Thermal Dewatering Research Articles

Electrochemical Dewatering of Cellulosic Nanomaterials

Cellulose is the most abundant biomass material in nature utilized for the manufacturing of cellulosic nanomaterials that exhibit great potential in a variety of industrial applications. Although cellulosic nanomaterial is cost-effective to produce, it is not economical to ship long distances while containing significant water content (>95 wt.%). Therefore, a need has been identified by manufacturers to develop energy-efficient, dewatering or drying of cellulosic nanomaterials.Accordingly, Faraday Technology in collaboration with GranBio USA, manufacturers of cellulosic nanomaterials, is addressing this need by developing electrochemical based dewatering system and process to dewater cellulosic nanomaterials while maintaining material properties when dried and re-dispersed. Energy-efficient (70% reduction in energy requirements compared to thermal dewatering), environmentally beneficial (51% reduction in greenhouse gas emissions), economical (31% reduction in cost/ton of dried material), and industrially viable electrochemical based dewatering approach to process up to 2 tons/year of dried nanocellulose at alpha-scale has been demonstrated. The approach is capable of achieving >50 wt.% final solids and 18 wt.% final solids, that could be rehydrated under vortex and confirmed for re-dispersibility. Material properties (structure, particle size) were maintained by the dewatered cellulosic nanomaterials. Specifically, this talk will discuss the results of these advancements. Acknowledgements: The financial support of DOE Contract No. DE-SC0018787 is acknowledged.

Measurement and modeling of the evaporation rate of loess under high temperature

The high-temperature dewatering method has a broad application prospect in loess reinforcement, and the evaporation boundary is a crucial factor in determining the dewatering effect. This study conducts evaporation tests on unsaturated loess columns at high temperatures using a self-made high-temperature evaporation test apparatus to reveal the laws of water and heat transfer and surface evaporation in unsaturated loess under high temperatures. Based on the study's results, high temperatures have a significant driving effect on water. Under high temperatures, the portion of soil near the hot end is rapidly dewatered, forming a drying zone. The presence of an evaporation boundary intensifies the high-temperature dewatering effect. Under hot-end dewatering and surface evaporation, soil water content presents the distribution laws of high at both ends and low in the middle. High temperatures greatly increase surface evaporation. The water content and temperature of surface soil significantly affect evaporation intensity, as do the water gradient and temperature gradient of shallow soil. The evaporation coefficient, defined as the ratio of evaporation intensity to saturated evaporation intensity (potential evaporation intensity), is employed to characterize soil evaporation efficiency. The evaporation coefficient measured under high temperatures is found to be higher than that calculated by the existing models for the evaporation coefficient. A new evaporation coefficient model is built using modifying existing models. The new model comprehensively considers surface and shallow soil temperatures and water contents. Validation results showed that the model can more precisely calculate the evaporation rate of surface soil under the influence of a high-temperature heat source. The research results of this paper reveal the evaporation characteristics of the surface and water migration characteristics inside loess under high temperature, which is helpful for promoting the application of thermal dewatering method in the reinforcement engineering of loess pit slopes.

Electrochemical Dewatering of Cellulosic Nanomaterials

Renewable cellulosic nanomaterials exhibit great potential in various applications due to unique properties. Abundant availability of feedstock has led to industrialization of production. A significant cost-limiting factor to utilize cellulosic nanomaterials is dewatering/drying as cellulosic nanomaterials are not economical to ship long distances while containing significant water content (>95 wt.%). This represents a critical driver for increased costs of nanocellulose products.Accordingly, Faraday Technology in collaboration with GranBio USA, manufacturers of cellulosic nanomaterials, is addressing this need by developing electrochemical based dewatering system and process to dewater cellulosic nanomaterials while maintaining material properties when dried and re-dispersed. Energy-efficient (70% reduction in energy requirements compared to thermal dewatering), environmentally beneficial (51% reduction in greenhouse gas emissions), economical (31% reduction in cost/ton of dried material), and industrially viable electrochemical based dewatering approach to process up to 2 tons/year of dried nanocellulose at alpha-scale has been demonstrated. The approach is capable of achieving >50 wt.% final solids and 18 wt.% final solids, that could be rehydrated under vortex and confirmed for re-dispersibility. Material properties (structure, particle size) were maintained by the dewatered cellulosic nanomaterials. Specifically, this talk will discuss the results of these advancements. Acknowledgements: The financial support of DOE Contract No. DE-SC0018787 is acknowledged.

Feasibility Study to Retrofit Existing Rotary Drum into A Chemical Sludge Thermal Dewatering System Through Lab-Scale Experimental Investigations

The adoption of the landfill method for chemical sludge management is an issue of concern as landfill leachates can cause negative impacts on the environment. Furthermore, the high moisture content in chemical sludge has resulted in higher disposal costs due to its heavyweight. This research study is conducted to determine the optimum thermal dewatering condition for chemical sludge through experimental testing and thereafter deduce a recommendation to retrofit an existing rotary drum for chemical sludge dewatering. The water removal rate from chemical sludge was evaluated through thermal dewatering experiments using a lab-scale furnace. Referring to results obtained, increased dewatering temperature and dewatering time, and decreased volume of chemical sludge has improved the water removal rate. The highest water removal rate is 82% when 1.0 cm³ chemical sludge sample is dewatered under a temperature of 250ºC for 90.0 min. Based on the economic evaluation between current chemical sludge handling and newly installed rotary drum dewatering methods, an estimate of one hundred and fifty-four thousand Malaysian Ringgit in annual net-saving is expected to be achieved through dewatering of chemical sludge in retrofitted equipment. The finding has justified the feasibility of retrofitting the current rotary drum for chemical sludge dewatering.

Physical and chemical changes in lignite during mechanical and thermal dewatering process and associated changes in the organic compounds in the wastewater

ABSTRACT Mechanical thermal expression (MTE) was used for dewatering two lignites, Loy Yang (LY) from Australia and Shengli (SL) from China. The dewatering process was carried out with temperatures ranging from 24°C to 240°C. It was found that the moisture content of the MTE products decreased linearly with increasing temperature, and the residual moisture content was a function of compressibility. The MTE process was more effective for the low-rank LY lignite. The characterization of the lignite includes moisture content, C/H ratio, pore volume distribution from mercury intrusion porosimetry and, coal–water interaction from low-field nuclear magnetic resonance (LFNMR). Coal–water interaction only changed slightly with mechanical compression alone. Combined with heat mechanical effect found to compress the residual moisture into smaller pores. The coal–water interaction is stronger in the smaller pores, which makes dewatering progressively more difficult. The chemical characteristics were studied by solid-state 13C NMR, where no significant changes were apparent. Total organic carbon (TOC) analysis showed higher content of organics in the LY wastewater than in the SL wastewater. The chemical composition of the wastewater was analyzed by gas chromatography–mass spectrometry (GC-MS) and it was found that the majority of the compounds from LY and SL detected were acids, accounting for more than 50% of the organic compounds, followed by aromatic hydrocarbons, accounting for 27% in LY and 38% in SL wastewater. Lower levels of alkenes, alcohols, esters, and aliphatic hydrocarbons were also found in the wastewater.

Study on Frost Resistance Characteristics of the Large Channel Thermal Insulation Lining

The frost heave pattern and the frost heave design of the large channel in the cold area are still not yet fully solved. In this study, based on the large channel of Hada Mountain Water Conservancy Project, the in-situ large-scale thermal protection slope test was carried out, and the frost heave deformation law of the thermal dewatering slope was obtained. The results have certain guiding significance for the frost heave design of the large channel in the cold area.

Precise Measurement of the Hydrogen Isotope Composition of Phyllosilicates by Continuous Flow Off-Axis Integrated Cavity Output Spectroscopy.

New methodology is presented for analyzing hydrogen isotope ratios (D/H) in phyllosilicate minerals by laser absorption spectroscopy. D/H measurements were carried out using an off-axis integrated cavity output spectroscopy (OA-ICOS) instrument operated in a continuous flow configuration. Water was extracted from minerals in a high temperature quartz column and advanced to the analyzer in a dry air carrier gas stream. We report the first D/H measurements by a laser system for serpentine, muscovite, sericite, talc, and biotite. We also measure kaolinite, gypsum, and small volumes of water. Materials, excluding biotite, were calibrated to within 1.5‰ of IRMS-measured δDVSMOW values, with an average precision of 1.1‰. Biotite δD measurements were up to 10‰ more positive than established IRMS values, due to partial reduction of evolved waters by Fe in the high temperature column. We provide recommendations for overcoming redox interference for measurements of biotite, and other ferrous materials, by OA-ICOS. Rapid, precise, and accurate analyses were carried out on water volumes as low as 0.25 μL extracted from minerals. With the exception of talc, the time required for thermal dewatering and measurement is 140 s, which translates into a throughput of up to 6 mineral samples per hour, including replicates. By demonstrating high precision, rapid throughput, low cost, and ease of operation, we provide a tool that should enable researchers at institutions with limited funding to routinely measure D/H in hydrous minerals. The protocols presented herein should also be useful to commercial users seeking to produce high density isotope data sets relevant to exploration of hydrothermal ore deposits and geothermal fields.

Mechanical Thermal Dewatering of Wheat Straw in Production of Chip Board

Mechanical Thermal Dewatering of Wheat Straw in Production of Chip Board

Superabsorbent polymer (SAP) hydrogels for protein enrichment

Superabsorbent polymer (SAP) hydrogels are mainly acrylic based polymer hydrogels which are capable of absorbing water around 100 times of their own weight. Thus these are supposed to be the promising material which can be incorporated as a draw agent in forward osmosis (FO) process. In this paper, superabsorbent polymer hydrogels are used as a draw agent for protein enrichment in FO process so that structure of protein remains intact during dewatering process. Though the free swelling capacity of hydrogels in aqueous medium is high, due to their slow swelling rates water fluxes obtained in FO process are much lower as compared to conventional salts used as a draw solute. Thus in this paper research emphasis was given on increasing swelling rates of hydrogels to improve water fluxes by graft copolymerizing acrylic acid monomer on carboxymethyl cellulose (CMC) polymer. Moreover, for feasible recycling of these draw agents, a thermoresponsive polymer N-isopropyl acrylamide (NIPAM) was copolymerized with superabsorbing acrylic acid monomer and thermal dewatering process was used to regenerate the hydrogels.The synthesized hydrogels were tested as a draw agent in FO for bovine serum albumin (BSA) protein enrichment experiments. As the enrichment is directly related to the absolute weight of water extracted from the feed solution, the performance was presented in terms of enrichment factors. Thermally regenerated hydrogels were again recycled back to the process, and some reduction in enrichment was observed. Further based on the results obtained with different membrane area, mass of hydrogels, swelling ratios and water recovery rates, parameters for hydrogel assisted FO process are predicted for various applications.

Thermal Dewatering of Waste Sludge in an Agitated Drum Dryer

This study presents experiences of drying waste sludge in an agitated drum dryer. Measurements were performed on an agitated drum dryer apparatus equipped with up-to- date instrumentation. As waste sludge is prone to adhesion and balling, it is important to identify the conditions appropriate for drying. Different cases were examined; during measurements, the rotational speed of the agitator, the quantity and moisture content of the sludge fed in as well as the temperature of the wall and the drying gas were changed. The measurement data were used to represent the temperatures characteristic of drying and the mass changes of the product. Volumetric mass transfer coefficients were determined from the measurements and a modified Sherwood number was derived from them. The dimensionless Sh'-Re' equation enables to dimension agitated drum dryers.

A Study for Development of Real-Scale Thermal Filter Press Dewatering (TFPD)

Real-scale thermal filter press dewatering equipment (plate size: 630 mm × 630 mm) was installed and operated at a waterworks for one year in an attempt to achieve sludge reduction. During the period, the dewaterability was evaluated according to the seasonal sludge properties in order to compare the dewaterability of thermal dewatering and mechanical dewatering, as well as to determine the economics of thermal dewatering. According to the results, the winter season sludge showed a 36% decrease in water content and a two-thirds reduction in dewatering velocity compared to the summertime sludge. In addition, the dewatered cakes of the thermal filter press dewatering equipment showed a lower specific cake resistance and water content in the dewatered cakes than the mechanical filter press dewatering equipment, indicating superior dewaterability. This was attributed to the easier removal of the filtrate remaining in the capillary tubes due to thermal dewatering. The energy consumption for thermal dewatering was 300 kJ/dry solids (DS) kg. A comparison of the sludge dryers indicated that it is possible to produce dewatered cakes that consume less energy and can be recycled. According to the performance evaluation results, the real-scale thermal filter press dewatering equipment had high adaptability to the changes in seasonal sludge, showing excellent dewaterability compared to the mechanical filter press dewatering equipment, and was economical due to the lower energy consumption.

Effect of Hydrodynamics During Crystallization on Mechanical Dewatering of Salicylic Acid

Mechanical cake dewatering is always desired to reduce the load on thermal dewatering (drying). Any change in the upstream process such as crystallization can have a significant influence on the filtration as well as cake dewatering characteristics. The present study deals with the effect of hydrodynamics (mixing intensity) during salicylic acid crystallization on the air dewatering characteristics in the subsequent pressure filtration. The mixing conditions during crystallization were varied by using three different types of agitators (anchor impeller [AI], curved blade turbine [CBT], and bar turbine [BT]) and by varying the speed of agitation. The effect of operating pressure and dewatering time on the final moisture content of the cake was also studied. The crystal properties (crystal size and size distribution) were found to vary with the mixing intensity, which further influenced the cake dewatering kinetics as well as the residual moisture content. An AI, which is a laminar flow impeller, produced crystals with a wide size distribution and higher mean particle size, which resulted in cake with high porosity and hence higher moisture content. The high porosity (as well as high cake permeability) caused early air breakthrough, which resulted in ineffective dewatering of cake. Therefore, in this case the residual moisture in cake was found to be higher (27%) even at higher dewatering pressure (1.5 bar gauge) and longer dewatering time (90 s). A BT creates high turbulence during mixing and produced crystals with a relatively narrow size distribution and lower mean particle size, which provided low-porosity cakes. Such cakes could be efficiently dewatered and the final cake moisture content was found to decrease to about 15%, a significant improvement in the filterability of the cake. The dewatering data were modeled according to the correlation between irreducible cake saturation and capillary number for predicting the cake dewatering characteristics (residual moisture as well as dewatering kinetics) and the results were compared with the experimental data.

Steam Dewatering of Filter Cakes in a Vertical Filter Press

Steam dewatering of filter cakes is recognized as a competitive alternative to conventional air drying and thermally assisted mechanical dewatering (TAMD). The main benefit of cake dewatering with high-pressure steam is that mechanical and thermal dewatering can be efficiently performed in a single process step. The target of this study was to determine the potential of a steam-dewatering technique for two industrial mineral suspensions. The first mineral, kaolin, was very difficult to dewater using conventional mechanical dewatering techniques, whereas the second one, ground calcium carbonate (GCC), represented only moderate resistance to filtration. The secondary objective was to compare the filterability of the original kaolin slurry with the same slurry treated with a coagulant (aluminum sulphate, Al2(SO4)3 · 16H2O). Four different kinds of experiments were performed: tests without any kind of cake dewatering, tests with air drying, tests with steam drying, and tests with both coagulation and steam drying. The obtained results show that steam dewatering is an efficient technique for achieving lower cake-moisture contents. Also, the positive influence of coagulation on the filtration capacity was found to be considerable in the case of kaolin. An approximate energy balance was created for the steam-drying process and the determined energy efficiencies were compared with those obtainable with an ideal thermal drier. The main conclusion from these comparisons is that steam drying can be effectively used instead of traditional thermal drying if the large energy losses can be reduced by proper insulation and heat recovery systems.

Life cycle assessment of dewatering routes for algae derived biodiesel processes

Biodiesel derived from algae is considered as a sustainable fuel, but proper downstream processing is necessary to minimize the environmental footprint of this process. Algae is grown in dilute liquid cultures, and achieving the low water contents required for extraction represents one of the greatest challenges for the production of algae derived biodiesel. An analysis of the life cycle emissions associated with harvesting, dewatering, extraction, reaction, and product purification stages for algae biodiesel were performed. This “base case” found 10,500 kg of total emissions per t of biodiesel with 96 % of those attributed to the spray dryer used for dewatering. Alternative cases were evaluated for various sequences of mechanical and thermal dewatering techniques. The best case, consisted of a disk-stack centrifuge, followed by the chamber filter press, and a heat integrated dryer. This resulted in 875 kg emissions/t of biodiesel, a 91 % reduction from the base case. Significant reductions in life cycle emissions were achieved for all mechanical dewatering alternatives compared to the base case, but further improvements using these existing technologies were limited. Additional improvements will require the development of new techniques for water removal or wet extractions.

Experimental Study on Thermal Hydrolysis and Dewatering Characteristics of Mechanically Dewatered Sewage Sludge

After mechanical dewatering, sewage sludge has a moisture content of around 80 wt% and further disposal is required. A new sewage sludge semi-drying (dewatering) process is proposed and verified. It combines thermal hydrolysis and subsequent mechanical dewatering, with less energy consumption than traditional thermal drying. Sludge treated using this new process satisfies further disposal requirements (e.g., landfill or autothermal incineration). In the present study, a high-pressure test reactor was used to study the thermal hydrolysis of dewatered sludge. Thermally hydrolyzed sludge was subsequently dewatered by centrifugal sedimentation or by pressure filtration. The amount of organic compounds returning to the water phase was also measured. According to the results from centrifugal settling tests, the optimal thermal hydrolysis treatment temperature was 180°C. The moisture content then dropped to 1.44 kg/kg dry solids (DS; 59 wt%) after dewatering under relative centrifugal force of 9,000 × g from 5.67 kg/kg DS (85 wt%). Pressure filtration further reduced the moisture content of filter cakes to only 0.5 kg/kg DS (33 wt%, hydrolysis temperature 180°C). After thermal hydrolysis, the heating value of sludge (moisture-free basis) was about 80% that of the untreated sludge.

Abatement of Organic Pollutant Concentrations in Residual Treatment Sludges: A Review of Selected Treatment Technologies Including Drying

As a result of increasing population, industrialization, and effluent quality, sludge production has increased worldwide. Organic micropollutants in sludge have become a more critical environmental health concern compared to heavy metals. New sludge disposal regulations limit persistent organic pollutants (POPs) in addition to conventional organic indicators like total and dissolved organic carbon. This study aims at providing a brief review on POP concentration in the sludge in different regions of the world, sludge regulations, assessment of conventional biological sludge stabilization methods according to their ability to remove POPs, and discussions on alternative sludge treatment methods. The impact of sludge treatment unit operations including conditioning, thickening, mechanical and thermal dewatering, and biological and thermal stabilization on sludge management is also discussed in the context of organics. The occurrence and removal of micropollutants such as absorbable organic halogen compounds (AOX), nonylphenol and nonylphenol ethoxylates (NPE), di-2-(ethyl-hexyl)-phthalate (DEHP), dibenzo-p-dioxins and furans (PCDD/F), polycyclic aromatic hydrocarbons (PAHs), and polychlorinated biphenyls (PCBs) are also evaluated specifically for sludge treatment unit operations. A concise discussion is also included on different drying technologies suitable for drying of sludge.

Improving Thermal Dewatering Characteristics of Mechanically Dewatered Sludge: Response Surface Analysis of Combined Lime‐Heat Treatment

In this study, disintegration of dewatered sludge (dry solids content [DS%] = 23 +/- 2) was studied to assess the possibility of enhancing the overall performance of a thermal dewatering processes. Powdered lime was used as an alkaline disintegrator. The combined effects of drying temperature, powdered lime dosage, and organic content on the thermal drying rate of dewatered sludge were investigated in a full-scale wastewater treatment plant. Effects of selected design parameters on the sludge drying rate were modeled using a response surface method. In addition, the possible interaction between lost on ignition and total organic carbon parameters also was investigated statistically. Specific resistance to filtration and free water contents of raw and disintegrated mixed sludge (DS% = 1.0 to 1.8) samples were compared statistically. The obtained results indicated that all of the selected design parameters have a significant effect on thermal dewatering characteristics, and the alkaline disintegration technique could remarkably improve thermal evaporation rate of dewatered sludge. These results are important because they could help to establish a sustainable sludge management model, which is critical in reducing environmental health risks.

Life cycle analysis of algae biodiesel

Algae biomass has great promise as a sustainable alternative to conventional transportation fuels. In this study, a well-to-pump life cycle assessment (LCA) was performed to investigate the overall sustainability and net energy balance of an algal biodiesel process. The goal of this LCA was to provide baseline information for the algae biodiesel process. The functional unit was 1,000 MJ of energy from algal biodiesel using existing technology. Systematic boundary identification was performed using relative mass, energy, and economic value method using a 5% cutoff value. Primary data for this study were obtained from The USLCI database and the Greenhouse Gases, Regulated Emissions and Energy use in Transportation model. Carbohydrates in coproducts from algae biodiesel production were assumed to displace corn as a feedstock for ethanol production. For every 24 kg of algal biodiesel produced (1,000 MJ algae biodiesel), 34 kg coproducts are also produced. Total energy input without solar drying is 3,292 and 6,194 MJ for the process with filter press and centrifuge as the initial filtering step, respectively. Net CO2 emissions are −20.9 and 135.7 kg/functional unit for a process utilizing a filter press and centrifuge, respectively. In addition to the −13.96 kg of total air emissions per functional unit, 18.6 kg of waterborne wastes, 0.28 kg of solid waste, and 5.54 Bq are emitted. The largest energy input (89%) is in the natural gas drying of the algal cake. Although net energy for both filter press and centrifuge processes are −6,670 and −3,778 MJ/functional unit, respectively, CO2 emissions are positive for the centrifuge process while they are negative for the filter press process. Additionally, 20.4 m3 of wastewater per functional unit is lost from the growth ponds during the 4-day growth cycle due to evaporation. This LCA has quantified one major obstacle in algae technology: the need to efficiently process the algae into its usable components. Thermal dewatering of algae requires high amounts of fossil fuel derived energy (3,556 kJ/kg of water removed) and consequently presents an opportunity for significant reduction in energy use. The potential of green algae as a fuel source is not a new idea; however, this LCA and other sources clearly show a need for new technologies to make algae biofuels a sustainable, commercial reality.

Mechanical/thermal dewatering of lignite. Part 3: Physical properties and pore structure of MTE product coals

The mechanical thermal dewatering (MTE) process has been shown to effectively dewater high moisture content low rank coals via the application of mechanical force at elevated temperatures. Using mercury intrusion porosimetry (MIP) as an investigative tool, this study examines how MTE processing conditions, such as temperature and pressure, affect the compressibility, pore size distribution, apparent (skeletal) density and shrinkage behaviour of three low rank coals sourced from Australia, Greece and Germany. As both pore filling and sample compression occurred at high mercury intrusion pressures, all MIP data were corrected for compression effects by using compressibility values derived from mercury extrusion data. The MTE process is shown to produce a low porosity coal, which, depending upon the processing conditions used, undergoes further shrinkage upon oven drying at 105 °C. An increase in MTE temperature (above about 85 °C) led to an increase in mesopore volume, which is caused by a hardening of the coal structure, leading to pore volume retention and a consequent reduction in percent shrinkage on oven drying. The increase in measured mesopore volume is also associated with an increase in measured surface area. The reverse trend is seen with increasing MTE pressure, where both the macro and mesopore volume decrease with pressure, causing the percent shrinkage to increase accordingly. This effect may be due to an increase in capillary forces caused by a decrease in the average pore diameter. The percent shrinkage increased up to a pore volume of about 0.1 cm 3/g, beyond which no further reduction in pore volume was achieved. The decrease in mesopore volume is also associated with a decrease in measured surface area. Compressibility values derived from mercury extrusion data show that the MTE process has little impact on the network strength of the skeletal network structure of all three coals investigated. Likewise, the skeletal density remained relatively unchanged. The reduction in water content, pore volume and the changes in shrinkage behaviour under increasingly severe MTE conditions are suggestive of the physical changes that accompany increased coalification (rank) within the lignitic range.

Dewatering of Biomaterials by Mechanical Thermal Expression

Dewatering by mechanical thermal expression (MTE) for a range of materials is explored using a laboratory-scale MTE compression-permeability cell. It is shown that MTE can be used to effectively dewater a range of biomaterials including lignite, biosolids, and bagasse. The underlying dewatering mechanisms relevant to MTE, namely (1) filtration of water expelled due to thermal dewatering, (2) consolidation, and (3) flash evaporation, are discussed. At lower temperatures, the dominating dewatering mechanism is consolidation, but with increasing temperature, thermal dewatering becomes more important. A major focus is an investigation of the effects of processing parameters, including temperature (20 to 200°C) and pressure (1.5 to 24 MPa), on material permeability, a fundamental dewatering parameter. It is illustrated that permeability is particularly dependent on the processing temperature, owing to changes in both the material structure and the water properties. In addition, a comparison of permeability in the direction of applied force (axial) and perpendicular to the direction of applied force (radial) is presented. It is shown that, due to alignment of particles under the applied force, the permeability and, hence, rate of water removal in the radial direction is greater than in the axial direction. SEM micrographs are presented to illustrate the particle alignment.