Electrokinetic Conditions Research Articles

Effect of electrokinetic process on in situ stabilization and detoxification of arsenic-contaminated soil with high content of calcium

Owing to the high risk of human exposure to arsenic-contaminated soil, reducing its toxicity is essential. This study used the electrokinetic (EK) process with iron-rich electrodes to synchronously achieve the accumulate, stabilize and detoxify soil arsenic. Changes in arsenic valence, leaching toxicity, and microbial communities related to toxicity were comprehensively considered. The results demonstrated that arsenic was mainly transported toward the anode and accumulated by electromigration owing to the negatively charged arsenic anions under EK conditions. The cathode approaching effectively promote arsenic movement to the anode; the largest As(T) transportation rate of 30.61% was achieved near the cathode (S4). The transportation ratio of As(III) was 1.84 times more than that of As(V). The As(III) content and leaching toxicity of soil arsenic in all treatments decreased after applying the EK process. In particular, the anode approaching effectively elevated the average ratios of soil As(III) oxidation and stabilization to 37.88% and 61.73%, respectively. Correspondingly, the total phospholipid fatty acid content increased substantially after EK treatment and showed a pollution stress elimination effect. The electrokinetic effect can essentially cause highly active and easily migrated arsenic to accumulate near the anode and middle sections. The electric field mediated iron mineralization and stabilized arsenic by oxidizing As(III) and reacting with newly formed iron-rich phases (S). Meanwhile, the electric field regulated the form of soil calcium from CaCO3 to CaSO4 and caused calcium-bound arsenic to change to a more stable form. According to these results, in situ stabilization and detoxification of arsenic-contaminated soil can be realized by the EK process, avoiding stabilizer addition and excavation.

Electro-membrane Bioreactor Combined Solar Powered Processes: MATLAB Modelling

In this study, it is researched that could use (PV) panel for solar energy instead of DC power supply used in leachate treatment by submerged electro membrane bioreactor for Antalya in Turkey. The study was made the analysis and modeling by MATLAB Simulink of electric energy obtained solar powered or PV panels and present an engineering approach. SMEBR was operated under electrokinetic conditions at a current density of 24 mA/cm2 (11,5 A), exposure time 3+3 minutes. As a result, in the light of SMEBR electrokinetic experimental results, it was found that a pair of PV panels connected in parallel provide 11.5 A for the SMEBR process for this region. In obtained modelling, it was determined the number of panels increases dependent on the amount of volume. Also, it was understood that PV system can work without battery via a control mechanism turn off the system, and it provides direct current. If a battery is added to the system, it can continue treatment without interruption. But since this system will run for about six minutes, no battery cost will be required.

Diffusiophoresis in suspensions of highly charged soft particles.

Diffusiophoresis phenomenon of aoft particles suspended in binary electrolyte solutions is explored theoretically in this study based on the spherical cell model, focusing on the chemiphoresis component in absence of diffusion potential. Both the electrostatic and hydrodynamic aspects of the boundary confinement, or steric effect, due to the presence of neighboring particles are examined extensively under various electrokinetic conditions. Significant local extrema are found in mobility profiles expressed as functions of the Debye length in general, synchronized with the strength of the motion-inducing double layer polarization. Moreover, a seemingly peculiar phenomenon is observed that the soft particles may move faster in more concentrated suspensions. The competition between the simultaneous enhancement of the motion-inducing electric driving force and the motion-retarding hydrodynamic drag force from the boundary confinement effect of the neighboring particles is found to be responsible for it. The above findings are also demonstrated experimentally in a very recent study on the diffusiophoretic motion of soft particles through porous collagen hydrogels. The results presented here are useful in various practical applications of soft particles like drug delivery.

An AC electrokinetics-based electrochemical aptasensor for the rapid detection of microRNA-155

Traditional immunosensors are often limited by low sensitivity and long detection times, for they usually depend on passive diffusion-dominated transport of target analytes for the binding reaction with a bio-recognition element such as enzymes, antibodies, and aptamers. Numerous studies rely on electric field manipulation by using alternating current (AC) electrokinetics to enhance the hybridization rate and reduce the hybridization time for faster and more efficient detection. This study demonstrated a rapid electrochemical aptasensor integrated with an AC electroosmotic (ACEO) flow phenomenon for the enhanced target hybridization of microRNA-155 (miR-155). Optimization of the electrokinetic conditions for target collection resulted in a saturation point after 75 s miR-155 was detected within the range of 1 aM–10 pM with a detection limit of 1 aM, which is 100 times lower and about 50 times faster compared with the conventional diffusion-dependent detection done for 1 h. The detection was also done in spiked serum samples, and a concentration range within the required detection range was obtained. The highly sensitive and specific results allow for the rapid and real-time sensing of target biomarkers, which can be used for the early detection of infection.

Comparison on the phytoextraction efficiency of Bidens pilosa at heavy metal contaminated site in natural and electrokinetic conditions

The plant samples of Bidens pilosa were collected from a coal gangue vacant site and its surrounding area, located in central China, to study the remediation effect of the plant species on heavy metal (HM) contamination in both natural and electrokinetic (EK) conditions. The analytical results showed that the effect of phytoextraction and bioconcentration on the heavy metals in the sample of the EK group is more significant than those in the other control group. Compared with the results of natural condition, under the EK condition the concentrations of cadmium (Cd), lead (Pb), copper (Cu) and zinc (Zn) in the stems and leaves of the Bidens pilosa increased to 0.40 mg/kg, 4.23 mg/kg, 7.27 mg/kg, 830.24 mg/kg, respectively, with their increments of 292%, 1731%, 141%, 2076%. For root samples, the Cd, Pb, Cu and Zn concentrations increased to 0.52 mg/kg, 4.36 mg/kg, 10.87 mg/kg, and 98.12 mg/kg and the increase rates were 1034%, 140%, 29%, and 181%, respectively. The phytoextraction efficiency of the Bidens pilosa was significantly higher than that of control group. The removal efficiency of Cd, Pb, Cu and Zn in soil increased to 26%, 72%, 27%, and 79% with the EK applied. In addition, the mechanism of HM migration, extraction and enrichment in Bidens pilosa under the EK condition was discussed.

Transportation and augmentation of the deposited soil bacteria in the electrokinetic process: Interactions between soil particles and bacteria

The use of electrokinetic (EK) phenomena can facilitate bioaugmentation by enhancing the mobility and redistribution of deposited soil bacteria through heterogeneous soil. In this research, batch treatments (T1-T6) were used to assess the characteristics of bacterial transportation and proliferation under a weak electric field (1 V/cm). The strain Bacillus cereus was mainly transported toward the cathode by electro-osmosis flow (EOF). The bacterial transport efficiency was 1.07 × 107 CFUs/mL from days 0–9 when deionized water was used as the electrolyte solution and was elevated by 46% when EOF was enhanced with 0.010 mol/L NaHCO3 solution containing 0.04 mol/L Na2SO4. However, in all treatments, bacterial transport efficiency decreased by 70%-95% after 9 days. The bacterial transport efficiency was closely related to the EOF effective action distance (ED) which narrowed as soil and bacterial properties changed after the EK process. Correspondingly, the bacteria in soil were transformed from loose-bound to tight-bound status due to the deepened secondary minimum depth of XDLVO interaction energy after EK treatment. In addition to bacterial transportation, the electric field stimulated the proliferation of bacteria to achieve higher counts by promoting bacterial adhesion and facilitating fluid contact between ions, dissolved organic carbon, and bacteria. The stimulatory effect of electric field on bacteria was stronger than the transportation effect of the electric field on bacteria. Improvements in both bacterial migration and proliferation contributed to bioaugmentation under EK conditions. Near-cathode sections (S3, S4) are optimal for bacterial augmentation under the EK treatment for a long duration.

Diffusiophoresis of a highly charged soft particle in electrolyte solutions induced by diffusion potential

Diffusiophoresis of a single soft particle in an electrolyte solution with induced diffusion potential is investigated theoretically in this study. A pseudo-spectral method based on Chebyshev polynomials is adopted to solve the resultant governing electrokinetic equations. Parameters of electrokinetic interest are examined extensively to explore their respective effect upon the particle motion, such as the fixed charge density and the permeability of the outer porous layer, the surface potential and size of the inner rigid core, and the electrolyte strength and magnitude of the induced diffusion potential in the solution. The nonlinear effects pertinent to highly charged particles, such as the double layer polarization effect and the counterion condensation effect, are scrutinized, in particular. Here, nonlinear effects refer to the effects that can only be properly revealed by accurately solving the complete nonlinear Poisson–Boltzmann equation governing the electric potential instead of the simplified linear Helmholtz equation under the Debye–Hückel approximation, valid for lowly charged particles only. We found, among other things, that characteristic local extrema in mobility profiles are mainly due to these two effects. Moreover, a soft particle moves fastest in dilute electrolyte solutions, in general. The smaller the soft particle is, the faster it moves under otherwise identical structural and electrokinetic conditions, provided that the particle radius is smaller than the Debye length, the characteristic thickness of the double layer. The shape of the double layer polarization takes an undulating multilayer form at large electrolyte strength. The results provided here are useful in practical applications such as drug delivery as well as microfluidic and nanofluidic operations.

Evaluation of electrochemical treatment of real hospital wastewater with different electrode materials

In this paper, the treatment of real hospital wastewater (HWW) by electrocoagulation process (EC), which is one of the electrochemical treatment methods, has been evaluated. In the EC process, aluminum (Al) and iron (Fe) plates as anode and cathode are used. Experimental studies were conducted at 5, 10, 20, 30 voltage (V) and 5, 10, 20, 30, 45 minutes (min) exposure times. pH, temperature, and conductivity were monitored. COD and phenol removal were evaluated. As a result of experimental studies, Al and Fe electrodes were effective in the treatment of HWW with EC. The highest COD removal efficiency was 93% at 30V 10 min and 95% at 30V 5 min for Al and Fe electrode, respectively. The highest phenol removal efficiency is 97% at 10V 10 min and 97% at 10V 5 min for Al and Fe electrode. When all parameters are evaluated, optimum electro kinetic conditions for treatment of HWW was obtained for 10V 5 min by the Fe electrode.

Evaluating the performance of an electro-membrane bioreactor in treatment of young leachate

Leachate generated from landfill, typically contains high amounts of different pollutions. Its composition may vary according to the origin and age of landfill. In this study, the performance of a laboratory-scale submerged electro-membrane bioreactor (SMEBR), an integrated process consisting of an electro-coagulation unit and a conventional submerged membrane bioreactor (SMBR) for treating young leachate was evaluated. SMEBR and SMBR as control reactor were operated simultaneously to compare. In SMEBR, perforated aluminum (Al) electrodes were used. SMEBR was operated under electrokinetic conditions at a current density of 24 mA/cm 2 for 50 days: at 180 s/day for 25 days (Stage I) and 360 s/day for 25 days (Stage II). Chemical oxygen demand (COD), ammonia nitrogen (NH 3 –N), color and metal removal performances were evaluated for both reactors. Also, the membrane fouling was examined by monitoring the change in transmembrane pressure over time. The concentration of dissolved oxygen (DO) was determined using the oxygen uptake rate in a period covering SMEBR operating conditions. Based on the results obtained, positive effects of electrical field SMEBR were clearly observed at Stage II. At the Stage II, the removal efficiency of COD was 6–15% higher in SMEBR compared to SMBR. The average NH 3 –N removal efficiencies in SMEBR and SMBR were 86 and 78%, respectively. Following the introduction of electrical current to SMEBR, DO concentrations were measured about 0.8 mg/L lower than SMBR; however, nitrification was not affected adversely. Additionally, chemical properties of SMEBR and SMBR membranes surfaces were characterized by using the Fourier-transform infrared spectroscopy.

The effects of different electric fields and electrodes on Solanum nigrum L. Cd hyperaccumulation in soil.

Electrokinetics is a new attempt of strengthening hyperaccumulator Solanum nigrum L. Cd extraction. The effects of different electric fields and electrodes on S.nigrum accumulating Cd among of four electric field conditions (1Vcm-1) and two electrodes were determined. The results showed that the AC electric field significantly stimulated (p<0.05) the growth of S.nigrum, and the biomass increased nearly by 40% compared with the control, while the DC electric field (including the switching polarity) had no significant effect. Electric field significantly increased (p<0.05) Cd concentration in S.nigrum and the highest one was recorded for the DC electric field with switching polarity. S.nigrum Cd accumulation (ug pot-1) was the highest under the AC electric field, which was nearly 70% higher compared to the control. The innovation found was that the role of biomass enhancement for S.nigrum accumulating Cd (ug pot-1) was the first and increased Cd concentration was secondary under AC electrical field, which might be relative with S.nigrum is a weed species. Basically, there was no significant difference between the graphite and stainless steel electrode, but under AC electric field conditions, Cd accumulation of S.nigrum was significantly higher (p<0.05) than stainless steel electrode, which is worthy of further revelation besides of statistic factor. In general, the accumulation (ug pot-1) of Cd by S.nigrum was the highest under the AC electric field, which was a very important reference for the electrokinetic conditions to be used in the practice of phytoremediation.

Recent Progress and Perspectives in the Electrokinetic Characterization of Polyelectrolyte Films.

The analysis of the charge, structure and molecular interactions of/within polymeric substrates defines an important analytical challenge in materials science. Accordingly, advanced electrokinetic methods and theories have been developed to investigate the charging mechanisms and structure of soft material coatings. In particular, there has been significant progress in the quantitative interpretation of streaming current and surface conductivity data of polymeric films from the application of recent theories developed for the electrohydrodynamics of diffuse soft planar interfaces. Here, we review the theory and experimental strategies to analyze the interrelations of the charge and structure of polyelectrolyte layers supported by planar carriers under electrokinetic conditions. To illustrate the options arising from these developments, we discuss experimental and simulation data for plasma-immobilized poly(acrylic acid) films and for a polyelectrolyte bilayer consisting of poly(ethylene imine) and poly(acrylic acid). Finally, we briefly outline potential future developments in the field of the electrokinetics of polyelectrolyte layers.

Isolation and characterization of heavy polycyclic aromatic hydrocarbon-degrading bacteria adapted to electrokinetic conditions.

Polycyclic aromatic hydrocarbon (PAH)-degrading bacteria capable of growing under electrokinetic conditions were isolated using an adjusted acclimation and enrichment procedure based on soil contaminated with heavy PAHs in the presence of an electric field. Their ability to degrade heavy PAHs under an electric field was individually investigated in artificially contaminated soils. The results showed that strains PB4 (Pseudomonas fluorescens) and FB6 (Kocuria sp.) were the most efficient heavy PAH degraders under electrokinetic conditions. They were re-inoculated into a polluted soil from an industrial site with a PAH concentration of 184.95 mg kg(-1). Compared to the experiments without an electric field, the degradation capability of Pseudomonas fluorescens and Kocuria sp. was enhanced in the industrially polluted soil under electrokinetic conditions. The degradation extents of total PAHs were increased by 15.4 and 14.0% in the electrokinetic PB4 and FB6 experiments (PB4 + EK and FB6 + EK) relative to the PB4 and FB6 experiments without electrokinetic conditions (PB4 and FB6), respectively. These results indicated that P. fluorescens and Kocuria sp. could efficiently degrade heavy PAHs under electrokinetic conditions and have the potential to be used for the electro-bioremediation of PAH-contaminated soil, especially if the soil is contaminated with heavy PAHs.

Electrokinetics-enhanced biodegradation of heavy polycyclic aromatic hydrocarbons in soil around iron and steel industries

Bioremediation is a safe and cost-effective technology for the removal of polycyclic aromatic hydrocarbons (PAHs) contaminated soils, but its remediation rate is usually very slow at soils contaminated with heavy PAHs in high concentrations. This paper describes the feasibility of using electrokinetics to enhance the degradation of heavy PAHs in soil around iron and steel industries. Three bench-scale experiments were conducted for 90 days using historically polluted soil with a total PAHs content of 220.01mg/kg dry soil. All of the experiments were inoculated with PAHs degrading bacteria, but experiments II and III were performed using constant polarity and alternating polarity electrokinetic conditions, respectively. Results were compared with those from the control experiment (experiment I), which did not receive any electrokinetic treatment. The results demonstrated that the electrokinetic process could enhance the biodegradation extent of total PAHs and heavy PAHs in the soil. The final degradation extents of total PAHs were 9.5% and 13.5% higher in experiments II and III, respectively, as compared to experiment I. Under the electrokinetic and bacteria conditions, the relative enhancement in the degradation of four- to six-ring PAHs compared to the control experiment was much stronger and increased with increasing ring number. The final degradation extents of four- to six-ring PAHs increased by 7.9–8.6%, 11.0–18.4% and 17.2–25.6% in experiments II and III compared to experiment I, respectively. The results also showed that the electrokinetic operation mode could affect not only the degradation extent of total PAHs but also bacterial counts and soil moisture of different regions in soils. The use of alternating polarity electrokinetics was favorable to the bacterial growth and kept the soil properties uniform. In addition, there was a positive correlation between the degradation extent of PAHs, bacterial counts and moisture content by Pearson correlation analysis under electrokinetics. The results of this work demonstrate that the use of electrokinetics can significantly enhance the degradation of PAHs by influencing soil conditions. Therefore, the use of electrokinetic technology may provide a useful tool for enhancing the bioremediation of heavy PAHs in soil.

Determination of trace anions in liquefied petroleum gas using liquid absorption and electrokinetic migration for enrichment followed by ion chromatography

A simple sample enrichment technique, electrokinetic migration enrichment in single phase using a designed device, coupled with ion chromatography is presented for the determination of four anions (H(2)PO(4)(-), Cl(-), NO(3)(-), and SO(4)(2-)) in liquefied petroleum gas by liquid adsorption. The electrokinetic migration enrichment is based on the phenomenon of ion electrokinetic migration to the opposite electrode. When the anions migrated to the anode in a smaller volume chamber under the electric field, the concentration was realized. The main parameters affecting enrichment efficiency of applied voltage and enrichment time were investigated. The ion chromatography condition for anions separation was also studied. Under the optimal electrokinetic migration enrichment and ion chromatography conditions, the four anions were detected simultaneously with good linear relationship (r(2) = 0.9908-0.9968) and high precisions (less than 5% of the relative standard deviations of peak areas). The limits of detection of anions (S/N of 3) were in the range of 8-600 μg L(-1). The enrichment factors of the four anions ranged from 3.1 to 5.8. The established method was successfully applied to the analysis of the trace anions in liquefied petroleum gas by liquid adsorption with satisfactory results. The advantages of this method are simple operation and low cost.

Electrokinetic-enhanced bioaugmentation for remediation of chlorinated solvents contaminated clay

Successful bioremediation of contaminated soils is controlled by the ability to deliver bioremediation additives, such as bacteria and/or nutrients, to the contaminated zone. Because hydraulic advection is not practical for delivery in clays, electrokinetic (EK) injection is an alternative for efficient and uniform delivery of bioremediation additive into low-permeability soil and heterogeneous deposits. EK-enhanced bioaugmentation for remediation of clays contaminated with chlorinated solvents is evaluated. Dehalococcoides (Dhc) bacterial strain and lactate ions are uniformly injected in contaminated clay and complete dechlorination of chlorinated ethene is observed in laboratory experiments. The injected bacteria can survive, grow, and promote effective dechlorination under EK conditions and after EK application. The distribution of Dhc within the clay suggests that electrokinetic transport of Dhc is primarily driven by electroosmosis. In addition to biodegradation due to bioaugmentation of Dhc, an EK-driven transport of chlorinated ethenes is observed in the clay, which accelerates cleanup of chlorinated ethenes from the anode side. Compared with conventional advection-based delivery, EK injection is significantly more effective for establishing microbial reductive dechlorination capacity in low-permeability soils.

Activity and viability of polycyclic aromatic hydrocarbon‐degrading Sphingomonas sp. LB126 in a DC‐electrical field typical for electrobioremediation measures

SummaryThere has been growing interest in employing electro‐bioremediation, a hybrid technology of bioremediation and electrokinetics for the treatment of contaminated soil. Knowledge however on the effect of weak electrokinetic conditions on the activity and viability of pollutant‐degrading microorganisms is scarce. Here we present data about the influence of direct current (DC) on the membrane integrity, adenosine triphosphate (ATP) pools, physico‐chemical cell surface properties, degradation kinetics and culturability of fluorene‐degrading Sphingomonas sp. LB126. Flow cytometry was applied to quantify the uptake of propidium iodide (PI) and the membrane potential‐related fluorescence intensities (MPRFI) of individual cells within a population. Adenosine tri‐phosphate contents and fluorene biodegradation rates of bulk cultures were determined and expressed on a per cell basis. The cells' surface hydrophobicity and electric charge were assessed by contact angle and zeta potential measurements respectively. Relative to the control, DC‐exposed cells exhibited up to 60% elevated intracellular ATP levels and yet remained unaffected on all other levels of cellular integrity and functionality tested. Our data suggest that direct current (X = 1 V cm−1; J = 10.2 mA cm−2) as typically used for electrobioremediation measures has no negative effect on the activity of the polycyclic aromatic hydrocarbon (PAH)‐degrading soil microorganism, thereby filling a serious gap of the current knowledge of the electrobioremediation methodology.

Epimerization study of the l, l- and l, d-diastereoisomers of the calpain inhibitor MDL 28170 by capillary electrophoresis

MDL 28170, Cbz-( l)–Val-( d, l)–Phe-H, which exists as a mixture of l, l- and l, d-diastereoisomers, is a calpain inhibitor currently investigated as a novel therapeutic agent for the treatment of ischemic stroke and head and spinal trauma. This report describes a capillary electrophoresis (CE) method that uses sodium dodecyl sulfate (SDS) micellar electrokinetic conditions for the separation of the l, l- and l, d-diastereoisomers of MDL 28170. The report also describes the applications of this CE method to the study of epimerization of the l, l- and l, d-diastereoisomers in pH 7.4 phosphate buffered saline solution (PBS), rat and human plasma at 37 °C. The relative percent-time courses obtained showed interconversion of the diastereoisomers in all three matrices studied. However, the epimerization process in rat and human plasma was found to be at least 50 times faster than that in PBS. The epimerization half-life of the l, l-diastereoisomer in rat plasma was approximately 30 min, which is about three-fold faster than the observed elimination half-life of the l, l-diastereoisomer reported in a pharmacokinetic study following intravenous bolus dosing.

Dynamic enhancements of sample loading and analyte concentration in capillary isoelectric focusing for proteome studies.

Capillary isoelectric focusing (CIEF) involves the use of the entire capillary filled with a mixture containing protein/peptide analytes and carrier ampholytes. Thus, the preparative capabilities of CIEF are inherently greater than most capillary-based electrokinetic separation techniques. To further increase sample loading and, therefore, the concentrations of focused analytes, a dynamic approach, which is based on electrokinetic injection of proteins/peptides from a solution reservoir, is demonstrated using a low p/ protein calibration kit and tryptic peptides from Saccharomyces cerevisiae. The proteins/peptides continuously migrate into the capillary and encounter a pH gradient established by carrier ampholytes originally present in the capillary for focusing and separation. Dynamic introduction and focusing in CIEF can be directly controlled by various electrokinetic conditions, including the injection time and the applied electric field strength. Differences in the sample loading are contributed by electrokinetic injection bias and are affected by the individual analyte's electrophoretic mobility. Depending on the mobilities of yeast peptides, the loading capacity of each peptide is measured to be around 8 to 45-fold of that obtained in conventional CIEF. By comparing with the concentrations of dilute yeast peptides originally present in the reservoir, an overall concentration factor of 1400-7700 together with excellent separation resolution is achieved using dynamic introduction and focusing. This concentration effect is further illustrated by detecting 10 pg/microL of bradykinin peptide spiked in yeast protein digest using only ultraviolet absorption.

Electroosmotic Flow in a Microcapillary with One Solution Displacing Another Solution

Displacing one electrolyte solution with another solution in a microchannel is often required in many biomedical lab-on-a-chip devices. This paper discusses both theoretical and experimental studies of electroosmotic flow in a capillary with one electrolyte solution displacing another solution. A theoretical model was developed to predict the electroosmotic flow displacing process. This model considered the mixing process between the two different solutions and the induced pressure gradient in the capillary due to the different electrolyte solutions and hence the different electrokinetic conditions in different sections of the capillary. In the experiments, deionized ultrafiltered water, 10−2 M KCl solution, 10−4 M KCl solution, and 10−4 M LaCl3 solution were used as the testing fluid. Polyamide-coated silica capillary tubes 100 μm in internal diameter and 10 cm in length were used in this study. The nonlinear change of the current with time was found during such a displacing process under a constant applied electrical field. A good agreement between the experimentally measured current change and the model prediction of the current change was found. The characteristics of the mixing process are also discussed in the paper.

Streaming Potential during Cake Filtration of Slightly Compressible Particles

The electrokinetic properties of the process of cake filtration were investigated. Special interest was given to the streaming potential as a phenomenon and also as a measurement in the characterization of the dewatering properties of clay slurries. An apparatus capable of determining both the streaming potential and traditional dewatering properties such as specific resistance to filtration was developed and is described. Investigations regarding the influence of varying electrokinetic conditions on filterability and vice versa were conducted. The parameters deliberately varied were solid loading, filtration pressure, ionic species, and conductivity. The streaming potential observed during a single filtration run was constant. This is in accordance with the Helmholtz-Smoluchowski equation used in conjunction with D'Arcyan-based filtration theory, in which flow times superficial pore length is constant. The effects of conductivity, obtained by the use of various monovalent and divalent ions, showed that the specific resistance to filtration correlated with E/P, defined by specific pressure and conductivity. The significant effect of surface conductivity was demonstrated by varying the filtration pressure and by the tentative use of the corrections suggested by C. L. Rice and R. Whitehead [ J. Phys. Chem. 69(11), 4017, 1965].