• Journal of Korean Society of Environmental Engineers
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• v.22 no.2
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• pp.251-264
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• 2000

Organic removal from synthetic wastewater by electrochemical methods was investigated with various operating parameters, such as current density, retention time, electrode gap and $Cl^-/COD_{Cr}$ ratio. In electrolysis, dioxide iridium coated titanium ($IrO_2/Ti$) and stainless steel plate were used for anode and cathode respectively. The $COD_{Cr}$ removal efficiencies between plate type anode and net type anode were about same effect, but electrolytic power using net type anode is low than plate type anode. The $Cl^-/COD_{Cr}$ ratio was about $1.3kgCl^-/kgCOD_{Cr}$ when organic removal obtained 70 %, $Cl^-/COD_{Cr}$ ratio needs $2.2kgCl^-/kgCOD_{Cr}$ so as to organic completely remove. The removal efficiency of organics increased with current density, retention time and $Cl^-/COD_{Cr}$ ratio, but decreased with increasing electrode gap. The relationship of operating conditions and $COD_{Cr}$ removal efficiencies are as follows. $$COD_{Cr}(%)=80.0360(Current\;density)^{0.4451}{\times}(HRT)^{0.8102}{\times}(Gap)^{-0.4915}{\times}(Cl^-/COD_{Cr})^{0.5805}$$ There existed a competition between the removals for $COD_{Cr}$ and ammonium during electrolysis, the removal of ammonium was shown to be dominant and $COD_{Cr}$ removal was low. But $COD_{Cr}$ removal was raised as addition of alkalinity.

• Journal of Korean Society of Environmental Engineers
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• v.22 no.5
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• pp.811-817
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• 2000

The objectives of this study are to determine optimal operation condition of chemical coagulation with ferric chloride($FeCl_3$) and fenton reagent oxidation for effluents of a biological denitrification treatment and an existing lagoon treatment of landfill leachate, and to investigate the effect of alkalinity on fenton oxidation. In jar-tester, optimum dosage of ferric chloride for removal of COD was $1,500mgFe^{3+}/L$, removal efficiencies of $COD_{Cr}$ and $COD_{Mn}$ under this condition were about 55% and 64%, respectively. After chemical precipitation($1,500mgFe^{3+}/L$) of biological treatment effluent, optimum $Fe^{2+}/H_2O_2$ ratio of fenton oxidation was 1.5, the maximum removal efficiency of COD was about 80%, and optimum dosages of ferrous sulfate and hydrogen peroxide were $600mgFe^{2+}/L$ and $400mgH_2O_2/L$, respectively. The removal efficiency of COD was decreased as alkalinity was increased.

• Journal of Korean Society of Environmental Engineers
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• v.27 no.11
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• pp.1168-1173
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• 2005

Pilot scale vertical-type membrane bioreactor was operated to examine the effect of $FeCl_3$ injection on the removal of organics, nitrogen and phosphorous, and additionally trans-membrane pressure (TMP) was observed. The membrane type was hollow fiber membrane with pore size of $0.25\;{\mu}m$, and the material was polytetrafluoroethylene (PTFE). The membrane permeate was continuously removed by a pump under a constant flux ($25\;L/m^2/h$). Air back-flushing technique were adopted to reduce fouling. As a result, TMP was increased more slowly than that of the operation without air back-flushing, During long-term operation, approximately 310 days, the injection of $FeCl_3$ was effective not only in removing phosphorous chemically but also in reducing TMP increase. Furthermore, while the average COD and T-N concentration of the effluent without $FeCl_3$ injection was 14.3 mg/L and 6.0 mg/L respectively, that of effluent with $FeCl_3$ was 11.3 mg/L and 6.0 mg/L respectively, which confirmed the effects of $FeCl_3$.

• Journal of environmental and Sanitary engineering
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• v.5 no.1
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• pp.7-13
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• 1990

The water environmental characters of the Nakdong River, Geumho River and Sin Stream, both before-flood (Aug. 24) and after-flood (Sept. 8), have been compared, and their effects on the growth of Spirodela polyrhiza Shleiden have been examined. Before the flood, the concentrations of most of the chemical components of the Geumho River were similar to those of the Sin Stream; (COD, 19.6~21.4; alkalinity, 177~183; $NH_4\;^+$, 20.7~24.4; $NO_3\;^-$, 3.9~4.3; $PO_\;4^{3-}$, 3.4~3.7; $Mg^{2+}$, 42; $Ca^{2+}$, 68.5~69.7; $Cl^-$, 90~92; $SiO_2$, 10.4~11.2; , 11~32; LAS, 3.0~3.8; , 0.007~0.010ppm) but much higher than those of the Nakdong River (30~40 fold for $NH_4\;^+$, , $PO_\;4^{3-}$ and LAS, and 2~5 fold for COD, alkalinity, $NO_3\;^-$, $Mg^{2+}$, Cl- and ). Especially in the Geumho River, Secchi disk transparency was very low (17cm) and DO was not detected. The flood caused significant increases in some chemical components: $NH_4\;^+$, 1.0;$NO_3\;^-$, 9.6; , 12.8 and , 5.4 ppm in the Nakdong River; DO, 1.0; $NO_2\;^-$, 0.92; $NO_3\;^-$, 22.2 and $SiO_2$, 17.6ppm in the Geumho River; DO, 3.0; $NO_2\;^-$, 1.4; $NO_3\;^-$, 22.2; SiO2$SiO_2$, 19.2 and , 25.0ppm in the Sin Stream. General species diversity index (H) of phytoplankton community in the Nakdong River, Geumho River and Sin Stream before flood was 3.1, 2.7 and 1.6, respectively. After the flood, the phytoplankton growth was highly sparse in each river water, hence indices have no significance. The growth of S. polyrhiza was enhanced in Geumho River water (max. RGR=26%/day), while it ceased within 7days in Nakdong River water.

• Journal of Korean Society of Environmental Engineers
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• v.22 no.2
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• pp.265-277
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• 2000

Laboratory experiments were conducted to investigate characteristics for removing ammonia-nitrogens by electrolysis methods. A stainless steel plate is used as the cathode and either $IrO_2{\backslash}Ti$ plate serves as the anode. Experiments were conducted to examine the effects of the operating conditions, such as the current density, retention time, electrode gap, $Cl^-/NH_4{^+}-N$ on the $NH_4{^+}-N$ removal efficiency. Possible optimum range for these operating variables are experimentally determined. The $NH_4{^+}-N$ removal efficiencies between plate type anode and net type anode were about same effect, but electrolytic power using net type anode is low than plate type anode. The $Cl^-/NH_4{^+}-N$ ratio was about $20.0kgCl^-/kgNH_4{^+}-N$ when $NH_4{^+}-N$ removal obtained 73 %, $Cl^-/NH_4{^+}-N$ ratio needs $27.6kgCl^-/kgNH_4{^+}-N$ so as to $NH_4{^+}-N$ completely remove. The removal efficiency of $NH_4{^+}-N$ increase with current density, retention time and $Cl^-/NH_4{^+}-N$ ratio, but decreased with increasing electrode gap. The relationship of operating conditions and $NH_4{^+}-N$ removal efficiencies are $$NH_4{^+}-N_{re}(%)=14.5364(Current\;density)^{0.7093}{\times}(HRT)^{1.0060}{\times}(Gap)^{-0.9926}{\times}(Cl^-/NH_4{^+}-N)^{1.0024}$$ With adding COD or/and alkalinity, relationships are $$NH_4{^+}-N_{re}(%)=9.8408(Current\;density)^{0.6232}{\times}(HRT)^{1.0534}$$ There existed a competition between the removals for $NH_4{^+}-N$ and $COD_{Cr}$ during electrolysis, the removal of $NH_4{^+}-N$ was shown to be dominant. $NH_4{^+}-N$ removal was high as addition of glucose and alkalinity.

• Journal of the Korean Society of Groundwater Environment
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• v.5 no.4
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• pp.223-232
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• 1998

The Okmyong Waste Landfill which is one of major industrial waste landfills in Korea has been used for 10 years since January, 1988. The groundwater in range of 2∼3 km from the landfill is a little acidic and has high concentrations of EC, NO$_3$, and SO$_4$ because of acidic rain in Pohang. The groundwater pattern in Piper's trilinear diagram belongs to Ca-SO$_4$and Na-SO$_4$types, but Ca-SO$_4$type is more predominant. The groundwater of five monitoring wells at the landfill area is a litle alkaline and has high concentrations of TS, COD, Na, Cl, SO$_4$, Alkalinity and F because of the effect of the leachates. They also have high heavy metals of Mn, Zn, Pb, Cr and Ni but toxic organic compounds are not detected. Their groundwater pattern is Na-SO$_4$type and distinguished from the groundwater pattern Na-Cl types of the Nanjido and the Seokdae Municipal Waste Landfills. The range of groundwater contamination which is validated up to now is about 120m west from the entrance of the Okmyong Waste Landfill. To prevent the dispersion of the leachates to the outside, cutoff walls should be constructed at the boundary of the landfill. Several pumping wells should also be developed at the landfill so that the contaminated groundwater can be pumped and treated at a leachate-treatment plant in the landfill.

• Korean Journal of Environmental Agriculture
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• v.27 no.2
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• pp.111-119
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• 2008

This study was conducted to evaluate water quality and pollutant loads on small agricultural watershed in Jeonbuk province. The EC level of investigated watershed ranged from 0.07 to 0.52 dS/m, BOD level ranged from 0.1 to 5.0 mg/L, and $COD_{Cr}$ level ranged from 0.6 to 17.7 mg/L. As above, contents of water quality indicators covered wide range, but each indicator was alike in mean content every other year. The contents of EC, $Ca^{2+},\;Mg^{2+},\;K^+\;and\;Na^+$ were decreased in rainy season, but the contents of BOD, $COD_{Cr},\;COD_{Mn}$, T-N and T-P were not greatly different as compared to dry season. And high content of SS showed substantial sediments near the surface flow out and influence on water system in rainy season. The pollutant loads measured in terminal of watershed were $9.6{\sim}757.9$ kg/day for BOD, $51.2{\sim}1418.5$ kg/day for T-N and $0.3{\sim}44.7$ kg/day for T-P. The pollutant loads of BOD, T-N and T-P in rainy season increased several times as compared to dry season. In rainy season, watershed with more than 30% in the proportion of paddy field to land showed relatively low discharge and pollutant loads in comparison to watershed with less than 30%. The discharge of watershed in rainy season increased 5.7times compared with the dry season in watershed with less than 30% in the proportion of paddy field to land, whereas was only 2.3times in watershed with more than 30%. The correlation coefficient($R^2$) of regression between discharge and pollutant loads of T-N were higher than those of BOD and T-P.

• Korean Journal of Environmental Agriculture
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• v.1 no.1
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• pp.22-30
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• 1982

Water quality of downstream of the Nagdong river, using for agricultural irrigation of the Gimhae plain, were observed. Water temperature, turbidity, residue, pH, BOD, COD, DO, hardness, chloride, sulphate, phosphate, inorganic nitrogenous compounds, sodium, general bacteria, E. coli and heavy metals of the water were investigated at Daejeo, Sikman, Bongrim, Noksan, Machal and Jangyou pumping stations in the Gimhae plain in May, July and October, 1981. The results obtained were as follows; 1) Average value of analyzed components of the water at all sampling sites were 7.8 pH, 6.3 ppm BOD, 6.5 ppm COD, 6.4 ppm DO, 231 ppm hardness, 582 ppm Cl-, 412 ppm $SO_4--$, 2.32 ppm $PO_4---$, 3.8 ppm $NH_4+,\;478\;ppm\;Na+$, 2964 No. /100 ml total coliform, 0.0040 ppm Cd, 0.0066 ppm Pb, respectively. 2) The most heavily polluted site of all investigated ones was Sikman. It seemed to be caused by the vast quantity of wastewater discharged from industrial district in Gimhae city. The next polluted sites were Bongrim, Daejeo and Noksan, and comparatively less polluted sites were Machal and Jangyou, judging from both appearance and physicochemical observation. 3) At Sikman, the most heavily polluted site, average value of components were 8.0 pH, 8.1 ppm BOD, 8.2 ppm COD. These values were close to the limit point of agricultural water quality standard of 8.0 ppm BOD (COD). 4) Any apparent variation was not observed by the sampling season in most components except DO and $NH_4+$. DO of October was higher than that of May or July but $NH_4+$ was low. 5) $NH_4+$ content was comparatively high in downstream of the Nagdong river of which water is used as the agricultural irrigation in the Gimhae plain. Therefore, fertilizer application on the farming land must make account of nitrogen content of the irrigation water 6) It was considered that chloride and sodium contents would not influence the crop cultivation in common season, but in dry season irrigation must be done carefully.

• Journal of Korean Society of Environmental Engineers
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• v.22 no.4
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• pp.765-773
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• 2000

The degradation of humic acid using $TiO_2$ coatings was studied, $TiO_2$ coatings were prepared by dip-coating method. Sol solutions for coating were prepared by mixing the gel, which can be produced by the reaction of $TiOCl_2$ and $NH_4OH$ solution, and hydrogen peroxide solution, and hydrolysis of titanium tetraisopropoxide (TTIP). It was shown from XRD that coatings from sol aged at $100^{\circ}C$ for 18h with titanium peroxo solution were crystallized to anatase in the range of temperatures of $25^{\circ}C$ to $500^{\circ}C$. In contrast, those coated from TTIP were crystallized to anatase at temperature above $400^{\circ}C$. So the sols originated from $TiCl_4$ can be applied for not only on the heat-resistance substrates but on the plastic substrates. Thickness and the quality of the films were dependent on the withdrawing speed, the concentration of sol, and the number of coating. The films showed various interference colors depending on the thickness of them. In the case that the films coated 2 times at withdrawing speed of 2.5cm per minute by 0.2M sol, the films had a transparent light blue color with thickness of around 50nm. It was known from the result of photo-degradation by $TiO_2$ coatings using humic acid that the removal efficiency of $COD_{cr}$ was over 85% after illumination of $UV/H_2O_2$ for 40min. and that of UV/VIS absorbable materials was over 95%.