• Journal of Korean Society on Water Environment
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• v.27 no.2
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• pp.235-241
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• 2011

This study was performed to investigate the characteristics of nutrient removal of municipal wastewater in the submerged membrane bioreactor by addition of alum directly into aerobic tank. Membrane bioreactor consists of three reactors such as two intermittent anaerobic tanks and the aerobic tank with hollow fiber membrane. The removal efficiencies of $COD_{cr}$, BOD, SS, TN and TP on the membrane bioreactor were 94.0%, 99.1%, 99.9%, 66.9%, and 58.9%, respectively. In addition, The removal efficiencies of $COD_{cr}$, BOD, SS, TN and TP on the membrane bioreactor with alum addition were 93.4%, 99.0%, 99.9%, 63.2%, and 96.8%, respectively. There was little difference between them on the nutrient removal efficiencies except phophorus removal. The estimated sludge production, specific denitrification rate, specific nitrification rate and phosphorus removal content on the membrane bioreactor were 1.76 kgTSS/d, $0.055mgNO_3-N/mgVSS{\cdot}d$, $0.031mgNH_4-N/mgVSS{\cdot}d$, and 0.095 kgP/d, respectively. And The estimated sludge production, specific denitrification rate, specific nitrification rate and phosphorus removal content on the membrane bioreactor with alum addition were 2.90 kgTSS/d, $0.049mgNO_3-N/mgVSS{\cdot}d$, $0.030mgNH_4-N/mgVSS{\cdot}d$, and 0.160 kgP/d, respectively. The alum content added was 1.7 molAl/molP on an average. The increasing ratio of tran-membrane pressure on the membrane bioreactor was $0.0056kgf/cm^2{\cdot}compared$ to $0.0033kgf/cm^2{\cdot}d$ on the membrane bioreactor with alum addition. There was a slightly reduction effect on membrane fouling by alum addition.

• Microbiology and Biotechnology Letters
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• v.30 no.2
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• pp.189-197
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• 2002

Twenty nine strains of photosynthetic purple nonsulfur bacteria were isolated from Kyonggi area in Korea. The isolated strains were identified as Rhodopseudomonas blastica, Rhodocyclus gelatinosus, Rhodocyclus tenuis, and Rhodopseudomonas rutila. The enhanced nutrients removal system for wastewater using phototrophic purple non-sulfur bacteria was developed. Experiments were performed into two Phases and the results were compared: the synthetic wastewater was tested for the removal efficiency of nutrients and organics during Phase 1 and the real wastewater during Phase2. Results showed that 97∼99％ of organics were removed during Phase 1 and 96∼99％ during Phase 2. Nutrients (nitrogen and phosphorus) were also removed efficiently: 85∼91％ removal of T-N and 78∼92％ removal of T-P were achieved for Phase 1, and 76∼89％ removal of T-N and 73∼88％ removal of T-P for Phase 2.

• Journal of the Korean Society of Environmental Restoration Technology
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• v.14 no.1
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• pp.121-132
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• 2011

Removal rates of $NO_3$-N and TN in the free-water surface wetland system during winter; December, January, February and March, spring and fall; April, May, October and November, and summer; Jun, July, August and September were investigated. The system was established on floodplain in the downstream reach of the Gwangju Stream in 2008. It measures 50 meters in length and 5.5 meters in width. Iris pseudacorus L. grown in pots for about two years were planted in the system. The water stream was funneled in by gravity and its effluent was discharged back in. Volumes and water quality of inflow and outflow were analyzed from December 2008 to November 2010. The inflow was averaged approximately 350 $m^3/day$ and hydraulic residence time was about 3 hours. Average influent and effluent $NO_3$-N concentration was 3.75 and 3.35 mg/L, respectively and $NO_3$-N retention was amounted to 10.6%. Influent and effluent TN concentration were averaged 4.93 and 4.30 mg/L, respectively and TN abatement reached to 12.9%. One-way ANOVA statistics claimed that the average removal rates of $NO_3$-N and TN during winter, spring and fall, and summer were not always the same (p<0.001). The t-Tests of three pairs among $NO_3$-N removal rates of winter, spring and fall, and summer illustrated that the removal rates of winter ($5.04{\pm}1.94$), spring and fall ($10.53{\pm}2.24$), and summer ($18.61{\pm}2.26$) were significantly different each others (p<0.001). Among TN removal rates, the three pairs of t-Tests of three seasons showed that the removal rates of winter ($5.21{\pm}2.51$), spring and fall ($11.71{\pm}3.12$), and summer ($21.53{\pm}4.86$) were significantly different from each others (p<0.001).

• Journal of Korean Society of Water and Wastewater
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• v.29 no.2
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• pp.211-222
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• 2015

This study focused on evaluating the efficiency of the removal of non-point source pollution by Daecheong Lake Juwon Stream constructed wetlands. The constructed wetland system is a surface flow type designed in the year 2007 for purifying eutrophic water of Daecheong Lake Juwon Stream. The value of conductivity, suspended solids(SS), chemical oxygen demand using a potassium permanganate($COD_{Mn}$), five-day biochemical oxygen demand($BOD_5$), total nitrogen(T-N), total phosphorous(T-P), and pH in inflow averaged 220.2, 2.46, 3.33, 1.34, 2.00, 0.04 mg/L and 7.24, respectively and in outflow averaged 227.9, 1.12, 3.34, 0.87, 1.16, 0.02 mg/L and 7.45, respectively. The average removal efficiency of constructed wetlands was 30 % for SS, 22 % for $BOD_5$, 45 % for T-N and 31 % for T-P. The removal rates of SS, $BOD_5$ and T-N in the spring, summer and autumn were higher than those in winter. The removal rate of T-P was not significant different in all seasons. The amounts of pollutants removal in the constructed wetlands were higher in the order of $3^{rd}$ < $2^{nd}$ < $1^{st}$ wetland for SS and T-P, $2^{nd}$ < $3^{rd}$ < $1^{st}$ wetland for $BOD_5$ and T-N. Therefore, our findings suggest that the constructed wetlands could well treat the eutrophic Daecheong Lake Juwon Stream waters.

• Journal of Korean Society of Water and Wastewater
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• v.11 no.2
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• pp.65-75
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• 1997

Removal characteristics of volatile organic carbons(VOCs) by ozone oxidation and other processes in the raw water of the 1st Nakdong water treatment plant were investigated. Dichrolomethane, toluene and other 7 compounds were detected in the raw water. With regard to detected 4 compounds in finally treated water, it was found that VOCs could not be removed effectively by traditional water treatment process. Benzene, 1,2-dichlorobenzne were not detected in the raw water but they were detected in the process of treatment. The compound of highest detection frequency was dichloromethane. When the raw water was controlled at pH 7, temperature $20^{\circ}C$, 5 minutes as contact time, 10 minutes as reaction time, the removal rate of THMFP, $KMnO_4$ demand, TOC, $UV_{254nm}$ and $NH_3-N$ were 46.4%, 22%, 19.6%, 31% and 8%, respectively. From estimating the finally treated water qualities in 7 kinds of treatment processes, P-6 process(raw water-chlorination-coagulation-ozonation) was most effective for organics removal and THMs control. Removal efficiencies for $KMnO_4$ demand and TOC by the process which combined preozonation with coagulation was twice better than only preozonation. $NH_3-N$ removal rate was shown as 10% by P-3 process(raw water-coagulation-ozonation), but 83% of $NH_3-N$ was removed by P-4 process(raw water-coagulation-chlorination). It was found that the chlorination is more effective than the ozonation for the NH3-N removal as commonly known.

• Journal of Aquaculture
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• v.10 no.3
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• pp.335-346
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• 1997

Denitrification is one of the important processes of removing nitrate from in recirculating aquaculture systems. And this process is affected by many factors such as external organic carbon sources, hydraulic retention time (HRT), COD/NO3--N (C:N) ratio, etc. However, not many studies were done for the optimum conditions of denitrification in the recirculation system for aquaculture. Therefore, this study was conducted to find out the optimum removal condition of NO3--N using submerged denitrification biofilter. The combinations of two external organic carbon sources (glucose and methanol), two HRT (4 and 8-hour) and four differnent C : N ratios (3, 4, 5, 6) were tested. The removal efficiencies of NO3--N and total inorganic nitrogen (TIM) at 8-hour HRT were better than those at 4-hour's (P<0.05). The maximum removal efficiency of NO3--N by methanol (97.8%) was achieved at HRT and C : N ratio were 8-hour and 4.0 respectively. The efficiencies of methanol for the removal of NO3--N and TIN were always better than those of glucose (P<0.05). The maximum removal efficiencies of total inorgainc nitrogen (TIN) were gained at C : N ration of 5.0. The maximum removel efficiencies of TIN using methanol and glucose were 96.9% and 71.5% respectively. Anaerobic condition which is necessary for denitrification process was not made until the 8-hour HRT and higher C : N ratio (5.0). Removal of NO3--N at 4-hour HRT and C : N ration lower than 5.0 were inhibited by oxygen and/or low quantity of external organic carbon. Removal efficiencies of NO3--N were also inhibited by high C : N (6.0) ratio when HRT was 8-hour.

• Korean Journal of Environmental Agriculture
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• v.19 no.2
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• pp.134-141
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• 2000

For electrochemical treatment of industrial wastewater, the effects of voltage, distance between electrodes, initial pH and NaCl concentrations on removal of pollutants were investigated in a batch electrolysis system. Temperature and pH in electrochemical reactor increased with increase in supplied voltage, but no significant change in EC was found. Removal of COD, turbidity, T-N and T-P were also enhanced with increase in the voltage. On the conditions of short distances between electrodes and long electrochemical reaction times, it was found that COD and T-N were very effectively removed in the system. Regardless of the distances, more than 80% of turbidity and T-P were removed at the beginning of reaction. When initial pH of the wastewater was about 7, the highest efficiency of COD removal was found in the system. On the other hand, removal efficiency of turbidity was unlikely affected by initial pH of the wastewater. T-N removal was increased with increase in initial pH. T-P was successfully removed in the pH range of 5 to 9 with varying removal efficiency of 79 to 96% after 2 minutes of electrochemical reaction time. Addition of NaCl into the electrochemical reactor increased removal efficiency of electrochemical treatment. The highest removal efficiency of COD and T-P, turbidity and T-N was obtained at NaCl concentrations of 500mg/L, 1,000 mg/L and 500mg/L, respectively.

• Journal of the Korean Wood Science and Technology
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• v.12 no.3
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• pp.9-14
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• 1984

The removal and readsorption effects of pine and oak bark grown in Korea on water pollution caused by heavy metal ions have been investigated. Bark saturated with heavy metal ions is refleshed with 0.1 N ammonium acetate and then its readsorption has been done. The results obtained are as follows: 1. Adsorption effect of pine bark is similiar to that of oak bark, and 20-40 meshed bark gives the best results. 2. 0.1 N amonium acetate of pH 7 shows more elutriative than the others such as pH 3 hydrochloric acid, pH 10 ammonium hydroxide and pH 7 water. 3 Pine bark refleshed with 0.1 N ammonium acetate gets two times as effective in adsorption as raw bark, and shows more effective than oak bark.

• Journal of Environmental Health Sciences
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• v.29 no.1
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• pp.28-33
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• 2003

This study was carried out to treat sewage using sand trench combined with septic tank process in rural areas. In order to find optimum parameters, design and operation mode was changed from Run 1 to Run 4. In order to facilitate nitrification and T-P removal, diffuser and iron plate was installed in the 3rd trench of Run 2 period. The septic tank played a role as pre-application process of sand trench system. The removal efficiencies of COD, NH$_4$-N, T-P at steady state were 94.6%, 87.9% and 54.5%, respectively. Addition of diffuser and iron plate in the 3rd trench has increased the removal efficiencies of the NIL-N and T-P. In this system, denitrification were not occurred because of the high DO.

• Journal of Korean Society on Water Environment
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• v.28 no.1
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• pp.63-70
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• 2012

This study was carried out to investigate change in influent concentration of domestic wastewater flowed from a newly constructed separate sewer system (SSS) and biological nutrients removal efficiency of a full scale Air-vent sequential batch reactor (SBR, $600m^3/d$). The average concentration of $BOD_5$, SS, T-N and T-P from SSS were 246.5 mg/L, 231.6 mg/L, 42.974 mg/L, 5.360 mg/L, respectively which corresponds to 2.2times, 1.2times, 1.8times and 2.1times higher than those from the conventional combined sewer system (CSS). The removal efficiency of $BOD_5$, SS, T-N, and T-P for the Air-vent SBR operated with influent from SSS averaged 99.1%, 99.0%, 91.2%, and 93.5%, respectively. Especially the respective nitrogen and phosphorus removal was 15% greater than that of the SBR operated with influent from CSS. Simultaneous nitrification and denitrification (SND) was observed in an aerobic reactor(II) as a result of DO concentration gradient developed along the depth by the Air-vent system. In order to achieve T-N removal greater than 90%, the C/N ratio should be over 6.0 and the difference between $BOD_5$ loading and nitrogen loading rate be over 100 kg/day (0.130 kg $T-N/m^3{\cdot}d$). Even with high influent T-P concentration of 5.360 mg/L from SSS (compared with 2.465 mg/L from CSS) T-P removal achieved 93.5% which was 15.5% higher than that of the SBR with influent from CSS. This is probably due to high influent $BOD_5$ concentration from SSS that could provide soluble carbon source to release phosphorus at anaerobic condition. In order to achieve T-P removal greater than 90%, the difference between $BOD_5$ loading and phosphorus loading rate should be over 100 kg /day (0.130 kg $T-N/m^3{\cdot}d$).