Modeling and analysis of concentration profiles obtained by in-situ SAXS during cross-flow ultrafiltration of colloids

2017 ◽  
Vol 528 ◽  
pp. 34-45 ◽  
Author(s):  
Y. Jin ◽  
N. Hengl ◽  
S. Baup ◽  
G. Maitrejean ◽  
F. Pignon
Keyword(s):  
Cross Flow ◽  
Concentration Profiles ◽  
Modeling And Analysis

scholarly journals Quantifying Concentration Polarization – Raman Microspectroscopy for In-Situ Measurement in a Flat Sheet Cross-flow Nanofiltration Membrane Unit

2019 ◽  
Vol 9 (1) ◽  
Author(s):  
Oliver Jung ◽  
Florencia Saravia ◽  
Michael Wagner ◽  
Stefan Heißler ◽  
Harald Horn
Keyword(s):  
Concentration Polarization ◽  
Cross Flow ◽  
Raman Microspectroscopy ◽  
Channel Height ◽  
Concentration Profiles ◽  
Operating Pressure ◽  
Membrane Unit ◽  
Lower Velocity ◽  
Flat Sheet

Abstract In this work, the concentration polarization layer (CPL) of sulphate in a cross-flow membrane system was measured in-situ using Raman microspectroscopy (RM). The focus of this work is to introduce RM as a new tool for the study of mass transfer inside membrane channels in reverse osmosis (RO) and nanofiltration (NF) generally. Specifically, this work demonstrates how to use RM for locally resolved measurement of sulphate concentration in a cross-flow flat-sheet NF membrane flow cell with channel dimensions similar to commonly applied RO/NF spiral wound modules (channel height about 0.7 mm). Concentration polarization profiles of an aqueous magnesium sulphate solution of 10 gsulphate·L−1 were obtained at operating pressure of 10 bar and cross-flow velocities of 0.04 and 0.2 m·s−1. The ability of RM to provide accurate concentration profiles is discussed thoroughly. Optical effects due to refraction present one of the main challenges of the method by substantially affecting signal intensity and depth resolution. The concentration profiles obtained in this concept study are consistent with theory and show reduced CPL thickness and membrane wall concentration with increasing cross-flow velocity. The severity of CP was quantified to reach almost double the bulk concentration at the lower velocity.

Microbial ecology of sulfate-reducing bacteria in wastewater biofilms analyzed by microelectrodes and fish (fluorescent in situ hybridization) technique

1999 ◽  
Vol 39 (7) ◽  
pp. 41-47 ◽  
Author(s):  
Satoshi Okabe ◽  
Hisashi Satoh ◽  
Tsukasa Itoh ◽  
Yoshimasa Watanabe
Keyword(s):  
In Situ Hybridization ◽  
Sulfate Reduction ◽  
Sulfate Reducing Bacteria ◽  
Hybridization Technique ◽  
Concentration Profiles ◽  
Reduction Zone ◽  
Sulfate Reducing ◽  
Reducing Bacteria ◽  
Culture Dependent

The vertical distribution of sulfate-reducing bacteria (SRB) in microaerophilic wastewater biofilms grown on fully submerged rotating disk reactors (RDR) was determined by the conventional culture-dependent MPN method and in situ hybridization of fluorescently-labelled 16S rRNA-targeted oligonucleotide probes for SRB in parallel. Chemical concentration profiles within the biofilm were also measured using microelectrodes for O2, S2-, NO3- and pH. In situ hybridization revealed that the SRB probe-stained cells were distributed throughout the biofilm even in the oxic surface zone in all states from single scattered cells to clustered cells. The higher fluorescence intensity and abundance of SRB probe-stained cells were found in the middle part of the biofilm. This result corresponded well with O2 and H2S concentration profiles measured by microelectrodes, showing sulfate reduction was restricted to a narrow anaerobic zone located about 500 μm below the biofilm surface. Results of the MPN and potential sulfate reducing activity (culture-dependent approaches) indicated a similar distribution of cultivable SRB in the biofilm. The majority of the general SRB probe-stained cells were hybridized with SRB 660 probe, suggesting that one important member of the SRB in the wastewater biofilm could be the genus Desulfobulbus. An addition of nitrate forced the sulfate reduction zone deeper in the biofilm and reduced the specific sulfate reduction rate as well. The sulfate reduction zone was consequently separated from O2 and NO3- respiration zones. Anaerobic H2S oxidation with NO3- was also induced by addition of nitrate to the medium.

Surface modification of reverse osmosis membranes with zwitterionic polymer to reduce biofouling

2015 ◽  
Vol 15 (5) ◽  
pp. 999-1010 ◽  
Author(s):  
Ahmed E. Abdelhamid ◽  
Mahmoud M. Elawady ◽  
Mahmoud Ahmed Abd El-Ghaffar ◽  
Abdelgawad M. Rabie ◽  
Poul Larsen ◽  
...  
Keyword(s):  
Reverse Osmosis ◽  
Tap Water ◽  
Membrane Surface ◽  
Salt Content ◽  
Cross Flow ◽  
Membrane Properties ◽  
Cleaning Efficiency ◽  
Bacteria Growth ◽  
Cross Flow Filtration

The zwitterionic homopolymer poly[2-(methacryloyloxy)ethyl-dimethyl-(3-sulfopropyl) ammonium hydroxide was coated onto the surface of commercial polyamide reverse osmosis (RO) membranes. Aqueous solutions of the polymer at different concentrations were applied to modify the polyamide membranes through an in situ surface coating procedure. After membrane modification, cross-flow filtration testing was used to test the antifouling potential of the modified membranes. The obtained data were compared with experimental data for unmodified membranes. Each test was done by cross-flow filtering tap water for 60 hours. Yeast extract was added as a nutrient source for the naturally occurring bacteria in tap water, to accelerate bacteria growth. Fourier transform infrared spectroscopy, contact angle, scanning electron microscopy, atomic force microscopy, and permeation tests were employed to characterize membrane properties. The results confirmed that modifying the membranes enhanced their antifouling properties and cleaning efficiency, the fouling resistance to bacteria improving due to the increased hydrophilicity of the membrane surface after coating. In addition, the water permeability and salt rejection improved. This in situ surface treatment approach for RO membranes could be very important for modifying membranes in their original module assemblies as it increases water production and reduces the salt content.

scholarly journals Evidence for long-lived polar vortex air in the mid-latitude summer stratosphere from in situ laser diode CH<sub>4</sub> and H<sub>2</sub>O measurements

2005 ◽  
Vol 5 (6) ◽  
pp. 1467-1472 ◽  
Author(s):  
G. Durry ◽  
A. Hauchecorne
Keyword(s):  
High Resolution ◽  
Laser Diode ◽  
Polar Vortex ◽  
The Arctic ◽  
Concentration Profiles ◽  
Spatial Structures ◽  
Laser Spectrometer ◽  
Southern France ◽  
Diode Laser Spectrometer

Abstract. A balloon borne diode laser spectrometer was launched in southern France in June 2000 to yield in situ stratospheric CH4 and H2O measurements. In the altitude region ranging from 20km to 25km, striking large spatial structures were observed in the vertical concentration profiles of both species. We suggest these patterns are due to the presence of long-lived remnants of the wintertime polar vortex in the mid-latitude summer stratosphere. To support this interpretation, a high resolution advection model for potential vorticity is used to investigate the evolution of the Arctic vortex after its breakdown phase in spring 2000.

Structure of Propylene Turbulent Diffusion Flames in Cross-Flow Near Smoke Point

2006 ◽  
Author(s):  
S. F. Goh ◽  
C. Periasamy ◽  
S. R. Gollahalli
Keyword(s):  
Transition Region ◽  
Flow Rate ◽  
Cross Flow ◽  
Smoke Point ◽  
Concentration Profiles ◽  
Temperature Profiles ◽  
Fuel Flow Rate ◽  
Number Range ◽  
Jet Flame ◽  
Fuel Flow

An experimental study of a propylene diffusion flame at its smoke point in a cross-flow with velocities ranging from 2 to 4 m/s and a series of diluted conditions was conducted. A gas jet flame from a circular tube burner (ID = 3.2 mm) with a range of exit velocities (4.2 to 34 m/s) corresponding to a Reynolds number range of 520 to 6065 was studied. Nitrogen was added to the fuel stream to eliminate smoking when the fuel flow rate was lower than the flow rate of pure fuel at smoke point condition (which is defined as the Critical Fuel Mass Flow Rate, CFMFR). The curve of N2 flow rate with fuel flow rate at the smoke point showed a skewed bell shape with two distinct regions. In the first region, the diluent flow rate increased with the fuel flow rate, and in the subsequent region the trend was reversed. These two regions were separated by a transition region. Our previous studies on flames in quiescent conditions concluded that these two regions were controlled by jet momentum and chemical kinetics, respectively. This study presents flame structure details such as transverse temperature and concentration profiles in typical flames representing these two regimes. Most of the temperature profiles show a dual peak structure, where the peak nearer to the burner was higher than the other. Furthermore, the peaks in the transition region flame were more distinct than those in the momentum dominated flame. Most of the flames in the 2 m/s cross-flow had lower O2 concentrations than the flames in the 3 and 4 m/s cross-flow. The temperature profiles, and the concentration profiles of O2 and soot change significantly when cross-flow velocity was changed from 2 to 4 m/s. Findings from this study enable us to understand industrial flares that are commonly used in petroleum refineries and chemical plants.

scholarly journals Measuring concentration fields in microfluidic channels in situ with a Fabry–Perot interferometer

Lab on a Chip ◽  
2015 ◽  
Vol 15 (7) ◽  
pp. 1689-1696 ◽  
Author(s):  
Douglas R. Vogus ◽  
Vincent Mansard ◽  
Michael V. Rapp ◽  
Todd M. Squires
Keyword(s):  
Fluorescent Labeling ◽  
Microfluidic Channels ◽  
Concentration Profiles ◽  
Complex Chemical ◽  
Chemical Gradients ◽  
Microfluidic Technology ◽  
Fabry Perot ◽  
Spatio Temporal ◽  
And Control

Recent advancements in microfluidic technology have allowed for the generation and control of complex chemical gradients; however, few general techniques can measure these spatio-temporal concentration profiles without fluorescent labeling.

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