• 2006

It was analysed that spatial and temporal change patterns of COD, TN and TP were measured monthly from 2002 to 2005 in Jumunjin Harbour. Cenerally, concentration of upper layer higher than lower layer, concentration difference of COD, TN and TP on upper lower layer at inner zone in Jumunjin Harbour higher than sea area front of breakwater. Seasonal change width of COD concentration different, but seasonal change pattern of COD, $NH_{4}-N$ and TN clearly showed. Water quality improvement effect of seawater exchange facilities and sewage treatment plants is analysed quantitatively using averaged spatial and temporal data set. Change of COD small at 2003, concentration reduced about $34{\sim}47%$ at all zones on 2004 and 2005. TN was influenced largely effect of seawater exchange facilities. Concentration reduction at zone 1, 2, 3 estimated about $60{\sim}70%,\;40{\sim}60%,\;40%$, respectively. As a consequence, concentration reduction of COD and TN that is, effect of water quality improvement influenced seawater exchange facilities appeared not only at inner zone, also sea area front of breakwater and entrance of Jumunjin Harbour.

• Journal of Environmental Science International
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• v.29 no.6
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• pp.659-672
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• 2020

Water and sediment qualities were investigated in the Oncheon Stream and at the Wondong bridge of the Suyoung River, during the summer rainy season, 2019. Dissolved oxygen (DO) showed the lowest levels at 4.7 and 5.0 m/L, and biogeochemical oxygen demand (BOD) showed the highest at 5.3 mg/L downstream where the tributary flows into the main river. Chemical oxygen demand (COD) increased from 2.0 to 5.9 mg/L on average as it flowed downstream, The COD/BOD ratio decreased gradually as it flowed downstream, reaching 1.0. However, COD/BOD ratio at the Wondong bridge was 5.8-22.2, indicating that easily biodegradable and non-biodegradable organic matter flows into the Oncheon Stream and Suyoung River, respectively. Total nitrogen (T-N) / total phosphorus (T-P) ratio tended to decrease from 72 to 21 as it flowed downstream, measuring 71 to 86 at the Wondong bridge. The water quality index (WQI) generally improved better than grade IV after heavy rainfalls. However, DO and T-P were the parameters that deteriorated the WQI. Ignition loss (IL), COD, T-N, and T-P of sediments had distribution of 1.44 ± 1.01%, 0.35 ± 0.16%, 43 ± 63 mg/kg, and 10.9 ± 21.9 mg/kg, respectively. These were several times lower than the annual averages of IL, T-N, and T-P in 2017 before the dredging project was conducted in the first half of 2018.

• 한국생물공학회:학술대회논문집
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• 2000.11a
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• pp.745-748
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• 2000

Anaerobic digester coupled with hollow fiber membrane unit. Treatment of starch waste with anaerobic digester-membrane system was studied. $0.17\;m^2$ area of hollow fiber membrane unit of known pore size was immersed into laboratory-scale anaerobic digestion system. The gas production was about $0.74\;m^3/kg$ COD treated. The COD removal efficient was about 80-95% depending on the hydraulic retention time. Crossflow ultrafiltration as Post treatment to anaerobic filter. The study conducted with different membrane pore size indicated that membrane with 1,000,000 molecular weight cut-off size gave a higher COD removal efficiency in the range of 83-87% while giving a study flux of $120-130\;L/m^2\;{\cdot}\;h$. A study was conducted to see the long term clogging effect of membrane also.

• Applied Biological Chemistry
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• v.37 no.4
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• pp.303-309
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• 1994

To develop the treatment process of swine wastewater using Rhodopseudomonas palustris KK14 with high utilizable ability of organic acids, some operating conditions were investigated and optimized in flask-scale and laboratory-scale reactors. The optimal operating conditions in photosynthetic bacteria (PSB) reactor of semi-continuous type were obtained at HRT 6 day, 5% (v/v/day) seeding rate of PSB sludge and 10% (v/v/day) returning rate of PSB return sludge. Under the above operating condition, COD level of the wastewater (initial COD: 10 g/l) was reduced to about 1.7 g/l after 4 days treatment and MLSS was held constant at $4{\sim}5\;g$ per liter. In laboratory-scale process consisted of 5.2 l anaearobic digestion reactor and 15 l PSB reactor, the total removal rates of COD and BOD were increased to 95% and 96% by the continuous operation for 5.36 days, respectively, showing $3kg\;COD/m^3/day$ COD loading rate and 1.1 Kg COD/Kg MLSS/day sludge loading rate in PSB reactor. The offensive odor was considerably removed through the treatment process of swine wastewater.

• Journal of the Korean Society of Marine Environment & Safety
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• v.10 no.2 s.21
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• pp.69-79
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• 2004

This study focuses on the relationship between pollution factors around Masan, Changwon and Chinhae city considerd as main pollution sources and marine environment in Masan bay of Korea. Water quality data measured In Jinhae bay and environmental investigation data in Masan, Changwon and Jinhae cities from 1981 to 1998 were used for this study. Annual means and standard deviations of COD, DIN and DIP concentrations from 1981 to 1998 showed that both their concentration and fluctuations were higher in the inner part of Masan bay (region A) than near Somodo (region B). Sediment dredging in Masan bay had been done from 1990 to 1994. After dredging, COD concentration has been decreasing In surface layer. Also water pollution was gradually spreaded from the inner part to the outer part of the bay due to the continuous inflow of domestic sewage and industrial wastewater. In the late of 1990s, the pollution was heavier. DIN and DIP concentrations were found to be increased by establishment of industry complex and decreased by sewage treatment plant near the city adjacent to Jinhae bay, 1993. The correlation between COD, DIN and DIP changes and neighbor cities' pollution sources were calculated From 1981 to 1998, correlation coefficient (r) was over 0.8 except for the bottom of region A From 1981 to 1998, r between the DIP concentration and population was over 0.65 except for the surface of region A, and the r between the DIP and the number of factories was over 0.6 too, in region B.

• Journal of the Korean Society for Marine Environment & Energy
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• v.11 no.2
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• pp.63-69
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• 2008

As a basic study on the creation of artificial tidal flats using dredged sediments, the pilot-scale artificial tidal flats with 4 different mixing ratio of ocean dredged sediment were constructed in Nakdong river estuary. The phragmites australis was transplanted from the adjacent phragmites australis community after construction, and then the survival and growth rate of the planted phragmites australis were measured. Also the changes of soil chemical oxygen demand (COD), ignition loss (IL), and the heterotrophic microbial numbers were monitored. The survival rate of the planted phragmites australis decreased as the mixing ratio of dredged sediment increased but there was little difference of length and diameter of the shoots. 30% of COD and 9% of IL in the tidal flat with 100% dredged sediment decreased after 202 day, however, fluctuations of COD and IL concentrations were also observed possibly due to the open system. It was suggested that the construction of tidal flats using ocean dredged sediment and biological remediation of contaminated ocean dredged sediment can be possible considering the growth rate of transplanted phragmites australis, decrease of organic matter and increased heterotrophic microbial number in the pilot plant with 100% dredged sediment. However, the continuous monitoring on the vegetation and various environmental factors in the artificial tidal flat should be necessary to evaluate the success of creation of artificial flats using dredged sediments.

• Journal of Environmental Science International
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• v.9 no.2
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• pp.137-144
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• 2000

The observations on the seasonal fluctuation and distributional characteristic of organic matters on surface sediments and its origin were carried out at the 25 stations in Keogeum-sudo, southern coast of Korean Peninsula from February to October in 1993. I made an analysis on the environmental factors for surface sediments such as temperature, ignition loss, chemical oxygen demand, pheopigment, total sulphide, water content, mud content in grain size, COD/IL ratio and COD/sulphide ratio. The results are as follows ; 1) The range of temperature on the surface sediments was between 6.2${\circ}C$ and 24.6${\circ}C$. The highest mean temperatuer of mud was 24.0${\circ}C$ in summer, the lowest 6.6${\circ}C$ in winter. 2) Ignition loss(IL) fluctuated between 1.2% in winter and 16.8% in spring, that is to say, the seasons of increasing in temperature were very high ignition loss. 3) Chemical oxygen demand(COD) showed the highest mean value of 20.52 mg/g dry in summer within the range of 15/46~32.78 mg/g dry, while showed the lowest of 5.79 mg/g dry in winter within the range of 7.4~17.39 mg/g dry. 4) Pheopigment concentrations showed the highest mean value of 4.85 $\mu\textrm{g}$/g dry in autumn within the range of 0.84~9.21 $\mu\textrm{g}$/g dry, while it did the lowest mean value of 1.97 $\mu\textrm{g}$/g dry in summer within the range of 0.23~4.83 $\mu\textrm{g}$/g dry. 5) Total sulphide (H2S) fluctuated between no detect(ND) in spring, and 2.43 mg/g dry in sutumn. The highest mean value was 0.68 mg/g dry in sutumn, the lowest was 0.16 mg/g dry in spring. 6) Water content(WC) and mud content in grain size showed the mean value of 43.2% within the range of 26.5~59.7% and 91.0% within the range of 57.8~99.2%, respectively. 7) By the analytical results on the source of organic matter, it had been dumped from the seaweed farms in Keogeum-sudo coastal waters.

• Economic and Environmental Geology
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• v.35 no.1
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• pp.43-54
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• 2002

The Chonju and Samchun streams are palling though Chonju City and several contamination sources are located along these streams. The Samchun stream joins the Chonju stream in the Gosapyeong waste disposal site and the Chonju stream finally joint to the Mankyeong River. The Chonju and Samchun streams are now contaminated with BOD, COD, T-N and T-P and the amounts of each contamination are increasing from upper stream to downstream. At the downstream the amounts of COD. T-N.T-P are several times higher than fifth grade of water quality thor lacustrine. Sewage from Chonju provides BOD, COD,T-N and T-P into the Chonju and Samchun streams and Chonju Waste Water Treatment Plant il a main source of COD, T-N and T-P contamination. Gosapyeong waste disposal site may be the source of BOD and COD contamination. T-N is higher than fifth grade of water quality for lacustrine at the upper stream indicationg that the rivers are contaminated with T-N before inflowing into Chonju by agricultural activity. The Chonju stream asffects the contamination of the Mankyeong river with BOD. COD, T-N,T-P. Other branch steams of the Mankyeong river also affects the contamination of the Mankyeong river by BOD, COD, T-N and T-P, Among the branch streams, the Ikasn stream is a main contamination source. Amounts of concentrations inflowing from the Chonju and Sanchun Streams on Aug. 1999 are calculated by using yeasured flow rate find concentrations of contaminants The result are as fikkiws; 1) the amounts of influent from the Gosan Stream are 0.49, 0.86, 1.61 and 0.01 ton/day for BOD, COD, T-N and T-P, respectively, 2) compared to the amounts of influent from the Gosan Stream, BOD, COD,T-N,T-P supplied from the Chonju river are higher by about 5, 7, 7. 36 times, respectively, and those supplied from the Iksan stream are higher by about 13, 10, 10, 147 times, respectively.

• Ocean and Polar Research
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• v.33 no.1
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• pp.13-20
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• 2011

Comprehensive data collection was carried out between 2001-2006 to investigate the concentration levels of chlorophyll-a, nutrients (DIN and DIP), and COD for surface waters of Korean coastal areas. A statistical analysis of these parameters was carried out on the basis of the frequency distribution of their concentration. Furthermore, the numeric grading for chlorophyll-a, DIN, DIP, and COD concentrations were derived statistically from the normalized frequency distribution of log-transformed data. The statistical grading clearly reflects the water quality characteristics of three Korean coastal water bodies (Western, Southern and Eastern coastal zones), which indicate common environmental and ecological characteristics. So, this study could provide useful information to set up the guideline for water quality assessment of Korean coasts.