• Journal of environmental and Sanitary engineering
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• v.5 no.1
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• pp.83-92
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• 1990

Adapting two step aeration system to a waste water treatment of W-paper manufactory as Full-Scale Plants, we drew a following conclusion from its practical working. 1. Because BOD removal efficiency was 20% in A-Stage, 90% in B-Stage and total removal efficiency was 97%. It worked treatment plant well and was suitable for effluent water standard as well. Because COD removal efficiency was 42% in A-stage, 71% in B-stage and the total removal efficiency was 94% COD control was possible in effluent water quality. 2. Treatment efficiency according to a load capacity was average 20% in 1.401 BOD kg/m3/d load of A-Stage and average 90% in 0.273 BOD kg/$\textrm {m}^3$ / d load of B-Stage. 3. Treatment efficiency according to a ratio of F/M was 2.657--5.024 kg BOD/kg MLSS/d in A-Stage and BOD removal efficiency was 16-261 in the same stage. The ratio of F/M was 0.068-0.094 kg BOD /kg MLSS/d and BOD removal efficiency ratio was 85-94%. Therefore treatment efficiency could be kept stably and volume of aeration tank could be reduced wholly. 4. Treatment efficiency according to MLSS appeared BOD 20%. COD 42%, in A-Stage and removal efficiency appeared BOD 90%, COD 71% in B-Stage. They were suitable for plan condition. 5. Because of working of complemented treatment plant by AB-Process. 20,000,000 Won a month was saved than the ordinary working cost. Therefore, it was assumed that invested cost could be recollected in 19 months or so consequently.

• Clean Technology
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• v.25 no.4
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• pp.302-310
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• 2019

A constructed wetland with the aerobic tank and anaerobic/anoxic tank connected in series was employed in order to treat highly polluted stream water. The aerobic tank was maintained aerobic with a continuous supply of air through the natural air draft system. Five pilot plants having different residence times were employed together to obtain parameters for the best performances of the wetland. BOD and COD removals at the aerobic tank followed the first order kinetics. COD removal rate constants were slightly lower than BOD. The temperature dependence of COD (θ = 1.0079) and BOD (θ = 1.0083) was almost the same, but the temperature dependence (θ_N) of T-N removal was 1.0189. The SS removal rate was as high as 98% and the removal efficiency showed a tendency to increase with increasing hydraulic loading rate (Q/A). The main mechanism of BOD and COD removal at the anaerobic/anoxic tank was entirely different from that of the aerobic tank. BOD and COD were supplied as the carbon source for biological denitrification. T-P was believed to be removed though the cation exchange between orthophosphate and gravels within the anaerobic and anoxic tanks. The wetland could successfully be operated without being blocked by the filtered solid which subsequently decomposed at an extremely fast rate.

• KSBB Journal
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• v.24 no.4
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• pp.353-360
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• 2009

This study was accomplished using Anaerobic/Anoxic/Oxic upflow packed-bed column reactors with fixed media and Loop Reactor with fluidized media instead of Oxic reactor. The objectives of this study was to investigate the characteristics of organics, nitrogen and phosphorus removal from sewage with the HRT. The average removal efficiencies of $BOD_5$ and SS increase as increasing the hydraulic retention time (HRT) until 16 h of the HRT, and they were constant over 16 h of the HRT. The removal efficiency of $BOD_5$ in case of packed-bed reactor and Loop Reactor was about 86.6% and 90.9% respectively at 16 h of the HRT. The removal efficiency of SS in packed-bed reactor and Loop Reactor was about 78.0% and 88.2% respectively at 16 h of the HRT. The average removal efficiencies of $COD_{Cr}$ and $COD_{Mn}$ showed similar trends as those of $BOD_5$ and SS. At the HRT of 16 h, the removal efficiency of $COD_{Cr}$ in case of packed-bed reactor and Loop Reactor was 63.5%, 75.2% and that of $COD_{Mn}$ was 60.7%, 73.6% respectively. The average removal efficiencies of T-N and T-P increase as increasing the HRT. The removal efficiencies of T-N and T-P in Loop Reactor were 33.6% and 54.5% respectively at 16 h of the HRT and T-N and T-P were better removed in Loop Reactor. From this result, it was found that the performance of Loop Reactor was much higher than the performance of packed-bed reactor and the optimum HRT was 16 h.

• Journal of Environmental Health Sciences
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• v.19 no.3
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• pp.36-40
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• 1993

The objective of this research was to retrofit an on-site sewage treatment system suitable to current situation of Korea to reduce the pollution loading and preserve the invaluable water resources. Operation at the F/M ratio of 0.1 kg. BOD/kg MLSS day showed 87.1% BOD removal efficiency and 84.5% COD removal efficiency, and its effluent concentration was 6.4 mg/l as BOD and 21.7 mg/l as COD. Average removal of total nitrogen showed high removal efficiency of 80%.

• Journal of the Korean Society of Fisheries and Ocean Technology
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• v.17 no.1
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• pp.41-47
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• 1981

The characteristics of septic tank sludges were investigated and the kinetic coefficients in the aerobic biodegradation were evaluated from bach treatability tests. Using an unbiased statistical method, the estimated values, k (substrate removal rate coefficient) =0. 0175hr-1 at 17\ulcornerC, K. (Michaelis Menten constant) = 248mg/ e, a (cell yield coefficient)=0.625, and Kd (cell decay coefficient:' =0. 00192hr-1 were obtained based on biodegradable COD(mg/ \ulcorner) and volatile suspended solids(mg/\ulcorner). The relationship between COD and BOD, COD (mg/\ulcorner) =2. 1 BOD(mg/\ulcorner) +250, also was established for the septic tank sludges. Dilution was inevitable for the grit removal because of the high viscosity of the sludges. An aerobic activated sludge process rather than anaerobic processes was recommended for the removal of soluble organics after the removal of grit and suspended solids. A multi-stage activated sludge process was adapted for this highly concentrated and not easily-degradable waste. It was estimated that a four-stage activated sludge process would require 40 hours retention time compared to 92 hours for a single-stage process, 52 hours for a double-stage process, and 46 hours for a three stage process in order to achieve an effluent quality of 84mg/ e COD( 40mg/ e BOD) with about 4, OOOmg/ \ulcorner MLSS from an influent quality of I, 500mg/ t COD(714mg/.e BOD), while multi-stages beyond four stage would not save the required retention time significantly.

• Journal of environmental and Sanitary engineering
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• v.14 no.2
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• pp.105-112
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• 1999

The removal characteristic of BOD, COD,T-N, and T-P was investigated in municipal wastewater treatment with anoxic and membrane submerged aerobic reactor. It was found that BOD and COD removal rate were obtained 90% and 92%, respectively, for 90 days operation. BOD and COD loading rate did not affect to the removal efficiency because MLSS concentration in aerobic tank was highly maintained.In the case of first reactor operated with anoxic and second reactor operated as aerobic, T-N, T-P removal rate were obtained 93% and 99% respectively.It was shown that removal efficiency could be maintained stable due to the complete removal of SS and sludge production decreased with increasing of sludge retention time.

• 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.

• Journal of Wetlands Research
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• v.3 no.1
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• pp.75-89
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• 2001

Constructed wetlands were typically cost less to build and operate, and require less energy than standard mechanical treatment technology but they have similar performance to centralized wastewater treatment plants. Therefore, they were constructed especially many in rural areas, where are small villages but not industries. Accordingly, plantless column tests were performed to investigate the possibility on using zeolite as a filter medium of constructed wetland for the wastewater treatment. $COD_{cr}$ removal efficiency was 94.63% at hydraulic load $314L/m^2{\cdot}d$ and filtering hight 100cm filled with a zeolite mixture. This zeolite mixture consisted of 1 : 1 by volume of a zeolite in the diameter range of 0.5 to 1mm to a zeolite in the diameter range of 1 to 3mm. According, hydraulic load $314L/m^2{\cdot}d$ was considered as optimal. Three zeolite mixture were used to determine the optimal mixing ratio by volume of a zeolite(A) in the diameter range of 0.5 to 1mm to a zeolite(B) in the diameter range of 1 to 3mm diameter. 1 : 3, 1 : 1 and only B in A to B by volume were tested at hydraulic load $314L/m^2{\cdot}d$ and filtering hight 100cm. $COD_{cr}$ removal efficiency was more than 89% at mixing ratios of 1 : 3 and 1 : 1 in A to B. Removal efficiency was lower at the column filled with only B. Removal efficiency was better at filter medium filled with mixing ratio 1 : 1 in A to B than with the other mixing ratios. Thus, it was found that the mixture of mixing ratio 1 : 1 in A to B was appropriate for filter medium of constructed wetland. Removal efficiency was higher in down-flow than in up-flow, and $COD_{cr}$ and BOD were removed best in 20cm filter height near feeding area.

• Journal of Marine Life Science
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• v.2 no.2
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• pp.49-55
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• 2017

Four chemical treatments with hydrogen peroxide (H₂O₂), copper sulfate (CuSO₄), potassium permanganate (KMnO₄) and chlorine (Cl₂) were applied to the effluent pond water of a hybrid striped bass saltwater recirculating aquaculture system to compare their oxidation power. Four chemicals were applied at concentrations of 0 (control), 1, 5, 10 and 20 mg/l. An additional concentration of 40 mg/l was included in the chlorine treatment. Water samples from four hybrid striped bass ponds were tested with KMnO₄ and Cl₂. H₂O₂ did not reduce any of BOD, COD and chlorophyll-a, and copper sulfate was only effective on chlorophyll-a for the effluent pond. Removal efficiencies for chlorophyll-a by copper sulfate were 19.2%, 37.5%, 54.2% and 74.1% dose-dependently. Potassium permanganate effectively removed the BOD, COD and chlorophyll-a. The COD removal rates in four fish ponds varied from 15.9% to 31.6% at the concentration of 10 mg/l. Interestingly, Cl₂ did not reduce the BOD and COD at all, but the BOD and COD instead increased drastically with increasing the Cl₂ concentration. The pond water with the highest initial BOD and COD values among the fish ponds tested increased by 350% in the BOD and 150% in the COD at 20 mg/l. Furthermore, Cl₂ did not significantly reduce any types of solid matter in this study, while KMnO₄ seemed to reduce some extent volatile dissolved solid in the fish pond.

• Korean Journal of Environmental Agriculture
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• v.27 no.1
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• pp.44-49
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• 2008

The purpose of this study is to investigate the current status, including the maintenance problems and removal efficiency, of small sewage treatment facilities in Chung-nam province(Asan, Buyeo, and Gongju city). Our results showed that inflow water quality of Asan city was 19.1 mg/L of BOD, 29.0 mg/L of COD, 13.4 mg/L of T-N and 1.5 mg/L of T-P, respectively, which was much higher than any other site. Among the factors known to be an important index of water quality, the SS and BOD removal efficiency was about 70% and 50% respectively. However, the nitrogen removal efficiency was less than 10%. The total removal efficiency of pollutant was 71.1% of SS, 52.6% of BOD, 46.2% of COD, 9.2% of T-P and 4.6% of T-N respectively. Therefore nitrogen removal processes are required to prevent serious eutrophication of small river. Removal efficiency for BOD and SS of high-efficient sewage treatment facilities (STFs) and contact oxidation process was much higher than another process. Performance of these sewage treatment facilities(STFs) is not optimal due to ineffective planning for the inflow water quality. To improve these facilities, it is proposed that a technical expert analysis of water quality at these facilities is periodically required.