• 전기학회논문지
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• 제67권11호
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• pp.1477-1485
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• 2018

There are two major issues for activated sludge process in sewage treatment plant. One is how to make sewage be more clean and the other is the energy saving in sewage treatment process. The major monitoring sewage qualities are chemical oxygen demand, phosphorus, nitrogen, suspended solid in effluent. These are transmitted to the national TMS(Telemetry Monitoring System) at every hour. If these exceed the environmental standard, the environmental charges imposed. So, these water qualities are to be controlled below the environmental standard in operation of sewage treatment plant. And recently, the energy saving is also important in process operation. Over 50% energy is consumed in blowers and motors for injection oxygen into aeration tank. So, with the water qualities to be controlled below the environmental standard, the energy saving also is to be accomplished for efficient plant management. Almost researches are aimed to control water quality without considering energy saving. AI techniques have been used for control water quality. AI modeling simulator provided the optimal control inputs(blower speed, waste sludge, return sludge) for control water quality. Blower speed is the main control input for activated sludge process. To make sewage be more clean, the excessive blower speed is supplied, but water quality is not better than the previous. In results, non necessary energy is consumed. In this paper we propose a new method that the energy saving also is to be accomplished with the water qualities to be controlled below the environmental standard for efficient plant management. Water qualities in only aeration tank are used the inputs of fuzzy models. Outputs of these models are chemical oxygen demand, phosphorus, nitrogen, suspended solid in effluent and have the environmental standards. In test, we found this method could save 10% energy than the previous methods.

• 상하수도학회지
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• 제27권5호
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• pp.555-560
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• 2013

A cost analysis method for pretreament processes of a large scale seawater desalination plant was considered using a cost estimation model, WaTER (Water Treatment Estimation Routine). This model is based on cost functions of U.S. EPA to conduct economic analysis of water treatment facilities. A virtual seawater desalination plant which has pretreatment production capacity of $100,000m^3$ per day was chosen as a model plant. Dual media filtration and microfiltration systems were compared as pretreatment process, and the following reverse osmosis process was modeled. As a result, microfiltration showed a price competitiveness in condition of operating with reverse osmosis process by reducing the loads of water treatment and membrane cleaning despite it's high annual cost.

• 한국환경과학회지
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• 제25권2호
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• pp.231-238
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• 2016

In this study, we have investigated to find optimal pre-treatment flocculation condition by analyzing the floc growth rate with mixing conditions and the membrane permeation flux for pre-treatment step of the membrane process. The higher mixing intensity showed a constant floc size index (FSI) values, and lower mixing intensity increased the degree of dispersion of the FSI values. Results of comparing the distribution characteristics of the FSI value and the permeation flux were more effective in increasing flux when the FSI values were 0.2 or higher. The degree of dispersion of FSI was relatively large in 40 rpm mixing condition compared to 120 rpm. In 40 rpm mixing condition, it decreased the permeation flux compared to 120 rpm because various sizes of flocs were distributed. Coagulation-UF membrane process enhanced 30%~40% of the flux rate compare to UF alone process, and the coagulation-MF process increased up to 5% of the flux rate compare to MF alone process. Pre-treatment, that is, coagulation process, has been found to be less effects on relatively larger pore size for MF membrane. For UF membrane, the flux was a little bit same when applying only the rapid mixing process or rapid mixing with slow mixing processes together. In case of MF membrane, the flux was improved when rapid mixing process applied with slow mixing process together.

• 상하수도학회지
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• 제27권5호
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• pp.581-590
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• 2013

A research was performed for zero discharge system of waste water which is produced from energy recovery process of waste and biomass. Leachate and all kinds of waste water should be separated and integrated into three categories in addition to converting existing leachate treatment facility into waste water treatment facility as well as introducing a management system of reverse osmosis membrane facility and bioreactor landfill. Following these conditions to better water treatment process, it was likely to produce over 3,000 tons of low-grade recycling water and 2,000 tons of high-grade recycling water per day when zero discharge system of waste water is applied starting from 2016. Economical efficiency was also surveyed in total treatment fee. Present system costs 18,129 million won per year, and suggested zero discharge system would cost 15,789 million won per year.

• 한국환경과학회지
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• 제17권10호
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• pp.1121-1127
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• 2008

The free-living amoeba and Acanthamoeba sp. are widely distributed in fresh water, soil, air and dust in the world. We studied distribution of amoeba from low Nakdong River(Mulgum and Maeri) and removal efficiency in water treatment process of Busan metropolitan city. During this investigation, water quality showed pH $7.4{\sim}9.6({\pm}1.1)$, water temperature $2.0{\sim}29.0({\pm}17)^{\circ}C$, turbidity $4.8{\sim}27.4({\pm}11.0)$ NTU, chlorophyll-a $10.3{\sim}109.0({\pm}44.3)\;mg/m^{3}$, BOD $1.7\sim4.9({\pm}2.6)$ mg/L, COD $3.1\sim-6.9({\pm}5.0)$ mg/L and total coliform $17\sim920({\pm}200.5)$ MPN/100 mL. The free-living amoeba were detected highly than Acanthamoeba sp., 11 out of 22 in raw water samples were positive (50%) for Acanthamoeba sp. from February 2005 to December 2005. The seasonal characteristics of tree-living amoeba and Acanthamoeba sp. in raw water were mainly distributed through the spring to the early fall. When tree-living amoeba and Acanthamoeba sp. were passed through the water treatment of pilot-plant, approximately 80% was sure to be removed through pre-ozonation, sedimentation, send filtration. 100% was removed after post-ozonation process. All of the isolated amoebas from Nakdong River were Acanthamoeba sp. AC311 18S ribosomal RNA gene with 98% nucleotide sequence homology.

• 상하수도학회지
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• 제34권6호
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• pp.445-462
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• 2020

Industrial wastewater often contains a number of recalcitrant organic contaminants. These contaminants are hardly degradable by biological wastewater treatment processes, which requires a more powerful treatment method based on chemical oxidation. Advanced oxidation technology (AOT) has been extensively studied for the treatment of nonbiodegradable organics in water and wastewater. Among different AOTs developed up to date, ozonation and the Fenton process are the representative technologies that widely used in the field. Based on the traditional ozonation and the Fenton process, several modified processes have been also developed to accelerate the production of reactive radicals. This article reviews the chemistry of ozonation and the Fenton process as well as the cases of application of these two AOTs to industrial wastewater treatment. In addition, research needs to improve the cost efficiency of ozonation and the Fenton process were discussed.

• 대한위생학회:학술대회논문집
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• 대한위생학회 2004년도 심포지움
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• pp.54-65
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• 2004

Use of aluminum salts as coagulants In water treatment may lead to increased concentrations of aluminum in finished water. Aluminum is a suspected causative agent of neurological disorders such as Alzheimer's disease. The objective of this study was to examine variation and minimizing in residual aluminum concentration during water treatment process. The aluminum sources at Bokjeong Water Plant were present naturally aluminum in the raw water and derived due to use of PACS as a coagulant. Much of the raw water total aluminum were in particulate and suspended aluminum. In this study was compared the optimize condition to minimize the concentration of residual aluminum using Jar-test with the various coagulants such as alum, PAC, PACS. The results indicated that PACS was more effective than alum, PAC and insufficient or excessive alum, PAC, PACS addition led to increase residual aluminum. Adjustment raw water pH $6.5\~7.0$ before coagulation using PACS was capable of minimizing total and dissolved aluminum. Thus it is important that the optimal dosage of coagulant and the optimal pH adjustment before coagulation can decided to minimize the concentration of residual aluminum in treated water.

• Membrane and Water Treatment
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• 제13권1호
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• pp.1-6
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• 2022

The regulations of the International Maritime Organization (IMO) have been steadily strengthened in ship emissions. Accordingly, there is a growing need for development of related technologies for the removal of contaminants that may occur during the treatment of SOx and NOx using a wet scrubber. However, this system also leads to wastewater production when the exhaust gas is scrubbed. In this research, we evaluated the performance of an ion selective resin process in accordance with scrubber wastewater discharge regulations, specifically nitrate discharge, by the IMO. Accelerated real and synthetic wastewater of wet scrubbers, contained high amounts of TDS with high nitrate, is used as feed water in lab scale systems. Furthermore, a pilot scale dissolved air flotation (DAF) using microbubble generator with ion exchange resin process was combined and developed in order to apply for the treatment of wet scrubber wastewater. The results of the present study revealed that operating conditions, such as resin property, bed volume (BV), and inlet wastewater flow rate, significantly affect the removal performance. Finally, through a pilot test, DAF with ion exchange resin process showed a noticeable improvement of the nitrate removal rate compared to the single DAF process.

• 한국지반환경공학회 논문집
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• 제14권4호
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• pp.15-27
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• 2013

본 연구에서는 대구 G정수장 막여과 정수처리시설을 계획하기 위해 원수수질 처리에 적합하고 경제적인 시스템을 적용하고자 현장모형실험을 통하여 동절기를 포함한 6개월 동안의 연속운전에 따른 수량과 수질, 그리고 공정의 안정성을 평가하였다. 환경부 막여과 정수시설의 설치기준에 의해 실시된 현장모형실험에서 1계열 목표수질 검증설비와 2계열 막공정 평가설비로 나누어 2계열로 수행되었다. 공정수질은 탁도 0.03 NTU 이하로서, 증류수 수질의 탁도를 나타내었으며 먹는 물 수질기준을 모두 충족하였다. 공정운전에서 99%의 회수율로 안정된 막차압을 나타내어 공정운전에 수질 및 수온 등의 영향에 대비한 공정설계가 되었음을 확인하였다. 따라서 지속적인 기술개발을 통해 설계 및 시공 노하우에 대한 지속적인 경험이 축적되어 막여과 고도정수처리 기술에 대한 엔지니어링 원천기술을 확립하고자 한다.

• 한국물환경학회지
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• 제23권6호
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• pp.843-849
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• 2007

Monitoring of NOM characteristics is important for improving removal efficiency of natural organic matter (NOM) in water treatment processes. In this study, several NOM characteristics, which include specific UV absorbance (SUVA), total carbonate content, molecular weight distribution, and fluorescence properties, were measured using samples collected from a pilot-scale water treatment plant consisting of coagulation/flocculation (C/F), filtration, ozonation and granular activated carbon (GAC) processes. The highest removal of NOM was observed in C/F and filtration processes as demonstrated by the reduction of dissolved organic carbon (DOC) by 25% and 21%, respectively. Despite nearly no change in DOC, however, the lowest SUVA value and the highest total carbohydrate content were observed in the sample from ozonation process. This indicates that non-degradable aromatic compounds become depleted and biodegradable organic compounds are enriched during the process. Comparison of synchronous fluorescence spectra of the samples showed that ozoation process increased protein-like fluorescence while it decreased fulvic-like and terrestrial humic-like fluorescence. Consistently, a slight peak of protein-like fluorescence was observed in the sample from ozonation process. The greatest change in molecular weight distributions of the samples was observed in C/F process. Comparison of size exclusion chromatogram of the samples revealed that NOM fractions with the molecular weight greater than 2000 Da were reduced by over 90% after C/F process. SUVA values and total carbohydrate content of the samples were well correlated with a ratio of protein-like fluorescence and terrestrial humic-like fluorescence intensities with the correlation coefficients of 0.99 and 0.91, respectively. This suggests that synchronous fluorescence properties of NOM could be used as useful tolls for monitoring changes of some NOM characteristics during water treatment processes.