scholarly journals Effects of Filtration Mode on the Performance of Gravity-Driven Membrane (GDM) Filtration: Cross-Flow Filtration and Dead-End Filtration

Water ◽  
2022 ◽  
Vol 14 (2) ◽  
pp. 190
Author(s):  
Qian Wang ◽  
Xiaobin Tang ◽  
Heng Liang ◽  
Wenjun Cheng ◽  
Guibai Li ◽  
...  
Keyword(s):  
Fluorescent Protein ◽  
Cross Flow ◽  
Drinking Water Treatment ◽  
Flow Mode ◽  
Cross Flow Filtration ◽  
Dead End ◽  
Gravity Driven ◽  
Flux Level ◽  
Flow Filtration

Gravity-driven membrane (GDM) filtration technology has been extensively in the employed drinking water treatment, however, the effect filtration mode (i.e., dead-end mode vs. cross-flow mode) on its long-term performance has not been systematically investigated. In this study, pilot-scale GDM systems were operated using two submerged filtration mode (SGDM) and cross-flow mode (CGDM) at the gravity-driven pressures 120 mbar and 200 mbar, respectively. The results showed that flux stabilization was observed both in the SGDM and CGDM during long-term filtration, and importantly the stabilized flux level of CGDM was elevated by 3.5–67.5%, which indicated that the filtration mode would not influence the occurrence of flux stability, but significantly improve the stable flux level. Interestingly, the stable flux level was not significantly improved with the increase of driven pressure, and the optimized driven pressure was 120 mbar. In addition, the GDM process conferred effective removals of turbidity, UV254, CODMn, and DOC, with average removals of 99%, 43%, 41%, and 20%, respectively. With the assistance of cross flow to avert the overaccumulation of contaminants on the membrane surface, CGDM process exhibited even higher removal efficiency than SGDM process. Furthermore, it can be found that the CGDM system can effectively remove the fluorescent protein-like substances, and the intensities of tryptophans substance and soluble microbial products were reduced by 64.61% and 55.08%, respectively, higher than that of the SGDM. Therefore, it can be determined that the filtration mode played an important role in the flux stabilization of GDM system during long-term filtration, and the cross-flow filtration mode can simultaneously improve the stabilized flux level and removal performance.

scholarly journals Living biofouling-resistant membranes as a model for the beneficial use of engineered biofilms

2016 ◽  
Vol 113 (20) ◽  
pp. E2802-E2811 ◽  
Author(s):  
Thammajun L. Wood ◽  
Rajarshi Guha ◽  
Li Tang ◽  
Michael Geitner ◽  
Manish Kumar ◽  
...  
Keyword(s):  
Cross Flow ◽  
Membrane System ◽  
Environmental Pollutant ◽  
Cross Flow Filtration ◽  
Membrane Biofouling ◽  
Dead End ◽  
Dispersal Agent ◽  
Microbial Film ◽  
Flow Filtration

Membrane systems are used increasingly for water treatment, recycling water from wastewater, during food processing, and energy production. They thus are a key technology to ensure water, energy, and food sustainability. However, biofouling, the build-up of microbes and their polymeric matrix, clogs these systems and reduces their efficiency. Realizing that a microbial film is inevitable, we engineered a beneficial biofilm that prevents membrane biofouling, limiting its own thickness by sensing the number of its cells that are present via a quorum-sensing circuit. The beneficial biofilm also prevents biofilm formation by deleterious bacteria by secreting nitric oxide, a general biofilm dispersal agent, as demonstrated by both short-term dead-end filtration and long-term cross-flow filtration tests. In addition, the beneficial biofilm was engineered to produce an epoxide hydrolase so that it efficiently removes the environmental pollutant epichlorohydrin. Thus, we have created a living biofouling-resistant membrane system that simultaneously reduces biofouling and provides a platform for biodegradation of persistent organic pollutants.

Introducing a slow cross-flow at the capillary outlet in comparison to conventional dead-end mode—a trajectory analysis of the effects

2008 ◽  
Vol 8 (4) ◽  
pp. 389-399
Author(s):  
A. Lerch
Keyword(s):  
Flow Field ◽  
Trajectory Analysis ◽  
Cross Flow ◽  
Flow Mode ◽  
Membrane Area ◽  
Operation Conditions ◽  
Cross Flow Filtration ◽  
Cross Section Area ◽  
Dead End ◽  
Flow Filtration

A model has been developed, based on the finite element method (FEM) of computational fluid dynamics (CFD), for the description of the complete flow field and concentration distribution inside a membrane capillary, driven in inside-out and dead-end or ‘slow’ cross-flow mode, sometimes referred to as ‘bleed flow’. Particle or floc transport and deposition have been described by trajectory analysis, i.e. superimposing the calculation of forces and torques acting on the particles or flocs, based on the previously modelled fluid flow field. The model is used to give an overview of deposition behaviour and fouling layer formation of particles and flocs of a certain size in dead-end and cross-flow filtration. Example results are shown for different sized flocs. It is shown that the choice of dead-end or cross-flow operation is more significant if small floc aggregates have to be filtered by the membrane. Small flocs will be deposited more or less homogeneously along the membrane wall after some significant distance to the capillary inlet, leaving the first part of the membrane area unused for deposition. A ‘slow’ cross-flow could be used to transport small flocs out of the capillary which entered the capillary cross section area in the neighbourhood of the axis. The faster the chosen cross-flow velocity, the larger the area. Larger flocs will be ‘accumulated’ in one resulting equilibrium trajectory and are transported to the rear end of the capillary, independent of their starting radial position at the inlet and operation conditions. It was calculated, that larger flocs will not be significantly transported out of the capillary lumen by introducing ‘slow’ cross-flow velocities at the capillaries outlet only.

scholarly journals Real time imaging of single extracellular vesicle pH regulation in a microfluidic cross-flow filtration platform

2022 ◽  
Vol 5 (1) ◽  
Author(s):  
Vladimir Riazanski ◽  
Gerardo Mauleon ◽  
Kilean Lucas ◽  
Samuel Walker ◽  
Adriana M. Zimnicka ◽  
...  
Keyword(s):  
Ph Regulation ◽  
Cross Flow ◽  
Extracellular Vesicle ◽  
Nanoporous Silicon ◽  
Cross Flow Filtration ◽  
Dead End ◽  
Sodium Hydrogen Exchanger ◽  
Flow Filtration ◽  
Single Vesicle ◽  
Solution Changes

AbstractExtracellular vesicles (EVs) are cell-derived membranous structures carrying transmembrane proteins and luminal cargo. Their complex cargo requires pH stability in EVs while traversing diverse body fluids. We used a filtration-based platform to capture and stabilize EVs based on their size and studied their pH regulation at the single EV level. Dead-end filtration facilitated EV capture in the pores of an ultrathin (100 nm thick) and nanoporous silicon nitride (NPN) membrane within a custom microfluidic device. Immobilized EVs were rapidly exposed to test solution changes driven across the backside of the membrane using tangential flow without exposing the EVs to fluid shear forces. The epithelial sodium-hydrogen exchanger, NHE1, is a ubiquitous plasma membrane protein tasked with the maintenance of cytoplasmic pH at neutrality. We show that NHE1 identified on the membrane of EVs is functional in the maintenance of pH neutrality within single vesicles. This is the first mechanistic description of EV function on the single vesicle level.

Preparation and Characterization of Ultrafiltration TiO2 Nanoparticles-Polysulfone Membranes

2017 ◽  
Vol 68 (11) ◽  
pp. 2635-2640 ◽  
Author(s):  
Daniela Florentina Enache ◽  
George Alexandru Popa ◽  
Eugeniu Vasile ◽  
Anca Razvan ◽  
Ovidiu Oprea ◽  
...  
Keyword(s):  
Tio2 Nanoparticles ◽  
Water Flux ◽  
Cross Flow ◽  
Hydrodynamic Performance ◽  
Tio2 Anatase ◽  
Cross Flow Filtration ◽  
Dead End ◽  
Large Water ◽  
Flow Filtration ◽  
Polysulfone Membranes

This paper presents the preparation route for new TiO2 nanoparticles-polysulfone membranes: M1 (Psf 12%), M2 (Psf 12% + TiO2 anatase), and M3 (Psf 12% + TiO2 76% anatase+ 24% rutile) that were structurally characterized by FTIR, TG-DSC and by scanning electron microscopy (SEM) coupled with energy dispersive spectroscopy (EDAX). Contact angle measurements, dead-end and cross-flow filtration experiments were carried out to characterize the morphology and hydrodynamic performance of the prepared membranes. Improved mechanical properties, enhanced hydrophilicity and the relative large water flux measured for M2-M3 (721.83 L/m2�h and 305.4 L/m2�h, respectively) in cross-flow filtration experiments, make these membranes appropriate for ultrafiltration applications.

Ultrafiltration of Aqueous Solutions of Food Dye in the Presence of Surfactants

2017 ◽  
Vol 68 (1) ◽  
pp. 6-10
Author(s):  
George Alexandru Popa ◽  
Daniela Florentina Popa (Enache) ◽  
Dumitra Daniela Slave (Clej) ◽  
Ion Din Spiridon ◽  
Cristina Monica Mirea ◽  
...  
Keyword(s):  
Aqueous Solutions ◽  
Membrane Surface ◽  
Cross Flow ◽  
Sodium Octanoate ◽  
Food Dye ◽  
Cross Flow Filtration ◽  
Dead End ◽  
Food Dyes ◽  
Flow Filtration ◽  
Quinoline Yellow

The objective of the study is the low-pressure membrane process for treating aqueous solutions containing food dyes and surfactants. The influence of surfactants (SDS � sodium dedecil sulphate, SO � sodium octanoate) in the separation of synthetic food dyes (E104 � quinoline yellow) was analyzed. Polysulfone and polysulfone-polyaniline membranes were used. Dye and surfactant concentrations used were 10% (equivalent to 100g/m3). The pressures used in the ultrafiltration process were 0.1, 0.2 and 0.3 MPa. When dye containing solutions were passed through the membranes, an increase in their flux was observed. The presence of surfactants in the solutions lead to a decline in flux when pressures of 0.1 and 0.2 MPa were used, but an improvement could be seen as the pressure increased to 0.3 MPa, for both dead-end and cross-flow filtration. Using only dead-end alternative, higher fluxes were achieved for both membranes, but it decreases with time due to accumulation on the membrane surface. The use of cross-flow filtration did not allow accumulation on the membrane surface so that the flux was constant in time.The use of anionic surfactants improved the food dye retention. The interactions between membranes and surfactants can be an important factor supporting the efficiency of the ultrafiltration.

scholarly journals Ultrafiltration Mixed Matrix Membranes Based on Mesoporous Silica (MCM-41, HMS)Embedded in Polysulfone

2019 ◽  
Vol 70 (9) ◽  
pp. 3089-3093
Author(s):  
Anca Razvan ◽  
Daniela F. Popa ◽  
Ovidiu Oprea ◽  
Eugeniu Vasile ◽  
Florina Dumitru ◽  
...  
Keyword(s):  
Mesoporous Silica ◽  
Cross Flow ◽  
Composite Membranes ◽  
Mixed Matrix Membranes ◽  
Inversion Method ◽  
Cross Flow Filtration ◽  
Dead End ◽  
Flow Filtration ◽  
Phase Inversion Method ◽  
Mcm 41

Three composite membranes (M1-M3), with mesoporous silica (MCM-41 or HMS-C12/C16-type) embedded in polysulfone (Psf) were obtained by phase-inversion method and their performances were tested for use in ultrafiltration membrane processes. The structures of M (Psf 12%, reference membrane), M1 (Psf 12% + MCM-41), M2 (Psf 12% + HMS-C12), M3 (Psf 12% + HMS-C16) have been assessed by FTIR, TG-DSC and SEM-EDAX and the morphology and their hydrodynamic performances have been evaluated by contact angle measurements, dead-end and cross-flow filtration experiments.

Experimental assessment of the efficacy of microfiltration and ultrafiltration for Cryptosporidium removal

1998 ◽  
Vol 38 (12) ◽  
pp. 103-107 ◽  
Author(s):  
T. Hirata ◽  
A. Hashimoto
Keyword(s):  
Cryptosporidium Oocyst ◽  
Cross Flow ◽  
Drinking Water Treatment ◽  
Flow Mode ◽  
Additional Experiment ◽  
Experimental Assessment ◽  
Dead End ◽  
Single Process ◽  
Scale Experiment ◽  
Annual Risk

In order to evaluate the efficacy of microfiltration and ultrafiltration for Cryptosporidium oocyst removal, a bench-scale experiment was carried out using two 0.2m2 molecules, MF (nominal pore size 0.25μm) and UF (nominal cut-off MW 13,000 daltons) in cross-flow mode at an oocyst level of 106/L. Both of the membranes eliminated the oocysts from the influents with removal efficiency estimated to be >7 log10. As for the MF, an additional experiment was conducted at a much higher oocyst level up to 108 oocysts/L in both cross-flow and dead-end modes and which achieved >7 log10 removal, although some oocysts appeared in the filtrate in both modes. Based on these results, microfiltration and ultrafiltration are conclusively considered to be excellent processes for drinking water treatment as a single process that produces safe (an annual risk 10−4) water from highly polluted source waters.

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