• Proceedings of KOSOMES biannual meeting
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• 2006.11a
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• pp.217-219
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• 2006

This study focused an water quality response to land-based pollution loads and the appropriate pollutant load reduction in Chinhae Bay using an eco-hydrodynamic model. Land-based discharge foam urban areas, industrial complex and sewage treatment plant was the greatest contributor to cause red-tide blooms and summer hypoxia. Tidal currents velocity af the ebb tide was about 10 cm/s stronger than that of the flood tide. A residual current was simulated to. have a slightly complicated pattern with ranging from 0.1 to. 2.7 cm/s. In Masan Bay, pollutant materials cannot flaw from the inner to the outer bay easily because af residual currents flaw southward at surface and northward at the bottom. The simulation results of COD distribution showedhigh concentrations aver 3 mg/L in the inner part of Masan Bay related pollutant discharge, and charge, and lower levels less than 1.5mg/L in the central part of Chinhae Bay. For improvement water quality in Chinhae Bay, it is necessary to reduce the organic and inorganic loads from paint sources by mare than 50% and ameliorate severe polluted sediment.

• Journal of Korean Society on Water Environment
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• v.25 no.5
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• pp.713-719
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• 2009

A natural wetland in the Nakdong River basin which effectively removes non-point source pollutants was investigated for 2 years to understand wetland topography, vegetation types, and water quality characteristics. The water depth of the natural wetland was in the range of 0.5~1.9 m which is suitable for the growth of non-emergent hydrophytes. The wetland has a high length to width ratio (3.3:1) and a relatively large wetland to watershed area ratio (0.057). A broad-crested weir at the outlet increases the retention time of the wetland whose hydrology is mainly dependent on storm events. The concentrations of dissolved oxygen in the growing season and the winter season showed anoxic and oxic conditions, respectively. Diurnal variations of DO and pH in the growing season were also observed due to weather change and submerged plants. COD and TP concentrations were low in the winter season due to low inflow rate and increased retention time. Increased TP concentrations in the spring season were caused by degradation of dead wetland plants. Nitrogen in the wetland was mostly in organic nitrogen form (>75%). During the growing season, ammonium concentration was high but nitrate nitrogen concentration was low, possibly due to anoxic and low pH conditions which are adverse conditions for ammonificaiton and nitrification. The results of this study can be used as preliminary data for design, operation, monitoring and management of a constructed wetland which is designed to treat diffuse pollutants in the Nakdong river watershed.

• Korean Journal of Environmental Agriculture
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• v.29 no.3
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• pp.232-238
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• 2010

The objective of this study was to investigate a small sewage treatment system. This system was developed to improve a nitrogen and phosphorus removal efficiency and generate less solid using upflow septic tank(UST) - aerobic filter(AF) system. The UST equipped with an aerobic filter, the filter was fed with both raw sewage and recycled effluent from the UST to induce the denitrification and solid reduction simultaneously. Overall removal efficiencies of COD and total nitrogen(TN) were above 96% and 73% at recycle ratio of 200%, respectively. Critical coagulant dose without the biochemical activity was found to be 40 mg/L. Removal efficiency of total phosphorus(TP) in influent was above 90% by chemical and biological reactions. Although the phosphorus concentration was low under the high alkalinity in raw sewage, the pH value was unchanged by the coagulant dose.

• Proceedings of the Korea Water Resources Association Conference
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• 2011.05a
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• pp.283-287
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• 2011

농업비점오염원의 오염원 관리를 위해서는 오염물질의 발생과 운반에 직접적으로 영향을 미치는 농업수문학 기술에 바탕을 두고 우리나라의 집약농업의 특성을 정확히 반영할 수 있는 최적관리방법의 개발과 비점오염저감효과를 검증할 수 있는 현장실험이 수반되어야 한다. 따라서 본 연구에서는 지표피복재를 이용하여 밭의 토양침투를 증가시고 유속 및 유출량 감소를 통해 토양유실과 비점오염원을 저감하고자 하였다. 실험방법은 실제 영농과 동일하게 무를 재배한 뒤 볏짚거적을 이용하여 밭의 토양 표면을 피복하여 유량과 수질농도를 측정하였다. 연구기간 동안 총 3차례(2010년 9월 9~12일, 9월 21일, 10월 2~3일)의 강우가 발생하였고, 이때 발생한 강우량은 각 359.2 mm, 49 mm, 28.8 mm이였다. 각 시험포에서 볏짚거적으로 인해 저감된 유출량의 저감효율은 볏짚거적을 피복하지 않은 나지상태의 밭 보다 약 33∼75%의 저감효과가 있는 것으로 나타났다. 75%의 유출률 저감 효과가 가장 크게 나타난 강우사상은 30 mm 이하의 강우가 발생한 10월 2~3일의 강우사상에서 나타났다. 강우량과 강우강도는 28.8 mm와 1.92 mm/hr으로 나타났으며, 이때 발생한 유출량은 나지에서 $0.36\;m^3$, 볏짚거적을 피복한 시험포에서는 $0.08\;m^3$이 발생하였다. 나지상태와 볏짚거적을 피복한 시험포의 오염부하의 값을 비교한 결과 볏짚거적을 피복한 시험포에서 $BOD_5$ 항목은 64.3%, SS 80.8%, $COD_{Mn}$ 66.7%, DOC 80.2%, T-N 56.6% 그리고 T-P 56.1%의 오염부하 저감효과가 나타났다. 본 연구의 결과와 같이 지표를 볏짚거적으로 피복할 경우 시험포에서 유출시작 시간 지연효과와 강우에 의한 첨두유출량 및 유출량 감소 효과가 나타나는 것으로 나타났으며, 연구결과는 농업 비점오염원의 최적관리를 위한 과학적 근거자료 제공 및 기초자료로 활용할 수 있을 것으로 판단된다.

• Journal of Korean Society on Water Environment
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• v.22 no.1
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• pp.23-29
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• 2006

Biosorption technology was used to remove hazardous materials from wastewater, herbicide, heavy metals, and radioactive compounds, based on binding capacities of various biological materials. Biosorption process can be explained by two steps; the first step is that target contaminants is in contact with microorganisms and the second is that the adsorbed target contaminants is infiltrated with inner cell through metabolically mediated or physico-chemical pathways of uptake. Until recently, no information is available to explain the definitive mechanism of biosorption. The purpose of this study is to evaluate biosorption capabilities of organic matters using activated sludge and to investigate affecting factors upon biosorption. Over 49% of organic matter could be removed by positive biosorption reaction under anoxic condition within 10 minutes. The biosorption capacities were constant at around 50 mg-COD/mg-MLSS for all batch experiments. As starvation time increased under aerobic or anaerobic conditions, biosorption capacity increased since higher stressed microorganisms by starvation was more brisk. Starvation stress of microorganisms was higher at aerobic condition than anaerobic one. As temperature increased or easily biodegradable carbon sources were used, biosorption capacities increased. Consequently, biosorption can be estimated by biological -adsorbed capability of the bacterial cell-wall and we can achieve the cost-effective and non -residual denitrification with applying biosorption to the bio-reduction of nitrate.

• Journal of Korean Society of Environmental Engineers
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• v.37 no.1
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• pp.14-22
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• 2015

In order to analyze the flow and pollutant runoff characteristics of industrial area, SWMM (Storm Water Management Model) was applied. The model was calibrated based on the measured data in the waterway of Sihwa industrial complex during six events, 2008-2009. The build-up process of pollutants is expressed as Power-linear form and washoff as Power-Exponential form. The validated model was used to analyze the change of the runoff characteristics in the industrial area. In the study area, runoff flow is decreased with an increase in impervious area, but there is no significant change in peak time. The results of this study will be used as basic information of impervious area reduction and watershed management in industrial areas.

• Membrane and Water Treatment
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• v.9 no.4
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• pp.255-262
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• 2018

This study attempted to evaluate the process of self-forming dynamic membrane formation on mesh filter in membrane bioreactor with a two-stage method of batch (agitation) and continues (aeration) stage at different sludge concentrations. Four concentrations of activated sludge including $6{\pm}0.4$, $8{\pm}0.5$, $10{\pm}0.3$, $14{\pm}0.3g/L$ were used to demonstrate the optimal concentration of sludge for treating municipal wastewater and reducing fouling in dynamic membrane bioreactor. The formation time and effluent turbidity were decreased in the batch stage when increasing the activated sludge concentration. The minimum values of formation time and effluent turbidity were 14 min and 43 NTU for the optimum mixed liqueur suspended solids of $8{\pm}0.5g/L$, respectively. To improve operational condition and fouling reduction in the aeration stage, critical fluxes were measured for all concentrations by flux-step method. With increasing the sludge concentration, the relevant critical fluxes reduced. The optimum subcritical flux of $30L/m^2/h$ was applied as operating flux in the second stage. The maximum COD removal efficiency of 98% was achieved by the concentration of $8{\pm}0.5g/L$. Compressibility index of self-forming dynamic membrane and transmembrane pressure trend remained somewhat constant until the optimal concentration of $8{\pm}0.5g/L$ and thereafter they increased steeply.

• Journal of Korean Society of Water and Wastewater
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• v.12 no.4
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• pp.86-96
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• 1998

In this study, an intermittently aerated activated sludge process, modified process from conventional activated sludge process, was developed to treat high strength swine wastewater, which has been blamed as major pollutant for stream pollution. Therefore, the optimum cycle for oxic and anoxic period, SRT, and OLR were studied as design parameters. The effects of different time interval for oxic and anoxic period on nitrification and denitrification were examined by operating two reactors with 60/60min and 60/90min as oxic/anoxic period. Although the reactor with 60/60min showed complete denitrification of $NO_x-N$ generated during oxic period, the reactor with 60/90min showed incomplete nitrification due to the inactivity of nitrifier by accumulated $NH_3-N$ toxicity during anoxic period. Therefore, it is recommended to operate same interval for oxic and anoxic period. In order to determine the optimum cycle for oxic/anoxic period, four different reactors with 30/30, 60/60, 90/90 and 120/120min were examined. The reactor operation with 90/90min was optimum to get the most stable results in this study. However, the optimum cycle for oxic and anoxic period should be changed with characteristics of influent wastewater and operating conditions. According to lie operation results of three reactors with SRT of 15, 20 and 30days. The reactor with 2Odays SRT showed best removal efficiency of T-N. The optimum OLR would be $2.5Kg\;COD/m^3/day$ which showed the most stable nitrification and denitrification. Since characteristics of influent wastewater in the real system has a severe fluctuation, so it is very difficult to determine each interval for oxic and anoxic period. Therefore, ORP curves, describing the change of oxidation/reduction potential in reactor, can be used as a control parameter for automatic control of oxic and anoxic period. In other words, bending point (Nitrate Knee) of ORP curve during anoxic period could be used as a starting point of oxic period.

• Journal of Korean Society on Water Environment
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• v.35 no.1
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• pp.9-18
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• 2019

Recently, it was realized that a significant portion of pollution from urban areas originates from non-point sources such as construction sites, washoff from impervious surfaces, and sewage input from unsewered areas and combined sewer overflows. Especially, Urban stormwater runoff is one of the most extensive cause of the deterioration of the water quality in streams located in urban area. The objective of this study was to investigate runoff characteristics of non-point pollutants source at the urban area in the Suyeong River. Water quality variations were investigated at two points of Suyeong River during a period of 10 rainfall events. Concentration difference of non-point pollution source appeared big by precedent number of days of no rainfall. In addition, Event mean Concentration (EMCs) that well represents runoff characteristics of storm water during rainfall, was calculated, and runoff pollutants loading was also examined. The probability distribution of EMCs of BOD, COD, TOC, T-N, T-P, and TSS were analyzed and the mean values of observed EMC and the median values of estimated EMCs compared through probability distribution. Other objectives of this study were the characterization of discharge from non-point source, the analysis of the pollutant loads and an establishment of a management plan for non-point source of Suyeong River. Also, It was established that the most important thing for the administration of non-point pollution source is to come up with the solution for the reduction of effluent at the beginning.

• Journal of Korean Society of Water Science and Technology
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• v.26 no.6
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• pp.73-80
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• 2018

In this study, the solids removal characteristics using T-P sludge generated from PACl coagulation were analyzed by laboratory scale and full scale experiment. As the amounts of T-P sludge injection into the raw sewage influent increased at the rate of 0, 1, 2, 3, 4 %, the suspended solids concentrations after 20 minutes setting test decreased to 210, 137, 91, 64, 43 mg/L, respectively. The filtration time required for dewatering test of the raw sewage influent decreased to 982, 728, 658, 581, 492 sec for 0, 1, 2, 3, 4% of T-P sludge injection, respectively. As the amounts of PACl coagulant into the effluent from final setting tank increased at 0, 10, 20, 30, 40 mg/L, the required filtration times for T-P sludge increased into 12.3, 41.7, 53.7, 67.2, 79.5 sec and the dewaterability of T-P sludge decreased. After T-P sludge returned into the primary settling tank on J-si sewage treatment plants, the effluent concentrations of COD, SS, T-N and T-P from primary settling tank into bioreactor decreased by 35.9, 27.9, 22.2, and 52.6% due to the coagulation effects of the T-P sludge. Finally, it was found that the return of T-P sludge into the primary settling tank could result into the sludge reduction having a lower water content of 3.03% p than in case of the only T-P sludge dehydration.