중수 재이용을 위한 오존 고도산화 및 세라믹 분리막 일체형 공정의 최적화 연구

이종훈,노호정,박광덕,우윤철 한국물환경학회 2021 한국물환경학회지 Vol.37 No.6

The aim of this study was to optimize the ozonation and ceramic membrane integrated process for greywater reclamation. The integrated process is a repeated sequential process of filtration and backwash with the same ceramic membrane. Also, this study used ozone and oxygen gas for the backwashing process to compare backwashing efficiency. The study results revealed that the optimum filtration and backwash time for the process was 10 minutes each when comparing the filtrate flow and membrane recovery rate. The integrated process was operated at three different operating conditions with i) 10 minutes for filtration and 10 minutes for ozonation, ii) 10 minutes for filtration and 10 minute for oxygen aeration, and iii) continuous filtration without any aeration for synthetic greywater. The integrated process with ozone backwashing could produce 0.55 L/min of filtrate with an average of 18.42% permeability recovery, while the oxygen backwashing produced 0.47 L/min and 6.26%, respectively. And without any backwashing, the integrated process could produce 0.29 L/min. This shows that the ozone backwash process is capable of periodically recovering from membrane fouling. The resistance of the fouled membrane was approximately 34.4% for the process with ozone backwashing, whereas the resistance was restored by 10.8% for the process with oxygen backwashing. Despite the periodical ozone backwashing and chemical cleaning, irreversible fouling gradually increased approximately 3 to 4%. Approximately 97.6% and 15% turbidity and TOC were removed by ceramic membrane filtration, respectively. Therefore, the integrated process with ozonation and ceramic membrane filtration is a potential greywater treatment process.

응집 플록 성장률 측정기를 이용한 멤브레인 공정의 전처리 응집공정 평가

손희종 ( Hee Jong Son ),김상구 ( Sang Goo Kim ),김도환 ( Do Hwan Kim ),강소원 ( So Won Kang ),최영익 ( Young Ik Choi ) 한국환경과학회 2016 한국환경과학회지 Vol.25 No.2

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.

Automated process design and optimization of membrane-based CO₂ capture for a coal-based power plant

Lee, Sunghoon,Binns, Michael,Kim, Jin-Kuk Elsevier 2018 Journal of membrane science Vol.563 No.-

<P><B>Abstract</B></P> <P>A systematic optimization framework is proposed with the aim to automate the design of multi-stage membrane processes for CO<SUB>2</SUB> capture from flue gas of a coal-fired power plant. This framework utilizes a superstructure approach to determine the optimal configuration of membrane systems and identify the most appropriate operating conditions in a holistic manner. Certain design specifications are satisfied through the use of penalty functions which are used in a Genetic Algorithm (GA) optimization method employed to identify design solutions at or near to the global optimal point. Sensitivity analysis is used to analyze multi-stage membrane designs to understand the effects of different structural and operating parameters on the economics of membrane-based carbon capture. As part of a case study the proposed design framework is applied to design membrane processes for the capture of CO<SUB>2</SUB> from a 600 MW<SUB>e</SUB> coal-fired power plant. Fixed membrane permeance and selectivity values are used to analyze sensitivities with respect to costing and structural design parameters. Additionally, the Robeson upper bound correlation between CO<SUB>2</SUB> permeance and CO<SUB>2</SUB>/N<SUB>2</SUB> selectivity is used within this framework to identify the optimal membrane properties which give economical separation of CO<SUB>2</SUB> and N<SUB>2</SUB>. It is found that membranes having at least 4000 GPU CO<SUB>2</SUB> permeance and over 50 of CO<SUB>2</SUB>/N<SUB>2</SUB> selectivity with a commercial available module gave the optimal performance and would be a good guideline for future membrane material development. Also, if different membrane properties are used in each stage (in a multi-stage configuration) then using a higher CO<SUB>2</SUB> permeance for the first stage (e.g. 6000 GPU CO<SUB>2</SUB> permeance and CO<SUB>2</SUB>/N<SUB>2</SUB> selectivity of 40) and higher selectivity membranes are used for subsequent downstream membrane stages (e.g. 1334 GPU CO<SUB>2</SUB> permeance and CO<SUB>2</SUB>/N<SUB>2</SUB> selectivity of 72) helps to reduce the electricity consumption and product purity which can reduce the overall cost of CO<SUB>2</SUB> capture.</P> <P><B>Highlights</B></P> <P> <UL> <LI> Systematic process design framework for multi-stage membrane process. </LI> <LI> Superstructure-based optimization using Genetic Algorithm (GA). </LI> <LI> Identification of optimal membrane performance for multi-stage membrane network. </LI> <LI> Sensitivity analysis of the main design variables for membrane processes. </LI> </UL> </P>

Membrane separation process for CO₂ capture from mixed gases using TR and XTR hollow fiber membranes: Process modeling and experiments

Lee, Sunghoon,Binns, Michael,Lee, Jung Hyun,Moon, Jong-Ho,Yeo, Jeong-gu,Yeo, Yeong-Koo,Lee, Young Moo,Kim, Jin-Kuk Elsevier 2017 Journal of membrane science Vol.541 No.-

<P><B>Abstract</B></P> <P>Numerous membrane models have been developed and tested for the simulation of membrane processes. However, these models are often either simplified or only validated with a narrow range of experimental data. For the model-based process design of membrane systems it is necessary to have a validated and accurate model which is accurate for the range of possible operating conditions under consideration. Hence, in this study a modeling framework is developed for hollow fiber membranes which can be adjusted systematically to accurately predict the performance of a given membrane. Mixed-gas (CO<SUB>2</SUB>/O<SUB>2</SUB>/N<SUB>2</SUB> and CO<SUB>2</SUB>/N<SUB>2</SUB>) separation experiments are carried out over a range of different feed conditions to evaluate membrane performance and to provide reliable measurements of gas permeance. In particular the feed pressure (1–4bar), permeate pressure (0.1–0.5bar) and feed flow rates (0.096–0.4Nm<SUP>3</SUP>/h) are varied in these experiments (the ranges specified in brackets). Interpolation of these measured permeance allows for the accurate prediction of membrane performance at any conditions inside the measured range. A tanks-in-series modeling approach is employed here where the number of tanks (used to represent the membrane behavior in a numerical formulation) can be adjusted to calibrate and fit the membrane model to experimental results. For the membranes tested in this study it is found that using a relatively small number of tanks both minimizes the difference between model and experimental results and reduces the numerical complexity in the membrane model.</P> <P><B>Highlights</B></P> <P> <UL> <LI> Experimental results of TR and XTR membrane modules. </LI> <LI> Effective membrane modeling via tuning the number of tanks in tanks-in-series model. </LI> <LI> Regression of membrane permeance data for accurate fitting of experimental results. </LI> <LI> Validation of the model through comparison with experimental results. </LI> </UL> </P> <P><B>Graphical abstract</B></P> <P>[DISPLAY OMISSION]</P>

Separation of Cd(II) from Aqueous Solutions by A New Consecutive Process Consisting of Supported Liquid Membrane and Electrodialysis

Altin, Sureyya,Altin, Ahmet The Korean Electrochemical Society 2019 Journal of electrochemical science and technology Vol.10 No.1

Supported liquid membrane process usually is used for recovering or enrichment of valuable metals in the industrial wastewater. But, even if the metals in the wastewater was separated with high chemical selectivity, it cannot be enough concentrated since separation performance of supported liquid membrane (SLM) process is limited by concentration gradient between feed solution and stripping solution. If metal concentration in the stripping solution to be enough low, transport of metal through membrane can be accomplishment constantly. Therefore, Electrodialysis (ED) has been placed after SLM process and the stripping solution of SLM was used as the feed solution for the ED process. Transport of ions in the solutions is successfully performed by ED process. Thus, the metal concentration in the stripping solution does not rise as to stop ion transport. Besides, valuable metals easily are concentrated by ED process for re-use. In this study, effects of operation parameters like initial Cd(II) concentration, HCl concentration in the feed solution of SLM and applied voltage are investigated on separation efficiency, flux and permeability of the both processes. As the feed solution concentration increased, all performance values has increased. When initial concentration of 100 mg/L is used, separation performances (SP) are 55% and 70%, for SLM and consecutive process, respectively. The best HCl concentration in the feed solution of SLM has determined as 2 M, in this conditions SP are 64% and 72%, for SLM and consecutive process, respectively. With increased of applied voltage on ED process, SP of the consecutive process has been raised from 72% to 83%. According to the obtained experimental data, consecutive process has better separation performance than SLM. When the separation performances of both processes were compared for the same operating conditions, it was determined higher the separation efficiency, permeability and flux values of the consecutive process, 8%, 9% and %10.6, respectively. Consequently, the use of the consecutive process increases the performance efficiency of both processes. The consecutive process studied has quite a good chemical separation efficiency, and enrichment capability. Moreover, this process requires few water and energy.

Application of volume-retarded osmosis and low-pressure membrane hybrid process for water reclamation

Im, Sung-Ju,Choi, Jungwon,Lee, Jung-Gil,Jeong, Sanghyun,Jang, Am Elsevier 2018 CHEMOSPHERE - Vol.194 No.-

<P><B>Abstract</B></P> <P>A new concept of volume-retarded osmosis and low-pressure membrane (VRO-LPM) hybrid process was developed and evaluated for the first time in this study. Commercially available forward osmosis (FO) and ultrafiltration (UF) membranes were employed in a VRO-LPM hybrid process to overcome energy limitations of draw solution (DS) regeneration and production of permeate in the FO process. To evaluate its feasibility as a water reclamation process, and to optimize the operational conditions, cross-flow FO and dead-end mode UF processes were individually evaluated. For the FO process, a DS concentration of 0.15 g mL<SUP>−1</SUP> of polysulfonate styrene (PSS) was determined to be optimal, having a high flux with a low reverse salt flux. The UF membrane with a molecular weight cut-off of 1 kDa was chosen for its high PSS rejection in the LPM process. As a single process, UF (LPM) exhibited a higher flux than FO, but this could be controlled by adjusting the effective membrane area of the FO and UF membranes in the VRO-LPM system. The VRO-LPM hybrid process only required a circulation pump for the FO process. This led to a decrease in the specific energy consumption of the VRO-LPM process for potable water production, that was similar to the single FO process. Therefore, the newly developed VRO-LPM hybrid process, with an appropriate DS selection, can be used as an energy efficient water production method, and can outperform conventional water reclamation processes.</P> <P><B>Highlights</B></P> <P> <UL> <LI> New energy saving forward osmosis-low pressure membrane hybrid process was tested. </LI> <LI> The system could produce final product with an increase in inner pressure of tank. </LI> <LI> A polymeric draw solute was effective in the operation of this hybrid system. </LI> <LI> A mass balance modeling was used for optimization. </LI> <LI> An applicability of this hybrid process in wastewater treatment was confirmed. </LI> </UL> </P> <P><B>Graphical abstract</B></P> <P>[DISPLAY OMISSION]</P>

Deployment simulation of membrane structures based on elastic-plastic behavior parameterization of the crease

Youqing Shen,Jing Zhang,Hongwei Guo,Rongqiang Liu,Ziming Kou 대한기계학회 2021 JOURNAL OF MECHANICAL SCIENCE AND TECHNOLOGY Vol.35 No.5

Aiming at the problem that the membrane structure is prone to creases in the process of folding and compaction, a proxy model is used to replace the creases to introduce initial defects for the folded membrane to realize the research of the deployment simulation of the membrane. Based on the finite-element method, the Z-folding and deploying process of the membrane is simulated and the elastic-plastic behavior of the crease is parameterized. The ABAQUS connector is used to replace the crease area of the membrane to simulate the characteristics of the crease and its effectiveness is verified. The deployment of Miura-ori membrane is simulated to explore the influence of force driving and constant-speed driving on the deploying process and deployment results of the membrane. In view of the self-contact phenomenon in the membrane deploying process when driven at a constant-speed, referring to the motion trajectory of the membrane loading corner of the force drive, a step-speed driving method is proposed. The research results show that using a step-speed to drive the deployment of folded membrane can reduce the curvature of the membrane surface, solve the problem of membrane self-contact, and eliminate the phenomenon of stress concentration of membrane surface. In addition, compared with other driving methods, the step-speed driving method has a significant advantage in improving the stability of the deploying process of a membrane.

MLE공법과 황이용 탈질 프로세스의 전과정 탄소 배출량 평가

문진영,황용우 대한상하수도학회 2012 상하수도학회지 Vol.26 No.5

In order to determine reduction of greenhouse gas emissions (GHGs) when the submerged membrane bioreactor with granular sulfur (MBR-GS) is used in wastewater treatment plant (WTP), the amount of GHGs was compared and analyzed in the advanced treatment process of P wastewater treatment plant (WTP). The amount of GHGs was estimated by classifying as construction and operation phase in WTP. The amount of GHGs in construction phase was evaluated from multiplying raw materials by using carbon emission factors. Also the amount of GHGs in operating phase was calculated by using total electricity consumption and carbon emission factor. The construction of anoxic tank and secondary settling tank is unnecessary, because the MBR-GS conducts simultaneously the nitrification and denitrification in aeration tank and filtration by hollow fiber membrane. The amount of CO2, CH4, and N2O emitted by constructing the MBR-GS was 6.44E+06 kg, 8.16E+03 kg and 1.38E+01 kg, respectively. The result shows that the GHGs was reduced about 47% as compared with the construction in the MLE process. In operating the MBR-GS, the electricity is not required in the biological reactor and secondary setting tank. Thus, the amount of CO2, CH4, and N2O emitted by operating in the MBR-GS was 7.39E+05 kg/yr, 5.80E+02 kg/yr and 2.44E+00 kg/yr, respectively. The result shows that the GHGs were reduced about 37% as compared with the operation in the MLE process. Also, LCCO2(Life Cycle CO2) was compared and analyzed between MLE process and MBR-GS. The amount of LCCO2 emitted from the MLE process and MBR-GS was 3.56E+04 ton CO2 and 2.12E+04 ton CO2, respectively. The result shows that the GHGs in MBR-GS were reduced to about 40% as compared in the MLE process during life cycle. As a result, sulfur-utilizing autotrophic denitrification process (SADP) is expected to be utilized as the cost-effective advanced treatment process, owing to not only high nitrogen removal efficiency but also the GHGs reduction in construction and operation stage. In order to determine reduction of greenhouse gas emissions (GHGs) when the submerged membrane bioreactor with granular sulfur (MBR-GS) is used in wastewater treatment plant (WTP), the amount of GHGs was compared and analyzed in the advanced treatment process of P wastewater treatment plant (WTP). The amount of GHGs was estimated by classifying as construction and operation phase in WTP. The amount of GHGs in construction phase was evaluated from multiplying raw materials by using carbon emission factors. Also the amount of GHGs in operating phase was calculated by using total electricity consumption and carbon emission factor. The construction of anoxic tank and secondary settling tank is unnecessary, because the MBR-GS conducts simultaneously the nitrification and denitrification in aeration tank and filtration by hollow fiber membrane. The amount of CO2, CH4, and N2O emitted by constructing the MBR-GS was 6.44E+06 kg, 8.16E+03 kg and 1.38E+01 kg, respectively. The result shows that the GHGs was reduced about 47% as compared with the construction in the MLE process. In operating the MBR-GS, the electricity is not required in the biological reactor and secondary setting tank. Thus, the amount of CO2, CH4, and N2O emitted by operating in the MBR-GS was 7.39E+05 kg/yr, 5.80E+02 kg/yr and 2.44E+00 kg/yr, respectively. The result shows that the GHGs were reduced about 37% as compared with the operation in the MLE process. Also, LCCO2(Life Cycle CO2) was compared and analyzed between MLE process and MBR-GS. The amount of LCCO2 emitted from the MLE process and MBR-GS was 3.56E+04 ton CO2 and 2.12E+04 ton CO2, respectively. The result shows that the GHGs in MBR-GS were reduced to about 40% as compared in the MLE process during life cycle. As a result, sulfur-utilizing autotrophic denitrification process (SADP) is expected to be utilized as the cost-effective advanced treatment process, owing to not only high nitrogen removal efficiency but also the GHGs reduction in construction and operation stage.

Preparation of a Water-Selective Ceramic Membrane on a Porous Stainless Steel Support by Sol-Gel Process and Its Application to Dehydration Membrane Reactor

Lee, Kew-Ho,Sea, Bongkuk,Youn, Min-Young,Lee, Yoon-Gyu,Lee, Dong-Wook The Membrane Society of Korea 2004 Korean Membrane Journal Vol.6 No.1

We developed a water-selective ceramic composite membrane for use as a dehydration membrane reactor for dimethylether (DME) synthesis from methanol. The membranes were modified on the porous stainless steel support by the sol-gel method accompanied by a suction process. The improved membrane modification process was effective in increasing the vapour permselectivity by removal of defects and pinholes. The optimized alumina/silica composite membrane exhibited a water permeance of 1.14${\times}$10$^{-7}$ mol/$m^2$.sec.Pa and a water/methanol selectivity of 8.4 at permeation temperature of 25$0^{\circ}C$. The catalytic reaction for DME synthesis from methanol using the membrane was performed at 23$0^{\circ}C$, and the reaction conversion was compared with that of the conventional fixed-bed reactor. The reaction conversion of the membrane reactor was much higher than that of the conventional fixed-bed reactor. The reaction conversion of the membrane reactor and the conventional fixed-bed reactor was 82.5 and 68.0%, respectively. This improvement of reaction efficiency can last if the water vapour produced in the reaction zone is removed continuously.

Effect of biofouling in pressure retarded osmosis (PRO) process

서동우,백영빈,김정찬,유지현,윤제용 한국공업화학회 2014 한국공업화학회 연구논문 초록집 Vol.2014 No.1

PressureRetarded Osmosis (PRO) is one of membrane processes for harvesting renewableenergy. In PRO process, membrane fouling phenomena, accumulation of variouscontaminants on membrane surface, is serious issue since it reduces process efficiency.Biofouling, membrane contamination by microorganisms in water, has known as themost severe fouling factor in most of membrane processes. However, there is alack of biofouling study in PRO process until now. In this study, effect of biofouling in PRO process was investigated. Pseudomonasaeruginosa (PA01) was used as model microorganism. Biofouling effect wasinvestigated by changing process conditions such as applied hydraulic pressure, membrane material, and initial bacteria concentration. Effect of biofouling wasanalyzed by performance of the membrane expressed as permeate flux, biofilmcell concentration on membrane surface, and confocal laser scanning microscopy(CLSM) image.