Filter Cake Research Articles

Preparation and performance evaluation of PDDSA-MS composite as high temperature and high salinity filtration additive

Drilling operations in deep and ultra-deep wells encounter challenges arising from high temperature and saltwater intrusion, leading to reduced drilling efficiency and deteriorated performance of water-based drilling fluids. In order to alleviate the problem of increased filtration of drilling fluid under harsh environment, the composite (PDDSA-MS) was prepared by free radical polymerization using N, N-dimethyl acrylamide (DMAA), Dimethyl diallyl ammonium chloride (DMDAAC), Sodium styrene sulfonate (SSS), 2-acrylamido-2-methylpropanesulfonic acid (AMPS) and KH570 modified SiO2 as raw materials. This composite contained absorption groups, hydration groups, rigid groups and nanomaterials. Through rigorous performance evaluations, it was observed that the addition of 1 wt% composite to a fresh water drilling fluid, resulting in a remarkably low filtration of 8.8 mL after aging at 260 °C. Furthermore, when 3 wt% composite was added to the 15 wt% NaCl salt water drilling fluid, the filtration was 8 mL after aging at 220 °C. This was attributed to the particle size of the composite and its ability to maintain the dispersion stability of drilling fluid, decelerate bentonite agglomeration, and make the surface of the formed filter cake dense and smooth. These findings demonstrated the thermal stability exhibited by composite, offering an effective solution for drilling operations in deep and ultra-deep wells.

Digital Cake Analysis: A Novel Coal Filter Cake Examination Technique Using Microcomputed Tomography

Filtration is crucial for separating solids and liquids in various industries. Understanding slurry properties and filter cake structures is essential for optimising filtration performance. Conventional methods focus on interpreting filtration data to improve the understanding of filtration mechanisms. However, examining fragile filter cakes is challenging, and current techniques often alter their structure. Conventional methods only provide an average representation of cake porosity, neglecting variations in porosity and pore distribution across the cake thickness. This study introduces the Digital cake analysis, a non-destructive technique for evaluating filter cake structure. Filtration experiments using a custom-built unit were conducted on coal slurries to obtain filter cake samples. X-ray-microcomputed tomography (µCT) imaging was utilized for cake analysis. Image enhancement techniques were employed to improve the quality of the µCT images. The enhanced images were segmented into three phases (resolved pore, subresolution pore, and solid phases) for quantitative analysis. This segmentation technique allocated partial pore volume to voxels in the subresolution phase based on their intermediate grey-scale intensity, enabling more accurate porosity calculations. Unlike conventional methods, this approach computed porosity values for resolved (100% void) and subresolution (partially void) pores. This image segmentation technique facilitated accurate computations of porosity, pore size distribution, and pore properties, significantly advancing the understanding of cake structures. Digital cake analysis produced porosity measurements similar to the experimental results.

Rapid and clean dewatering of dredged sediment via coupling of a two-step flocculation and geotextile filtration

The use of flocculation processes coupled with geotextile technology for dredged sediment dewatering is promising in recent years. However, two main issues are encountered: firstly, the occurrence of clogging resulting in reduced dewatering rate, and secondly, contamination of the residual water, necessitating additional treatment, consequently leading to an increase in operational costs. Therefore, this study proposed an innovative approach employing a two-step flocculation combined with geotextile filtration method to achieve rapid and clean dewatering of dredged sediment. The jar test implementation of a two-step flocculation process at the optimal flocculation dosages resulted in a dewatering rate that was about 16.7 times compared to commercial flocculant (APAM) conditioning. The increased dewatering rate is mainly attributed to the formation of large and compact flocs aggregates (d50 > 160 μm) formed through the two-step flocculation. These aggregates facilitate the formation of a filter cake with a high porosity of 45 %, a low tortuosity of 1.53, a uniform pore-throat structure, and excellent connectivity of pore space. Compared with APAM, the value of turbidity, COD, NH4+-N, and phosphorus in the residual water can be decreased from 36.4 to 3.8 NTU, 28.6 to 8.3 mg/L, 2.3 to 1.6 mg/L, 0.15 to 0.04 mg/L, respectively, which meet the environmental quality standards for surface water (type V) in China. In addition, the technology is proven to be economical as the cost of flocculants is less than half the cost of other reported flocculants. Overall, this work presents a new and cost-effective approach for achieving both rapid and clean dewatering of dredged sediments, which is very promising for practical applications.

Analytical and numerical modelling of the effect of filter medium resistance on the mechanical dewatering of wastes and industrial filter cakes

A nonlinear model is proposed to predict the effect of filter medium resistance on the filter cake compression and dewatering at constant pressure. This model is based on the Darcy-Terzaghi-Shirato filtration-compression equations presented in material coordinates and modified to consider the power-law pressure dependence of the specific cake resistance α. Above mentioned model is extended to consider the filter medium resistance Rmintroducing the number of Biot, Bi=αavWRm.Local profiles of compressive pressure and filter cake characteristics, as well as consolidation ratio and cake dryness, are simulated and compared for different moderately and highly compressible filter cakes (silica, activated sludge, Baker’s yeast, and CaCO3) based on the analytical and numerical solutions of the model. It is shown that the behavior of cake compression and dewatering significantly depends on the filter medium resistance Rm, especially at the small numbers of Bi≤1.

MECHANISM OF MEMBRANE FOULING IN HYBRID MEMBRANE PHOTOCATALYTIC REACTOR FOR PALM OIL MILL SECONDARY EFFLUENT TREATMENT

Palm oil mill secondary effluent (POMSE) is a byproduct of the biological treatment of palm oil mill effluent. This research aims to investigate the mechanism of membrane fouling in the treatment of POMSE using a hybrid membrane photocatalytic reactor (MPR). The effectiveness of MPR in POMSE treatment is currently limited due to membrane fouling on the membrane surface. This study focuses on understanding the various mechanisms of membrane fouling, including complete blocking, intermediate blocking, standard blocking, and cake filtration. The determination of each fouling mechanism is achieved through an analysis of normalized flux data employing the Wiesner and Aptel equation. The results demonstrate a high degree of model fitness (R2 = 0.9576) for MPR Run 3, confirming its effectiveness. Based on the (R2) values and the fitted parameter (Ks^(-1)), it is evident that, under varying pH levels, catalyst types, catalyst loading, and initial POMSE concentrations, the cake formation fouling mechanism prevails in MPR Run. In conclusion, this research holds promising potential for implementation in the wastewater treatment industry while ensuring compliance with environmental regulations.

Karakteristik Pupuk Organik Cair Berbasis Limbah Vinasse Melalui Teknologi Aktivasi

Utilization of vinasse waste as POC has great potential in the agricultural sector. This is because there is an abundance of vinasse waste originating from the bioethanol industry sector. So action is needed so that vinasse waste can be utilized into a profitable product. This research aims to test the potential of vinasse waste if it is processed into POC. Apart from using vinasse waste as the main raw material, the formula also added organic ingredients such as straw ash, humate, husk charcoal and filter cake dregs which were fermented for 5 weeks. Based on the research results, the content of N, P, K and C-organic elements cannot comply with the 2019 Ministry of Agriculture Quality Standards. Meanwhile, the content of Na and pH elements is appropriate, but for Fe only the F2 and F4 T1 treatments can be appropriate.

Investigation on permeability of filter cake with different particle sizes: Experimental and simulation study

Cake permeability is a crucial macroscopic physical property in characterizing filtration behavior for coal slurry. However, there is still no appropriate model derived to establish the essential relationship between the cake permeability and complex particle property. In this study, the three-dimensional microstructures with different particle gradation and porosity were generated using particle discrete element software. The permeability of each constructed model was calculated utilizing Lattice Boltzmann Method (LBM). Simulation result shows that the Kozeny–Carman (KC) model is proper to predict the permeability of porous media with different gradations. When the gradation parameters are not considered, it shows that d30 can best represent the particle size characteristics of the particle systems. When the porosity and average particle size remain unchanged, the permeability increases with the increasing of the non-uniformity coefficient (Cu) and the curvature coefficient (Cc). Moreover, we proposed an analytical expression for the permeability estimation with different gradation characteristics, which contains the parameters that can be easily measured in engineering. Then a set of coal slurry samples with different particle size distributions were selected to conduct the filtration test, the permeability of each sample was measured to compare with the predicted results of the gradation permeability model. It is clear that the KC equation in this case can not calculate the cake permeability effectively. Although the gradation model is relatively appropriate to estimate the cake permeability, its accuracy still needs to be improved by considering the pore structure property to eliminate the effect of constant terms.

MnFe2O4 composited polyvinylidene fluoride catalytic ultrafiltration membrane via peroxymonosulfate activation for humic acid treatment: Exploration of synergistic mechanisms

Membrane separation has become the most promising technology in the field of wastewater purification, but there will inevitably be membrane fouling. Catalytic polymer membranes combining membrane filtration and advanced oxidation technologies (AOPs) offered an alternative for mitigating membrane fouling. This work successfully synthesized a MnFe2O4 catalytic polyvinylidene fluoride (MnFe2O4-PVDF) ultrafiltration membrane and systematically investigated the performance of peroxymonosulfate (PMS)/MnFe2O4 membrane oxidation filtration system for removing humic acid (HA). The results showed that the PVDF@MnFe2O4/PMS synergistic system oxidized HA into small molecules and further repelled them to the membrane surface by size exclusion to form a filter cake layer. The PVDF@MnFe2O4/PMS system exhibited the lowest irreversible fouling (0.414 × 1010m−1) and the highest HA removal efficiency (83.4 %) compared with PVDF single filtration. After hydrodynamic cleaning, PVDF@MnFe2O4 can achieve 73.2 % water flux recovery. The membrane fouling mitigation mechanisms were investigated by the Extended Derjaguin-Landau-Verwey-Overbeek (XDLVO) theory and the combined pore blockage-cake filtration model. Quenching experiment and density functional theory calculation (DFT) revealed the HA degradation as a result of the synergistic action of free radicals (SO4⋅-, ⋅OH) and non-free radicals(1O2) in PVDF@MnFe2O4/PMS system. Additionally, we evaluated the effectiveness of the system in the removal of natural organic matter (NOM) from surface water. The results suggested that the PVDF@MnFe2O4/PMS system could validly remove the main fluorescent matters from surface water. In conclusion, this work provides a promising route for solving the membrane fouling caused by NOM in water.

Effects of nanosilica on the properties of brine-base drilling fluid

In the process of drilling oil and gas wells, the shrinkage and falling of wellbore walls are often caused by the expansion of mud shale water. To date, conventional additives have been unable to plug the pore throats of shale rock with nanoscale pores and thus cannot effectively solve the problem of wellbore instability encountered in shale formation drilling. In view of this situation, the idea of using nanosilica to plug the nanopore throat of mud shale is proposed to reduce its permeability and to slow water intrusion. The influences of nanosilica on the properties of brine-base drilling fluid drilling fluid are evaluated by measuring the viscosity, filtration loss and swelling of the drilling fluid. The results of laboratory experiments show that the improvement in drilling fluid properties can only be achieved on the basis of salt resistance; that is, a salt-resistant soil slurry should be used. A concentration of 1–5% nanosilica can improve the viscosity of the drilling fluid by increasing the internal friction between particles. However, nanosilica materials are sensitive to salt concentration. Nanosilica particles can be deposited on the surface of a filter cake to block the pores of the filter paper, and the filtration loss reduction rate can reach 40.2%. Blocking the pores of the clay plays a role in preventing the clay from absorbing water and expanding. The optimal addition amount of silica is 3%, and its salt resistance can reach 16%. Considering the experimental results of filtration loss, swelling amount and cost performance, 3%NP + 4%NaCl + SWM-B is selected as the optimal formula. The results of this study can be applied to effectively improve the phenomenon of wellbore instability during drilling in shale formations, and it has important application value.

Ultrasonic intensification of flocculation filtration for kaolinite: Unraveling mechanisms and performance gains

The mining industry produces substantial tailings, which present environmental challenges. This necessitates the adoption of efficient solid–liquid separation technologies to convert these tailings into a dewatered and environmentally manageable dry stack form. This work aims to investigate the transformative potential of ultrasonic treatment in the context of flocculation filtration for kaolinite dewatering and to elucidate the underlying mechanism. Through Uniform Design optimization, we determined the optimal conditions: 40 W ultrasound power, 12 min duration, and 40 kHz frequency. Experimental validation emphasized the effectiveness of these parameters, revealing a 2.02 % reduction in filter cake water content alongside a significant 2.5-fold enhancement in filtration rate. Furthermore, this combined treatment surpassed the performance of flocculation alone, resulting in the formation of smaller, more desirable flocs. The 3D structural analysis of the filter cake using micro-CT revealed that the synergistic application of ultrasound and flocculation led to a notable decrease in overall porosity. More significantly, there was a substantial reduction of isolated pores (down to 9.32 %). This phenomenon remarkably improved pore connectivity, enlarged pore and channel radii, and effectively mitigated capillary resistance during water transport. Additionally, the filter cake subjected to ultrasound and flocculation treatment showcased a uniform distribution of pore space, indicative of a promising trend towards homogenization across different sections. Ultrasound plays a role in refining flocs and suppressing segregation during tailings flocculation and filtration processes, primarily attributed to the cavitation and acoustic streaming effects of ultrasound. This comprehensive investigation sheds light on the transformative role of ultrasonic treatment in advancing the efficiency and performance of kaolinite dewatering processes.

Silicon Poisoning and Effects of Tantalum on AlSi Alloys

Grain refinement in Al-Si alloys is crucial for enhancing material castability and mechanical properties. Industrial practice involves adding inoculants, composed of TiB2 particles coated with metastable Al3Ti via adsorption, to the melt. This introduces essential free titanium for metastable phase formation and subsequent growth restriction. The superstoichiometric grain refiner Al-5Ti-1B, with 2.2 wt.% free titanium, is applied for this purpose. A peritectic reaction forms α-aluminium from this layer. However, when silicon content exceeds 3.5 wt.%, grain coarsening occurs due to silicon’s detrimental effect. This study quantified silicon poisoning in an Al-10Si alloy using stoichiometric and superstoichiometric grain refiners through ASTM-standardized TP1 tests. Adding 0.02 wt.% tantalum acted as an antidote to the τ1 phase, resulting in a finer microstructure. This was attributed to the formation of a Ta-rich layer on TiB2 particles, which causes α-aluminium formation via a peritectic reaction without generating ternary phases with Ti or Si. Correlating to the increasing particle size curves from the TP1 tests, phases were collected in the filter cake with the help of a PoDFA apparatus. These could be examined more closely on the SEM and identified as needle- or plate-shaped. By using an EDS unit, the phases found were assigned to the poisoning phase and further investigated. After the addition of tantalum, a solubility of tantalum could be detected in former poisoning phases. In combination with the gradients of the grain size, it can thus be assumed that tantalum is both an antidote for silicon poisoning in the Al-Si-Ti system and can itself have a grain-refining effect in this system.

Silane-modified bentonite clay-coated membrane development on ceramic support for oil/water emulsion separation using tuning of hydrophobicity

Bentonite clay-coated and silane-modified hydrophobic composite membranes were prepared on the ceramic support by facile sol-gel deposition route to effectively separate various oil-water colloidal solutions. This study explores the correlation of silane content involved in optimizing and modifying surface hydrophobicity, membrane pore characteristics, and the solvent permeation properties in terms of oil permeation rate and water rejection (%) in oil-water emulsion solutions. Membrane surface modifications with relatively higher silane content (∼15%) reduced the membrane pores extensively, increasing the water rejection properties but the oil flux was reduced modestly. The oil flux increases with the introduction of reduced silane content (∼2%) but the water rejection properties were compromised. Silane: solvent ratio of 1:100 (silane loading ∼10%) proved to be efficient for the separation (94–99%) of various hydrocarbons such as hexane, toluene, cyclohexane, and heptane from emulsified solutions with permeate flux of 25–40 Lm−2h−1. Cake filtration model was found suitable to explain the membrane fouling. The optimized membrane also recorded a minimal loss of hydrophobicity and mechanical strength enduring oil atmosphere and corrosive environments. The overall study supported by suitable physicochemical material characterizing techniques reveals that optimizing silane concentration in bentonite-based clay composite membrane surface modification can be an effective oil/water separation strategy.

A simple photocatalytic assisted strategy by MIL-100 (Fe) for fabrication of polymer based on H-bonding as filtrate reducer to resist salt and temperature in ultra-deep wells

Improving the performance of water-based drilling fluids for high temperature, salt and calcium resistance in the exploration of deep and ultra-deep wells is a matter of great urgency. In this study, MIL-100 (Fe) nanosphere catalyst with regular shape, uniform size and good monodispersity is prepared ahead of time. XRD, SEM and BET tests indicates that the MIL-100 (Fe) owning large specific surface areas, adjustable pore sizes and high porosity can display to be a photocatalyst. Based on the excellent photocatalytic activity under visible light, a new one-pot method strategy was supposed to achieve the graft modification on N atom in acrylamide using aziridine, and obtained the multi-amine allyl monomer. Finally, the poly (AM/AMPS/PSMM) (PAAP) filtrate reducer with significant hydrogen bonding effect was successfully synthesized by free radical copolymerization with acrylamide (AM), 2-acrylamide-2-methylpropanesulfonic acid (AMPS) and the pre-synthesized multi-amine allyl monomer. Due to the three dimensional hydrogen bonding interaction and resulted supramolecular association structure, the PAAP-based drilling fluids exhibit outstanding rheological and filtration properties even after aging at high temperatures and high salinity. The filtration volume after aging at 180 °C for 16 h is only 6.0 mL, meanwhile, the 20 wt% NaCl and 1.5 wt% CaCl2 copolymer base slurry aged at 180 °C both show the satisfactory filtration loss and offering performance higher than commercial filtrate reducers. Specifically, after aging at 180 °C, the filtration losses of DSP-1/BM and DSP-2/BM were 19.8 and 37.2 mL with 20 wt% NaCl contamination, respectively, while the filtration loss of PAAP was only 10.8 mL. Even under both 1.5 wt% CaCl2 contamination and 180 °C aging, the filtration loss of PAAP was only 11.0 mL, whereas the filtration loss of DSP-1 and DSP-2 reached 26.0 and 20.0 mL. Finally, the filtration control mechanism of poly (AM/AMPS/PSMM) was proposed via XPS test, hydrogen bonding analysis, filter cake morphologies observation by SEM and particle size distribution measurement.

Investigation of Carbonate Matrix Damage and Remediation Methods for Preformed Particle Gel Conformance Control Treatments

Summary Preformed particle gels (PPGs) have been widely applied to control excessive water production in mature oil fields with fractures or fracture-like features, especially in sandstones, but with limited attention to carbonates. However, a vital concern arises regarding the potential damage of PPGs on the adjacent matrix that might promote negative results. This paper comprehensively evaluates PPGs’ potential damage to the carbonate matrix and seeks design optimization solutions. Filtration tests were applied to compare PPGs’ penetration into the matrix under different sets of conditions. The filtration regimes were defined by filtration curves, and the gel damage on the matrix was determined by permeability measurement results. Experiments were conducted to investigate the efficiency of an oxidizer as a remediation method to remove the damage. The qualitative description of gel particles’ invasion and plugging behavior in the carbonate matrix was presented based on the analysis of filtration test results and permeability measurements. The results show that the swollen gel filtration curves can be divided into three regions: prior-filter-cake, filter-cake-building, and stable stages according to the gel particles’ response to the injection pressure and effluent flow rates. PPGs can form cakes on the rock surface to prevent particles’ further penetration into the carbonate matrix, and the penetration was only limited to less than a few millimeters. The smallest gel particles (50–70 US mesh size) were more likely to form external and internal filter cakes at higher pressure values (700 psi) and result in more damage to the matrix. To restore the matrix permeability after filtration tests, oxidizer soaking proved to be a reliable solution. In all, the results indicated that unintentional matrix permeability damage induced by gel injection is generally unavoidable but conditionally treatable.

Gravity driven ceramic membrane loaded birnessite functional layer for manganese removal from groundwater: The significance of disinfection on biofilm

Gravity-Driven Ceramic Membrane (GDCM) technology has gained popularity and recognition in water purification on account of its low energy consumption and convenient operation. This study aimed to comprehensively assess the effects of different disinfectants, including hydrogen peroxide (H2O2) and sodium hypochlorite (NaClO), on GDCM performance. It focused on the change in manganese removal and structure of the powdered activated carbon (PAC) - manganese oxides (MnOx) pre-deposited at the membrane interface and as well membrane fouling mitigation. The results showed that after the first two disinfection cycles, the flux recovery was 15 LMH for H2O2, while using NaClO only achieved an average recovery of 2 LMH and increased the effluent manganese, exceeding 0.1 mg/L within a short period of time. During the disinfection process, H2O2 exhibited better performance in mitigating membrane fouling compared to NaClO in the GDCM system. Additionally, by observing the recovery time of Mn2+ after disinfection, it can be deduced that the initial manganese removal mainly resulted from biological action of manganese-oxidizing bacteria (MnOB), while the later stage relied primarily on the catalytic oxidation action of birnessite. Fluorescence excitation–emission matrix analysis (EEM) indicated that most organic compounds dissolved in the disinfectant solution after disinfection, with some permeating through the membrane, while the remaining portion continued to accumulate in the filter cake layer. This accumulation was further confirmed by the enhanced absorbance peaks of functional groups (–NH and –OH) in the Fourier-transform infrared spectroscopy (FTIR). Scanning electron microscope - energy dispersive x-ray spectroscopy (SEM-EDS) mapping analysis revealed that MnOx formed more lamellar structures between nano-flower balls after disinfection. This increased the number of active sites and opened up water flow channels, contributing to improved flux. X-ray photoelectron spectroscopy (XPS) analysis demonstrated that Mn3+ as the dominant valence in MnOx exhibited excellent catalytic oxidation ability. Raman analysis and X-ray diffraction (XRD) indicated that MnOx showed consistent Raman spectra with birnessite before and after disinfection, and the oxidative effect of disinfection did not alter the crystal structure of MnOx. This result demonstrates the importance of applying effective disinfection in the GDCMs.

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.

Comb polymer/layered double hydroxide (LDH) composite as an ultrahigh temperature filtration reducer for water-based drilling fluids

In deep-formation drilling, effective filter loss control in ultrahigh-temperature conditions and high-salt conditions faces challenges. Comb polymer/LDH composites (P-LDH) with partially intercalated and partially exfoliated structures were prepared by in-situ polymerization as fluid loss materials. A series of characterization results showed that the P-LDH composites were successfully synthesized. P-LDH had partially intercalated and partially exfoliated structures and excellent thermal stability. In addition, the rheological evaluation results showed that P-LDH had a low viscosity effect while maintaining the rheological properties of the drilling fluid. P-LDH can significantly reduce the filtrate loss of drilling fluids at ultrahigh temperatures and high salt concentrations. At 240 °C and 15 wt% NaCl, the filtration loss was only 6.3 mL, and the high-temperature and high-pressure filtration loss was only 29.6 mL. Through the analysis of drilling fluid particle size and filter cake microstructure, based on hydrogen, ionic bonds, and intercalation effects, P-LDH acted closely with bentonite to promote stable dispersion, improve the drilling fluid’s stability, and form a dense filter cake to reduce the filtration loss. Therefore, P-LDH has broad application prospects in ultrahigh-temperature and high-salinity formation drilling.

Atomization of composite liquid fuels in experimental setup with variated gas temperature and pressure

The efficiency of slurry fuel combustion can be improved by developing a predictive mechanism to estimate fuel atomization characteristics. However, no data are available on slurry fuel atomization behavior under near-real conditions. This paper presents the experimental research findings on the combined and separate effect of gas temperature and pressure on slurry fuel atomization characteristics. The experiments involved composite liquid fuels based on water and filter cake (typical coal processing waste) in variable concentrations. These conditions are the same as in advanced fuel slurry preparation units involving pre-combustors, swirlers, and other elements. In this research we have recorded such spray characteristics as droplet sizes and velocities, volume fraction of droplets with given sizes, jet angle, as well as the angle its deviation from the original trajectory. As has been observed, an increase in the ambient gas temperature leads to a 30% increase in the jet velocity and a 40–60% increase in the volume fraction of small droplets, whereas a pressure increase, on the contrary, reduces these parameters by 11–32% and 100%, respectively). Combined effects of chamber gas pressure and temperature on atomization characteristics have been identified: the variation of atomization characteristics did not exceed 18%. Mathematical expressions have been obtained to predict the atomization characteristics of composite liquid fuels in power-generating units with the known gas temperature and pressure. Maps have been plotted using a set of dimensionless parameters that can help control droplet size, velocity, jet angles, and angles of its deviation from its original path.

Wet classification behavior of bidisperse colloidal particles through nanofibrous membrane

Membrane separation has emerged as a prominent method for the removal of undesirable particles from wastewater in the field of water treatment. However, classification of particles with varying sizes by membrane is still poorly understood, warranting further exploration. This study is to investigate the wet classification behaviors of polydisperse particles using a nanofibrous membrane that features a complex three-dimensional network structure and high porosity. The experimental results demonstrate that the nanofibrous membrane is effective in retaining larger particles, while its high porosity facilitates the smooth passage of smaller particles. To clarify the classification mechanism, we analyzed the filtration model and employed SEM images taken at different stages of the process to investigate the retention behavior of larger particles. The filtration of larger particles through microfiltration membrane exhibited a cake filtration model. The blockage of large particles on the membrane surface formed a cake layer, significantly reducing the filtration rate. Conversely, the nanofibrous membrane exhibited continuous intermediate blocking filtration at pH 11, resulting in effective retention of larger particles inside the membrane rather than solely on membrane surface. This enabled better utilization of the pore space within the nanofibrous membrane, thus highlighting it as a potential area for future research.

Improved plant yield of potato through exogenously applied potassium fertilizer sources and biofertilizer

Excessive usage of chemical fertilizers has detrimental effects on the environment and the safety of food. Conversely, utilizing organic fertilizers such as sage offers several advantages, including cost-effectiveness, soil enhancement, and promotion of root development. A two-year field experiment was conducted to investigate the impact of different potassium fertilizer sources and biofertilizers (specifically Bacillus cereus (MBc)) on potato plants. The experiment employed a split-plot design with three replicates, where the main plot factor was MBc (with and without), and the subplot factor was the sources of potassium fertilizer (control without K fertilizer, 100% Feldspar (FD), 100% Filter cake (FC), 75% FD + 25% FC, 25% FD + 75% FC, and 50% FD + 50% FC). The purpose was to examine the growth response of potato plants to these treatments. The results indicated that all treatments increased plant height, stem count, and tuber dry matter compared to the control. Furthermore, all treatments exhibited a higher uptake of macronutrients (N, P, and K) compared to the control. Notably, the plants treated with 100FC combined with MBc showed a significant 104.74% increase in total tuber weight compared to the control treatment. Additionally, the addition of 100FC with MBc significantly enhanced the availability of N, P, and K by 73.13%, 110.33%, and 51.88% respectively, compared to the control treatment. Apart from the biofertilizers, the individual application of FC and its combination with FD also demonstrated positive effects on soil fertility, potato growth, and yield.