• Title/Summary/Keyword: Membrane diffuser

Search Result 19, Processing Time 0.022 seconds

Performance of a Hellow Fiber Membrane Diffuser for the Biological Removal of Gaseous BTX (Diffuer 형태의 중공사막 생물반응기를 이용한 기체상 BTX 제거)

  • Son, Young-Gyu;Khim, Jee-Hyeong;Song, Ji-Hyeon
    • Journal of Soil and Groundwater Environment
    • /
    • v.11 no.4
    • /
    • pp.25-32
    • /
    • 2006
  • In this study, a novel bioreactor system using a diffuser type hollow fiber membranes (hollow fiber membrane diffuser, HFMD) was applied to investigate the feasibility and biodegradation capacity for the treatment of a gaseous mixture consisting of benzene, toluene and p-xylene(BTX). First, A mixed culture pre-acclimated to toluene effectively biodegraded the BTX mixture at an overall removal efficiency of approximately 70% for a 20-day operational period. It was found that the biodegradation of toluene was slightly inhibited because of the presence of benzene and p-xylene. Second, the elimination capacity (EC) of total BTX increased up to 360 $g/m^3/hr$, which was substantially higher than maximum ECs for BTEX reported in the biofiltration literature. Consequently, the hollow fiber membrane diffuser was considered as an alternative method over other conventional VOC-treating technologies such as biofilters.

Utilization of Image Analysis Technique for Characterization of Micro-Bubbles Generated by Polymeric Membrane Module (고분자 중공사막 모듈을 이용한 미세기포 발생과 이미지 분석기법을 이용한 기포 특성 파악)

  • Kim, Jun-Young;Chang, In-Soung
    • Journal of Korean Society of Environmental Engineers
    • /
    • v.33 no.6
    • /
    • pp.447-452
    • /
    • 2011
  • In this study, the polymeric membrane module is used as a diffuser and an image analysis technique based on visual information is applied to get bubble characteristics. The bubble size generated passed through polymeric membrane module was smaller from 30 to 64% than that of air stone, and bubble volume over 70% was ranged from 0.2 to 0.82 mm. But over 80% the bubbles from air stone diffuser ranged from 0.77 to 1.08 mm. The air stone and polymeric membrane module used as diffuser for a flotation system. The floc size inside the flotation reactor using air stone diffuser was bigger than that of the polymeric membrane module, which means that the micro-bubbles generated from polymeric membrane module could provide better opportunities for collisions between colloidal particles than those from air stone diffuser. Therefore, there is a possibility to apply the polymeric membrane module as a diffuser to increase the removal efficiency in the flotation process. Also, the image analysis technique used in this study could be applied as a useful analytical tool for acquisition of an information about the bubble characteristic.

A study on the Development and Evaluation of Sludge Occlusion Reduced Diffuser (폐색 저감형 산기관의 개발 및 적용성 평가)

  • Kim, Young-Hoon;Kim, Kwan-Yeop;Lee, Eui-Jong;Nam, Jong-Woo;Lee, Chang-Ha;Jeon, Min-Jung;Kim, Hyung-Soo
    • Journal of Korean Society of Water and Wastewater
    • /
    • v.25 no.1
    • /
    • pp.41-49
    • /
    • 2011
  • The diffuser which is conventionally adapted to MBR, has problem that decreasing the cleaning effect of membrane module by inflexible air supply due to the occlusion of sludge from diffuser hole. To solve this problem, diffuser structure of submerged module should be improved to discharge sludge which is flow into the diffuser for prevent occlusion in the diffuser. In this study, the structure of the diffuser was reformed to open lower part for preclusion the blocking. And the outlet diameter of the diffuser was drawn through the condition for the depth of water and air rate, to prevent air-leak condition of improved diffuser. Moreover, application is evaluated by comparing test with occlusion effect of the conventional and improved diffuser. From the results, air-water boundary changes are steady with changes of water depth and it shows linear relation about air rate. By using this linear numerical formula, the height of diffuser's outlet can be decided. Also, it displays that it can prevent the occlusion effect during the comparing test. Hereafter, if this diffuser is applied to practical MBR process, the occlusion problem of diffuser will be disappeared.

A Pilot Study on Air Flotation Processes for Retrofitting of Conventional Wastewater Treatment Facilities (하수처리시설의 Retrofitting을 위한 파일럿 규모 공기부상공정 연구)

  • Park, Chanhyuk;Hong, Seok-Won;Lee, Sanghyup;Choi, Yong-Su
    • Journal of Korean Society of Water and Wastewater
    • /
    • v.22 no.3
    • /
    • pp.329-336
    • /
    • 2008
  • The pilot study was conducted to evaluate the applicability of air flotation(AF) processes combined with biological nutrient removal(BNR) for the retrofitting of conventional wastewater treatment facilities. The BNR system was operated in pre-denitrification and intermittent aeration; developed ceramic membrane diffusers were installed to separate the solid-liquid of activated sludge at the bottom of a flotation tank. Before performing a pilot scale study, the size distribution of microbubbles generated by silica or alumina-based ceramic membrane diffusers was tested to identify the ability of solid-liquid separation. According to the experimental results, the separation and thickening efficiency of the alumina-based ceramic membrane diffuser was higher than the silica-based ceramic membrane diffuser. In a $100m^3/d$ pilot plant, thickened and return sludge concentration was measured to be higher than 15,000mg SS/L, therefore, the MLSS in the bioreactor was maintained at over 3,000mg SS/L. The effluent quality of the AF-BNR process was 4.2mg/L, 3.7mg/L, 10.6mg/L and 1.6mg/L for $BOD_5$, SS, T-N and T-P, respectively. Lastly, it was revealed that the unit treatment cost by flotation process is lower than about $1won/m^3$ compared to a gravity sedimentation process.

Effect of Inlet and Outlet Position on the Pumping Characteristics of a Diffuser/Nozzle Based Piezoelectric Micropumps (디퓨저/노즐을 이용한 압전형 마이크로 펌프의 펌핑 특성에 미치는 입출구 위치의 영향)

  • Jang, Hun-Hee;Kim, Chang-Nyung;Jung, Jin
    • Korean Journal of Air-Conditioning and Refrigeration Engineering
    • /
    • v.19 no.5
    • /
    • pp.411-417
    • /
    • 2007
  • This study has been conducted to investigate pumping characteristics of diffuser/nozzle based piezoelectric micropumps. The micropumps include a piezo disk (an actuator), a chamber and a set of diffuser and nozzle. Flow in the current micropumps is controlled by a set of diffuser and nozzle, not by a nap valve. The diffuser/nozzle based micropumps are more reliable in operation and are easier in manufacturing than the flap valve based micropumps. The flow rates of the piezoelectric micropumps have been closely analyzed with a numerical calculation. It has been found that the positions of the inlet and outlet of the micropump can influence the performance of the diffuser/nozzle based piezoelectric micropumps. This study may provide fundamental understanding for the design and analysis of the piezoelectric micropumps.

An Experimental Study on the Pumping Characteristics of Diffuser-Nozzle Based Thermopneumatic Micropumps with Different Input Voltages and Frequencies (디퓨져와 노즐을 이용한 열공압형 마이크로 펌프의 입력 전압과 주파수에 따른 펌핑 특성에 관한 실험적 연구)

  • Jeong, Jin;Chae, Hee-Moon;Kim, Chang-Nyung
    • Korean Journal of Air-Conditioning and Refrigeration Engineering
    • /
    • v.19 no.9
    • /
    • pp.654-661
    • /
    • 2007
  • This study has been conducted to investigate the pumping characteristics of diffuser-nozzle based thermopneumatic micropumps with different input voltages and frequencies. In this study, the displacements of the membrane have been obtained changing the input voltage and frequency in load-free state because it is very difficult to measure the displacement of the membrane in an actual load state. It has been found that the amplitude of the membrane displacement increases as the input voltage increases. The pressure head of the thermopneumatic micropump increases almost linearly over some range of the input voltage and decreases almost linearly as the frequency increases. Also, the results show that the thermopneumatic micropump can pump the fluid over a certain input voltage. This study can be utilized as basic data for design and evaluation of thermopneumatic micropumps.

Membrane Diffuser Coupled Bioreactor for Methanotrophic Denitrification under Non-aerated Condition: Suggestion as a Post-denitrification Option

  • Lee, Kwanhyoung;Choi, Oh Kyung;Song, Ji Hyun;Lee, Jae Woo
    • Environmental Engineering Research
    • /
    • v.19 no.1
    • /
    • pp.75-81
    • /
    • 2014
  • Methanotrophic denitrification under a non-aerated condition (without external supply of oxygen or air) was investigated in a bioreactor coupled with a membrane diffuser. Batch experiment demonstrated that both methane consumption and nitrogen production rates were not high in the absence of oxygen, but most of the nitrate was reduced into $N_2$ with 88% recovery efficiency. The methane utilized for nitrate reduction was determined at 1.63 mmol $CH_4$/mmol $NO_3{^-}$-N, which was 2.6 times higher than the theoretical value. In spite of no oxygen supply, methanotrophic denitrification was well performed in the bioreactor, due to enhanced mass transfer of the methane by the membrane diffuser and utilization of oxygen remaining in the influent. The denitrification efficiency and specific denitrification rate were 47% and 1.69 mg $NO_3{^-}-N/g\;VSS{\cdot}hr$, respectively, which were slightly lower than for methanotrophic denitrification under an aerobic condition. The average concentration of total organic carbon in the effluent was as low as 2.45 mg/L, which indicates that it can be applicable as a post-denitrification method for the reclamation of secondary wastewater effluent. The dominant fatty acid methyl ester of mixed culture in the bioreactor was $C_{16:1{\omega}7c}$ and $C_{18:1{\omega}7c}$, which was predominantly found in type I and II methanotrophs, respectively. This study presents the potential of methanotrophic denitrification without externally excess oxygen supply as a post-denitrification option for various water treatment or reclamation.

A Numerical Study on the Thermopneumatic and Flow Characteristics of Diffuser-Nozzle Based Thermopneumatic Micropumps (디퓨져와 노즐을 이용한 열공압형 마이크로 펌프의 열공압 및 유동특성에 관한 수치해석적 연구)

  • Jeong Jin;Kim Chang Nyung
    • Korean Journal of Air-Conditioning and Refrigeration Engineering
    • /
    • v.17 no.7
    • /
    • pp.642-648
    • /
    • 2005
  • This study has been conducted to investigate the thermopneumatic and flow characteristics of diffuser/nozzle based thermopneumatic micropumps. In this study, a transient three-dimensional numerical analysis using FSI (Fluid-Structure Interaction) model has been employed to analyze the effects of the interaction between the membrane and two fluids (air and water) in the thermopneumtic micropump. The transient temperature and pressure in the cavity, the transient displacements of the membrane and the net flow rate of the micropump have been closely calculated for the frequency of 1 Hz. It has been found that the difference of the flow rates at the inlet and outlet is larger in the cooling period than in the heating period and that the duty ratio is very important in association with pump performance because the temperature in the cavity ascends drastically in the heating period and descends slowly in the cooling period. This study can be regarded as fundamental understandings for the design and analysis of thermopneumatic micropumps.

Analysis of Low Reynolds Number Flow in Nozzle and Diffuser (노즐-디류저 내에서의 저 Reynolds수 해독특성 해석)

  • Song, Gwi-Eun;Lee, Joon-Sik
    • Proceedings of the KSME Conference
    • /
    • 2007.05b
    • /
    • pp.2672-2677
    • /
    • 2007
  • An investigation of low Reynolds number flow in nozzles and diffusers which are widely used in the valveless micropump is presented. Flow characteristics in the nozzle and diffuser are explained in view of viscous effect and flow oscillation induced by pumping membrane. These calculation results show that the rectification property of valveless micropump is due to a flow separation in the diffuser and the separation is largely originated from the flow oscillation. Under the assumptions of steady flow velocity profile and flow separation in the diffuser, simplified analytical models are provided to see the dependency of rectification on the micropump geometry. Geometric parameters of channel length, nozzle throat, chamber size, and converging/diverging angle are depicted through the analytical models in low Reynolds number flow, and the prediction and experimental results are compared. This theoretical study can be used to determine the optimum geometry of valveless micropump.

  • PDF

Numerical Analysis about the Flow Characteristics for Different Figures of Inlet and Outlet in Diffuser/Nozzle based on Piezoelectric Micropump (디퓨져/노즐을 이용한 압전형 마이크로 펌프의 입 . 출구 형상 차이에 따른 유동특성에 관한 수치해석적 연구)

  • Kim, Chang-Nyung;Kim, Chin-Uck
    • Proceedings of the KSME Conference
    • /
    • 2007.05b
    • /
    • pp.3104-3109
    • /
    • 2007
  • The present study has been carried out to investigate the pumping characteristics for different figures of inlet and outlet in diffuser/nozzle based on piezoelectric micropump. Piezoelectric micropump system consists of several parts like a pumping chamber, diffuser/nozzle, piezoelectric element and tubes. Parts of the micropump connected with diffuser/nozzle and tubes have been analyzed.. The magnified parts have been classified into two different models based on their resistance. These models have been further classified into six models with each one having three different angles at the magnified parts. Each model has been compared and analyzed using the simulation tool, namely, CFD-ACE depending on their flow rates and characteristics.

  • PDF