• 한국물환경학회지
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• 제23권5호
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• pp.766-775
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• 2007

The use of toxic chemicals was extended as the industry in Korea has grown dramatically during the last three decades. However, list of toxic substances and limit concentrations in the water environment are not consistent within management of ambient water, drinking water and industrial effluent. This article suggests the systematic framework to classify toxic substances in the water environment and deriving their effluent limits. The most important factor for decision-making to classify toxic substances is whether their concentrations in the water environment are higher than the reference concentrations, estimated by considering human health risk and ecological risk. Using a risk-based reference concentration, the ambient water quality criterion, it is possible to derive the regulatory limit concentrations of toxic substances in drinking water and in industrial effluent. The goal concentrations in the effluent, which guarantee the human and ecological safety, should be determined with scientific investigation, balancing environmental benefit and economical effect, considering availability of treatment technology and identifying characteristics of wastewater from different industries.

• 한국물환경학회지
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• 제23권5호
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• pp.642-649
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• 2007

The effectiveness of add-on tertiary treatment processes for the polishing of the effluent of a biological nutrient removal (BNR) system from a modified $A^2/O$ process has been examined under the field condition with pilot-scale plants. The add-on treatment processes of 1) combined biofilm anoxic reactor and sand filtration, and 2) two-stage denitrification filter had been operated with various operating conditions. The experimental results indicated that two-stage denitrification filter could produced a better polished tertiary effluent. Filtration rate of $150m^3/m^2{\cdot}d$ for the 2-stage denitrifying filter could decrease the nitrate removal probably due to shorter detention time that caused insufficient reaction for denitrification. Two stage denitrification filter operated with M/N ratio of 3.0 and filtration rate of $100m^3/m^2{\cdot}d$ produced the tertiary effluent with nitrate and SS concentraitons of 2.8 mg/L and 2.3 mg/L, respectively. When the operating temperature reduced $30^{\circ}C$ to $18^{\circ}C$, $NO_3{^-}-N$ removal efficiency decreased from 73% to 68%.

• Bulletin of the Korean Chemical Society
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• 제26권4호
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• pp.579-584
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• 2005

The 3-[(2-furylmethylene)amino]-2-thioxo-1,3-thiazolidin-4-one (FTT) was used as an excellent ionophore in construction of a $Zn^{2+}$ PVC-based membrane sensor. The best performance was obtained with a membrane composition of 30% poly(vinyl chloride), 62% nitrobenzen (NB), 3% FTT and 5% sodium tetraphenyl borate (TBP). This membrane sensor shows very good selectivity and sensitivity towards $Zn^{2+}$ over a wide variety of cations, including alkali, alkaline earth, transition and heavy metal ions. The membrane sensor revealed a great enhancement in selectivity coefficients for $Zn^{2+}$ ions, in comparison to the previously reported $Zn^{2+}$ membrane sensors. Theoretical studies also showed the selective interaction of TFF and $Zn^{2+}$ ions. The proposed membrane sensor exhibits a Nernstian behavior (with slope of 29.3 ${\pm}$ 0.3 mV per decade) over a wide concentration range (1.0 ${\times}$ $10^{-6}$-1.0 ${\times}$ $10^{-2}$) with a detection limit of 8.5 ${\times}$ $10^{-7}$ M (52 ng mL$^{-1}$). It shows relatively fast response time, in the whole concentration range ($\lt$ 20 s), and can be used for at least 10 weeks in a pH range of 3.0-7.0. The proposed membrane sensor was successfully used in direct determination of $Zn^{2+}$ ions in wastewater of industrial zinc electroplating companies, and also as an indicator electrode in titration with EDTA.

• 대한전자공학회:학술대회논문집
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• 대한전자공학회 2001년도 The 6th International Symposium of East Asian Resources Recycling Technology
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• pp.453-458
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• 2001

This study was performed to reuse the dyeing wastewater sludge treated by Fenton process through the solidification/stabilization technique. To solidify the dyeing sludge the industrial by-products such as blast furnace slag, fly ash and waste sand with cement were used. The laboratory scale and pilot scale test were conducted at room temperature to make construction brick which has high compressive strength and low leaching of heavy metals. The experimental results showed that blast furnace slag and fly ash could be used instead of cement and the products satisfied the regulation of Korean Standards. The blast furnace slag increased the compressive strength and the optimum ratio of slag/dyeing sludge on dry basis was found 0.4. The solidifying agent of SB series could increase rapidly the compressive strength and the optimum ratio of solidifying agent/sludge on dry basis was 0.26 at which the strength was two times compared with non-added condition. The portion of waste and industrial by-products in matrix was over 80%. From the pilot test the optimum pressure in molding was 100kg/$\textrm{cm}^2$ at which the compressive strength was over 100kg/$\textrm{cm}^2$. And the strength increased continuously to 160kg/$\textrm{cm}^2$ until 120 days curing time due to pozzolanic reaction. When SB-20 as a solidifying agent was used, the unconfined compressive strength of dyeing sludge could be obtained 110kg/$\textrm{cm}^2$ which satisfied the regulation of cement brick in Korea Standard(KS).

• 한국대기환경학회지
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• 제32권1호
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• pp.9-20
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• 2016

Ozone has been a problem in big cities. That is secondary air pollutant produced by nitrogen oxide and VOCs in the atmosphere. In order to solve this, the first to be the analysis of the $NO_x$ and VOCs. The main source of nitrogen oxide is the road mobile. Industrial sources in Seoul are particularly low, and mobile traffics on roads are large, so 45% of total $NO_x$ are estimated that road mobile emissions in Seoul. Thus, it is necessary to clarify the relation with the activity of road mobile source and $NO_x$ concentration. In this study, we analyzed the 4 locations with roadside automatic monitoring systems in their center. The V.K.T. calculating areas are set in circles with 50 meter spacing, 50 meter to 500 meter from their center. We assumed the total V.K.T. in the set radius affect the $NO_x$ concentration in the center. We used the hourly $NO_x$ concentrations data for the 4 observation points in July for the interference of the other sources are minimized. We used the intersection traffic survey data of all direction for construction of the V.K.T. data, the mobile activities on the roads. ArcGIS application was used for calculating the length of roads in the set radius. The V.K.T. data are multiplied by segment traffic volume and length of roads. As a result, the $NO_x$ concentration can be expressed as linear function formula for V.K.T. with high predictive power. Moreover we separated background concentration and concentrations due to road mobile source. These results can be used for forecasting the effect of traffic demand management plan.

• 한국수자원학회논문집
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• 제48권3호
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• pp.233-243
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• 2015

이군집 응집현상은 수자원환경에서 점착성 유사가 결합-해체의 과정을 통해 응집핵-응집체의 이군집 입자크기분포 (Biomodal Floc Size Distribution)를 형성하는 일련의 과정을 의미한다. 본 연구는 저난류 및 고난류 두 가지 조건에서 수행한 응집-침전관 실험결과를 바탕으로 이군집 응집모형(TCPBE: Two Class Population Balance Equation)의 적용성을 단일군집 응집모형(SCPBE: Single Class Population Balance Equation) 및 다군집 응집모형(MCPBE: Multi Class Population Balance Equation)과 비교 평가하였다. 기존 SCPBE에 비하여, TCPBE는 응집핵-응집체의 상호작용 및 침강속도차에 따른 응집 기작을 모의할 수 있었다. 또한, 3개의 연립미분방정식을 가진 TCPBE는 30개 미분방정식을 가진 다군집 응집모형(MCPBE: Multi Class Population Balance Equation)과 대등한 모의 결과를 나타내었다. 따라서 TCPBE는 이군집 응집현상을 모의 할 수 있는 가장 단순한 모델로 검증되었고, 향후 수자원환경이나 수처리 공정에 다양하게 적용할 수 있으리라 판단된다.

• 한국물환경학회지
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• 제33권1호
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• pp.51-62
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• 2017

The purpose of this study is to evaluate on the applicability of Load Duration Curve (LDC) method using Maintenance of Variance Extension types 2 method and sampling data for efficient total maximum daily loads at the Nakbon-A unit watershed in Korea. The LDC method allows for characterizing water quality data such as BOD, TOC, T-N and T-P in this study at different flow regimes(or quarters). BOD usually exceeded the standard value (exceedance probability 50%) at low flow zone. On the other hand, TOC, T-N, T-P usually exceeded the standard value at dry and low flow zone. Seasonally all water quality variables usually exceeded the standard value at Q1(Jan-Mar) and Q2(Apr-Jun) zones. Improvement of effluent control from wastewater treatment plants are effective to improve BOD and T-P.

• 수도
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• 제24권5호통권86호
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• pp.29-44
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• 1997

Sewage sludge produced in Korea was 1,275,800 tons (dewatered sludge cake) per year in 1996, which is 3,495 tons per day, 0.303% of 11,526,100 tons per day of sewage treated in 79 sewage treatment plants. Sludge production has been and will be increasing in accordance with construction of new facilities for sewage treatment. Most of the sludge is currently disposed by landfill and ocean dumping, but it is becoming difficult to find suitable sites for landfill, particularly in big cities such as Seoul. In addition, rapid increase of landfill cost is anticipated in a near future. Current trend for sludge disposal in advanced countries is land application. Over the past 10 to 20 years in the United States, sludge management practices have changed significantly, moving from disposal to beneficial use. They use biosolid for utilization instead of sludge for disposal. Under the Clean Water Act of 1972, amended in 1987 by Congress, the U.S. EPA was required to develop regulations for the use and disposal of sewage sludge. The EPA assessed the potential for pollutants in sewage sludge to affect public health and the environment through a number of different routes of exposure. The Agency also assessed the potential risk to human health through contamination of drinking water sources or surface water when sludge is disposed on land. The Final Rules were signed by the EPA Administrator and were published (Federal Register, 1993). These rules state that sewage sludge shall not be applied to land if the concentration of any pollutant in the sludge exceeds the ceiling concentration. In addition, the cumulative loading rate for each pollutant shall not exceed the cumulative pollutant loading rate nor should the concentration of each pollutant in the sludge exceed the monthly average concentration for the pollutant. The annual pollutant loading rate generally applies to applications of sewage sludge on agricultural lands. The most popular beneficial use of sewage sludge is land application. The sludge has to be stabilized for appling to land. One of the stabilization process for sewage sludge is lime stabilization process. The stabilization process is consisted of the stabilizing process and the drying process. Stabilization reactor can be a drum type reactor in which a crossed mixer is equipped. The additive agents are a very reactive mixture of calcium oxide and others. The stabilized sludge is dried in sun drier or rotary kiln.

• 유기물자원화
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• 제9권3호
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• pp.119-126
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• 2001

혼합배양계에서 활성오니를 이용하여 유기성폐수로부터 생분해성프라스틱 생산 공정이 연구 검토되었다. 공정은 크게 PHA를 생산할 수 있는 미생물을 선택 분리하는 선택반응기와 분리된 미생물을 이용하여 PHA를 축적 생산하는 축적반응기로 구성되었는데 선택반응기로는 연속회분식반응기(SBR)가 이용되어 초기 접종된 활성오니로부터 PHA 축적미생물을 분리하기 위해 부영양/빈영양 영역을 반복 운전하였으며 PHA 축적미생물은 어떠한 성장 제한이 없는 SBR에서 잘 성장하였으나 PHA 축적률은 미미하였다. 미생물내 PHA 축적을 증대시키기 위해서는 비탄소원의 영양원이 제한된 조건에서 배양이 필요하게되어 별도의 축적반응기를 이용 실험을 실시한 결과 산소 제한은 효율적이지 못하였고 인과 질소 성분의 제한 조건에서 PHA 축적이 비교적 높게 나타났다. 특히 질소 제한조건하의 유가식 기질 공급 실험에서 PHA가 건량기준으로 미생물내 60%까지 축적되는 결과를 보여주었고 PHA 축적속도는 미생물내 PHA 함량에 크게 의존하여 PHA의 함량이 증가됨에 따라 감소하였다.

• 한국지반공학회논문집
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• 제36권8호
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• pp.27-34
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• 2020

터널시공 현장에서는 콘크리트와 숏크리트 및 각종 그라우팅 공법의 사용으로 다량의 알칼리성 폐수가 발생되고 있으며 하천오염을 방지하기 위해 중성화 처리를 해서 방류해야 한다. 현재는 이를 황산과 같은 강산으로 중화 처리하고 있으나 취급상의 위험이 내재 되어있다. 그 대안으로 이산화탄소(CO₂) 사용이 부각되었고 다양한 실내실험 연구가 진행되어 그 가능성이 입증되고 있다. 하지만 아직 CO₂의 현장 적용연구가 절대 부족하고 특히 건설현장에서는 실내 실험 결과와는 다른 특성을 보이고 있기 때문에 현장 적용이 어려운 실정이다. 이에 본 연구에서는 현장 실험을 통하여 실제 현장 적용 가능성을 검증하고자 한다.