동강유역의 포유동물상 및 어류 조사

김대원 ( Dae Won Kim ),김동석 ( Dong Seog Kim ) 대구가톨릭대학교 자연과학연구소 2003 자연과학연구논문집 Vol.1 No.2

역 유동층 생물막 반응기에서 유기물의 농도 부하와 수리학적 부하의 변동에 따른 생물막 성상과 COD 처리효율

김동석,최윤찬,박영식,서정호,추석열,송승구 ( Dong Seog Kim,Yoon Chan Choi,Young Seek Park,Jung Ho Suh,Suck Reul Choo,Seung Koo Song ) 한국화학공학회 1996 Korean Chemical Engineering Research(HWAHAK KONGHA Vol.34 No.1

The effects of substrate or hydraulic loading on COD removal efficiency, biofilm thickness, biofilm density and biomass concentration were investigated in an inverse fluidized-bed biofilm reactor(IFBBR). The shock on the microorganisms in the case of hydraulic loading was smaller than in that of substrate loading. Thus, the reactor was more stably operated in hydraulic loading in comparison with in substrate loading. At the change of substrate loading the external biomass of bioparticle was more loosely fitted and filamentous, and the biofilm dry density was lower than those in the case of hydraulic loading. The maximum specific substrate removal rate of hydraulic loading was also found about twice higher than that in the case of substrate loading.

SBR에서 포기기간 변경에 따른 질소.인 제거 특성

김동석,박영식,Kim, Dong-Seog,Park, Young-Seek 한국환경보건학회 2009 한국환경보건학회지 Vol.35 No.2

Laboratory scale experiments were conducted to investigate the removal characteristics of nitrogen and phosphorus by the variation of aeration time in four sequencing batch reactors (SBRs). In R1 which has the shortest aeration time as 1 h, MLVSS concentration in reactor decreased by the wash-out of biomass because of the poor sedimentation. The TOC removal efficiencies were almost similar in 3 reactors except R1. At the low aeration time as 1 h, the nitrification was severely inhibited by the deficiency of oxygen. ${NH_4}^+$-N removal efficiency was decreased by the decrease of aeration time. At the aeration time over 2 h, the phosphorus removal efficiency was not affected by the variation of aeration time. The nitrification was inhibited but the phosphorus release and uptake was not inhibited by the decrease of low aeration time. Therefore, we can see that the phosphorus removal microorganisms are superior to nitrification microorganisms in oxygen utilization.

전기응집/부상 공정에서 반응표면분석법을 이용한 TiO₂ 수용액의 탁도 처리조건 최적화

김동석,박영식,Kim, Dong-Seog,Park, Young-Seek 한국환경보건학회 2009 한국환경보건학회지 Vol.35 No.6

The removal of turbidity from $TiO_2$ wastewater by an electrocoagulation/flotation process was studied in a batch reactor. The response surface methodology (RSM) was applied to evaluate the simple and combined effects of the three main independent parameters, current, NaCl dosage and initial pH of the $TiO_2$ solution on the turbidity removal efficiency, and to optimize the operating conditions of the treatment process. The reaction of electrocoagulation/flotation was modeled by use of the Box-Behnken method, which was used for the fitting of a 2nd order response surface model. The application of RSM yielded the following regression equation, which is an empirical relationship between the turbidity removal efficiency of $TiO_2$ wastewater and test variables in uncoded unit: Turbidity removal (%)=69.76+59.76Current+11.98NaCl+4.67pH+5.00Current${\times}$pH-160.11$Current^2-0.34pH^2$. The optimum current, NaCl dosage and pH of the $TiO_2$ solution to reach maximum removal rates were found to be 0.186 A, 0.161 g/l and 7.599, respectively. This study clearly showed that response surface methodology was one of the most suitable method to optimize the operating conditions for maximizing the turbidity removal. Graphical response surface and contour plots were used to locate the optimum point.

SBR에서 BNR 슬러지 식종비에 따른 영양염류 제거 특성

김동석,박영식,Kim, Dong-Seog,Park, Young-Seek 한국환경보건학회 2008 한국환경보건학회지 Vol.34 No.1

Biological nutrient removal (BNR) sludge was added to a sequencing batch reactor (SBR) in the addition ratios of 0%, 20%, 40%, 50% while observing the variation of nutrient removal characteristics and microorganism groups. When the BNR sludge was added in a ratio over 40%, the characteristics of EBPR (enhanced biological phosphorus removal) was shown at the 27 days. However, a distinct BNR was not shown when the addition ratio of BNR sludge was lower than 40%. The organic removal efficiency were shown as 90% in all SBRs irrespective of the addition ratio of BNR sludge. At the 27 days, the phosphorus removal efficiencies were shown as 40%, 55%, 77% and 69%, respectively, according to the addition ratio of BNR sludge. Overall, efficient nitrification and phosphorus removal was shown when the added BNR sludge ratio was over 40%.

전기-펜톤 반응을 이용한 해수 중의 염료 분해

김동석,박영식,Kim, Dong-Seog,Park, Young-Seek 한국환경과학회 2020 한국환경과학회지 Vol.29 No.4

To increase electrolysis performance, the applicability of seawater to the iron-fed electro-Fenton process was considered. Three kinds of graphite electrodes (activated carbon fiber-ACF, carbon felt, graphite) and dimensionally stable anode (DSA) electrode were used to select a cathode having excellent hydrogen peroxide generation and organic decomposition ability. The concentration of hydrogen peroxide produced by ACF was 11.2 mg/L and those of DSA, graphite, and carbon felt cathodes were 12.9 ~ 13.9 mg/L. In consideration of durability, the DSA electrode was selected as the cathode. The optimum current density was found to be 0.11 A/㎠, the optimal Fe²⁺ dose was 10 mg/L, and the optimal ratio of Fe²⁺ dose and hydrogen peroxide was determined to be 1:1. The optimum air supply for hydrogen peroxide production and Rhodamine B (RhB) degradation was determined to be 1 L/min. The electro-Fenton process of adding iron salt to the electrolysis reaction may be shown to be more advantageous for RhB degradation than when using iron electrode to produce hydrogen peroxide and iron ion, or electro-Fenton reaction with DSA electrode after generating iron ions using an iron electrode.

3차원 전극을 사용한 Rhodamine B의 전기분해에 미치는 운전인자의 영향

김동석,박영식,Kim, Dong-Seog,Park, Young-Seek 한국환경보건학회 2009 한국환경보건학회지 Vol.35 No.4

A simulated wastewater containing the dye Rhodamine B (RhB) was electrolytically treated using a three-dimensional electrode reactor equipped with granular activated carbon (GAC) as particle electrode. The effect of type of packing material (GAC, ACF, Nonwoven fabric fiber coated with activated carbon), amounts of GAC packing (25-100 g), current (0.5-3 A) and electrolyte concentration (0.5-3 g/l) was evaluated. Experimental results showed that performance for RhB decolorization of the 3 three-dimensional electrodes lie in: GAC > Nonwoven fabric fiber > ACF. When considered RhB decolorization, oxidants concentration and electric power, optimum GAC dosage was 50 g. Generated concentration of 3 oxidants ($ClO_2$, free Cl, $H_2O_2$) was increased with increase of applied current, however optimum current for RhB degradation was 2.5 A. The oxidants concentration was increased with increase of NaCl concentration and optimum NaCl dosage for RhB degradation was 1.5 g/l.

Box-Behnken법을 이용한 E. coli 소독에서 전기-UV-초음파 복합 공정의 최적화

김동석,박영식,Kim, Dong-Seog,Park, Young-Seek 대한환경공학회 2011 대한환경공학회지 Vol.33 No.3

수중에서 E. coli 소독을 위한 전기-UV-초음파 복합 공정에 대해 실험계획법과 반응표면분석법(RSM)을 적용하였다. 2차반응표면 모형식을 추정할 수 있는 Box-Behnken법을 이용하여 전기-UV-초음파 복합 공정의 소독 반응에서 전기분해($X_1$), UV ($X_2$), 및 초음파 공정($X_3$)의 전력을 독립변수로 선정하여 수학적으로 모형화하였다. 소독 후 잔류 E. coli 수와 독립변수 사이의 실험에서 독립변수에 대해 다음의 모형식이 얻어졌다. 잔류 E. coli number (Ln CFU) = 23.69 - 3.75 Electrolysis - 0.67 UV - 0.26 Ultrasonic - 0.16 Electrolysis UV + 0.05 Electrolysis Ultrasonic + 0.27 $Electrolysis^2$ + 0.14 $UV^2$ - 0.01 $Ultrasonic^2$). 예측된 모형식은 실험 자료와 잘 일치하였다($R^2$ = 0.983). 2차원 등고선도와 3차원 반응표면도가 잔류 E. coli 수에 대한 최적 범위를 구하기 위하여 사용되었다. Design-Expert 소프트웨어의 '수치 최적화'를 이용하여 잔류 E. coli 수에 대한 최적 값을 찾은 결과 1.47 Ln CFU/L이었고, 최적 조건은 전기분해 6.94 W, UV 6.72 W 및 초음파 공정 14.23 W로 나타났다. 본 연구는 반응표면분석법이 복합 소독 공정에서 잔류 E. coli 수를 최소화하고 운전 조건을 최적화하기 위한 적절한 방법 중의 하나라는 것을 보여주었다. This experimental design and response surface methodology (RSM) have been applied to the investigation of the electro-UV-ultrasonic complex process for the disinfection of E. coli in the water. The disinfection reactions of electro-UV-ultrasonic process were mathematically described as a function of parameters power of electrolysis ($X_1$), UV ($X_2$), and ultrasonic process ($X_3$) being modeled by use of the Box-Behnken technique, which was used for fitting 2nd order response surface model. The application of RSM yielded the following regression equation, which is empirical relationship between the residual E. coli number (Ln CFU) in water and test variables in coded unit: residual E. coli number (Ln CFU) = 23.69 - 3.75 Electrolysis - 0.67 UV - 0.26 Ultrasonic - 0.16 Electrolysis UV + 0.05 Electrolysis Ultrasonic + 0.27 $Electrolysis^2$ + 0.14 $UV^2$ - 0.01 $Ultrasonic^2$). The model predictions agreed well with the experimentally observed result ($R^2$ = 0.983). Graphical 2D contour and 3D response surface plots were used to locate the optimum range. The estimated ridge of maximum response and optimal conditions for residual E. coli number (Ln CFU) using 'numerical optimization' of Design-Expert software were 1.47 Ln CFU/L and 6.94 W of electrolysis, 6.72 W of UV and 14.23 W of ultrasonic process. This study clearly showed that response surface methodology was one of the suitable methods to optimize the operating conditions and minimize the residual E. coli number of the complex disinfection.

수중 플라즈마 공정을 이용한 Rhodamine B 염료의 제거

김동석,박영식,Kim, Dong-Seog,Park, Young-Seek 한국환경보건학회 2011 한국환경보건학회지 Vol.37 No.3

Objectives: In this paper, a dielectric barrier discharge (DBD) plasma reactor was investigated for degrading the dye Rhodamine B (RhB) in aqueous solutions. Methods: The DBD plasma reactor system in this study consisted of a plasma component [titanium discharge (inner), ground (outer) electrode and quartz dielectric tube], power source, and gas supply. The effects of various parameters such as first voltage (input power), gas flow rate, second voltage (output power), conductivity and pH were investigated. Results: Experimental results showed that a 99% aqueous solution of 20 mg/l Rhodamine B is decolorized following an eleven minute plasma treatment. When comparing the performance of electrolysis and plasma treatment, the RhB degradation of the plasma process was higher that of the electrolysis. The optimum first voltage and air flow rate were 160 V (voltage of trans is 15 kV) and 3 l/min, respectively. With increased second voltage (4 kV to 15 kV), RhB degradation was increased. The higher the pH and the lower conductivity, the more Rhodamine B degradation was observed. Conclusions: OH radical generation of dielectric plasma process was identified by degradation of N, N-dimethyl-4-nitrosoaniline (RNO, indicator of OH radical generation). It was observed that the effect of UV light, which was generated as streamer discharge, on Rhodamine B degradation was not high. Rhodamine B removal was influenced by real second voltage regardless of initial first and second voltage. The effects of pH and conductivity were not high on the Rhodamine B degradation.

응집과 균질화가 팽화슬러지의 용존공기부상과 침전에 미치는 영향

김동석,박영식,Kim, Dong-Seog,Park, Young-Seek 한국환경보건학회 2007 한국환경보건학회지 Vol.33 No.1

The objective of this study is to examine the effect of the coagulation and homogenization in bulking sludge thickening of paper manufacturing plant using DAF(Dissolved Air Flotation) and gravitational sedimentation. The effects of parameters such as dosage of coagulant and homogenization time were examined. The results showed that DAF and sedimentation was affected aluminum sulfate and anion polymer coagulant differently. At the optimum dosage of aluminum sulfate, thickening efficiency of DAF and sedimentation process were increase 1.25 time and 2.02 time, respectively. At the optimum dosage of anion polymer coagulant, thickening efficiency of DAF process was increase 1.35 time, but thickening efficiency at sedimentation was 1.06 time. When anion polymer coagulant of 0.5 mg/l was added in DAF process, water content of sludge was decreased from 96.6% to 90.7% in dewatering process using Buchner funnel test device. After homogenization(20500 rpm, 10 min), Sauter mean diameter of sludge floc was decreased from 631 ${\mu}m$ to 427 ${\mu}m$, however increase of flotation efficiency by DAF was only 1.09 time.