• Journal of Korean Society of Water and Wastewater
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• v.34 no.3
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• pp.211-220
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• 2020

When domestic sewage and rainwater runoff are discharged into a single sewer pipe, it is called a "combined sewer system." The sewage design standards in Korea specify the flow velocity based only on the volume of rainfall; therefore, sedimentation occurs on non-rainy days owing to the reduced flow rate and velocity. This sedimentation reduces the discharge capacity, causes unpleasant odors, and exacerbates the problem of combined sewer overflow concentration. To address this problem, the amount of sewage on non-rainy days, not just the volume of rainfall, should also be considered. There are various theories on sedimentation in sewer movement. This study introduces a self-cleansing velocity based on tractive force theory. By applying a self-cleansing velocity equivalent to the critical shear stress of a sand particle, sedimentation can be reduced on non-rainy days. The amount of sewage changes according to the water use pattern of citizens. The design hourly maximum wastewater flow was considered as a representative value, and the velocity of this flow should be more than the self-cleansing velocity. This design method requires a steeper gradient than existing design criteria. Therefore, the existing sewer pipelines need to be improved and repaired accordingly. In this study, five types of improvement and repair methods that can maximize the use of existing pipelines and minimize the depth of excavation are proposed. The key technologies utilized are trenchless sewer rehabilitation and complex cross-section pipes. Trenchless sewer rehabilitation is a popular sewage repair method. However, it is complex because the cross-section pipes do not have a universal design and require continuous research and development. In an old metropolis with a combined sewer system, it is difficult to carry out excavation work; hence, the methods presented in this study may be useful in the future.

• 수도
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• s.25
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• pp.60-73
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• 1981

• Journal of Environmental Health Sciences
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• v.35 no.6
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• pp.517-525
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• 2009

The water quality of Lake Shihwa had been rapidly deteriorating since 1994 due to wastewater input from the watersheds, limited water circulation and the lack of a wastewater treatment policy. In 2000, the government decided to open the tidal embankment and make a comprehensive management plan to improve the water quality, especially inflowing stream water around Shihwa and Banwol industrial complex. However, the water quality and microbial community have not as yet been fully evaluated. The purpose of this study is to investigate the influent water quality around the industrial area based on chemical and biological analysis, and collected surface water sample from the Siheung Stream, up-stream to down-stream through the industrial complex, Samples were collected in July 2009. The results show that the downstream site near the industrial complex had higher concentrations of heavy metals (Cu, Mn, Fe, Mg, and Zn) and organic matter than upstream sites. A combination of DGGE (Denaturing Gradient Gel Electrophoresis) gels, lists of K-WQI (Korean Water Quality Index), cluster analysis, MDS (Multi-Dimensional Scaling) and PCA (Principal Component Analysis) has demonstrated clear clustering between Siheung stream 3 and 4 and with a high similarity and detected metal reducing bacteria (Shewanella spp.) and biodegrading bacteria (Acinetobacter spp.). These results suggest that use of both chemical and microbiological marker would be useful to fully evaluate the water quality.

• Journal of Korean Society for Atmospheric Environment
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• v.19 no.6
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• pp.663-677
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• 2003

The concentrations of volatile organic compounds (VOCs) in the ambient air were measured at three sites (Samil-dong, SRO and EFMC) in Yeosu industrial complex during September 2000 to August 2001. Air samples were collected for 24 hours in Silicocan canister (6l) with constant flow samplers every 6 days and analyzed using a cryogenic preconcentration system and a GC/MS. At each site, we identified 35 species known as on both the carcinogenic and mutagenicity by the EPA US (TO-14 manual). No relationship was found between YOCs concentration at three sampling points. Furthermore, the result shows that there appears to be a variety distribution of the concentration. BTX, vinyl chloride and high concentrations of 1,2-dichloroethane were observed at the sampling sites. Especially, high concentration of toxic VOCs, such as vinyl chloride, chloroform, 1,2-dichloroethane and benzene were shown at environmental facilities management cooperation (EMFC) site. They seem to be emitted from the facility of wastewater treatment in Yeosu industrial complex. It was difficult to tell the seasonal variation of total VOCs concentration. Nevertheless, the concentration in winter was typically higher than in summer The concentrations of toxic VOCs contents in Yeosu industrial complex were generally lower than those in Ulsan complex, although those were similar or less than in Seoul and Daegu. Whereas, toluene and styrene emitted from Yeosu industrial complex were higher than those of Edmonton industrial complex in Canada. Especially, toluene was third times higher than those observed from Texas, USA.

• Journal of Environmental Science International
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• v.29 no.11
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• pp.1055-1064
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• 2020

In this research, heavy metals and T-P removal characteristics of plated wastewater are derived using BPC(Break Point Chlorination) process. AA sedimentation pond outflow(Influence) was evaluated for the removal efficiency of heavy metal(Ni) and T-P at a reaction time of 25 minutes by NaOCl input volume(9, 11, 13 and 15 mL). In the case, the higher the NaOCl input volumes, the higher the ORP values were maintained and the higher the removal efficiency tended to be. On the other hand, T-P was judged to have a low relationship between the ORP value and the removal efficiency. In addition, the efficiency of removal heavy metals and T-P in the plated wastewater by injecting 10 mL, 15 mL, 20 mL and 25 mL NaOCl, increased as the amount of NaOCl injected increased, the amount of NaOH input for pH increased. It was found that suspended solid in effluence also increased. It was also observed that the color of the plating wastewater changed from yellowish green to green to charcoal gray to black as the amount of NaOCl injected increased. Treatment characteristics of the reaction time, the longer the reaction time with the substance to be treated after the input of NaOCl, the more the heavy metal removal efficiency tended to increase. Through XRF analysis of the sludge, the constituents in the sludge such as NaCNO, CNCl, Na₃PO₄, CrO₄, 2Na₂CrO₄ and 2NaNO₃ will be analyzed in detail, and the mechanisms of the reaction between the plated wastewater and the complex compound will be elucidated.

• Journal of Environmental Health Sciences
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• v.42 no.4
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• pp.246-254
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• 2016

Objectives: This study evaluated the odor emission characteristics from fundamental environmental facilities at an industrial complex area in Daegu City. Methods: The odor samples were collected from May 2015 to January 2016 and were analyzed for specified offensive odor substances. The odor quotient and the odor contribution was calculated. Results: Ammonia was detected in all samples monitoring specified odor compounds, followed by hydrogen sulfide and acetaldehyde. According to contribution analysis, hydrogen sulfide shows the highest contribution in all facilities. At wastewater treatment plants A and B and sewage treatment plant F, it was followed by acetaldehyde. At wastewater treatment plant C, it was followed by imethyl sulfide. Conclusion: The major component of odor can be determined by evaluating the degree of contribution to the odor intensity rather than the concentration of the individual odor components. To increase the effectiveness of odor reduction, policies focused on materials with a high odor contribution are needed rather than focusing on high-concentration odor compounds.

• KSBB Journal
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• v.24 no.6
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• pp.556-562
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• 2009

The biological treatment of TNT-containing wastewater, known commonly as pink water, was investigated using a stirred tank reactor with Stenotrophomonas maltophilia OK-5 bacterial culture. S. maltophilia OK-5 exhibited effective degradation of TNT contained in pink water, completely degrading TNT (100 mg/L) within 6 days of incubation. The dark-red brown color derived from Hydride-Meisenheimer complex became more pronounced during the incubation period, which was determined quantitatively. High-pressure liquid chromatography was used to measure residual TNT, which also resolved the metabolic intermediates (i.e., 2,4-dinitrotoluene, 2,6-dinitrotoluene and 2,4-dinitro-6-hydroxytoluene). Gas chromatography-mass spectrometry was used to verify these intermediates. Quantification of the nitroreductase (pnrB) gene isolated from S. maltophilia OK-5 growing in pink water was performed with real-time PCR. The amount of pnrB gene copies increased to $10^3$-fold after 5 days of incubation time.

• Korean Journal of Environmental Agriculture
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• v.15 no.3
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• pp.306-315
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• 1996

This study was performed to develop the biological treatment technology of wastewater polluted with heavy metals. The lead-tolerant microorganism, Pseudomonas aeruginosa which possessed the ability to accumulate lead, was isolated from the industrial wastewater polluted with various heavy metals. The characteristics of lead accumulation in the cells and the recovery of the lead there from were investigated. Removal rate of lead from the solution containing 100mg/l of lead by the lead-tolerant microorganism was more than 97% at 48 hours after inoculation with the microorganism. A large number of the electron-dense granules were found mainly on the cell wall and cell membrane fractions, when determined by transmission electron microscopy. Energy dispersive X-ray spectroscopy revealed that the electron-dense granules were lead complex with the substances binding heavy metals. The lead accumulated into cells was not desorbed by distilled water, but more than 87% of the lead accumulated was desorbed by 0.1M-EDTA. The residues of the cells after combustion at $550^{\circ}C$ amounted to about 30% of the dry weight of the cells. EDS analysis showed that the residues were relatively pure lead compounds containing more than 86% of lead.

• Journal of Korean Society of Water and Wastewater
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• v.21 no.1
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• pp.113-122
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• 2007

Experimental studies were performed to investigate speciation and leaching potential of heavy metals(Cu, Cd, Pb Zn, Ni) in ten sediment samples collected from Nakdong River. Acid Volatile Sulfide (AVS) and Simultaneously Extractable Metals (SEM) measurements were used to estimate heavy metals that can be leached under anaerobic conditions. Sequential Extraction Procedure (SEP) and Toxicity Characteristic Leaching Procedure (TCLP) were used to characterize speciation and leaching potential of heavy metals under aerobic conditions. The results show that total concentrations of Cu, Zn and Ni were relatively high in the sediments from points Seongseo industrial complex stream (upper stream) (D), Seongseo industrial complex stream (midstream) (E), Dalseo stream (F), and Nakdong river estuary (J), and that Cd concentrations were higher in all sampling points except for Goriung Bridge (G) and Soosan Bridge (H). SEM and AVS analyses reveal that samples from points Ilsun Bridge (A), Namgumi Bridge (C), and Soosan Bridge (H) have potential of heavy metals leaching, although leachable concentrations are relatively low. The leaching potential of heavy metals in other points was low because of higher concentrations of AVS than SEM. SEP results show that more than 50% of Cu, Zn and Ni were present in residual fraction, which means these metals are less amenable to leaching in anaerobic conditions. On the other hand, more than 50% of Pb and Cd were extracted during the first through third step of the SEP, which means substantial fraction of these metals can be leached upon changing of redox conditions. TCLP tests predict that leaching potential of heavy metals was generally low, which is consistent with the results obtained by AVS and SEM measurements.

• Journal of Environmental Science International
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• v.6 no.3
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• pp.249-258
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• 1997

Mercury- and cadmium-resistant bacteria were Isolated from an Industrial complex wastewater of Taejon area. All of them were motile, gram negative rods. In the results of physicochemical test and VITEK card test. HM1 was Identified with Achetobacter cd- coaceucus, CM3 was Identified 65 Commonas acidovorns, HM2, HM3, CMI , and CM4 were Pseudomonas sp., but HM4 and CM2 were unidenteed. They were tested for subceptlbility to 14 heavy metals. Mercury-resistant bacteria(HM1, HM2, HM3, and HM4) were sensitive to low concentration(100~400ppm) of $Cd^{2+}$, $Co^{2+}$. $Zn^{2+}$, and Ni2+, while cadmium-resistant bacteria(CM1, CM2, CM3, and CM4) showed resistance up to the high concentration(600~ 1, 200ppm) of these metal loons. As a result of resistance spectrum test of mercury-resistant bacteria, HM1 was broad-spectrum strain, HM2. HM3, and HM4 were narrow-spectrum stratas. Transmission electron microscopic examination of cell wall of HM1 culture grown with and without 100ppm of $HgCl_2$ showed remarkably merphological abnormalities. In the result of atomic absorption spectrometric analysis of cadmium-resistant bacteria grown at 200ppm of $CdCl_2$ for 6h, all of them accumulated cadrnium(14ppm~57ppm) In cell. In cadinium-resistant bacteria, CM1, CM2, and CM4 were spared from the Inhibitory effect of $Cd^{2+}$ by the addition of $Mn^{2+}$, CM4 were also spared from the Inhibitory effect of $Cd^{2+}$ by the addition of $Mn^{2+}$ as well as $Zn^{2+}$.