• Journal of environmental and Sanitary engineering
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• v.17 no.3
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• pp.83-88
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• 2002

This study was performed to determine the possibility of sludge treatment by ozone for reducing the sludge production in sewage treatment. To evaluate the characteristics of the release of organic matters and nutrient from sludge degradation by ozone, SCOD, SBOD/TCOD, T-N and T-P were analyzed. From the results, we concluded that the concentration of soluble organic matters(SCOD) was increased with reaction time. Also, The concentration of T-N and T-P were increased with time like as organic matters. Quantities of released SCOD, SBOD, T-N and T-P by ozonization were 0.038g, 0.058 g, 0.011 g, 0.012 g per g MLSS, respectively.

• Journal of environmental and Sanitary engineering
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• v.16 no.1
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• pp.34-39
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• 2001

Submerged Membrane Bio-Reacter(SMBR) process was used to food wastewater treatment. From laboratory pilot-scale experiment data, it was confirmed that this process was very effective process for organics, suspended solid, and N, P treatment. It was found that BOD and COD removal rate were obtained 90% and 92%, respectively, for 150 days operation. Organics 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 95%, 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 and Sanitary engineering
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• v.17 no.4
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• pp.1-9
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• 2002

In order to define about concern with discharge and water-quality, it is calculated drought flow, low flow, normal flow and wet flow in Chungju watershed from flow duration analysis. Water quality modeling study is performed for forecasting at upstream of Chungju lake. It is devided method of modeling into before and after the equipment of environmental treatment institution. And it is estimated the change of water quality. Before the equipment of environmental treatment, BOD concentration is increased from 23000 to 2006 years at all site and decrease on 2012 years. The rate of increasing BOD concentration is showed height between 2000 years and 2003 years most of all site. And after the equipment of environmental treatment, it is showed first grade of BOD water quality in most of sample site beside Jucheon river. The result of water quality modeling using drought flow showed that a lot of pollution occurred. And water quality using wet flow is good, so much discharge make more improve water quality than little discharge.

• Journal of environmental and Sanitary engineering
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• v.12 no.3
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• pp.131-138
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• 1997

In this study, the effect of the various operating conditions on the removal of $Cr^{6+}$ from $Cr^{6+}$ containing wastewater which has strong toxicity by using electrolysis with iron electrode as anode and aluminum electrode as cathode was investigated. The removal efficiency of $Cr^{6+}$ was increased as the pH was decreased, as the distance of electrode was decreased and the voltage was increased. The reaction temperature slightly affected the removal efficiency. The optimum conditions for the treatment of $Cr^{6+}$ containing wastewater were initial pH 3, 5 volt and the distance of electrode was 1cm. The feasibility of the electrochemical treatment to the $Cr^{6+}$ containing industrial wastewater was verified from this study.

• Journal of environmental and Sanitary engineering
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• v.13 no.3
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• pp.85-92
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• 1998

In this study, the electrolytic treatment by one-stage electrolysis was investigated for electroplating wastewater containing $Cr^{6+}$ and $CN^{-}$. From the results, we concluded as follows : Optimum initial pH of wastewater was pH : 3. Amount of optimum addition of electroltyte(NaCl) was 0.1 wt%. Optimum potential for electrolysis was 5 volt. Concentration and removal efficiency for $Cr^{6+}$ and $CN^{-}$ were under 1 mg/L and above 99% at optimum conditions. And the feasibility of electrolytic treatment for electroplating wastewater containing $Cr^{6+}$ and $CN^{-}$ was certified.

• 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.

• Journal of environmental and Sanitary engineering
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• v.7 no.2
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• pp.37-52
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• 1992

Since the first sewage treatment plant was constructed in 1976, the sewerage systems of Korea have been rapidly expanded. As of the end of 1991, 22 sewage treatment plants with total capacity of 5.4 million tons/day are in operation which is equivalent of 3395 total daily sewage generation. Total extension of sewer 39.534 km in 1990 which is 55% of the target extension for the year 2001. However, the most sewage treatment plants employ activated sludge process which may not be suitable for medium and/or small scale plants. The poor existing sewer systems do not effectively collect and transport sewage to adversely affect the function of sewage treatment plant. To select the appropriate treatment system, the cities are classified into 3 categories such as large and medium size inland cities, small size cities and coastal cities. Considering the criteria suggested during this study, appropriate treatment processes were selected for each category. Conventional activated sludge process and step aeration process were found to be the most appropriate for big inland cities while biological nutrient removal processes should be considered for the cities discharge the effluent to lakes or reservoirs. RBC or Oxidation Ditch process might be appropriate for the medium size cities while several processes which do not require skilled operation and maintenance were suggested for the small cities. Ocean discharge after primary treatment can be considered for some east coast cities, Appropriate methodology to rehabilitate the existing sewers and strategy to convert combined sewer system to separate sewer system were proposed. This paper also include the appropriate management system for industrial wastewater, sludge and nightsoil.

• Journal of environmental and Sanitary engineering
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• v.17 no.4
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• pp.29-38
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• 2002

Advanced oxidation of wastewater was studied with a purpose to remove TOC and color by the ozone-assisted Fenton reaction. The optimal conditions were determined by hydrogen peroxide and ozone concentrations. Experimental results indicate that the ozone treatment after Fentons process was found to provide very efficient removal efficiency in the process, avoiding the exclusive ozone treatment. The combined process of ozone in the Fenton oxidation respectively was increased removal efficiences of 10.7％ in comparison with exclusive Fenton oxidation. Also, the treatments of ozone after Fenton's oxidation respectively had increased the removal efficiences of 16.％. As a result, the treatment of ozone after Fentons oxidation had the best removal efficiency of approximately 96％. Removal efficiency of color was significantly increased as mush as 26％ by the advanced Fenton's oxidation in comparison with exclusive Fenton's oxidation. The removal efficiencies in the biological treatment using Bacillus subtilis after Fenton's oxidation and after Fenton's and ozone's oxidation were increased by 14％ and 19％ respectively. Although these combined Bacillus subtilis-assisted Fenton's oxidation was determined to be effective method to treat the dyeing wastewater in an economic point of view, the choice of wastewater treatment can be varied depending on water quality.

• 수도
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• v.22 no.5 s.75
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• pp.64-75
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• 1995

• Water for future
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• v.9 no.1
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• pp.24-32
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• 1976