• Journal of the Korean GEO-environmental Society
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• v.11 no.8
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• pp.33-40
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• 2010

In this study, evaluation of basic unit of non-point pollutant, which is fundamental evaluation of non-point loading, was conducted using both road point and angle of intersection point in Maesong area, West coast highway by utilizing Event Mean Concentrations(EMC). Concentration of pollutants except heavy metals at these two points rapidly decreased in 30 minutes after start of runoff. According to the results of EMC, for both sampling points, it was determined that the concentrations of TSS(Total Suspended Solid), $BOD_5$(Biological Oxygen Demand), and DOC(Dissolved Organic Carbon) were higher than those of wastewater effluent standard in Korea, however, the concentrations of T-N(Total Nitrogen) and T-P(Total Phosphorus) were lower than those of the standard. In terms of heavy metals, Fe, Pb, and Zn showed higher concentrations than others. When compared with the units established by the Ministry of Environment in Korea, the basic units of $BOD_5$ and T-N in this study were lower. On the other hand, when compared with foreign units, Cu, Pb, and Zn showed approximately 10 times higher concentrations. It was estimated that a long term monitoring should be conducted for obtaining additional data and more reliable basic units for the non-point pollutnats based on the results from this study.

• Journal of Korean Society of Environmental Engineers
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• v.36 no.1
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• pp.35-41
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• 2014

Trihalomethanes (THMs) are formed as a results of the reaction of residual chlorine, used as a disinfectant in drinking water, with the organic matter in raw water. Although chlorinated and brominated THMs are the most common disinfection byproducts (DBPs) reported, iodinated THMs (I-THMs) can be formed when iodide is present in raw water. I-THMs have been usually associated with several medicinal or pharmaceutical taste and odor problems and is a potential health concern since they have been reported to be more toxic than their brominated and chlorinated analogs. Currently, there is no published standard analytical method for I-THMs in water. An automated headspace-gas chromatography/electron capture detector (GC/ECD) technique was developed for routine analysis of 10 THMs including 6 I-THMs in water samples. The optimization of the method is discussed. The limits of detection (LOD) and limits of quantification (LOQ) range from 12 ng/L to 56 ng/L and from 38 ng/L to 178 ng/L for 10 THMs, respectively. Matrix effects in river water, sea water and wastewater treatment plant (WWTP) final effluent water were investigated and it was shown that the method is suitable for the analysis of trace levels of I-THMs, in a wide range of waters. The method developed in the present study has the advantage of being rapid, simple and sensitive.

• Journal of Korean Society of Environmental Engineers
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• v.30 no.12
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• pp.1273-1280
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• 2008

This study sought to establish the optimum operating condition for the recovery of caustic (NaOH) solution from mercerization in textile process. As main factors, the silt density index (SDI) evaluation of ceramic membrane for the application of nanofiltration/reverse osmosis (NF/RO) membrane, the recovery yield measurement of caustic solution for the application of polymeric membrane, the optimum condition of chemical cleaning for the membrane regeneration, the optimum removal condition of total organic carbon (TOC), turbidity, color, and the permeate flux of ceramic membrane/polymeric membrane combined process were investigated. As results, ceramic ultrafiltration (UF) in the first step and nanofiltration (NF) in the second step were found to be suitable for the removal of total suspended solid (TSS), residual organics, turbidity including color, and the recovery of caustic solution from caustic wastewater stream in mercerization process. When only the ceramic UF membrane was used, the rejection efficiency of both of TSS and turbidity was more than 99.0%, and the color and TOC were rejected about 74.7% and 49.2%, respectively. Meanwhile, the combined membrane precess of UF and NF membranes showed even more efficient removal abilities and thus more than 99.9% of TSS and turbidity, 87.7% of color, and 78.2% of TOC were removed. In particular, 91.3% of NaOH was successfully recovered with 83.7% of total volume in the combined membrane process. With this regard, a clean caustic solution was obtained in a high purity, which can be reused for mercerization process, expecting to offer economical benefits.

• Applied Biological Chemistry
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• v.41 no.2
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• pp.181-186
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• 1998

The effects of sewage treatment on characteristics of sludge as a composting material were investigated for a year during the initial operation at the full-scale Chunan sewage treatment plant. Due to the shortage of design capacity of belt press, a sludge dewatering unit, non-volatile solids were recirculating and concentrating in the treatment plant, resulting in an increase of MLSS and a decrease in F/M ratio at the activated sludge system. Special attention is required for long term operations since the increase of non-volatile solids in the plant would deteriorates the treatment efficiency. The sewage sludge of the Chunan sewage treatment plant showed 79.5% of water content, 11.6% of organic content, and C/N ratio of 6.1, and contained As 1.8 mg/kg, Cd 27 mg/kg, Hg <0.1 mg/kg, Pb 54 mg/kg, T-Cr 370 mg/kg, and Cu 1,100mg/kg of heavy metals. In order to be used as raw material for optimum composting, the sewage sludge requires bulking agents for moistrure/porosity control and a carbon source for adjusting C/N ratio. However, the sewage sludge is not adequate as a soil conditioner after composing due to a high content of heavy metals. If the sewage sludge has to he used as a soil conditioner after composting, it as required to identify and remove tire industrial wastewater portions in tire influent of the plant since heavy metals in the influent were mostly concentrated in dewatered sludge.

• Journal of Korean Society of Environmental Engineers
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• v.37 no.1
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• pp.45-51
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• 2015

PBDEs (polybrominated diphenyl ehters) are rarely dissolved in water due to their strong hydrophobicity and large molecular mass so not many researches were done in aqueous environment compared to other environmental compartments. However, the mass loading from wastewater treatment plant into aquatic environment, re-suspension from bottom sediment and partitioning from floating particles and colloids may not be negligible. It is, therefore, important but also difficult to investigate PBDEs in water environment. Recent overcoming resolution towards this barrier to monitor hydrophobic organic compounds in aquatic environment is using passive sampling technique like semipermeable membrane device. By using passive sampling, it might be possible to obtain long-term reproducible monitoring result and detect the trace amounts of PBDEs, with controlling fluctuation of surrounding environmental factors during the sampling event. So therefore, this study is purposed to confirm the possibility of using SPMD (semi-permeable membrane device) as water monitoring tool. Grab samples, composite samples and SPMDs were applied in river bank to evaluate the concentration difference and temporal fluctuation by various water sampling method, and to assess the water concentration prediction capability of SPMD for the PBDEs.

• Korean Chemical Engineering Research
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• v.43 no.2
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• pp.318-323
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• 2005

Supercritical water oxidation (SCWO, P>221 bar, T>$374^{\circ}C$) is a promising method for the decomposition of refractory organic compounds. In this study, the SCWO of Ethylenediaminetetraacetic acid (EDTA) was carried out in a tubular-type continusous reactor system with an $H_2O_2$ oxidant at $387-500^{\circ}C$, 250 bar and residence time (RT) of 15.9-88.9 s. The decomposition efficiencies increased with increasing temperature and oxidant amount, while it was inversely proportional to feed flow rate. The decomposition efficiency of 99.6% was obtained at $500^{\circ}C$, 250 bar, oxidant amount of 400% and residence time of 40.1 s. The effect of temperature on the decomposition efficiency was more significant than that of oxidant amount. In the case of the decomposition efficiency of 5,000 mg/L of EDTA (3,063 mg/L as $COD_{Cr}$), the decompostion of 99% or higher was obtained at the condition of over 40.1 s (RT) and 200 stoichiometric % of $H_2O_2$ in the supercritical water of $500^{\circ}C$ and 250 bar.

• Journal of Korea Water Resources Association
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• v.35 no.2
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• pp.149-159
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• 2002

The monthly water quality data measured at 19 stations located in the Sapkyo reservoir watershed were clustered into 2 to 7 clusters and factor analysis was conducted to characterize the water quality, using the information obtained from cluster analysis. The result of cluster analysis shows that Sapkyo reservoir and each stream (Sapkyo stream, Muhan stream and Kokkyo stream) in Sapkyo reservoir watershed hove their own water quality characteristics. The result of water quality analysis indicates that the concentration of suspended solids from Sapkyo reservoir is much higher than those of other streams, and which is probably because of increment of phytoplankton biomass with rich nutrient flowing Into Sapkyo reservoir from the upper stream of watershed. Furthermore, the concentrations of biochemical oxygen demand and chemical oxygen demand were 3.5 to 4.8 times and 1.7 to 2.5 times those of other streams, respectively. The overall water quality of Sapkyo reservoir watershed was considered to exceed eutrophic condition. Based on factor analysis, the water quality characteristics of Sapkyo stream and Muhan stream were closely related with farm land and residence. The water quality of Kokkyo stream was influenced by superabundant organic matter flowing from Chonan city and district wastewater treatment plant located in the upper stream of Kokkyo stream. The water quality factor influencing Sapkyo reservoir was closely related with water quality factors of other three streams.

• Journal of Korean Society of Environmental Engineers
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• v.36 no.6
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• pp.387-395
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• 2014

A highly sensitive analytical method based on stir bar sorptive extraction (SBSE) technique and gas chromatography/tandem mass spectrometry (GC-MS/MS) has been developed, allowing the simultaneous multi-analyte determination of 11 synthetic fragrances (SFs) in water samples. The stir bar coated with polydimethylsiloxane (PDMS) was added to 40 mL of water sample at pH 3 and stirred at 1,100 rpm for 120 min. Other SBSE parameters (salt effect and presence of organic solvent) were optimised. The method shows good linearity (coefficients > 0.990) and reproducibility (RSD < 10.9%). The extraction efficiencies were above 83% for all the compounds. The limits of detections (LOD) and limits of quantification (LOQ) were 2.1~4.1 ng/L and 6.6~12.9 ng/L, respectively. The developed method offers the ability to detect 11 SFs at ultra-low concentration levels with only 40 mL of sample volume. Matrix effects in tap water, river water, wastewater treatment plant (WWTP) final effluent water and seawater were investigated and it was shown that the method is suitable for the analysis of trace level of 11 SFs. The method developed in the present study has the advantage of being rapid, simple, high-sensitive and both user and environmentally friendly.

• Journal of the Korean Society for Marine Environment & Energy
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• v.7 no.2
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• pp.104-110
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• 2004

This study was carried out to survey the pollution of bisphenol A(BPA) and total organic carbon(TOC) in surface sediments around Gwangyang bay. BPA is suspected chemicals as endocrine disruption. Gwangyang bay Is located on the mid south coast of Korea. It is a semi-closed bay which Yeosu petrochemical industrial complex, POSCO(Pohang Steel Company) and Gwangyang container harbor are located. The surface sediments were collected at 15 stations with gravity corer at October, 1999, February, May and August, 2000. Also, the stream and intertidal sediment were collected at 5 sites at August, 2000. Concentrations of BPA in surface sediments were in the range of 0.46 to 24.59 ng/g dry wt.. Seasonal range(mean value) of BPA are 0.59 to 9.00(1.88) ng/g dry wt. at October, 0.99 to 2.97(1.57) ng/g dry wt. at February, 0.46 to 24.59(2.53)ng/g dry wt. at May and 0.54 to 2.46 (1.29)ng/g dry wt. at August. BPA was seasonally fluctuated, and the highest mean value and range were detected at May, 2000. BPA was highly distributed in the inner part of Kwangyang bay than Yosu sound. Concentrations of BPA in stream and intertidal sediments showed the highest value in downstream near Yochon petrochemical industrial complex and Yondung stream. It suggests that the source of BPA are industrial wastewater and municipal sewage. TOC in surface sediments were in the range of 0.09∼1.22%. There was no any correlation between the BPA and TOC.

• Journal of The Korean Society of Agricultural Engineers
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• v.47 no.1
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• pp.79-91
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• 2005

Wetland systems are widely accepted natural water purification systems around the world in nonpoint sources pollution control. Constructed wetlands have become a popular technology for treating contaminated surface and wastewater. In this study, the field experiment to reduce nonpoint source pollution loadings from polluted stream waters using wetland system was performed from June 2002 to March 2004, including winter performance using four newly constructed wetlands. The Dangjin stream water flowing into Seokmun estuarine lake was pumped into wetlands, and inflow and hydraulic residence time of the system was $500m^{3}{\~}1500m^{3}/day\;and\;2{\~}5$ days respectively. After 3 years operation plant-coverage was about $80~90\%$ from zero at initial stage even with no plantation. Average water quality of the influent in growing season was BOD_{5}\;3.96mg/L$, TSS 22.98 mg/L, T-N 3.29 mg/L, T-P 0.30 mg/L. The average removal rate of four wetlands for $BOD_{5},\;TSS,\;T-N\;and\;T-P$ in growing season was $24\%$, $62\%$, $54\%$, and $51\%$, respectively. And average water quality of the influent in winter season was $BOD_{5}$ 4.92 mg/L, TSS 12.47 mg/L, T-N 5.54 mg/L, and T-P 0.32 mg/L, respectively. The average removal rate of four wetlands for them was $-21\%$. $23\%$, $33\%$, and $53\%$, respectively. The reason of higher BOD_{5} effluent concentration in winter season might be that low temperature restrained microorganism activity and a organic body from the withered plant and algae was flown out. Except the result of $BOD_{5}$, the effectiveness of water quality improvement in winter season was satisfactory for treating polluted stream waters, and $BOD_{5}$ variation was within the range of background concentration. Performance of the experimental system was compared with existing data base (NADB), and it was within the range of general system performance. Overall, the wetland system was found to be satisfactory for NPS control such as improvement of polluted stream water.