The Experts below are selected from a list of 44373 Experts worldwide ranked by ideXlab platform
Andrew Forbes Alexander Hoadley - One of the best experts on this subject based on the ideXlab platform.
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Advances in Mechanical Dewatering of Wastewater Sludge Treatment
Wastewater Reuse and Management, 2013Co-Authors: A Mahmoud, Jean Vaxelaire, Jeremy Olivier, Andrew Forbes Alexander HoadleyAbstract:Dewatering of wastewater sludge is a difficult process. The difficulty has been attributed mainly to the fact that particles are very fine, colloidal in nature and possess a gel-like structure due to polymeric flocculation. In order to tackle the limitations in wastewater sludge Dewatering, new technologies have been developed in recent years. Some technologies, such as wastewater sludge digestion, wastewater sludge mineralisation or peroxidation, allow to reduce the amount of wastewater sludge to be dewatered, or the dewaterability of the sludge, by changing the biochemical composition. Nevertheless, wastewater sludge remains hard to dewater, and therefore, an improvement in the conventional Dewatering equipments is desirable. Therefore, current research tends to propose potential alternatives to enhance the Dewatering ability of conventional processes, to increase the final dry solids content, and to accelerate the Dewatering process with low energy consumption compared to thermal drying. Different options have been investigated to enhance the wastewater sludge Dewatering. Some of the new developments to be assimilated and assembled in this chapter include intensification of the Dewatering process which combines (1) mechanical and thermal effects, (2) mechanical force and an electric field, (3) the superimposition of ultrasounds and/or magnetic fields, (4) the combined fields (e.g. electric and ultrasonic) applied simultaneously, (5) both shear and compressive forces, (6) and microwave-assisted Dewatering. This chapter focuses on the scientific and practical aspects of the application of an additional force field in laboratory/industrial Dewatering and discusses this in relation to conventional Dewatering techniques in terms of water content/or dry solids content and energy consumption. Indeed, the aim of this chapter is to provide a fundamental understanding of the different process variables and configurations in order to identify potential improvements and future innovative technologies for Dewatering enhancement. Following a detailed outline of research in one of the most promising alterative techniques, the electrically assisted Dewatering of wastewater sludge, experimental data obtained by the authors are presented in this chapter.
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electro Dewatering of wastewater sludge influence of the operating conditions and their interactions effects
Water Research, 2011Co-Authors: A Mahmoud, Jean Vaxelaire, Jeremy Olivier, Andrew Forbes Alexander HoadleyAbstract:Electric field-assisted Dewatering, also called electro-Dewatering (EDW), is a technology in which a conventional Dewatering mechanism such a pressure Dewatering is combined with electrokinetic effects to realize an improved liquid/solids separation, to increase the final dry solids content and to accelerate the Dewatering process with low energy consumption compared to thermal drying. The application of these additional fields can be applied to either or both Dewatering stages (filtration and/or compression), or as a pre-or post-treatment of the Dewatering process. In this study, the performance of the EDW on wastewater sludge was investigated. Experiments were carried out on a laboratory filtration/compression cell, provided with electrodes, in order to apply an electrical field. The chosen operating conditions pressure (200-1200 kPa) and voltage (10-50 V) are sufficient to remove a significant proportion of the water that cannot be removed using mechanical Dewatering technologies alone. A response surface methodology (RSM) was used to evaluate the effects of the processing parameters of EDW on (i) the final dry solids content, which is a fundamental Dewatering parameter and an excellent indicator of the extent of EDW and (ii) the energy consumption calculated for each additional mass of water removed. A two-factor central composite design was used to establish the optimum conditions for the EDW of wastewater sludge. Experiments showed that the use of an electric field combined with mechanical compression requires less than 10 and 25% of the theoretical thermal drying energy for the low and moderate voltages cases, respectively.
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electrical field a historical review of its application and contributions in wastewater sludge Dewatering
Water Research, 2010Co-Authors: A Mahmoud, Jean Vaxelaire, Jeremy Olivier, Andrew Forbes Alexander HoadleyAbstract:Electric field-assisted Dewatering, also called electro-Dewatering, is a technology in which a conventional Dewatering mechanism such a pressure Dewatering is combined with electrokinetic effects to realize an improved liquid/solids separation, to increase the final dry solids content and to accelerate the Dewatering process with low energy consumption compared to thermal drying. Electro-Dewatering is not a new idea, but the practical industrial applications have been limited to niche areas in soil mechanics, civil engineering, and the ceramics industry. Recently, it has received great attention, specially, in the fields of fine-particle sludge, gelatinous sludge, sewage sludge, pharmaceutical industries, food waste and bull kelp, which could not be successfully dewatered with conventional mechanical methods. This review focuses on the scientific and practical aspects of the application of an electrical field in laboratory/industrial Dewatering, and discusses this in relation to conventional Dewatering techniques. A comprehensive bibliography of research in the electro-Dewatering of wastewater sludges is included. As the fine-particle suspensions possess a surface charge, usually negative, they are surrounded by a layer with a higher density of positive charges, the electric double layer. When an electric field is applied, the usually negative charged particles move towards the electrode of the opposite charge. The water, commonly with cations, is driven towards the negative electrode. Electro-Dewatering thus involves the well-known phenomena of electrophoresis, electro-osmosis, and electromigration. Following a detailed outline of the role of the electric double layer and electrokinetic phenomena, an analysis of the components of applied voltage and their significance is presented from an electrochemical viewpoint. The aim of this elementary analysis is to provide a fundamental understanding of the different process variables and configurations in order to identify potential improvements. Also discussed herein is the investigation of the electrical behaviour of a porous medium, with particular emphasis on porous medium conductivity determination.
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Dewatering of biomaterials by mechanical thermal expression
Drying Technology, 2006Co-Authors: Sam Clayto, Andrew Forbes Alexander Hoadley, Oliver Nelso Scholes, Rory Alexande Wheele, Malcolm Joh Mcintosh, Danh Qua HuynhAbstract: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 ...
A Mahmoud - One of the best experts on this subject based on the ideXlab platform.
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electro Dewatering of wastewater sludge an investigation of the relationship between filtrate flow rate and electric current
Water Research, 2015Co-Authors: Jeremy Olivier, A Mahmoud, Jean-baptiste Conrardy, Jean VaxelaireAbstract:Compared to conventional Dewatering techniques, electrical assisted mechanical Dewatering, also called electro-Dewatering (EDW) is an alternative and an effective technology for the Dewatering of sewage sludge with low energy consumption. The objectives of this study were to evaluate the Dewatering performance and to determine the influence of the process parameters (e.g. applied electric current, applied voltage, and the initial amount of dry solids) on the kinetics of EDW-process for activated urban sludge. Also significant efforts have been devoted herein to provide comprehensive information about the EDW mechanisms and to understand the relationship between these operating conditions with regards to develop a qualitative and quantitative understanding model of the electro-Dewatering process and then produce a robust design methodology. The results showed a very strong correlation between the applied electric current and the filtrate flow rate and consequently the electro-Dewatering kinetics. A higher applied electric current leads to faster EDW kinetics and a higher final dry solids content. In contrast, the results of this work showed a significant enhancement of the Dewatering kinetics by decreasing the mass of the dry solids introduced into the cell (commonly known as the sludge loading).
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Electro-Dewatering of Wastewater Sludge: An Investigation of the Relationship between Filtrate Flow Rate and Electric Current
Water Research, 2015Co-Authors: Jeremy Olivier, A Mahmoud, Jean-baptiste Conrardy, Jean VaxelaireAbstract:Compared to conventional Dewatering techniques, electrical assisted mechanical Dewatering, also called electro-Dewatering (EDW) is an alternative and an effective technology for the Dewatering of sewage sludge with low energy consumption. The objectives of this study were to evaluate the Dewatering performance and to determine the influence of the process parameters (e.g. applied electric current, applied voltage, and the initial amount of dry solids) on the kinetics of EDW-process for activated urban sludge. Also significant efforts have been devoted herein to provide comprehensive information about the EDW mechanisms and to understand the relationship between these operating conditions with regards to develop a qualitative and quantitative understanding model of the electro-Dewatering process and then produce a robust design methodology. The results showed a very strong correlation between the applied electric current and the filtrate flow rate and consequently the electro-Dewatering kinetics. A higher applied electric current leads to faster EDW kinetics and a higher final dry solids content. In contrast, the results of this work showed a significant enhancement of the Dewatering kinetics by decreasing the mass of the dry solids introduced into the cell (commonly known as the sludge loading). \textcopyright 2015 Elsevier Ltd.
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Advances in Mechanical Dewatering of Wastewater Sludge Treatment
Wastewater Reuse and Management, 2013Co-Authors: A Mahmoud, Jean Vaxelaire, Jeremy Olivier, Andrew Forbes Alexander HoadleyAbstract:Dewatering of wastewater sludge is a difficult process. The difficulty has been attributed mainly to the fact that particles are very fine, colloidal in nature and possess a gel-like structure due to polymeric flocculation. In order to tackle the limitations in wastewater sludge Dewatering, new technologies have been developed in recent years. Some technologies, such as wastewater sludge digestion, wastewater sludge mineralisation or peroxidation, allow to reduce the amount of wastewater sludge to be dewatered, or the dewaterability of the sludge, by changing the biochemical composition. Nevertheless, wastewater sludge remains hard to dewater, and therefore, an improvement in the conventional Dewatering equipments is desirable. Therefore, current research tends to propose potential alternatives to enhance the Dewatering ability of conventional processes, to increase the final dry solids content, and to accelerate the Dewatering process with low energy consumption compared to thermal drying. Different options have been investigated to enhance the wastewater sludge Dewatering. Some of the new developments to be assimilated and assembled in this chapter include intensification of the Dewatering process which combines (1) mechanical and thermal effects, (2) mechanical force and an electric field, (3) the superimposition of ultrasounds and/or magnetic fields, (4) the combined fields (e.g. electric and ultrasonic) applied simultaneously, (5) both shear and compressive forces, (6) and microwave-assisted Dewatering. This chapter focuses on the scientific and practical aspects of the application of an additional force field in laboratory/industrial Dewatering and discusses this in relation to conventional Dewatering techniques in terms of water content/or dry solids content and energy consumption. Indeed, the aim of this chapter is to provide a fundamental understanding of the different process variables and configurations in order to identify potential improvements and future innovative technologies for Dewatering enhancement. Following a detailed outline of research in one of the most promising alterative techniques, the electrically assisted Dewatering of wastewater sludge, experimental data obtained by the authors are presented in this chapter.
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electro Dewatering of wastewater sludge influence of the operating conditions and their interactions effects
Water Research, 2011Co-Authors: A Mahmoud, Jean Vaxelaire, Jeremy Olivier, Andrew Forbes Alexander HoadleyAbstract:Electric field-assisted Dewatering, also called electro-Dewatering (EDW), is a technology in which a conventional Dewatering mechanism such a pressure Dewatering is combined with electrokinetic effects to realize an improved liquid/solids separation, to increase the final dry solids content and to accelerate the Dewatering process with low energy consumption compared to thermal drying. The application of these additional fields can be applied to either or both Dewatering stages (filtration and/or compression), or as a pre-or post-treatment of the Dewatering process. In this study, the performance of the EDW on wastewater sludge was investigated. Experiments were carried out on a laboratory filtration/compression cell, provided with electrodes, in order to apply an electrical field. The chosen operating conditions pressure (200-1200 kPa) and voltage (10-50 V) are sufficient to remove a significant proportion of the water that cannot be removed using mechanical Dewatering technologies alone. A response surface methodology (RSM) was used to evaluate the effects of the processing parameters of EDW on (i) the final dry solids content, which is a fundamental Dewatering parameter and an excellent indicator of the extent of EDW and (ii) the energy consumption calculated for each additional mass of water removed. A two-factor central composite design was used to establish the optimum conditions for the EDW of wastewater sludge. Experiments showed that the use of an electric field combined with mechanical compression requires less than 10 and 25% of the theoretical thermal drying energy for the low and moderate voltages cases, respectively.
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electrical field a historical review of its application and contributions in wastewater sludge Dewatering
Water Research, 2010Co-Authors: A Mahmoud, Jean Vaxelaire, Jeremy Olivier, Andrew Forbes Alexander HoadleyAbstract:Electric field-assisted Dewatering, also called electro-Dewatering, is a technology in which a conventional Dewatering mechanism such a pressure Dewatering is combined with electrokinetic effects to realize an improved liquid/solids separation, to increase the final dry solids content and to accelerate the Dewatering process with low energy consumption compared to thermal drying. Electro-Dewatering is not a new idea, but the practical industrial applications have been limited to niche areas in soil mechanics, civil engineering, and the ceramics industry. Recently, it has received great attention, specially, in the fields of fine-particle sludge, gelatinous sludge, sewage sludge, pharmaceutical industries, food waste and bull kelp, which could not be successfully dewatered with conventional mechanical methods. This review focuses on the scientific and practical aspects of the application of an electrical field in laboratory/industrial Dewatering, and discusses this in relation to conventional Dewatering techniques. A comprehensive bibliography of research in the electro-Dewatering of wastewater sludges is included. As the fine-particle suspensions possess a surface charge, usually negative, they are surrounded by a layer with a higher density of positive charges, the electric double layer. When an electric field is applied, the usually negative charged particles move towards the electrode of the opposite charge. The water, commonly with cations, is driven towards the negative electrode. Electro-Dewatering thus involves the well-known phenomena of electrophoresis, electro-osmosis, and electromigration. Following a detailed outline of the role of the electric double layer and electrokinetic phenomena, an analysis of the components of applied voltage and their significance is presented from an electrochemical viewpoint. The aim of this elementary analysis is to provide a fundamental understanding of the different process variables and configurations in order to identify potential improvements. Also discussed herein is the investigation of the electrical behaviour of a porous medium, with particular emphasis on porous medium conductivity determination.
Jean Vaxelaire - One of the best experts on this subject based on the ideXlab platform.
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electro Dewatering of wastewater sludge an investigation of the relationship between filtrate flow rate and electric current
Water Research, 2015Co-Authors: Jeremy Olivier, A Mahmoud, Jean-baptiste Conrardy, Jean VaxelaireAbstract:Compared to conventional Dewatering techniques, electrical assisted mechanical Dewatering, also called electro-Dewatering (EDW) is an alternative and an effective technology for the Dewatering of sewage sludge with low energy consumption. The objectives of this study were to evaluate the Dewatering performance and to determine the influence of the process parameters (e.g. applied electric current, applied voltage, and the initial amount of dry solids) on the kinetics of EDW-process for activated urban sludge. Also significant efforts have been devoted herein to provide comprehensive information about the EDW mechanisms and to understand the relationship between these operating conditions with regards to develop a qualitative and quantitative understanding model of the electro-Dewatering process and then produce a robust design methodology. The results showed a very strong correlation between the applied electric current and the filtrate flow rate and consequently the electro-Dewatering kinetics. A higher applied electric current leads to faster EDW kinetics and a higher final dry solids content. In contrast, the results of this work showed a significant enhancement of the Dewatering kinetics by decreasing the mass of the dry solids introduced into the cell (commonly known as the sludge loading).
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Electro-Dewatering of Wastewater Sludge: An Investigation of the Relationship between Filtrate Flow Rate and Electric Current
Water Research, 2015Co-Authors: Jeremy Olivier, A Mahmoud, Jean-baptiste Conrardy, Jean VaxelaireAbstract:Compared to conventional Dewatering techniques, electrical assisted mechanical Dewatering, also called electro-Dewatering (EDW) is an alternative and an effective technology for the Dewatering of sewage sludge with low energy consumption. The objectives of this study were to evaluate the Dewatering performance and to determine the influence of the process parameters (e.g. applied electric current, applied voltage, and the initial amount of dry solids) on the kinetics of EDW-process for activated urban sludge. Also significant efforts have been devoted herein to provide comprehensive information about the EDW mechanisms and to understand the relationship between these operating conditions with regards to develop a qualitative and quantitative understanding model of the electro-Dewatering process and then produce a robust design methodology. The results showed a very strong correlation between the applied electric current and the filtrate flow rate and consequently the electro-Dewatering kinetics. A higher applied electric current leads to faster EDW kinetics and a higher final dry solids content. In contrast, the results of this work showed a significant enhancement of the Dewatering kinetics by decreasing the mass of the dry solids introduced into the cell (commonly known as the sludge loading). \textcopyright 2015 Elsevier Ltd.
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Electro-Dewatering of activated sludge: filtrate flow rate analysis
2014Co-Authors: Jean-baptiste Conrardy, Jeremy Olivier, Jean VaxelaireAbstract:Dewatering of activated sludge is a difficult process. Assisting the Dewatering by an electrical field improves significantly the efficiency. The purpose of this study was to analyse the kinetics of the Dewatering process thanks to experiments carried out with a lab-scale pressurised electro-Dewatering device. Tests were conducted under constant current density and constant voltage, respectively. Different sludge loads were considered. The kinetics of the Dewatering process was monitored by calculating both, the dryness of the sludge cake and the mass flow rate of filtrate over time. It was found that only two key parameters affect significantly the mass flow rate of filtrate during the electro-Dewatering process, namely the electric current intensity and the dryness of sludge cake. The Dewatering kinetics of tests at constant voltage and constant current were both explained with this analysis. No influence of the sludge load was observed on the flow rate of filtrate.
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ELECTRO-Dewatering OF WASTEWATER SLUDGE: FACTORS AFFECTING KINETICS AND ENERGY CONSUMPTION
2013Co-Authors: Jean-baptiste Conrardy, Jeremy Olivier, Jean VaxelaireAbstract:The treatment of wastewater produces huge quantities of residue (sludge) which contains a large amount of water. A Dewatering step is usually carried out prior to further treatment in order to diminish sludge volume and consequently reduce handling and disposal cost. It is commonly conducted thanks to mechanical processes (plate or belt filter presses, centrifuges) which offer a relatively poor efficiency. The water content at the end of the Dewatering usually ranges between 65% and 85%. A way to improve the Dewatering efficiency is the implementation of an electric field during the mechanical Dewatering (electro-Dewatering). It has been shown that applying an electric current through the filter cake could reduce significantly the water content of sludge, down to 40%. A lab-scale device of electro-Dewatering has been used to study the phenomena involved in this hybrid process. The experimental setup consists in a cylindrical chamber where a piston presses the sludge cake on a filter cloth. Two electrodes, one anode and one cathode, are placed at the piston head and under the filter cloth, respectively. Dewatering kinetics and electrical behavior of the sludge cake can be studied with this setup. The results of experiments carried out with a constant voltage (or a constant current) show significant correlations between the filtrate flow-rate, the electric current, the electrical resistance of the filter-cake and the water content of sludge. The electric current and the water content of the sludge are found to be key factors that govern electro-Dewatering kinetics. Moreover, the electrical resistance through a given cake of sludge is highly correlated to its water content (which decreases during the process). The relationship seems to be valid for a wide range of water content. These results enable a better understanding of how Dewatering efficiency and energy consumption are related in the electro-Dewatering process.
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Advances in Mechanical Dewatering of Wastewater Sludge Treatment
Wastewater Reuse and Management, 2013Co-Authors: A Mahmoud, Jean Vaxelaire, Jeremy Olivier, Andrew Forbes Alexander HoadleyAbstract:Dewatering of wastewater sludge is a difficult process. The difficulty has been attributed mainly to the fact that particles are very fine, colloidal in nature and possess a gel-like structure due to polymeric flocculation. In order to tackle the limitations in wastewater sludge Dewatering, new technologies have been developed in recent years. Some technologies, such as wastewater sludge digestion, wastewater sludge mineralisation or peroxidation, allow to reduce the amount of wastewater sludge to be dewatered, or the dewaterability of the sludge, by changing the biochemical composition. Nevertheless, wastewater sludge remains hard to dewater, and therefore, an improvement in the conventional Dewatering equipments is desirable. Therefore, current research tends to propose potential alternatives to enhance the Dewatering ability of conventional processes, to increase the final dry solids content, and to accelerate the Dewatering process with low energy consumption compared to thermal drying. Different options have been investigated to enhance the wastewater sludge Dewatering. Some of the new developments to be assimilated and assembled in this chapter include intensification of the Dewatering process which combines (1) mechanical and thermal effects, (2) mechanical force and an electric field, (3) the superimposition of ultrasounds and/or magnetic fields, (4) the combined fields (e.g. electric and ultrasonic) applied simultaneously, (5) both shear and compressive forces, (6) and microwave-assisted Dewatering. This chapter focuses on the scientific and practical aspects of the application of an additional force field in laboratory/industrial Dewatering and discusses this in relation to conventional Dewatering techniques in terms of water content/or dry solids content and energy consumption. Indeed, the aim of this chapter is to provide a fundamental understanding of the different process variables and configurations in order to identify potential improvements and future innovative technologies for Dewatering enhancement. Following a detailed outline of research in one of the most promising alterative techniques, the electrically assisted Dewatering of wastewater sludge, experimental data obtained by the authors are presented in this chapter.
Jeremy Olivier - One of the best experts on this subject based on the ideXlab platform.
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electro Dewatering of wastewater sludge an investigation of the relationship between filtrate flow rate and electric current
Water Research, 2015Co-Authors: Jeremy Olivier, A Mahmoud, Jean-baptiste Conrardy, Jean VaxelaireAbstract:Compared to conventional Dewatering techniques, electrical assisted mechanical Dewatering, also called electro-Dewatering (EDW) is an alternative and an effective technology for the Dewatering of sewage sludge with low energy consumption. The objectives of this study were to evaluate the Dewatering performance and to determine the influence of the process parameters (e.g. applied electric current, applied voltage, and the initial amount of dry solids) on the kinetics of EDW-process for activated urban sludge. Also significant efforts have been devoted herein to provide comprehensive information about the EDW mechanisms and to understand the relationship between these operating conditions with regards to develop a qualitative and quantitative understanding model of the electro-Dewatering process and then produce a robust design methodology. The results showed a very strong correlation between the applied electric current and the filtrate flow rate and consequently the electro-Dewatering kinetics. A higher applied electric current leads to faster EDW kinetics and a higher final dry solids content. In contrast, the results of this work showed a significant enhancement of the Dewatering kinetics by decreasing the mass of the dry solids introduced into the cell (commonly known as the sludge loading).
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Electro-Dewatering of Wastewater Sludge: An Investigation of the Relationship between Filtrate Flow Rate and Electric Current
Water Research, 2015Co-Authors: Jeremy Olivier, A Mahmoud, Jean-baptiste Conrardy, Jean VaxelaireAbstract:Compared to conventional Dewatering techniques, electrical assisted mechanical Dewatering, also called electro-Dewatering (EDW) is an alternative and an effective technology for the Dewatering of sewage sludge with low energy consumption. The objectives of this study were to evaluate the Dewatering performance and to determine the influence of the process parameters (e.g. applied electric current, applied voltage, and the initial amount of dry solids) on the kinetics of EDW-process for activated urban sludge. Also significant efforts have been devoted herein to provide comprehensive information about the EDW mechanisms and to understand the relationship between these operating conditions with regards to develop a qualitative and quantitative understanding model of the electro-Dewatering process and then produce a robust design methodology. The results showed a very strong correlation between the applied electric current and the filtrate flow rate and consequently the electro-Dewatering kinetics. A higher applied electric current leads to faster EDW kinetics and a higher final dry solids content. In contrast, the results of this work showed a significant enhancement of the Dewatering kinetics by decreasing the mass of the dry solids introduced into the cell (commonly known as the sludge loading). \textcopyright 2015 Elsevier Ltd.
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Electro-Dewatering of activated sludge: filtrate flow rate analysis
2014Co-Authors: Jean-baptiste Conrardy, Jeremy Olivier, Jean VaxelaireAbstract:Dewatering of activated sludge is a difficult process. Assisting the Dewatering by an electrical field improves significantly the efficiency. The purpose of this study was to analyse the kinetics of the Dewatering process thanks to experiments carried out with a lab-scale pressurised electro-Dewatering device. Tests were conducted under constant current density and constant voltage, respectively. Different sludge loads were considered. The kinetics of the Dewatering process was monitored by calculating both, the dryness of the sludge cake and the mass flow rate of filtrate over time. It was found that only two key parameters affect significantly the mass flow rate of filtrate during the electro-Dewatering process, namely the electric current intensity and the dryness of sludge cake. The Dewatering kinetics of tests at constant voltage and constant current were both explained with this analysis. No influence of the sludge load was observed on the flow rate of filtrate.
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ELECTRO-Dewatering OF WASTEWATER SLUDGE: FACTORS AFFECTING KINETICS AND ENERGY CONSUMPTION
2013Co-Authors: Jean-baptiste Conrardy, Jeremy Olivier, Jean VaxelaireAbstract:The treatment of wastewater produces huge quantities of residue (sludge) which contains a large amount of water. A Dewatering step is usually carried out prior to further treatment in order to diminish sludge volume and consequently reduce handling and disposal cost. It is commonly conducted thanks to mechanical processes (plate or belt filter presses, centrifuges) which offer a relatively poor efficiency. The water content at the end of the Dewatering usually ranges between 65% and 85%. A way to improve the Dewatering efficiency is the implementation of an electric field during the mechanical Dewatering (electro-Dewatering). It has been shown that applying an electric current through the filter cake could reduce significantly the water content of sludge, down to 40%. A lab-scale device of electro-Dewatering has been used to study the phenomena involved in this hybrid process. The experimental setup consists in a cylindrical chamber where a piston presses the sludge cake on a filter cloth. Two electrodes, one anode and one cathode, are placed at the piston head and under the filter cloth, respectively. Dewatering kinetics and electrical behavior of the sludge cake can be studied with this setup. The results of experiments carried out with a constant voltage (or a constant current) show significant correlations between the filtrate flow-rate, the electric current, the electrical resistance of the filter-cake and the water content of sludge. The electric current and the water content of the sludge are found to be key factors that govern electro-Dewatering kinetics. Moreover, the electrical resistance through a given cake of sludge is highly correlated to its water content (which decreases during the process). The relationship seems to be valid for a wide range of water content. These results enable a better understanding of how Dewatering efficiency and energy consumption are related in the electro-Dewatering process.
-
Advances in Mechanical Dewatering of Wastewater Sludge Treatment
Wastewater Reuse and Management, 2013Co-Authors: A Mahmoud, Jean Vaxelaire, Jeremy Olivier, Andrew Forbes Alexander HoadleyAbstract:Dewatering of wastewater sludge is a difficult process. The difficulty has been attributed mainly to the fact that particles are very fine, colloidal in nature and possess a gel-like structure due to polymeric flocculation. In order to tackle the limitations in wastewater sludge Dewatering, new technologies have been developed in recent years. Some technologies, such as wastewater sludge digestion, wastewater sludge mineralisation or peroxidation, allow to reduce the amount of wastewater sludge to be dewatered, or the dewaterability of the sludge, by changing the biochemical composition. Nevertheless, wastewater sludge remains hard to dewater, and therefore, an improvement in the conventional Dewatering equipments is desirable. Therefore, current research tends to propose potential alternatives to enhance the Dewatering ability of conventional processes, to increase the final dry solids content, and to accelerate the Dewatering process with low energy consumption compared to thermal drying. Different options have been investigated to enhance the wastewater sludge Dewatering. Some of the new developments to be assimilated and assembled in this chapter include intensification of the Dewatering process which combines (1) mechanical and thermal effects, (2) mechanical force and an electric field, (3) the superimposition of ultrasounds and/or magnetic fields, (4) the combined fields (e.g. electric and ultrasonic) applied simultaneously, (5) both shear and compressive forces, (6) and microwave-assisted Dewatering. This chapter focuses on the scientific and practical aspects of the application of an additional force field in laboratory/industrial Dewatering and discusses this in relation to conventional Dewatering techniques in terms of water content/or dry solids content and energy consumption. Indeed, the aim of this chapter is to provide a fundamental understanding of the different process variables and configurations in order to identify potential improvements and future innovative technologies for Dewatering enhancement. Following a detailed outline of research in one of the most promising alterative techniques, the electrically assisted Dewatering of wastewater sludge, experimental data obtained by the authors are presented in this chapter.
Hu Yang - One of the best experts on this subject based on the ideXlab platform.
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coagulation flocculation in Dewatering of sludge a review
Water Research, 2018Co-Authors: Hua Wei, Boqiang Gao, Jie Ren, Hu YangAbstract:Abstract Sludge disposal is an integral part of wastewater treatment systems, and its cost usually accounts for more than half of the total operation cost. Sludge disposal technology is facing challenges and opportunities simultaneously and can still be improved. Sludge Dewatering is an essential process in sludge disposal, and it is important for the effective reduction of the final processing cost. Coagulation/flocculation is a relatively mature, cost-effective, user-friendly sludge Dewatering technology. In this work, coagulation/flocculation and their combinations with other pretreatments, including Dewatering mechanisms, are reviewed. Various coagulants/flocculants used in sludge Dewatering, including inorganic coagulants, organic synthetic and natural polymeric flocculants, and bioflocculants, are introduced in detail because coagulants/flocculants are the key in coagulation/flocculation. The different factors that influence the Dewatering performance of these coagulants/flocculants are also presented briefly. Moreover, aiming at the complicated composition of sludge and its treatment difficulty, the prospects and technical developments of coagulation/flocculation in sludge Dewatering are discussed.
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Coagulation/flocculation in Dewatering of sludge: A review.
Water research, 2018Co-Authors: Hua Wei, Boqiang Gao, Jie Ren, Hu YangAbstract:Abstract Sludge disposal is an integral part of wastewater treatment systems, and its cost usually accounts for more than half of the total operation cost. Sludge disposal technology is facing challenges and opportunities simultaneously and can still be improved. Sludge Dewatering is an essential process in sludge disposal, and it is important for the effective reduction of the final processing cost. Coagulation/flocculation is a relatively mature, cost-effective, user-friendly sludge Dewatering technology. In this work, coagulation/flocculation and their combinations with other pretreatments, including Dewatering mechanisms, are reviewed. Various coagulants/flocculants used in sludge Dewatering, including inorganic coagulants, organic synthetic and natural polymeric flocculants, and bioflocculants, are introduced in detail because coagulants/flocculants are the key in coagulation/flocculation. The different factors that influence the Dewatering performance of these coagulants/flocculants are also presented briefly. Moreover, aiming at the complicated composition of sludge and its treatment difficulty, the prospects and technical developments of coagulation/flocculation in sludge Dewatering are discussed.