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A novel design of an air injection zigzag system was developed to enhance the tubular membrane distillation module’s performance for desalination of water, unlike the basic design that works without an air injection system. Designed in a zigzag mode, the membrane distillation module is set to yield a high turbulence flow. Operating parameter effects, for example, the feed temperature (40°C, 50°C, 60°C, and 70°C), feed concentration (1, 3, and 5 g/L), and airflow rate (30–90 L/h), on process performance were investigated. The system proved its capability to enhance the heat and mass transfer coefficients. The basic and developed modules’ performances were compared in terms of permeate flux (Jm) and thermal efficiency (η). The Reynolds number increased threefold, which consequently, increased the mass transfer coefficient by 25% and the heat transfer coefficient twofold compared to the basic module at airflow rate of 90 L/h. Moreover, the thermal efficiency and permeate flux were higher than the basic module’s by roughly 1.4 and 1.5-fold, respectively, for a 5 g/L feed concentration.

•Thermal performance of horizontal and vertical LHTS experimentally and theoretically considered.•Finned and non-finned configurations of LHTS during charging were tested.•Fins enhanced melting process by an average of 50%.•Orientation was significantly affected melting in non-finned LHTS.•Only minor impact of orientation on finned LHTS Please make the changes as requested.

•Thermal performance of horizontal coiled tube LHTS device was experimentally considered.•Both charging and discharging of PCM were investigated.•Effect of initial temperature and flow rate of HTF on PCM in melting and solidification was tested.•Initial temperature of HTF was significantly affected the melting process.•Optimum HTF flow rate for melting was determined and it was 3 L/h.

This paper describes the preparation and characterization of different granular activated carbon (GAC) structures from date pits and also investigates their sorption efficiency to adsorb glucose and maltose draw solutions in forward osmosis (FO) desalination process. The dates pits chars were chemically activated using sulphuric acid, phosphoric acid and zinc chloride as dehydrating agents. Activation affected parameters such as temperature, time, impregnation ratios and the chars particle sizes were examined. Scanning electron microscopy and Fourier transform infrared spectroscopy techniques were used to determine the products surface morphology and types of functional groups, respectively. The activation increased pores networks and changed the surface morphology and functional groups. ZnCl2activated GAC showed the highest capacity to adsorb glucose and maltose from their aqueous solutions.

A dual stage PRO process has been proposed for power generation from a salinity gradient across a semi-permeable membrane. Both closed-loop and open-loop dual stage PRO system were evaluated using 2 M NaCl and Dead Sea as draw solutions, whereas the feed solution was either fresh water or seawater. The impact of feed salinity gradient resource and feed pressure on the net power generation and water flux were evaluated. The results showed that power density in stage one reached a maximum amount at ∆P= π/2, but the maximum net power generation occurred at ∆P= π/2. This result was mainly attributed to the variation of net driving pressure in stage one and two of the PRO process. The dual stage PRO process was found to perform better at high osmotic pressure gradient across the PRO membrane, for example when Dead Sea brine or highly concentrated NaCl was the draw solution. Total power generation in the dual stage PRO process was up to 40% higher than that in the conventional PRO process. This outcome was achieved through harvesting the rest of the energy remaining in the diluted draw solution. Therefore, a dual stage PRO process has the potential of maximizing power generation from a salinity gradient resource.

AbstractNovel desalination approaches are required to provide both drinking and agricultural water as there is ever increasing stress upon precious freshwater resources. It was our hypothesis that a modified Forward Osmosis (FO) process had the potential for production of irrigation water comprising of appropriate concentrations of fertilizers from a seawater feed. Four agents, KNO3, Na2SO4, CaNO3, and MgCl2, plus 35 g/L seawater were used as the draw and feed solutions of the FO process. Net Driving Pressure in the FO process was manipulated either by increasing the concentration of draw solution (FO process) or by increasing feed pressure (Pressure Assisted FO (PAFO) process). A series of nanofiltration (NF) and reverse osmosis (RO) membranes were used for the regeneration of draw solution. The results suggested that a PAFO process was more energy efficient than simple FO, provided the energy relating to the brine flow from the NF/RO membrane for pressurizing the feed solution of PAFO process was used. Furthermore, this study suggested using a mixture of a primary draw solution, MgCl2, and a secondary draw solution, KNO3, for NO3supply into the irrigation water was preferable. As such, MgCl2provided the driving force for fresh water extraction while KNO3was the source of fertilizer in the irrigation water. Results showed that water quality provided by application of a MgCl2 + KNO3draw solution was better than that from KNO3or Ca(NO3)2. The concentrations of NO3and SO4in irrigation water were within recommended levels when the diluted draw solution was regenerated by a dual stage low-pressure RO process.

Novel desalination approaches are required to provide both drinking and agricultural water as there is ever increasing stress upon precious freshwater resources. It was our hypothesis that a modified Forward Osmosis (FO) process had the potential for production of irrigation water comprising of appropriate concentrations of fertilizers from a seawater feed. Four agents, KNO3, Na2SO4, CaNO3, and MgCl2, plus 35 g/L seawater were used as the draw and feed solutions of the FO process. Net Driving Pressure in the FO process was manipulated either by increasing the concentration of draw solution (FO process) or by increasing feed pressure (Pressure Assisted FO (PAFO) process). A series of nanofiltration (NF) and reverse osmosis (RO) membranes were used for the regeneration of draw solution. The results suggested that a PAFO process was more energy efficient than simple FO, provided the energy relating to the brine flow from the NF/RO membrane for pressurizing the feed solution of PAFO process was used. Furthermore, this study suggested using a mixture of a primary draw solution, MgCl2, and a secondary draw solution, KNO3, for NO3supply into the irrigation water was preferable. As such, MgCl2provided the driving force for fresh water extraction while KNO3was the source of fertilizer in the irrigation water. Results showed that water quality provided by application of a MgCl2+ KNO3draw solution was better than that from KNO3or Ca(NO3)2. The concentrations of NO3and SO4in irrigation water were within recommended levels when the diluted draw solution was regenerated by a dual stage low-pressure RO process.

AbstractNanofiltration membrane system is proposed for the regeneration of draw solution in a two-stage forward osmosis (FO) process. Pilot plant experiments were carried out on two types of multivalent electrolyte draw solutions, MgSO4and MgCl2. Two commercial size NF90-4040 Filmtec Nanofiltration (NF) membranes were packed in a high-pressure vessel for the regeneration of draw solution. The concentrations of the draw solution used were between 20 and 118 g/L. The impact of feed concentration, flow rate and feed pressure on the performance of NF membrane was investigated. Both metal salts have shown a high rejection rate by the NF membrane. The rejection rate to the MgSO4was slightly higher than that to the MgCl2. Experimental results showed that NF rejection rate and permeate flow rate increased with increasing the feed pressure and flow rate but decreased with increasing the concentration of feed solution. However, this was achieved at the expense of higher power consumption. In general, the efficiency of NF system for the regeneration of draw solution was higher at lower feed concentration. This suggests that NF separation method is probably more suitable for the regeneration of low concentration draw solution which is generated from brackish water FO treatment plants. Furthermore, NF application in the regeneration of high-concentration draw solution is not yet feasible due to the limitations in the NF process such operating feed pressure and rejection rate.

Nanofiltration membrane system is proposed for the regeneration of draw solution in a two-stage forward osmosis (FO) process. Pilot plant experiments were carried out on two types of multivalent electrolyte draw solutions, MgSO4and MgCl2. Two commercial size NF90-4040 Filmtec Nanofiltration (NF) membranes were packed in a high-pressure vessel for the regeneration of draw solution. The concentrations of the draw solution used were between 20 and 118 g/L. The impact of feed concentration, flow rate and feed pressure on the performance of NF membrane was investigated. Both metal salts have shown a high rejection rate by the NF membrane. The rejection rate to the MgSO4was slightly higher than that to the MgCl2. Experimental results showed that NF rejection rate and permeate flow rate increased with increasing the feed pressure and flow rate but decreased with increasing the concentration of feed solution. However, this was achieved at the expense of higher power consumption. In general, the efficiency of NF system for the regeneration of draw solution was higher at lower feed concentration. This suggests that NF separation method is probably more suitable for the regeneration of low concentration draw solution which is generated from brackish water FO treatment plants. Furthermore, NF application in the regeneration of high-concentration draw solution is not yet feasible due to the limitations in the NF process such operating feed pressure and rejection rate.

AbstractIn this study, the regeneration performance of sodium chloride and sucrose draw solutions using a forward osmosis (FO) membrane was experimentally investigated in a FO–RO system. This efficiency was examined in terms of water flux (Jw), water recovery percentage (R%) and specific energy consumption (SEC) using a commercial RO membrane. Two sodium chloride feed solution concentrations of 9.3 g/l (osmotic pressure (OP) = 7.31 bars) and 17.9 g/l (osmotic pressure (OP) = 14.05 bars), as well as two sucrose feed solution concentrations of 150 g/l (OP = 11.21 bars) and 200 g/l (OP = 15.13 bars) were tested separately. At each experiment, feed solution is pumped to the RO membrane at different applied feed pressure values, while the flow rate and temperature of the solutions were kept constant throughout the experiments. The experimental results indicated that: water flux and water recovery percentage for sodium chloride and sucrose feed solutions in general are increased with rise in the RO feed pressure applied. Also, the SEC for sodium chloride and sucrose feed solutions decreased as the RO feed applied pressure was raised. The findings exhibit that the hollow fine fibre HR3155P RO membrane is more reliable for the regeneration of sodium chloride draw solution than sucrose draw solution. Moreover, the RO technique is not reliable to use in the regeneration of sucrose draw solution in a FO–RO system.

In this study, the regeneration performance of sodium chloride and sucrose draw solutions using a forward osmosis (FO) membrane was experimentally investigated in a FO–RO system. This efficiency was examined in terms of water flux (Jw), water recovery percentage (R%) and specific energy consumption (SEC) using a commercial RO membrane. Two sodium chloride feed solution concentrations of 9.3 g/l (osmotic pressure (OP) = 7.31 bars) and 17.9 g/l (osmotic pressure (OP) = 14.05 bars), as well as two sucrose feed solution concentrations of 150 g/l (OP = 11.21 bars) and 200 g/l (OP = 15.13 bars) were tested separately. At each experiment, feed solution is pumped to the RO membrane at different applied feed pressure values, while the flow rate and temperature of the solutions were kept constant throughout the experiments. The experimental results indicated that: water flux and water recovery percentage for sodium chloride and sucrose feed solutions in general are increased with rise in the RO feed pressure applied. Also, the SEC for sodium chloride and sucrose feed solutions decreased as the RO feed applied pressure was raised. The findings exhibit that the hollow fine fibre HR3155P RO membrane is more reliable for the regeneration of sodium chloride draw solution than sucrose draw solution. Moreover, the RO technique is not reliable to use in the regeneration of sucrose draw solution in a FO–RO system.

This work investigates the effectiveness of sodium chloride and sucrose binary draw solutions in a forward osmosis pilot plant unit with either deionised or salt water feeds. Specifically, the effects of draw solution concentration on water flux through the membrane, the overall water recovery and the specific energy consumption of the unit are considered. For both feed types, sodium chloride draw solution exhibited a relatively high effectiveness in terms of all the measured performance indicators. Further, improvements in flux and recovery were also achievable with an increase in the sodium chloride (draw solution) concentration. In contrast, a sucrose-based draw solution led to a severe deterioration of the membrane performance that could not be effectively overcome by an increase in the draw solution concentration. This observation was attributed to the relatively large increase in the viscosity of the draw solution with increase in sucrose concentration. Interestingly, in the case of a salt water feed, an increase in the sucrose draw solution concentration led to a relatively small increase in flux and recovery, suggesting some complex but favourable interaction between the salt and sucrose due to the reverse diffusion of the salt into the draw solution.

AbstractRecent installed power plants (PP) in Qatar and other Gulf Co-operation Countries (GCC) are using combined cycle (CC). The CC cycle consists of gas turbine (GT), heat recovery steam generators (HRSG), and steam turbine (ST). In these plants, GTs produce electric power (EP) and its exhaust hot gasses operate the HRSG to generate steam. The steam is supplied to ST that generates more EP, and its extracted (or discharged) steam is directed to thermally operated desalting plant (DP), e.g. multi stage flash (MSF) or multi-effect thermal vapor compression (ME-TVC) producing desalted seawater (DW). A plant producing both EP and DW is called co-generation power desalting plant (CPDP). The used ST type is either extraction condensing steam turbine or back-pressure steam turbine. The MSF or ME-TVC consumes about 280 MJ/m3thermal energy, besides pumping energy of 4 kWh/m3for MSF or 2 kWh/m3for ME-TVC systems. Because of high consumed energy, the MSF and ME-TVC systems have to be substituted by the much more energy-efficient seawater reverse osmosis (SWRO) desalting system, which consumes 4–5 kWh/m3only as pumping energy. Replacement of the MSF (or ME-TVC) with the SWRO system will ban the use of steam extracted (discharged) to the DP; the plants produce only EP, and become single-purpose PP. This reduces the plant overall efficiency unless major retrofitting is done by adding low pressure (LP) ST and condenser to expand the steam that was supplied to the DP in the turbine to produce more work. In this paper, it is suggested that the CPDP widely used in the GCC to become a tri-generation plant producing EP, DW (by SWRO), and chilled water for district cooling (DC). An analysis is presented for the newly suggested configuration. It showed that a reference plant can be fitted with SWRO to replace the DP of MSF or ME-TVC and gives almost the same DW production capacity for the identical consumed EP by the MSF units. The process heat that was supplied to the thermal desalting units would be utilized for DC system using an absorption cooling unit(s). Comparisons of absorption cooling with the EP driven mechanical vapor compression refrigeration; and SWRO with the MSF desalting systems are illustrated in this article. The benefits of using DC in the GCC are also presented.

Recent installed power plants (PP) in Qatar and other Gulf Co-operation Countries (GCC) are using combined cycle (CC). The CC cycle consists of gas turbine (GT), heat recovery steam generators (HRSG), and steam turbine (ST). In these plants, GTs produce electric power (EP) and its exhaust hot gasses operate the HRSG to generate steam. The steam is supplied to ST that generates more EP, and its extracted (or discharged) steam is directed to thermally operated desalting plant (DP), e.g. multi stage flash (MSF) or multi-effect thermal vapor compression (ME-TVC) producing desalted seawater (DW). A plant producing both EP and DW is called co-generation power desalting plant (CPDP). The used ST type is either extraction condensing steam turbine or back-pressure steam turbine. The MSF or ME-TVC consumes about 280 MJ/m3thermal energy, besides pumping energy of 4 kWh/m3for MSF or 2 kWh/m3for ME-TVC systems. Because of high consumed energy, the MSF and ME-TVC systems have to be substituted by the much more energy-efficient seawater reverse osmosis (SWRO) desalting system, which consumes 4–5 kWh/m3only as pumping energy. Replacement of the MSF (or ME-TVC) with the SWRO system will ban the use of steam extracted (discharged) to the DP; the plants produce only EP, and become single-purpose PP. This reduces the plant overall efficiency unless major retrofitting is done by adding low pressure (LP) ST and condenser to expand the steam that was supplied to the DP in the turbine to produce more work. In this paper, it is suggested that the CPDP widely used in the GCC to become a tri-generation plant producing EP, DW (by SWRO), and chilled water for district cooling (DC). An analysis is presented for the newly suggested configuration. It showed that a reference plant can be fitted with SWRO to replace the DP of MSF or ME-TVC and gives almost the same DW production capacity for the identical consumed EP by the MSF units. The process heat that was supplied to the thermal desalting units would be utilized for DC system using an absorption cooling unit(s). Comparisons of absorption cooling with the EP driven mechanical vapor compression refrigeration; and SWRO with the MSF desalting systems are illustrated in this article. The benefits of using DC in the GCC are also presented.

AbstractSeawater reverse osmosis (SWRO) is the most cost-effective, practical, and widely used desalting system. Its energy consumption, for Arabian Gulf seawater conditions is in the range of 5–6 kWh/m3. These are less than 1/3 of the equivalent mechanical energy of the thermal desalination systems presently used in Qatar. Besides, these thermal systems consume 2–4 kWh/m3for pumping. Therefore, using SWRO system in Qatar can save up to 75% of the desalination energy cost. For Qatar, current desalting water production using thermal methods is 480 Mm3/year at $0.1–1.2/kWh energy price; the energy cost is at least one Billion US dollars per annum. A SWRO pilot plant is to be built in Qatar prior to building a full size desalting plant (DP) in order to determine site-specific treatment guidelines and to provide a full range of performance information to be used in the design of a full-scale plant. The pilot plant will be tested when the feedwater quality is good, and when there are major storm events or algae blooms exist. Red tide events in 2008–2009 forced many DPs in Gulf Co-operation Countries area to shut down. This paper reviews the SWRO pretreatment process, which depends on local conditions and is the main factor affecting the SWRO reliability. These include the extensively used conventional pretreatment of coagulation–flocculation and granular media filtration (GMF). This is almost necessary for open sea intake. Sever red tide blooms, when occur, cause clogging of GMF, resulted in biological and organic foulants on SWRO membranes, and even DP shut down. So, low-pressure membranes such as ultrafiltration (UF) or microfiltration (MF) can replace or integrated with GMF. Since flotation is more robust than sedimentation (used in GMF) in dealing with high concentration of suspended matter, dissolved air flotation is started to be used as pretreatment. Since it is a new method that met success in several plants, it thoroughly reviewed in this paper when integrated with GMF or membrane treatment. Additionally, the expensive pretreatment with UF and MF is discussed with given examples. Preliminary experimentation with SWRO pretreatment in Qatar was presented. Moreover, energy recovery devices to be used with the pilot SWRO are discussed. Membranes configuration and the equipment to be included are also outlined.

Seawater reverse osmosis (SWRO) is the most cost-effective, practical, and widely used desalting system. Its energy consumption, for Arabian Gulf seawater conditions is in the range of 5–6 kWh/m3. These are less than 1/3 of the equivalent mechanical energy of the thermal desalination systems presently used in Qatar. Besides, these thermal systems consume 2–4 kWh/m3for pumping. Therefore, using SWRO system in Qatar can save up to 75% of the desalination energy cost. For Qatar, current desalting water production using thermal methods is 480 Mm3/year at $0.1–1.2/kWh energy price; the energy cost is at least one Billion US dollars per annum. A SWRO pilot plant is to be built in Qatar prior to building a full size desalting plant (DP) in order to determine site-specific treatment guidelines and to provide a full range of performance information to be used in the design of a full-scale plant. The pilot plant will be tested when the feedwater quality is good, and when there are major storm events or algae blooms exist. Red tide events in 2008–2009 forced many DPs in Gulf Co-operation Countries area to shut down. This paper reviews the SWRO pretreatment process, which depends on local conditions and is the main factor affecting the SWRO reliability. These include the extensively used conventional pretreatment of coagulation–flocculation and granular media filtration (GMF). This is almost necessary for open sea intake. Sever red tide blooms, when occur, cause clogging of GMF, resulted in biological and organic foulants on SWRO membranes, and even DP shut down. So, low-pressure membranes such as ultrafiltration (UF) or microfiltration (MF) can replace or integrated with GMF. Since flotation is more robust than sedimentation (used in GMF) in dealing with high concentration of suspended matter, dissolved air flotation is started to be used as pretreatment. Since it is a new method that met success in several plants, it thoroughly reviewed in this paper when integrated with GMF or membrane treatment. Additionally, the expensive pretreatment with UF and MF is discussed with given examples. Preliminary experimentation with SWRO pretreatment in Qatar was presented. Moreover, energy recovery devices to be used with the pilot SWRO are discussed. Membranes configuration and the equipment to be included are also outlined.

The purpose of this study is mainly to investigate the performance of a packed-bed continuous-recirculation flow reactor at high applied electric current in removing copper, Cu(II), from simulated electrolyte by electrodeposition. The effects of pHo, circulation rate of flow, initial copper concentration, intensity of the applied current and the method of application of electric current, as to have a constant value during all the time of electrolysis or to be decreased with time, on copper electrodeposition and current efficiency are revealed. The results showed that the increase in pH (provided not lead to the deposition of Cu(OH)2), initial concentration of the copper and flow rate increased the electrodeposition of copper as well as improved current efficiency. However, increasing intensity of the applied electric current led to an increase in the electrodeposition of copper and decreased electrical efficiency. It was also observed that reducing the intensity of applied electric current with time during the electrolysis process while maintaining other operating variables constant led to a significant reduction in the consumption of electrical energy used in the process of copper removal by electrodeposition; a reduction of 41.6% could be achieved.

A Galerkin finite-element approach combined with an error estimator and automatic mesh refinement has been used to provide a flexible numerical solution of the Poisson–Boltzmann equation. A Newton sequence technique was used to solve the nonlinear equations arising from the finite-element discretization procedure. Errors arising from the finite-element solution due to mesh refinement were calculated using the Zienkiewicz–Zhu error estimator, and an automatic remeshing strategy was adopted to achieve a solution satisfying a preset quality. Examples of the performance of the error estimator in adaptive mesh refinement are presented. The adaptive finite-element scheme presented in this study has proved to be an effective technique in minimizing errors in finite-element solutions for a given problem, in particular those of complex geometries. As an example, numerical solutions are presented for the case of a charged spherical particle at various distances from a charged cylindrical pore in a charged planar surface. Such a scheme provides a quantification of the significance of electrostatic interactions for an important industrial technology—membrane separation processes.

The transport of a particle-containing liquid through a capillary pore has been studied using a finite element method. Direct calculation has been made of flow fields, drag correction factors, and pressure drops for single particles and short chains of particles using the center-line approach. Three cases have been considered a moving sphere in a stationary liquid, a stationary sphere in a moving liquid, and a moving sphere in a moving liquid. The correction factors for the inner sphere in short chains agree well with the results of complex stream function calculations for infinite chains of particles. Two topics have been particularly addressed. First covered is the use of the numerical calculations to identify the limiting particle spacings for which single-sphere calculations give close agreement with the calculations for such inner spheres. It is shown that single-sphere calculations have a wide range of applicability, considerably simplifying the effort involved in numerical calculation. Second, we carry out calculations up to large values of the particle radius/pore radius ratio. The case of a moving sphere in a moving liquid is directly relevant to the third topic of the paper—transport of particles through microfiltration membranes. Application of the numerical results for conditions corresponding to a commercial capillary pore microfiltration membrane show that hydrodynamic interactions can result in the maximum achievable flux for particle-containing fluids being significantly less than the pure water flux. Such hydrodynamic flux reduction has previously been neglected by membrane researchers. Copyright 1994, 1999 Academic Press

The aquaporin superfamily of hydrophobic integral membrane proteins constitutes water channels essential to the movement of water across the cell membrane, maintaining homeostatic equilibrium. During the passage of water between the extracellular and intracellular sides of the cell, aquaporins act as ultra-sensitive filters. Owing to their hydrophobic nature, aquaporins self-assemble in phospholipids. If a proper choice of lipids is made then the aquaporin biomimetic membrane can be used in the design of an artificial kidney. In combination with graphene, the aquaporin biomimetic membrane finds practical application in desalination and water recycling using mostly Escherichia coliAqpZ. Recently, human aquaporin 1 has emerged as an important biomarker in renal cell carcinoma. At present, the ultra-sensitive sensing of renal cell carcinoma is cumbersome. Hence, we discuss the use of epitopes from monoclonal antibodies as a probe for a point-of-care device for sensing renal cell carcinoma. This device works by immobilizing the antibody on the surface of a single-layer graphene, that is, as a microfluidic device for sensing renal cell carcinoma.