Internal Clogging Research Articles

Full-cycle study on developing a novel structured micromixer and evaluating the nanoparticle products as mRNA delivery carriers

Achieving precise control of nanoparticle size while maintaining consistency and high uniformity is of paramount importance for improving the efficacy of nanoparticle-based therapies and minimizing potential side effects. Although microfluidic technologies are widely used for reliable nanoparticle synthesis, they face challenges in meeting critical homogeneity requirements, mainly due to imperfect mixing efficiency. Furthermore, channel clogging during continuous operation presents a significant obstacle in terms of quality control, as it progressively impedes the mixing behavior necessary for consistent nanoparticle production for therapeutic delivery and complicates the scaling-up process. This study entailed the development of a 3D-printed novel micromixer embedded with hemispherical baffle microstructures, a dual vortex mixer (DVM), which integrates Dean vortices to generate two symmetrical counter-rotating intensified secondary flows. The DVM with a relatively large mixer volume showed rapid mixing characteristics even at a flow rate of several mL min−1 and produced highly uniform lipids, liposomes, and polymer nanoparticles in a size range (50–130 nm) and polydispersity index (PDI) values below 0.15. For the evaluation of products, SARS-CoV-2 Spike mRNA-loaded lipid nanoparticles were examined to verify protein expression in vitro and in vivo using firefly luciferase (FLuc) mRNA. This showed that the performance of the system is comparable to that of a commercial toroidal mixer. Moreover, the vigorous in-situ dispersion of nanoparticles by harnessing the power of vortex physically minimizes the occurrence of aggregation, ensuring consistent production performance without internal clogging of a half-day operation and facilitating quality control of the nanoparticles at desired scales.

Bioclogging effects on mass transport using volume averaging method in bioretention cell treating wastewater: Theories

AbstractIn bioretention cell (BRC) systems, internal clogging in the hydraulic field caused by microbial organisms growing in the nonuniform porous media can lead to the reduction of denitrification capacity. To investigate microbial effect processes, a multispecies biological field‐hydraulic coupling transport model in BRC was developed based on the average volume method (AVM) and traditional convection‐diffusion–reaction equation. This model provides a method to establish a connection between the microscale biofilm thickness and the macroscale measurement of pollutant concentration, which has been less frequently discussed in previous research. The present work differs from earlier works by explicitly smoothing the diversity and complexity of media structure by upscaling the physical quantities using the AVM. The results suggest that the model is derived for enhancing a more comprehensive understanding the relationship between the microscopic biofilm thickness and the measured concentration. It is also found that the infiltration description is required adding porosity parameter in order to have an accurate simulation of permeable phenomena under biologically growing condition.

Study of the efficiency of well repair at the Karachaganak field

The assessment of the effectiveness of the choice of formulations of clay-free inhibited salt solutions, recommended for washing when drilling side shafts and horizontal sections, based on the study of biopolymers, in the conditions of the Karachaganak deposit, is considered. The duration of the fountaining of production wells at the Karachaganak field depends both on the methods used to increase the oil yield of layers (primary and secondary) and on the dimensional characteristics of the fountain system for lifting well production. As a result of a gradual decrease in reservoir pressure and water inflow into the downhole zone of the well, its stability is significantly reduced, the filtration characteristics of the reservoir deteriorate, the formation of mineral deposits, sand and gas hydrate plugs increases, and the corrosion activity of production increases. And as a result, the production capacity of producing oil and gas condensate wells is significantly reduced. The character of the composition of the reservoirs of the deposits of the Karachaganak deposit, in the overwhelming majority, contain clayey cement. At the same time, the "swelling" of clay rocks is a significant reason for the decrease in productivity of production wells. Collectors with low permeability with practically irreversible "internal clogging" are especially sensitive to this effect. The use of technological fluids has been found to be the most effective – solutions containing a biopolymer as the main component, possessing pseudo-plasticity and contributing to high-quality cleaning of the bottom hole from mud, as well as the maximum removal of mud residues from the well system, which have a minimal polluting effect on reservoir reservoir systems, since biopolymer the substance entering the collector is enzymatically decomposed after a certain time. The use of the composition of the inhibitory biopolymer salt solution based on the KCl complex salt (potassium chloride-electrolyte) will allow to fully preserve the properties of the productive layer. For maximum isolation of the watered downhole zone of the formation, the authors propose to use a tamping solution on an adhesive basis with properties sufficient for reliable isolation. Injection of tamping solution under pressure into the layer will increase the strength of the cement stone by an average of 1.5 times.

Experimental Study on the Migration and Clogging of Fine Particles in Coarse-Grained Soil with Seepage

The migration and clogging of fine particles in the pores of coarse-grained soil with seepage is of great significance to reduce the leakage of soil at the dam base and lower the permeability of soil. Therefore, the homemade infiltration test device was used to test the infiltration and clogging of soil samples with different particle size ratios D15/d85 (D15 represents the particle size corresponding to the cumulative percentage content of soil particles smaller than a certain particle size in the coarse particles which is 15%, and d85 represents the particle size corresponding to the cumulative percentage content of soil particles smaller than a certain particle size in the fine particles group which is 85%). The factors affecting the deposition of fine particles in coarse-grained soil and the characteristics of fine particle migration and penetration were analyzed. The clogging of coarse-grained soil, hydraulic gradient and pore changes characteristics before and after clogging were studied. The results show that: 1) The main factor affecting the retention of fine particles in coarse-grained soil is the particle size ratio, and the retention rules conforms to the Peak-Gauss function relationship. The penetration law of fine particles satisfies the Logistic function relationship, which can directly predict the internal clogging of coarse-grained soil. 2) The particle size ratio is the main factor affecting the blockage in each mode, followed by the influence of the water head, When the particle size ratio is less than 13.10, the clogging ratio decreases with the increase of particle size ratio, and the hydraulic gradient increases with the increase of particle size ratio. When is greater than 13.10, the clogging ratio increases with the increase of particle size ratio, and the hydraulic gradient decreases with the increase of particle size ratio. 3) The degree of clogging in coarsegrained soil is closely related to the change in porosityand and can be judged according to the change of porosity in coarse-grained soil. The research results deepen the understanding of fine particle migration on the rules of coarse-grained soil clogging and can provide a theoretical basis for related engineering applications.

Understanding the Microscopic Mechanism of Clogging of both Fibrous and Mesh Filters in Flooded-bed Wet Scrubbers

Flooded-bed scrubbers are commonly employed in continuous miners to capture and remove dust particles at the cutting face in underground coal mines. To date, the mechanism of filter clogging as well as the evolution of pressure drop has not been well understood. In this work, clogging of filters in a relevant flooded-bed scrubber environment have been investigated in a laboratory setting by spraying a slurry onto a filter assembly while pulling the air through. Two types of filters have been investigated, including a) a multi-layer mesh filter and 2) a fibrous woven filter. Results showed that the differential pressure (or pressure drop) increased with an accumulation of clogged particles within the filter. The timed evolution of the pressure drop varied with both pore size and pore structure of the filter medium. When dust particles were much smaller than the pore size of the filter, dust particles predominantly accumulated inside the filter pack. When dust particles had comparable or larger sizes compared with the pore (or mesh) size of the filter medium, the filter was dominantly clogged at its front layers. Experimental results were compared with a modified model to account for the development of the pressure drop across the filter. The clogging of scrubber filters may be presented in two mechanisms, namely a) internal clogging and b) caking. The present result demonstrates the fundamental mechanism of clogging of dust particles within fibrous and mesh filters during dust capture and removal by flooded-bed wet scrubbers as well as other engineering applications involving in multi-phase interaction within a porous medium.

Biofilm Formation and Biofouling Development on Different Ultrafiltration Membranes by Natural Anaerobes from an Anaerobic Membrane Bioreactor.

Biofouling in anaerobic membrane bioreactors (AnMBRs) has not been studied widely. Moreover, the effect of membrane surface properties on biofilm formation beyond initial deposition is controversial. We investigated biofouling with polyvinyldifluoride, polyacrylonitrile, and zwitterion-modified polyethersulfone ultrafiltration membranes having different properties during 72 h filtration using natural anaerobes isolated from AnMBR and analyzed biofilm characteristics by physicochemical and molecular techniques. A decrease in membrane performance was positively correlated with biofilm formation on polyvinyldifluoride and polyacrylonitrile membranes, and as expected, physical cleaning effectively mitigated biofilm on hydrophilic and low-roughness membranes. Surprisingly, while the biofilm on the hydrophilic and low-surface roughness zwitterion-modified membrane was significantly impaired, the impact on transmembrane pressure was the highest. This was ascribed to the formation of a soft compressible thin biofilm with high hydraulic resistance, and internal clogging and pore blocking due to high pore-size distribution. Anaerobe community analysis demonstrated some selection between the bulk and biofilm anaerobes and differences in the relative abundance of the dominant anaerobes among the membranes. However, correlation analyses revealed that all membrane properties studied affected microbial communities' composition, highlighting the system's complexity. Overall, our findings indicate that the membrane properties can affect biofilm formation and the anaerobic microbial population but not necessarily alleviate biofouling.

Exploring the Limitations of Osmotically Assisted Reverse Osmosis: Membrane Fouling and the Limiting Flux.

Osmotically assisted reverse osmosis (OARO) has shown great potential for low-cost and energy-efficient brine management. However, its performance can be significantly limited by membrane fouling. Here, we performed for the first time a comprehensive study on OARO membrane fouling, explored the associated fouling mechanisms, and evaluated fouling reversibility via simple physical cleaning strategies. First, internal membrane fouling at the draw (permeate) side was shown to be insignificant. Flux behavior in short-term operation was correlated to both the evolution of fouling and the change of internal concentration polarization. In long-term operation, membrane fouling constrained the OARO water flux to a singular, common upper limit, in terms of limiting flux, which was demonstrated to be independent of operating pressures and membrane properties. Generally, once the limiting flux was exceeded, the OARO process performance could not be improved by higher-pressure operation or by utilizing more permeable and selective membranes. Instead, different cyclic cleaning strategies were shown to be more promising alternatives for improving performance. While both surface flushing and osmotic backwashing (OB) were found to be highly effective when using pure water, a full flux recovery could not be achieved when a nonpure solution was used during OB due to severe internal clogging during OB. All in all, the presented findings provided significant implications for OARO operation and fouling control.

INFLUENCE OF THE SIDE VENTILATION ON THE DURABILITY OF THE FUNCTIONING OF DRYING BEDS WITH NON-SATURATED FLOW IN TREATEMENT OF SEPTIC TANK SLUDGE

The non-saturated Flow Drying Beds allow efficient treatment of septic tank sludge. However, they are vulnerable to clogging. To ensure the sustainability of this technology, through an additional supply of oxygen from the lateral surface, a flow model coupled with the variation of the biofilm has been developed. The calibration, validation and comparison of the simulated and experimental results were made from the NASH criterion. The simulations focused on two types of reactors. A reactor with pores on its side surface is called a ventilated reactor (VR). The second is then called an unventilated reactor (UVR). The results show that the maximum applicable organic load is 43.3 mgO2 / cm2 / d at the UVR level and 51.8 mgO2 / cm2 / d at the VR level. In addition, the reduction in free flow porosity is 93.33% at the UVR level and 81% at the AR level. In addition, the results show that when the hydraulic head is less than 5 cm / d, the COD removal efficiency is 96.19% at the UVR level and 95.64% at the VR level. But, when the load is greater than 5 cm / d, the yield is 92.65% at the level of the UVR and of 94.95% at the level of the VR. Thus, in the context of a large-scale operation, lateral ventilation is essential. It guarantees good purification efficiency, slows down internal clogging of beds and accelerates its reversibility when it occurs.

A review of key tools for oil pipe blockage operation in gas wells under pressure

Blockage in tubing is an important guarantee for gas wells under pressure. The internal blockage is to close the channel inside the tubing through a sealing device, the pipe string can be lifted and lowered under pressure. In order to prevent natural gas from leaking through the tubing channel during well completion and string lifting operations, a plugging tool in the tubing is required to block the tubing channel, and the blockage is removed after the operation is completed to effectively control the pressure in the well. This article starts with the key tools related to internal plugging operations in Snubbing operation, introduces the basic principles of setting the internal plugging barriers when running the tubing string in completion operations, and introduces the key tools for internal plugging when the tubing runs in completion operations. The internal plugging method of the pipe string under pressure is introduced. The key tools (bridge plugs) and setting methods that have been matured or formed at home and abroad when the pipe string is lifted in workover are introduced. Well technology and key tool selection provide reference. Finally, we analyze and think about the domestically developed self-developed internal plugging tools for pressurized operations in my country. It is believed that internal clogging is not an isolated process of oil, gas, and water plugging, but is usually a process of multi-system construction processes working together. The key domestic tools and equipment also need to further improve their autonomous capabilities in terms of overall performance and stability, as well as intelligence.

The Clogging Effect in the Process of Protein Separation by Ultrafiltration

In this study, five ultrafiltration membranes (polysulfone, cellulose acetate and polyethe-rsulfone) were tested in the treatment of aqueous protein solutions similar to wastewater from fermentation industries. The experiments were made in tangential flow filtration. The permeate flux for the five membranes tested at the optimum pressure of 3 bar decreased due to the effect of clogging the pores by the macromolecular protein solutions. Cellulose acetate membranes showed the lowest permeate flux (Ac-Cel1=152.4 L/m2.h and Ac-Cel2=40.3 L/m2.h) which doesn�t recommend them for the ultrafiltration process of bovine serum albumin. When a polysulfone membrane was used in several cycles of protein-containing wastewater ultrafiltration, the permeate flow decreased progressively from one cycle to another due to the internal clogging of the membrane (501.6 L/m2.h up to 444.0 L/m2.h). Regarding the ultrafiltration of protein solutions with a suspended yeast content, the clogging was predominant on the membrane�s surface, which results in a decrease of the permeate flux by over 50%.

Evaluation of Superficial and Internal Clogging of Geotextiles

The present work evaluated the clogging of nonwoven (two made of polyester, PET, and one made of polypropylene, PP) and woven (PP) geotextiles submitted to leachate flow from a municipal landfill. Long-term permeability tests were carried out by measuring the hydraulic conductivity over time. Then, scanning electron microscopy (SEM) was performed to evaluate the closure of the geotextile pores and bacterial growth. The main results obtained show a reduction in the hydraulic conductivity of the geotextiles after 35 days. The SEM results of the nonwoven geotextiles showed that the pores inside the geotextiles remained open, while a large part of the solid material was deposited on the surface of the geotextiles. Thus, the results support the idea that the process known as blinding, not clogging, occurred. In addition, SEM allowed us to visualize and confirm pore closure, showing how the formation of microbial colonies occurs and that these occur in a greater proportion in woven geotextiles since its flat surface helps the process, which was observed on a smaller scale in the other geotextiles. In this sense, SEM was essential in verifying the clogging process of geotextiles.

Wolfgang Beyer: A Groundwater Scientist from Dresden.

Wolfgang Beyer: A Groundwater Scientist from Dresden.

Effect of Clogging on Large Strain Consolidation with Prefabricated Vertical Drains by Vacuum Pressure

Clogging will inevitably occur while using vacuum preloading method to process super-soft soils with high water content. How to quantitatively evaluate the effect of clogging on the consolidation behavior is a key issue to be solved. Based on NALSC (negative axisymmetric large-strain consolidation) model, considering the “internal clogging” and the “external clogging”, a calculation method by using parameter “clogging rate” to reflect clogging problem is proposed for single-well consolidation theory. Effects of clogging rate and clogging occurred time on Us (degree of consolidation defined by strain) and Up (degree of consolidation defined by stress) are investigated. Differences of the effect of clogging on consolidation degree are determined between large-strain and small-strain consolidation theory. The results show that, the larger the clogging rate, the smaller the degree of consolidation of the soil at the same consolidation time. Effect of clogging on Up is greater than Us. The earlier the clogging occurs, the smaller the degree of consolidation at the same clogging rate. Influences on the degree of consolidation for large-strain and small-strain theory are the same. Consolidation rate of soil is determined to a certain extent by the “generalized clogging parameter μ”. The “external clogging” has a greater influence on the degree of consolidation than the “internal clogging” at the same clogging rate.

Influence of clogging and resting processes on flow patterns in vertical flow constructed wetlands

Vertical flow constructed wetlands are widely used for removing pollutants from wastewater. Substrate clogging is an operational challenge of constructed wetlands, which can result in impeded water flow and finally a significant decline in the ability of the system to treat the wastewater. The entire clogging process in a vertical flow constructed wetland (VFCW) was quantitatively analyzed by measurements of hydraulic conductivity. Tracer tests and model simulations were carried out to investigate internal flow patterns during the clogging and resting processes. This analysis revealed that hydraulic conductivity gradually decreased with operation time. Further, the distribution time of the flow field was different under different degrees of clogging. Non-uniformity in water flow was primarily observed in the first 400min after adding the tracer (NaCl) in the early clogging stage, as opposed to the last 400min in the late clogging stage. Variation in water flow divergence was closely correlated with piston flow; the reaction efficiency was highest in the early stages of clogging. In the later stages, stronger flow mixing was observed. Resting operations can reduce the dispersion of internal flow and improve reaction efficiency. After resting for approximately 15days, tracer concentration fluctuations decreased and internal flow back-mixing was alleviated. A simulation further described the internal flow pattern and elaborated and validated the tracer experiment. The outcomes of this study will assist in understanding how internal flow behavior varies in response to the clogging process and reveal details of the internal clogging mechanism in VFCWs.

Performance of geotextile filters after 18 years' service in drainage trenches

This study evaluates the long-term performance of two types of geotextiles that were used for 18 years in drainage trenches to stabilize slopes in the French Alps. The flow rate analysis of each trench enabled estimating an average permittivity at trench scale of between 10−5 and 10−6 s−1. After exhuming the geotextiles, their hydraulic and mechanical properties were assessed. The hydraulic tests performed on geotextiles alone gave permittivities greater than 10−3 s−1. Gradient ratio tests were performed on undisturbed soil/geotextile/drainage specimens and gave results in the order of 10−8 s−1. The aged specimens were examined using scanning electron microscopy. Quantifying the overall performance of the geotextile filter is complicated because of the brittleness of the calcite crust and the subsequent difficulty of characterizing undisturbed interfaces. Various possible explanatory mechanisms involved in the deterioration of trench performance were reviewed: filter cake blinding, internal clogging and downstream chemical clogging. Existing analytical models were used in order to predict the loss of hydraulic performance due to each of these clogging mechanisms. By comparing the measured permittivities to the calculated permittivities, we demonstrated that chemical clogging due to calcite precipitation on the downstream face of the geotextiles was probably the preponderant mechanism responsible for the poorer performance of geotextile filters at trench scale.

Riverbed clogging experiments at potential river bank filtration sites along the Ping River, Chiang Mai, Thailand

Riverbank filtration (RBF) is a process during which river water is subjected to subsurface flow prior to abstraction wells, often characterized by improved water quality. The induced infiltration of river water through the riverbed also creates a clogging layer. This decreases riverbed permeability and abstraction rates, particularly if the river water has high turbidity, as in Thailand. As Chiang Mai Province is one of the most favorable sites for future RBF construction in Thailand, two sites, Mae Rim and San Pa Tong, were selected to simulate clogging by using a channel experiment. The mobile experimental apparatus was set up at the bank of the river in order to use fresh river water. Riverbed sediment was used as channel bed and filling material for the columns. The aim was to simulate riverbed clogging using river water with high turbidity and determine the effect of clogging, which can be quantified using vertical hydraulic conductivity (Kv). An increase in channel flow velocity caused partial removal of a clogging layer in only the top 0.03 m of the sediment column. The combination of low channel flow and high turbidity leads to much more clogging than high channel flow and low turbidity. A complete manual removal of the external clogging layer led to an increase in Kv, but the initial Kv values were not recovered. The external clogging had a lower effect on Kv than internal clogging. For planning new RBF sites along high-turbidity rivers, reduction in Kv to estimate RBF well yield cannot be calculated based only on initial Kv but requires field experiments.

A combined network model for membrane fouling

Membrane fouling during particle filtration occurs through a variety of mechanisms, including internal pore clogging by contaminants, coverage of pore entrances, and deposition on the membrane surface. Each of these fouling mechanisms results in a decline in the observed flow rate over time, and the decrease in filtration efficiency can be characterized by a unique signature formed by plotting the volumetric flux, Q^, as a function of the total volume of fluid processed, V^. When membrane fouling takes place via any one of these mechanisms independently the Q^V^ signature is always convex downwards for filtration under a constant transmembrane pressure. However, in many such filtration scenarios, the fouling mechanisms are inherently coupled and the resulting signature is more difficult to interpret. For instance, blocking of a pore entrance will be exacerbated by the internal clogging of a pore, while the deposition of a layer of contaminants is more likely once the pores have been covered by particulates. As a result, the experimentally observed Q^V^ signature can vary dramatically from the canonical convex-downwards graph, revealing features that are not captured by existing continuum models. In a range of industrially relevant cases we observe a concave-downwardsQ^V^ signature, indicative of a fouling rate that becomes more severe with time. We derive a network model for membrane fouling that accounts for the inter-relation between fouling mechanisms and demonstrate the impact on the Q^V^ signature. Our formulation recovers the behaviour of existing models when the mechanisms are treated independently, but also elucidates the concave-downward Q^V^ signature for multiple interactive fouling mechanisms. The resulting model enables post-experiment analysis to identify the dominant fouling modality at each stage, and is able to provide insight into selecting appropriate operating regimes.

Filtration properties and skin formation of micro-crystalline cellulose

Solid–liquid filtration is an important unit operation used in several applications in the pulp and paper industry. It can be challenging especially for materials that forms filter cakes that has a tendency to be highly compressible. The formation of a skin, i.e. an initial cake with a considerably higher filtration resistance, can further increase the filtration resistance for these filter cakes. The separation process in these cases requires considerably larger filter areas.This study investigates skin formation during the filtration of micro-crystalline cellulose, examining the effect of the filter medium, filtration pressure and pH.Depending on the choice of filter medium, the average specific filtration resistance was found to vary by more than one order of magnitude. A decrease in the suspension pH from 6.3 to 2.9 lowered both the filtration resistance and the differences between the filtration media. Using local pressure profiles, a region of high filtration resistance for some of the filter media and pH values was identified close to the bottom of the filter cell. Characterisation of the media and micro-crystalline cellulose indicated that internal clogging of the filter medium was unlikely. This suggests that the filter cake closest to the filter medium had a considerably higher filtration resistance compared to the cake formed immediately after, i.e. a skin had been formed under certain conditions.

Coupled effects of internal concentration polarization and fouling on flux behavior of forward osmosis membranes during humic acid filtration

Forward osmosis (FO) is attracting increasing interest for its potential applications in water and wastewater treatment and desalination. One of the major drawbacks of FO is internal concentration polarization (ICP), which significantly limits the FO flux efficiency. In addition, FO membrane flux can be adversely affected by membrane fouling. The effects of ICP and fouling on FO flux behavior were systematically investigated in the current study. Both theoretical model and experimental results demonstrated that the FO flux was highly non-linear with respect to the apparent driving force (the concentration difference between the draw solution and the feed water) as a result of ICP. ICP played a dominant role on FO flux behavior at greater draw solution concentrations and/or greater membrane fluxes due to the exponential dependence of ICP on flux level. Compared to the active layer facing draw solution (AL-facing-DS) configuration, more severe ICP was observed when the membrane active layer faced the feed water (AL-facing-FW) as a result of dilutive ICP in the FO support layer. Interestingly, the AL-facing-FW configuration showed remarkable flux stability against both dilution of the bulk draw solution and membrane fouling. In this configuration, any attempt to reduce membrane flux was compensated by a reduced level of ICP. The net result was only a marginal flux reduction. In addition, foulant deposition was insignificant in this configuration. Thus, the AL-facing-FW configuration enjoyed inherently stable flux, however, at the expense of severer initial ICP. In contrast, the AL-facing-DS configuration suffered severe flux reduction as porous membrane support faced the humic acid containing feed water. The flux loss in this configuration was likely due to the combined effects of (1) the internal clogging of the FO support structure as well as (2) the resulting enhanced ICP in the support layer. The latter was caused by reduced porosity and reduced mass transfer coefficient of the support. The pore clogging enhanced ICP mechanism probably played a dominant role in FO flux reduction at higher flux levels. To the authors’ best knowledge, this is the first study to systematically demonstrate the coupled effects of ICP and fouling on the FO flux behavior.

Experimental study of pulse-jet cleaning of bag filters supported by rigid rings

This study embodies experimental characterisation of pulse-jet cleaning of filter bags supported by rigid rings. Tests were conducted on a semi-industrial pilot dust collector. Signals were monitored along bag filters (over their full height) to provide a record of key parameters: pressure drop, filter medium acceleration, face air velocity and axial velocity of the compressed air jet. These measurements provided a description of filter medium behaviour during cleaning. It was found that a number of mechanisms cause dust cake dislodgement. Sudden movement of the medium, recorded over the full height of the filter element, is linked to intense shaking of the medium at the top of the bag and strong permeation of reverse airflow through the fabric at the bottom of the bag. The top and bottom sections represent the bag areas in which regeneration is most efficient. Filter medium properties changes, following gradual internal clogging, modify extensively the reaction of the bag during pulse-jet cleaning. A further innovative aspect of this experimental study is that impacts of main cleaning parameter and filtration operating condition were investigated using the same test equipment. The number of results represents a significant contribution to understanding pulse-jet cleaning phenomena. This study highlights a potentially increasing factor involving downstream particle emission. This entails significant aspiration of dirty air near the top of the bag during pulse-jet cleaning, when the compressed air injection nozzle is too close to the mouth of the filter element.