Filter Cake Formation Research Articles

Intercalation of HKUST-1: A strategy for conferring GOM with accurate size-sieving, self-cleaning, and antibacterial multi-functionalities

Precise regulation of pore sizes and fouling issues related to filter cake formation and bacterial growth continue to impede the practical application of GOMs. Though metal-organic frameworks (MOFs) with specific structures and semiconductor features are a potential candidate for addressing the above issues, it is still difficult to accurately control the GOM pore with MOFs, due to the difficulty of removing interfacial gaps. In this study, we successfully employed the specific pore size of HKUST-1 (Cu-BTC, BTC: benzene-1,3,5-tricarboxylate) to control the channel size of GOMs by self-assembling a pH-regulated HKUST-1/GO dispersion, followed by moderate- to high-temperature vacuum drying. Consequently, the incorporation of HKUST-1 dramatically influenced the rejection performance of GOMs, enabling the selective rejection of molecules larger than 9 Å (e.g., Rh B, CV, and TB) while effectively separating sub-9 Å impurities (e.g., MB and NaCl), and resulting in a nearly 14-fold increase in water flux. Moreover, the photodegradation and Cu2+ release properties of HKUST-1 endowed the GO@HKUST-1 membrane (GHM) with remarkable self-cleaning, antibacterial and long-term stable characteristics. Our approach provides a simple and universal method for conferring GOM with accurate size-sieving, self-cleaning, and antibacterial multi-functionalities, thereby enabling high-quality and sustainable molecular separation and dye desalination.

Use of hybrid filters to optimize the process of the filtration in cement particles

Due to growing concern about air pollution and its harmful effects on the health of the population, especially in regard to sub-micrometric particles, some studies have reported that applying an electric field to particle suspensions can improve filter performance by enhancing the deposition of particles in the filter medium. This can result in better particulate retention, which is particularly important for industrial processes such as cement production. The objective of this study was to investigate the behavior of cement particles with electrostatic charges during cake formation in fabric filters. The particles (with a d50 % of 17 μm) were generated using a dust feeder at a flow rate of 0.083 kg s−1. The fiberglass filter medium was subjected to filtration tests with constant dust concentrations (9–12 g.m−³) and air surface velocities (6 cm.s−1and 10 cm s−1) until the pressure drop reached the maximum value of 400 Pa. The electrostatic precipitator utilized discharge voltages of 0, 4, 10, and 12 kV. The particles were initially passed through the electrostatic precipitator to become charged with voltages of 0, 4, 10, and 12 kV applied. The results indicated a reduction in pressure drop of up to 55 %. The study observed a change in the deposition behavior of particles on the filter medium surface and in the filter cake formation, demonstrating that the electrostatic charge improves air filtration performance, resulting in higher efficiency and cost-effectiveness.

Experimental investigation of filter cake deposition under cross-flow and static filtration conditions

Effects of cross-flow velocity, filtration pressure, and solid concentration on filter cake properties are studied by using a new filtration setup that allows performing filtration tests under a wide range of operating conditions. The main feature of this setup is that pressure and cross-flow velocity are decoupled, so it was possible to independently investigate the effect of these variables on filter cake properties. Filtration tests have demonstrated that particle invasion into filter media pores occurs initially, leading to the formation of an external filter cake. The increased cross-flow velocity creates an erosive shear stress at the surface of the external cake, which limits cake growth, indirectly maintaining a high filtrate flow rate. This high filtrate rate imparts a considerable drag force onto suspended particles, driving a high count into the porous substrate where these particles could deposit. Increasing pressure amplifies this internal particle deposition, particularly where there is no or limited external filter cake to limit filtrate drag and screen particles at the cake surface. The effect of cross-flow velocity on pore blocking and filter cake structure is observed and demonstrated by CT scanning and scanning electronic microscopy.

Formation of Bentonite Filter Cake over Crystalline Metamorphic Rocks by Means of a Pressure Chamber: A Laboratory Study

Abstract Bentonite is used as the drilling fluid for most of the cast-in-situ bored (CIB) pile constructions. It has been found that bentonite slurry significantly reduces the shaft resistance capacity because of the formation of filter cake in piles driven into sedimentary bed rocks. This effect is incorporated into pile designs by increasing safety factors. Even though crystalline metamorphic rocks do not support the formation of bentonite filter cake to the same extent as sedimentary rocks, conservative pile designs are being used mainly because of a lack of reliable experimental data. Some studies carried out in Sri Lanka on piles driven into metamorphic rocks indicate that the bentonite filter cake formations have a relatively insignificant effect on the shaft resistance capacity. This paper presents the results of experiments carried out on the formation of bentonite filter cake over several types of metamorphic rocks using a specifically built pressure chamber. The results indicate that bentonite filter cake formed over unfractured metamorphic rock is much less than those formed on sedimentary rocks and that the weathering grade of the rock has an influence on the thickness of the filter cake. These findings could lead to design practices that could avoid unnecessary conservatism in pile design.

Numerical analysis of slurry penetration and filter cake formation in front of tunnel face

The bentonite slurry penetration in front of the tunnel face significantly influences the face stability during slurry shield tunneling. In this study, the mechanism of slurry-soil interaction is clarified through the soil microstructural evolution. A transient model coupling the slurry transport and deposition theory is proposed to estimate the slurry penetration and filter cake formation. The time-dependent parameters are considered, including the flow parameters (flow path and pressure gradient) and the hydraulic resistance of soils (soil permeability, porosity, and shear resistance). The proposed model is compared with the infiltration column tests and shows a good agreement.Moreover, a parametric study is conducted to investigate the influence of the soil and slurry properties on the slurry-soil interaction. The results indicate the soil-bentonite relative size is the main factor influencing the formed filter cake type. The filter cake of type Ⅲ (external filter cake and penetration zone) could be formed when the bentonite particle size is between the range of 0.01d10–0.5d10. This type of filter cake has good tightness and could help to improve the face stability when tunneling by slurry shield machine.

Application of zwitterionic copolymer as a filtration control agent against high temperature and high salinity for water-based drilling fluids

Minimizing the filtration loss of water-based drilling fluids (WDFs) is critical for ensuring the safe development of oil. In this study, a zwitterionic copolymer (ZCP) was prepared to provide effective filtration control of WDFs. The expected product was verified using Fourier Transform Infrared (FT-IR). A thorough assessment was carried out to evaluate the rheological properties and filtration performance of WDF containing varying concentrations of ZCP. The mechanism of ZCP was proposed based on the analysis of the absorption, zeta potential, particle size distribution, and microstructure of filter cakes for bentonite. The results showed that ZCP could maintain thermally stable at 290 ℃. Even after thermal aging at 200 ℃, the filtration volume of the WDFs with 2% ZCP was only 9.6 ml despite the presence of saturated salt. This remarkable performance could be attributed to the strong adsorption of bentonite by multiple ZCP molecules through hydrogen bonding and electrostatic forces. The absorption of ZCP enhanced the dispersion of bentonite in WDFs, which facilitated the formation of an excellent filter cake to effectively suppress filtration loss. The research was instructive for polymeric filtration control agents with high temperature and salt resistance.

Poly(acrylamide-co-acrylic acid) grafted graphene oxide for improving the filtration performance of drilling fluids

An adequate drilling fluid filtration reduction additive should not only be able to minimize liquid leaking into the formation, but also be able to improve the applicability of drilling fluids in complex drilling conditions. In this study, polymer-grafted graphene oxide (GO) nanoadditives which could significantly improve the performance of drilling fluids are developed by surface modification of GO with charged polymer chains. The microstructures and compositions of the polymer-grafted GO nanoadditives are investigated with FT-IR, TEM with elemental mapping, ζ potential measurements, and TGA. Their performance as filtration reduction additives for drilling fluids is evaluated according to the American Petroleum Institute (API) standard. The results demonstrate that negatively charged poly (acrylamide-co-acrylic acid)-grafted GO nanoadditives are beneficial for water loss reduction in drilling fluids. The more negative charges on the surface, the higer the water loss reduction. This might be because the electrostatic repulsion between poly (acrylamide-co-acrylic acid)-grafted GO nanoadditives and bentonite particles slows down the formation of filter cake and make it denser, which slows down the penetration of water phase. Moreover, the results of filtration experiments under high salinity and high temperature conditions indicate that the addition of poly (acrylamide-co-acrylic acid)-grafted GO nanoadditives maintains the water loss reduction effect even at 180 °C or in fluids with 8 wt% NaCl. The presence of poly (acrylamide-co-acrylic acid)-grafted GO in the slurries could also improve their lubrication performance.

Bead and necklace-like silica-based hybrid materials for controlling montmorillonite dispersion filtration

Taking the advantage of well dispersing ability and unique pore plugging capacity, nanomaterials have been extensively used as filtration control additives in water-based drilling fluids (WBDFs). However, nanomaterials are seldom robust when exposed to high temperature and salinity which restricts their applications. Herein, we synthesize two inorganic/organic hybrid nanomaterials using silica as the core and grafted with zwitterionic polymer on the surface (ZSHNM-1 and ZSHNM-2), and conduct in-depth research on their filtration performance. ZSHNM exhibits bead- and necklace-like structures, adsorbs onto and promotes the homogenous dispersion of montmorillonite irrespective of the presence of salt, and facilitates the formation of filter cake with remarkably low permeability, according to experimental results and DFT simulation results. Notably, ZSHNM-2 has significantly stronger thermal resistance up to 250 °C, salt tolerance as high as 11 wt%, which is expected to use in filed applications of ultra-deep wells. It is attributed to the more appropriate particles size distribution and longer polymer tails, efficiently plugging the pores. In addition, these nanomaterials had high polyamine rejection, whereas had little influence on KCl, which should be paid attention to selecting shale inhibitors. This study can be a guide to technically related areas where nanomaterials are used extensively.

Infiltration behaviour and microstructure of filter cake from sand-modified bentonite slurry

This study uses a setup involving a scanning electron microscopy (SEM) to examine the infiltration behaviour and mechanism of the formation of filter cake from sand-modified bentonite slurry. We began by determining whether a filter cake can be formed by using water–bentonite slurry in samples of the fine, medium, and coarse sand (Series 1). Water–bentonite–sand slurries with different mass ratios of bentonite and fine sand (B:S) were subsequently tested using the medium and coarse sand (Series 2). The results show that for Series 1, a thin filter cake (<0.1 mm after drying) with extremely low permeability (∼10−8 m/s) was formed only when the fine sand was used. The filter cake consisted of layers of dense bentonite platelets arranged perpendicular to the infiltration direction. Similar results were obtained for Series 2 between the medium and coarse sand. Within the range of 1:1.5 ≤ B:S ≤ 1:0.5, the low permeable filter cake was formed on the deposited layer of fine sand and bentonite platelet. Contrary to expectations, adding more sand (B:S = 1:2) did not complete the formation of filter cake, and instead led to continuous deposition of fine sand and bentonite platelet, which may cause inadequate effective face support during slurry shield tunneling.

Effects of seawater on the infiltration behavior of bentonite slurry into sand

As a support fluid, bentonite slurry has been extensively used in slurry shield tunneling to stabilize the tunnel face by forming a low-permeable filter cake. However, the infiltration behavior of bentonite slurry in complex conditions such as when suffering from seawater intrusion has not been fully understood. In order to investigate the infiltration behavior and filter cake formation under seawater intrusion, seawater-based bentonite slurries with increased salt content were prepared to represent different seawater intrusion severities. The rheological properties and physical stability of these slurries were evaluated. A series of infiltration column tests were conducted on two saturated sand beds with different particle sizes. Scanning electron microscope (SEM) was performed to unravel the microstructure of the filter cake. The infiltration column test results show that the low-permeable filter cake can be formed on the fine sand bed regardless of the salt content of the slurry. The salt shortened the time span of the mud spurt and made the filter cake more permeable to water. For the medium sand, the filter cake cannot be formed when the salt content exceeds 1%, because the deterioration of rheological properties of the slurry weakened its rheological blocking effect when infiltrating the sand. Based on the SEM images, it was found that the filter cake under seawater intrusion contained many well-connected inter-agglomerate channels that reduced its sealing quality. The obtained results can provide guidance and reference for the application of bentonite slurry when tunneling in a sea environment.

Effect of microplastic aging degree on filter cake formation and membrane fouling characteristics in ultrafiltration process with pre-coagulation

Microplastic aging has gained more and more attentions in the field of environmental studies. However, it is not clear yet how aged microplastics possessing different aging degrees would affect membrane filterability and associated fouling mechanisms during ultrafiltration of pre-coagulated microplastic-containing waters. Here, four chemically-aged polypropylene (PP) microplastics were individually prepared by immersing pristine PP into either HCl or NaOH solution at two prearranged concentrations (1 and 5 mol/L). The aging degree of each chemically-aged PP was reflected by microplastic surface physicochemical changes after artificially-accelerated aging. All pre-coagulation and ultrafiltration experimental results demonstrated that microplastic aging degree indeed had a critical effect on permeate flux decline and membrane resistance distribution, along with microscopic characteristics of fouled cake layer. These expected effects were mainly induced by the involvement of different chemically-aged PP in microplastic-containing floc growth and subsequent filter cake formation. For HCl-based aging, aged microplastic particles produced at the higher concentration (5 mol/L) appeared to play a stronger skeleton role in filter cake formation than those obtained at 1 mol/L, giving an enhanced filterability of ultrafiltration membrane. In contrast, for the two cases of NaOH-based aging, the lower reagent-solution concentration corresponded to a rather slighter permeate flux decline during ultrafiltration, possibly arising from the predominated role of humic acid molecules in membrane pore blocking/narrowing fouling and steric hindrance effects.

Mechanics of the penetration and filtration of cement-based grout in porous media: New insights from CFD–DEM simulations

Cement permeation grouting is a standard ground improvement technique crucial for improving soil’s mechanical properties. This study applied the computational fluid dynamics and discrete element method (CFD–DEM) to investigate the penetration of cement-based grout in porous media and the filtration behaviours of the cement particles. A model of the interaction forces of cement particles from the literature is implemented and validated by comparing the simulation and experimental results. A series of simulations identified the different modes of penetration, the penetration-induced changes in pressure and the formation process of the filter cake. The size ratio of the available pore openings to the cement particle is critical among various factors that influence cement grouting because it determines the formation of a cement filter cake. The grouting pressures (from 100 kPa to 400 kPa) exert little effect on the penetration distance and cement distribution of the soil prone to filtration. The self-collapse of the retained particles was captured by visualising the filtration process to explain the filter cake’s destruction. Furthermore, four typical retention morphologies were discussed from a microscopic perspective. This study provides new insights into the mechanics of the penetration and filtration of cement-based grout in porous media.

Experimental investigation of plugging and fracturing mechanisms in unconsolidated sand reservoirs under injection of water containing suspended fine particles

Progressive plugging of the medium due to filter cake formation is considered as a major challenge during Produced Water Re-Injection (PWRI), leading decreased well injectivity during production. Field operations have shown that injectivity can be at least partially restored by fracturing the clogged medium when injecting in the frac-regime. An experimental investigation is performed to explore the effect of the injection of a suspension on the plugging and fracturing processes in an unconsolidated sand formation. The tests are performed by injecting water containing fine particles at a constant low flow rate to first clog a sand specimen (phase 1), then by increasing the flow rate until fracturing (phase 2). Experimental results exhibit a continuous increase of the injection pressure (decrease of injectivity) during phase 1 due to the formation of filter cake build-up caused by the deposition of injected solid particles. During phase 2 when the flow rate is increased, pressure drops are observed and attributed to the formation of fractures, resulting in the increase of the overall permeability of the medium. This is confirmed by post-mortem analysis of the specimens using X-ray Computed Tomography. Small radial fractures (“pseudo-cracks”) induced around the injection point are visible. They appear as localized zones of higher porosity. The effect of the confining pressure and of the suspended particles concentration on the clogging and fracturing of the medium is investigated. It is shown that the clogging process strongly depends on the concentration of particles in the injected fluid. A lower quantity of injected particles is needed to induce the same level of permeability impairment when a lower concentration is used. No significant effect of particle concentration is observed on the fracturing pressure. As with pure water injection, the fracturing pressure is proportional to the imposed confining stress. Moreover, it is observed that the clogged specimen requires a higher injection pressure to reach the frac-regime as compared to an injection scenario with pure water and no filter cake formation and that permeability recovery could be higher.

Modeling the influence of rheology on smooth rod coating systems

Rod coating methods are of interest for the application of barrier coatings, especially at off-line facilities that may run at moderate speeds and narrow web widths. At lower line speeds and lower coating solids, it is difficult to achieve good coat weight control because of poor loading of the rod. While there is extensive literature available about blade and roll coating, there seems to be less reported on the rod loading of smooth rods to obtain various coat weights. Much of the work is around metering rods working on applicator rolls at high speeds that are associated with the metered size press, with a focus on ribbing instabilities. This work employs a simplified model, neglecting some complex features of rubber deformation and film split, to estimate the influence of the process parameters such as speed, rod diameter, viscosity, and rod loading on the coat weight obtained. As found in practice, at low speed and low viscosities, the coat weight-load curve is steep, leading to poor control of the coat weight and coat weight uniformity. If the viscosity is increased, the curve is modified, and control is possible with rod loading in a normal range. For shear thinning fluids described by the Carreau model, the power law index and other parameters need to be in the correct range to obtain the desired effect. Modeling predictions show a steeper dependence of coat weight with rod pressure when compared to pilot coater data. This may be caused by missing details in the mechanical loading of the rod related to tube pressure or from neglecting the impact of filter cake formation of the applied coating in the model.

The Role of Particle Size Distribution for Fluid Loss Materials on Formation of Filter-Cakes and Avoiding Formation Damage

Abstract Numerous studies have shown that careful particle size selection is the main parameter for reducing fluid loss when drilling permeable or fractured formations. The methods are generally built around either the D50 or D90 values of the particles in the fluid as a relative size to the pore openings of the formation to minimize fluid loss. A series of studies were conducted with the aim of assessing if analysis of fluid loss could be used to separate the formation of internal and external filter-cakes, thereby enabling a more accurate estimate of the permeabilities of the internal and external filter-cakes. It was concluded that conventional particle size methods were found to be adequate for designing a fluid for wellbore stabilization purposes. This led to higher solids invasion and a more impermeable internal filter-cake. However, for optimization of reservoir drilling fluids, a different particle size selection method was found to be more useful to prevent reservoir formation damage. This method involves selecting particles that are resistant towards shear-degradation and with a D90 particle size ⪞3/2 the pore size of the formation. By analyzing fluid loss regression data and correlating these with indicators of formation damage, such as disc mass and permeability change, it was found that a ratio defined as the relative plugging factor could provide insight into the extent of solids invasion into the formation and potential formation damage.

DEVELOPMENT OF OPTIMAL COMPOSITION OF DRILLING FLUID FILLER FOR OPEN HOLE WELL COMPLETION

Experimental studies were carried out to determine the effect of inert fillers on the filtration properties of clay cakes during their formation. The sequence of experiments corresponds to the sequence of stages: formation of the main structure of the filter cake (simulation of the opening process by drilling), treatment of the bottomhole zone to restore the initial permeability (for example, during chemical destruction of the filter cakes) and washing out of process fluid filtrates from the bottomhole zone into the well. The solid phase in the drilling fluid can be represented by both structure-forming clay particles and fillers (barite, crushed cuttings, bridging agents, etc.). Moreover, fillers can have individual particles of a size of a colloidal degree of dispersion and significantly affect the filtration performance of drilling suspensions. It is especially important to evaluate the influence of the composition of the solid phase of the clay suspension on the filtration properties at the stage of formation of the main structure of the filter cake. This stage is characterized by a non-stationary filtration process. In essence, the bulk of the studies of filtration processes is carried out in this mode. In our case, it is necessary to determine the dependence of the filtration index of solutions Пр on the composition of the solid phase. In the course of experimental studies, it was confirmed that subsequent filtration through the cakes formed at stage 1 equally depends on the magnitude and nature of the drawdown application, as in stage 1, as well as on the permeability of the filter cake and the clogging zone. Therefore, the research methodology at stage 2 required supplementing experiments with the formation and modification of filter cakes during filtration through permeable sand packs.

Effect of eccentricity with different shape wellbores on the flushing efficiency of drilling fluid filter cake

The effective flushing of a drilling fluid filter cake is crucial for improving the zone isolation of cement sheaths during cementing operations, some studies have researched the flushing law of filter cake in circular wellbore, however, only a few have studied the flushing law and mechanism of elliptical wellbore and the irregularity of elliptical wellbore may lead to the increase of the non-uniformity of filter cake that may result in different flushing results than the circular wellbore. In this study, a filter cake formation and flushing experimental system is developed for circular and elliptical wellbore, and the formation and flushing experiments of drilling fluid filter cake in circular and elliptical wellbore are conducted, the flushing law and mechanism of drilling fluid filter cake in circular and elliptical wellbore are obtained by combining the computational fluid dynamics (CFD) simulation calculation results with the experimental results. The results revealed that the filter cake flushing efficiency of the same drilling fluid and displacement were primarily affected by the thickness of the initial drilling fluid filter cake, shear strength, wellbore shape, wall shear stress and eccentricity, the initial thickness and shear strength were higher, the filter cake flushing efficiency was lower, the wall shear stress of the flushing fluid was higher, the flushing efficiency of the filter cake was higher, and the change in wellbore shape and eccentricity led to an uneven distribution of annular velocity and reduced the flushing efficiency of the filter cake. The method and conclusion enable to gain an understanding for improving the flushing efficiency of the drilling fluid filter cake and forms a basis for the design of flushing fluids in cementing operations.

Influences of polyanionic celluloses and temperature on the rheological property of seawater slurries

As an increasing number of submarine tunnels are being constructed by the slurry shield tunnelling method, seawater intrusion into slurries and variations in strata temperature are inevitably encountered during construction. They will lead to obvious deterioration in rheological properties of slurries, which can be adverse for the filter cake formation and even cause tunnel face instability. Considering the design of the slurry parameters and the actual slurry support effect, it is essential to select a suitable slurry ingredient and investigate the rheological properties of seawater slurries under different temperature environments. Using polyanionic celluloses (PAC) as the additive to seawater slurries was proposed in this paper. The influence of PAC contents on the rheology and physical stability of seawater slurries was investigated through laboratory experiments, with PAC contents varying from 0 to 0.4%. The rheology enhancement mechanism of PAC was also analyzed. Furthermore, the flow pattern and constitution relationship of seawater slurries with 0.4% PAC were studied at different temperatures from 2℃ to 30℃. The results show the presence of PAC can significantly enhance the viscosity and physical stability of seawater slurries. The seawater slurries incorporating 0.4% PAC and 12% Na-bentonite can maintain an excellent colloidal rate with 97.5% and a high viscosity, which was recommended to be a prospective mixing proportion used in slurry projects. Additionally, the flow characteristic of seawater slurries with different PAC contents can be described by the power law model very well. Moreover, with the increase in temperature, the rheological index showed an increasing trend, but the consistency coefficient gradually decreased. The constitutive equation of seawater slurries considering the effect of temperature was proposed. This research will provide significant guidance for the selection of slurry parameters and the establishment of seawater slurry infiltration theories during the construction of submarine tunnels.

Infiltration behaviour into sand of bentonite slurry with guar gum

Bentonite slurry is widely used in various projects due to its excellent engineering properties. The behaviour of slurry infiltration, especially filter cake formation, is directly related to the effect of slurry. This paper proposes an improved apparatus to investigate the infiltration of a novel bentonite slurry, especially in the dynamic infiltration process of the slurry-driven shield, which provides significant references for tunnel excavation. According to monitoring indicators of water discharge volume, pore-water pressure and electrical conductivity, the hydraulic conductivity of filter cake and the major zone of infiltration were analysed. Besides, the results of scanning electron microscopy reveal the micro-interaction between slurry and the soil. The results illustrate that the bentonite slurry with guar gum could immediately form an external filter cake with an infiltrated zone. The external filter cake formed again with a denser bentonite clay platelet network after excavation in the condition of relatively short excavation distance. Therefore, this kind of slurry could rapidly stabilise the excavation surface in slurry-driven shield tunnelling.

Novel metal mesh filter equipped with pulse-jet regeneration for small-scale biomass boilers

Wood is a renewable fuel, however the combustion of wood can lead to significant dust emissions. The application of fabric filters is one possibility to ensure low particulate matter emissions. Nevertheless, these filters are so far not used for small-scale firing systems. In this work, the mitigation potential of a newly developed fabric filter concept with pulse-jet regeneration, based on a stainless-steel mesh was studied. The filter was tested on a commercially available 24 kW biomass boiler, which was operated with wood pellets and wood chips. Experiments showed a linear dependency of the separation efficiencies and clean gas concentrations on average pressure drop while a logarithmic dependency of the clean gas concentrations on an empirical factor k was proven. The filter showed good regenerability and dust separation efficiencies up to 83 % and 90 % during combustion of wood pellets and wood chips. The pulse-jet regeneration showed a short-time peak of dust emissions behind the filter which can represent between 24 and 60 % of the total dust emissions during a whole filtration cycle. Nevertheless, the application of different filters with 25 and 50 μm mesh size guarantees an efficient dust removal. In a first phase during filter cake formation, the concentrations can exceed the limit value, but once a filter cake had built up, the concentrations drop drastically below 0.01 g m−3. In summary, the filters show good regenerability and efficient dust separation and thus further development potential.