HAL (Le Centre pour la Communication Scientifique Directe), Sep 22, 2016
An organogel is firstly prepared by synthesizing an aminoacid-type organogelator which is able to... more An organogel is firstly prepared by synthesizing an aminoacid-type organogelator which is able to immobilize aromatic solvents, such as tetralin or toluene. Aerogels are obtained from organogels by extracting the solvent with a stream of supercritical CO 2 in an autoclave. The CO 2 / solvent mixture leaving the autoclave is separated in a cascade of three cyclone separators. The experimental results showed a good solvent recovery rate in the case of tetralin, exceeding 90%, but an unsatisfactory separation for toluene with a yield below 65%. A thermodynamic study was carried out to model the separation for both solvents. The Peng-Robinson equation of state with van der Waals mixing rules and temperature-dependent binary interaction coefficients was selected to predict the CO 2 /solvent thermodynamic behavior. Measurements of isothermal bubble points of the CO 2 /tetralin system were conducted using a high-pressure variable-volume visual cell confirming the relevancy of this model. Then, the first separator was simulated as a simple theoretical equilibrium stage. Simulations using PRO/II software were in good agreement with experimental solvent recovery rate for both toluene and tetralin. The best operating pressure and temperature for the separation were computed by a numerical parametric study. Graphical abstract Thermodynamic study to explain theoretical recovery in organogel supercritical drying: comparison between two solvents (T=20°C, P=50 bar).
This work reports the main results of an experimental investigation aimed to improve the purity o... more This work reports the main results of an experimental investigation aimed to improve the purity of lithium salts extracted from natural brines using two different nanofiltration (NF) membranes. The idea is to use NF membrane separation to further increase Li to Ca concentrations’ ratios. A synthetic brine, miming the reextraction water of a solvent extraction operation from Chilean Atacama Salar–inspired brines, was treated in a pilot unit. Two different membranes were investigated and compared for the best performances. The filtration results showed that a layer-by-layer (LbL)-modified hollow-fiber membranes, denoted dNF40 with end-of-Life NF90 flat-sheet membranes, referred to as EoL-NF90, operated at transmembrane pressures of 2 bar and 20 bar, respectively, show a 10 times lower energy consumption for dNF40. Also, both tested NF membranes were capable of selectively enriched permeates in Li versus Ca with a better performances observed for dNF40.
Pollutants derived from real textile wastewater present a high environmental risk. This work invo... more Pollutants derived from real textile wastewater present a high environmental risk. This work involves the study of the removal of chemical oxygen demand (COD), color, and turbidity from Tunisian real textile wastewater by two different water treatment technologies: chemical coagulation (CC) and electrocoagulation (EC). A comparative study between these two methods was conducted based on the separation performance and operating cost (OC). The effects of different operational parameters including electrolysis time (t), voltage, and pH for EC and the coagulant concentration, initial pH, and time of slow mixing (tsm) for CC were studied using response surface methodology. The developed quadratic models for the responses were in good agreement with the experimental data. The experiments proved the efficiency of both chemical and electrochemical techniques for the treatment of textile effluent. Indeed, by using EC, the reduction efficiencies of COD, color, and turbidity were 63.05, 99.07, and 96.31%, respectively, under optimal conditions (pH 9, t = 36.26 min, and voltage 4 V). For CC treatment, the achieved removal efficiencies of COD, color, and turbidity were 54.02, 96.21, and 93.7%, respectively, at pH 8.57, a coagulant concentration of 204.75 mg/L, and a tsm of 28.41 min as optimal operating conditions. The OC obtained for EC and CC was about 0.47 and 0.2 USD/m3, respectively. Even if the OC of the EC process was higher as compared to the CC process, the treated water obtained by EC meets the Tunisian Standards (NT 106.03 and NT 09-14) for textile wastewater discharge into the environment and demonstrates a high potential for its reuse in various industrial activities. EC technology can be integrated into a wastewater management system that ensures a zero liquid discharge of wastewater into the environment.
Electrocoagulation (EC) technique gained a significant attention owing to its efficiency in remov... more Electrocoagulation (EC) technique gained a significant attention owing to its efficiency in removing colors and contaminations in industrial effluents discharged from numerous industries as textiles, pulp and paper industry, landfill leachate, food processing industry and tannery industry, etc. These effluents are characterized by a wide range of chemical oxygen demand (COD), heavy metals, suspended solids, turbidity and color levels. Most published works focused on the optimization of the operational parameters of EC in order to enhance the simultaneous abatement of soluble and colloidal pollutants. Indeed, EC is influenced by several operation parameters such as pH, applied current density, electrodes material and configuration, conductivity of the solution, electrode gap, electrolysis time and mixing rate. The present work handles the implied mechanisms in removing such contaminants from wastewater together with discussing the major operating parameters influencing the EC performance. Special emphasis is accorded to reducing COD and colors from wastewater. Comparing economically of EC with other alternatives is also conducted aiming at providing a reference for process selection. Economic assessment gives the opportunity for further optimizing the appropriate technology of wastewater treatment through the different strategies of cost optimization.
Advances in science, technology & innovation, 2018
Pomegranate, especially the Punica granatum L. variety, is widely grown in Tunisia. This fruit is... more Pomegranate, especially the Punica granatum L. variety, is widely grown in Tunisia. This fruit is a rich source of phenolic compounds including ellagitannins, phenolic acids and flavonoids.
PurposeThe main purpose of this study resides essentially in the development of a new tool to qua... more PurposeThe main purpose of this study resides essentially in the development of a new tool to quantify the biomass in the bioreactor operating under steady state conditions.Design/methodology/approachModeling is the most relevant tool for understanding the functioning of some complex processes such as biological wastewater treatment. A steady state model equation of activated sludge model 1 (ASM1) was developed, especially for autotrophic biomass (XBA) and for oxygen uptake rate (OUR). Furthermore, a respirometric measurement, under steady state and endogenous conditions, was used as a new tool for quantifying the viable biomass concentration in the bioreactor.FindingsThe developed steady state equations simplified the sensitivity analysis and allowed the autotrophic biomass (XBA) quantification. Indeed, the XBA concentration was approximately 212 mg COD/L and 454 mgCOD/L for SRT, equal to 20 and 40 d, respectively. Under the steady state condition, monitoring of endogenous OUR perm...
Electrocoagulation (EC) technique gained a significant attention owing to its efficiency in remov... more Electrocoagulation (EC) technique gained a significant attention owing to its efficiency in removing colors and contaminations in industrial effluents discharged from numerous industries as textiles, pulp and paper industry, landfill leachate, food processing industry and tannery industry, etc. These effluents are characterized by a wide range of chemical oxygen demand (COD), heavy metals, suspended solids, turbidity and color levels. Most published works focused on the optimization of the operational parameters of EC in order to enhance the simultaneous abatement of soluble and colloidal pollutants. Indeed, EC is influenced by several operation parameters such as pH, applied current density, electrodes material and configuration, conductivity of the solution, electrode gap, electrolysis time and mixing rate. The present work handles the implied mechanisms in removing such contaminants from wastewater together with discussing the major operating parameters influencing the EC performance. Special emphasis is accorded to reducing COD and colors from wastewater. Comparing economically of EC with other alternatives is also conducted aiming at providing a reference for process selection. Economic assessment gives the opportunity for further optimizing the appropriate technology of wastewater treatment through the different strategies of cost optimization.
This article aims to present equipment designed and developed to study the effective thermal cond... more This article aims to present equipment designed and developed to study the effective thermal conductivity of composite panels. The composite panel used is a rigid polyurethane foam covered with a layer of aluminum on both sides. The panel is mounted in the test chamber equipped with several sensors and actuators connected via an Arduino platform. Tests have been carried out by applying heat to impose various interior temperatures. Sensors at different locations are used to monitor and record temperatures in and around the composite panel during heating and natural cooling. A model, based on the Fourier equations of thermal conduction and natural convection heat transfer for the steady state, was developed to assess the effective thermal conductivity. The performance of the system was confirmed using temperature signals through the panels for thermal characterization of composite materials. The determined effective thermal conductivity obtained was in agreement with the experimental values reported in the technical data sheets with relative deviations of less than 10 %.
Membrane processes are dominating desalination techniques. Reverse osmosis (RO) is currently the ... more Membrane processes are dominating desalination techniques. Reverse osmosis (RO) is currently the most used technique for seawater and brackish water desalination. Nanofiltration (NF) could be an interesting alternative option for brackish water desalination. As global warming unleashes its disastrous impact on freshwater availability, desalination techniques are helping ensuring water supplies cover the increasing demand for drinking and all economic sectors. The overall performances of such membrane processes depend on many factors. Flow hydrodynamics within membrane modules is particularly critical for ensuring better salt retention, higher recovery rate, and longer module life span by helping preventing scaling and fouling. In this work, we attempted to determine the residence time distribution as a flow hydrodynamics characterization method in spiral-wound membrane modules. The experimental work was performed on RO and NF modules of a laboratory scale unit. It proved that RO modules have better mixing quality compared to the case of NF which have a shorter mean residence time. It also confirmed that increasing the applied pressure, within the considered experimental domain, leads to better flow patterns approaching plug flow configuration.
A setup consisting of a glass column packed with calibrated glass rings has been achieved. It ope... more A setup consisting of a glass column packed with calibrated glass rings has been achieved. It operates on the principle of an air lift pump. It was designed for the best contact between air and water. Performances of this system were determined by measuring the displaced water flow rates for different submersion depths and various air flow rates. We studied the pressure drop versus the immersion depth in the column. The results show that the pressure loss is described by a second order polynomial equation. Efficiency was calculated for different conditions. The study shows that the proposed system can be set easily, has low power consumption, provides a good mix between phases and is very important for many applications where heat and mass transfer are involved.
Le surcout de fonctionnement d'un BRM immerge a pour origine essentielle la depense d'ene... more Le surcout de fonctionnement d'un BRM immerge a pour origine essentielle la depense d'energie liee a la maitrise de la permeabilite membranaire par aeration. La litterature montre les liens qui existent entre concentration en biomasse dans le reacteur et presence de produits microbiens solubles lies a l'activite bacterienne. Reduire la demande en energie signifie reduire l'aeration membrane, voire l'aeration process liee aux besoins en oxygene des populations epuratrices. Pour ce faire, il est donc determinant de reduire l'activite biologique au sein du reacteur sans pour autant degrader la qualite de l'eau traitee. Pour repondre a ce defi, il a ete propose de developper un BRM en association avec un pretraitement physico-chimique dont le role est de retenir une grande part de la matiere organique (mais aussi probablement les phosphates), le BRM n'a alors pour role que de traiter le residuel de matiere organique et d'eliminer les composes azotes p...
In the southern part of Tunisia, brackish water is desalinated and blended with raw water to be d... more In the southern part of Tunisia, brackish water is desalinated and blended with raw water to be delivered to the consumer. The desalination technique used is reverse osmosis (RO). However, it is an energy intensive process compared to other water treatment technologies such as nanofiltration (NF). The latter technique is capable of retaining polyvalent ions and could provide the same distributed water quality with much lower energy consumption. In this work, simulations were conducted in order to compare reverse osmosis and nanofiltration performances in brackish water desalination process within arid regions and to determine the best technique for desalting brackish water for lower energy and water consumptions. For a given distributed water quality, specific energy consumption could be reduced by 40% when nanofiltration is used instead of reverse osmosis. Water consumption when NF is applied is reduced as well. The distributed water quality is not significantly affected by applying NF instead of RO. Besides, these environmental aspects, scaling assessment favored NF as well.
Recently, several research works highlighted the interest of hybrid separation process combining ... more Recently, several research works highlighted the interest of hybrid separation process combining bipolar membrane electrodialysis (BMED) and ion exchange (IEX) for the recovery and concentration of organic acids from diluted effluents. The mechanisms involved in such hybrid systems are numerous. They include: transfer through ion exchange membranes, transport within aqueous solution, transport within ion exchange resin bed, and water dissociation within bipolar membranes. The present work aims at getting a better understanding of the mechanisms involved in this hybrid system and at proposing a methodology to minimize energy consumption as function of the required purity or concentration factor. For this purpose, an experimental investigation was carried out on a BMED-IEX hybrid pilot unit with different types of IEX resins. Experimental measurements conducted, consecutively with decoupled and coupled systems, allowed evaluating the contribution of each step in the overall energy consumption. The approach allowed as well identifying what would be the concentration factor to reduce energy consumption.
Journal of Chemical Engineering & Process Technology, 2012
Liquid-liquid solvent extraction technology is used in several industrial processes such as petro... more Liquid-liquid solvent extraction technology is used in several industrial processes such as petrochemical processing, pharmaceutical production, food and hydrometallurgy. It is successfully applied for the purification of Wet Phosphoric Acid (WPA) with fairly good purification performances. The purification process is basically carried out in three steps: extraction, washing and recovery, each of these steps is a liquid-liquid extraction operation. The aim was to develop a computer code that helps predicting the overall performance of the purification process for a given set of operating conditions. The adopted approach is based on determining the necessary theoretical stages for each step in the purification process using a numerical technique. Some simulation results for the WPA purification process with Tri-Butyl Phosphate (TBP) at 45°C, Methyl Isobutyl Ketone (MIBK) at 25°C and a mixture (MIBK+TBP) at 30°C are presented.
A mathematical model was developed to predict super saturation along reverse osmosis modules (RO)... more A mathematical model was developed to predict super saturation along reverse osmosis modules (RO) for water desalination. This model is based on conservation principles and chemical equilibrium equations for concentrated solutions. Pitzer's model was used for the activity coefficient calculations. An average rejection rate for each ionic species was also considered. Supersaturations with respect to all calcium carbonate forms and to calcium sulfate are calculated. The model allows assessing when scale is likely to occur along the RO modules. The results for two brackish water qualities and seawater are shown.
HAL (Le Centre pour la Communication Scientifique Directe), Sep 22, 2016
An organogel is firstly prepared by synthesizing an aminoacid-type organogelator which is able to... more An organogel is firstly prepared by synthesizing an aminoacid-type organogelator which is able to immobilize aromatic solvents, such as tetralin or toluene. Aerogels are obtained from organogels by extracting the solvent with a stream of supercritical CO 2 in an autoclave. The CO 2 / solvent mixture leaving the autoclave is separated in a cascade of three cyclone separators. The experimental results showed a good solvent recovery rate in the case of tetralin, exceeding 90%, but an unsatisfactory separation for toluene with a yield below 65%. A thermodynamic study was carried out to model the separation for both solvents. The Peng-Robinson equation of state with van der Waals mixing rules and temperature-dependent binary interaction coefficients was selected to predict the CO 2 /solvent thermodynamic behavior. Measurements of isothermal bubble points of the CO 2 /tetralin system were conducted using a high-pressure variable-volume visual cell confirming the relevancy of this model. Then, the first separator was simulated as a simple theoretical equilibrium stage. Simulations using PRO/II software were in good agreement with experimental solvent recovery rate for both toluene and tetralin. The best operating pressure and temperature for the separation were computed by a numerical parametric study. Graphical abstract Thermodynamic study to explain theoretical recovery in organogel supercritical drying: comparison between two solvents (T=20°C, P=50 bar).
This work reports the main results of an experimental investigation aimed to improve the purity o... more This work reports the main results of an experimental investigation aimed to improve the purity of lithium salts extracted from natural brines using two different nanofiltration (NF) membranes. The idea is to use NF membrane separation to further increase Li to Ca concentrations’ ratios. A synthetic brine, miming the reextraction water of a solvent extraction operation from Chilean Atacama Salar–inspired brines, was treated in a pilot unit. Two different membranes were investigated and compared for the best performances. The filtration results showed that a layer-by-layer (LbL)-modified hollow-fiber membranes, denoted dNF40 with end-of-Life NF90 flat-sheet membranes, referred to as EoL-NF90, operated at transmembrane pressures of 2 bar and 20 bar, respectively, show a 10 times lower energy consumption for dNF40. Also, both tested NF membranes were capable of selectively enriched permeates in Li versus Ca with a better performances observed for dNF40.
Pollutants derived from real textile wastewater present a high environmental risk. This work invo... more Pollutants derived from real textile wastewater present a high environmental risk. This work involves the study of the removal of chemical oxygen demand (COD), color, and turbidity from Tunisian real textile wastewater by two different water treatment technologies: chemical coagulation (CC) and electrocoagulation (EC). A comparative study between these two methods was conducted based on the separation performance and operating cost (OC). The effects of different operational parameters including electrolysis time (t), voltage, and pH for EC and the coagulant concentration, initial pH, and time of slow mixing (tsm) for CC were studied using response surface methodology. The developed quadratic models for the responses were in good agreement with the experimental data. The experiments proved the efficiency of both chemical and electrochemical techniques for the treatment of textile effluent. Indeed, by using EC, the reduction efficiencies of COD, color, and turbidity were 63.05, 99.07, and 96.31%, respectively, under optimal conditions (pH 9, t = 36.26 min, and voltage 4 V). For CC treatment, the achieved removal efficiencies of COD, color, and turbidity were 54.02, 96.21, and 93.7%, respectively, at pH 8.57, a coagulant concentration of 204.75 mg/L, and a tsm of 28.41 min as optimal operating conditions. The OC obtained for EC and CC was about 0.47 and 0.2 USD/m3, respectively. Even if the OC of the EC process was higher as compared to the CC process, the treated water obtained by EC meets the Tunisian Standards (NT 106.03 and NT 09-14) for textile wastewater discharge into the environment and demonstrates a high potential for its reuse in various industrial activities. EC technology can be integrated into a wastewater management system that ensures a zero liquid discharge of wastewater into the environment.
Electrocoagulation (EC) technique gained a significant attention owing to its efficiency in remov... more Electrocoagulation (EC) technique gained a significant attention owing to its efficiency in removing colors and contaminations in industrial effluents discharged from numerous industries as textiles, pulp and paper industry, landfill leachate, food processing industry and tannery industry, etc. These effluents are characterized by a wide range of chemical oxygen demand (COD), heavy metals, suspended solids, turbidity and color levels. Most published works focused on the optimization of the operational parameters of EC in order to enhance the simultaneous abatement of soluble and colloidal pollutants. Indeed, EC is influenced by several operation parameters such as pH, applied current density, electrodes material and configuration, conductivity of the solution, electrode gap, electrolysis time and mixing rate. The present work handles the implied mechanisms in removing such contaminants from wastewater together with discussing the major operating parameters influencing the EC performance. Special emphasis is accorded to reducing COD and colors from wastewater. Comparing economically of EC with other alternatives is also conducted aiming at providing a reference for process selection. Economic assessment gives the opportunity for further optimizing the appropriate technology of wastewater treatment through the different strategies of cost optimization.
Advances in science, technology & innovation, 2018
Pomegranate, especially the Punica granatum L. variety, is widely grown in Tunisia. This fruit is... more Pomegranate, especially the Punica granatum L. variety, is widely grown in Tunisia. This fruit is a rich source of phenolic compounds including ellagitannins, phenolic acids and flavonoids.
PurposeThe main purpose of this study resides essentially in the development of a new tool to qua... more PurposeThe main purpose of this study resides essentially in the development of a new tool to quantify the biomass in the bioreactor operating under steady state conditions.Design/methodology/approachModeling is the most relevant tool for understanding the functioning of some complex processes such as biological wastewater treatment. A steady state model equation of activated sludge model 1 (ASM1) was developed, especially for autotrophic biomass (XBA) and for oxygen uptake rate (OUR). Furthermore, a respirometric measurement, under steady state and endogenous conditions, was used as a new tool for quantifying the viable biomass concentration in the bioreactor.FindingsThe developed steady state equations simplified the sensitivity analysis and allowed the autotrophic biomass (XBA) quantification. Indeed, the XBA concentration was approximately 212 mg COD/L and 454 mgCOD/L for SRT, equal to 20 and 40 d, respectively. Under the steady state condition, monitoring of endogenous OUR perm...
Electrocoagulation (EC) technique gained a significant attention owing to its efficiency in remov... more Electrocoagulation (EC) technique gained a significant attention owing to its efficiency in removing colors and contaminations in industrial effluents discharged from numerous industries as textiles, pulp and paper industry, landfill leachate, food processing industry and tannery industry, etc. These effluents are characterized by a wide range of chemical oxygen demand (COD), heavy metals, suspended solids, turbidity and color levels. Most published works focused on the optimization of the operational parameters of EC in order to enhance the simultaneous abatement of soluble and colloidal pollutants. Indeed, EC is influenced by several operation parameters such as pH, applied current density, electrodes material and configuration, conductivity of the solution, electrode gap, electrolysis time and mixing rate. The present work handles the implied mechanisms in removing such contaminants from wastewater together with discussing the major operating parameters influencing the EC performance. Special emphasis is accorded to reducing COD and colors from wastewater. Comparing economically of EC with other alternatives is also conducted aiming at providing a reference for process selection. Economic assessment gives the opportunity for further optimizing the appropriate technology of wastewater treatment through the different strategies of cost optimization.
This article aims to present equipment designed and developed to study the effective thermal cond... more This article aims to present equipment designed and developed to study the effective thermal conductivity of composite panels. The composite panel used is a rigid polyurethane foam covered with a layer of aluminum on both sides. The panel is mounted in the test chamber equipped with several sensors and actuators connected via an Arduino platform. Tests have been carried out by applying heat to impose various interior temperatures. Sensors at different locations are used to monitor and record temperatures in and around the composite panel during heating and natural cooling. A model, based on the Fourier equations of thermal conduction and natural convection heat transfer for the steady state, was developed to assess the effective thermal conductivity. The performance of the system was confirmed using temperature signals through the panels for thermal characterization of composite materials. The determined effective thermal conductivity obtained was in agreement with the experimental values reported in the technical data sheets with relative deviations of less than 10 %.
Membrane processes are dominating desalination techniques. Reverse osmosis (RO) is currently the ... more Membrane processes are dominating desalination techniques. Reverse osmosis (RO) is currently the most used technique for seawater and brackish water desalination. Nanofiltration (NF) could be an interesting alternative option for brackish water desalination. As global warming unleashes its disastrous impact on freshwater availability, desalination techniques are helping ensuring water supplies cover the increasing demand for drinking and all economic sectors. The overall performances of such membrane processes depend on many factors. Flow hydrodynamics within membrane modules is particularly critical for ensuring better salt retention, higher recovery rate, and longer module life span by helping preventing scaling and fouling. In this work, we attempted to determine the residence time distribution as a flow hydrodynamics characterization method in spiral-wound membrane modules. The experimental work was performed on RO and NF modules of a laboratory scale unit. It proved that RO modules have better mixing quality compared to the case of NF which have a shorter mean residence time. It also confirmed that increasing the applied pressure, within the considered experimental domain, leads to better flow patterns approaching plug flow configuration.
A setup consisting of a glass column packed with calibrated glass rings has been achieved. It ope... more A setup consisting of a glass column packed with calibrated glass rings has been achieved. It operates on the principle of an air lift pump. It was designed for the best contact between air and water. Performances of this system were determined by measuring the displaced water flow rates for different submersion depths and various air flow rates. We studied the pressure drop versus the immersion depth in the column. The results show that the pressure loss is described by a second order polynomial equation. Efficiency was calculated for different conditions. The study shows that the proposed system can be set easily, has low power consumption, provides a good mix between phases and is very important for many applications where heat and mass transfer are involved.
Le surcout de fonctionnement d'un BRM immerge a pour origine essentielle la depense d'ene... more Le surcout de fonctionnement d'un BRM immerge a pour origine essentielle la depense d'energie liee a la maitrise de la permeabilite membranaire par aeration. La litterature montre les liens qui existent entre concentration en biomasse dans le reacteur et presence de produits microbiens solubles lies a l'activite bacterienne. Reduire la demande en energie signifie reduire l'aeration membrane, voire l'aeration process liee aux besoins en oxygene des populations epuratrices. Pour ce faire, il est donc determinant de reduire l'activite biologique au sein du reacteur sans pour autant degrader la qualite de l'eau traitee. Pour repondre a ce defi, il a ete propose de developper un BRM en association avec un pretraitement physico-chimique dont le role est de retenir une grande part de la matiere organique (mais aussi probablement les phosphates), le BRM n'a alors pour role que de traiter le residuel de matiere organique et d'eliminer les composes azotes p...
In the southern part of Tunisia, brackish water is desalinated and blended with raw water to be d... more In the southern part of Tunisia, brackish water is desalinated and blended with raw water to be delivered to the consumer. The desalination technique used is reverse osmosis (RO). However, it is an energy intensive process compared to other water treatment technologies such as nanofiltration (NF). The latter technique is capable of retaining polyvalent ions and could provide the same distributed water quality with much lower energy consumption. In this work, simulations were conducted in order to compare reverse osmosis and nanofiltration performances in brackish water desalination process within arid regions and to determine the best technique for desalting brackish water for lower energy and water consumptions. For a given distributed water quality, specific energy consumption could be reduced by 40% when nanofiltration is used instead of reverse osmosis. Water consumption when NF is applied is reduced as well. The distributed water quality is not significantly affected by applying NF instead of RO. Besides, these environmental aspects, scaling assessment favored NF as well.
Recently, several research works highlighted the interest of hybrid separation process combining ... more Recently, several research works highlighted the interest of hybrid separation process combining bipolar membrane electrodialysis (BMED) and ion exchange (IEX) for the recovery and concentration of organic acids from diluted effluents. The mechanisms involved in such hybrid systems are numerous. They include: transfer through ion exchange membranes, transport within aqueous solution, transport within ion exchange resin bed, and water dissociation within bipolar membranes. The present work aims at getting a better understanding of the mechanisms involved in this hybrid system and at proposing a methodology to minimize energy consumption as function of the required purity or concentration factor. For this purpose, an experimental investigation was carried out on a BMED-IEX hybrid pilot unit with different types of IEX resins. Experimental measurements conducted, consecutively with decoupled and coupled systems, allowed evaluating the contribution of each step in the overall energy consumption. The approach allowed as well identifying what would be the concentration factor to reduce energy consumption.
Journal of Chemical Engineering & Process Technology, 2012
Liquid-liquid solvent extraction technology is used in several industrial processes such as petro... more Liquid-liquid solvent extraction technology is used in several industrial processes such as petrochemical processing, pharmaceutical production, food and hydrometallurgy. It is successfully applied for the purification of Wet Phosphoric Acid (WPA) with fairly good purification performances. The purification process is basically carried out in three steps: extraction, washing and recovery, each of these steps is a liquid-liquid extraction operation. The aim was to develop a computer code that helps predicting the overall performance of the purification process for a given set of operating conditions. The adopted approach is based on determining the necessary theoretical stages for each step in the purification process using a numerical technique. Some simulation results for the WPA purification process with Tri-Butyl Phosphate (TBP) at 45°C, Methyl Isobutyl Ketone (MIBK) at 25°C and a mixture (MIBK+TBP) at 30°C are presented.
A mathematical model was developed to predict super saturation along reverse osmosis modules (RO)... more A mathematical model was developed to predict super saturation along reverse osmosis modules (RO) for water desalination. This model is based on conservation principles and chemical equilibrium equations for concentrated solutions. Pitzer's model was used for the activity coefficient calculations. An average rejection rate for each ionic species was also considered. Supersaturations with respect to all calcium carbonate forms and to calcium sulfate are calculated. The model allows assessing when scale is likely to occur along the RO modules. The results for two brackish water qualities and seawater are shown.
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Papers by Ahmed Hannachi