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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.

The feed to all Recirculation-multi-stage flash (R-MSF) desalting units in Qatar is pretreated with high temperature additive, which limits its top brine temperature (TBT) to 110°C. The daily capacity of these R-MSF units is about one Million cubic meters (Mm3/d). These units should continue their operation through their life time, (20–30 years). The capacity and performance of these units can be enhanced if Forward osmosis (FO) membrane system is used as pretreatment. The FO membranes can remove the scale constituents in the feed water and allows rising the TBT up to 135°C, and thus increases the capacity of these units. The viability of using FO as feed water pretreatment to an existing operating R-MSF unit is discussed in this paper. A suggested arrangement to use FO as MSF feed pretreatment is presented. Part of the cooling seawater leaving the heat rejection is directed to the FO pretreatment unit as feed solution (FS). The flashing brine leaving the last stage with the maximum brine salt concentration (about 1.5 times of the seawater feed) is directed to the FO unit as draw solution (DS) that absorbs an amount permeate water (D) from the FS while the Ca2+, CO3-, Mg2+, and SO42-are rejected. The diluted DS enters the last stage condenser of the heat recovery section. This arrangement allows to increase the TBT and thus the unit distillate capacity. The potential of calcium sulfate deposite index inside MSF condenser tubes is calculated at different TBTs and different FO recovery ratio. The calculations show that Skillman index in reference MSF (operates at TBT = 110°C) plant is greater than one which indicates the potential of scale deposit formation; however, antiscalant is used to disperse the crystalized scale. The simulation results showed that the potential of scale deposit is decreased as the FO recovery ratio increases due to the increase in divalent ions removal. The MSF can operate at TBT = 135°C safely without calcium sulfate scale at FO recovery ratio of 40%. On the other hand, the increase in the FO recovery ratio, will reduce the osmotic pressure difference across the membrane which requires higher membrane surface area. The impact of feed salinity is investigated, and the results showed that lowering the feed salinity gives better performance of FO unit. The cost of the FO membranes is a major factor in applying the suggested use of the FO as pretreatment for the R-MSF unit. The decision to apply this method depends on the availability and reasonable cost of the FO membranes.

AbstractThe feed to all Recirculation-multi-stage flash (R-MSF) desalting units in Qatar is pretreated with high temperature additive, which limits its top brine temperature (TBT) to 110°C. The daily capacity of these R-MSF units is about one Million cubic meters (Mm3/d). These units should continue their operation through their life time, (20–30 years). The capacity and performance of these units can be enhanced if Forward osmosis (FO) membrane system is used as pretreatment. The FO membranes can remove the scale constituents in the feed water and allows rising the TBT up to 135°C, and thus increases the capacity of these units. The viability of using FO as feed water pretreatment to an existing operating R-MSF unit is discussed in this paper. A suggested arrangement to use FO as MSF feed pretreatment is presented. Part of the cooling seawater leaving the heat rejection is directed to the FO pretreatment unit as feed solution (FS). The flashing brine leaving the last stage with the maximum brine salt concentration (about 1.5 times of the seawater feed) is directed to the FO unit as draw solution (DS) that absorbs an amount permeate water (D) from the FS while the Ca2+, , Mg2+, and are rejected. The diluted DS enters the last stage condenser of the heat recovery section. This arrangement allows to increase the TBT and thus the unit distillate capacity. The potential of calcium sulfate deposite index inside MSF condenser tubes is calculated at different TBTs and different FO recovery ratio. The calculations show that Skillman index in reference MSF (operates at TBT = 110°C) plant is greater than one which indicates the potential of scale deposit formation; however, antiscalant is used to disperse the crystalized scale. The simulation results showed that the potential of scale deposit is decreased as the FO recovery ratio increases due to the increase in divalent ions removal. The MSF can operate at TBT = 135°C safely without calcium sulfate scale at FO recovery ratio of 40%. On the other hand, the increase in the FO recovery ratio, will reduce the osmotic pressure difference across the membrane which requires higher membrane surface area. The impact of feed salinity is investigated, and the results showed that lowering the feed salinity gives better performance of FO unit. The cost of the FO membranes is a major factor in applying the suggested use of the FO as pretreatment for the R-MSF unit. The decision to apply this method depends on the availability and reasonable cost of the FO membranes.

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.

Hot corrosion of Inconel 625 in sodium chloride, potassium chloride, magnesium chloride, calcium chloride and their mixtures with different compositions is conducted at 900°C to investigate the effects of cations in chloride salts on corrosion behavior of the alloy. XRD, SEM/EDS were used to analyze the compositions, phases, and morphologies of the corrosion products. The results showed that Inconel 625 suffers more severe corrosion in alkaline earth metal chloride molten salts than alkaline metal chloride molten salts. For corrosion in mixture salts, the corrosion rate increased with increasing alkaline earth metal chloride salt content in the mixture. Cations in the chloride molten salts mainly affect the thermal and chemical properties of the salts such as vapor pressure and hydroscopicities, which can affect the basicity of the molten salt. Corrosion of Inconel 625 in alkaline earth metal chloride salts is accelerated with increasing basicity.

AbstractA dual stage pressure retarded osmosis (PRO) process was investigated for power generation using different types of membranes. Polyamide (PA) and cellulose triacetate (CTA) membranes were used in the first and second stage of the PRO process to improve the process performance due to the high water permeability of PA membranes. A comparison between dual stage PA–CTA and CTA–CTA membrane systems were carried out using seawater as a draw solution, while fresh water and wastewater effluent were the feed solution in the first and second stage of the process. The impact of draw solution flow rate on the process performance was evaluated. The performance of first and second stage of the PRO process increased by 11.5 and 28.6%, respectively, when the draw solution flow rate increased by a factor of 2.5. In return, there was a negligible increase in the total specific power consumption of the PRO process. In general, power consumption of the dual stage PRO process was as low as 0.3 kWh/m3. Furthermore, the results showed that the performance of the dual stage PRO process increased with increasing seawater salinity from 32 to 50 g/L due to the higher net driving pressure across the membrane. Finally, power generation in the PA–CTA system was up to 33% higher than that in the CTA–CTA system.

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.

A dual stage pressure retarded osmosis (PRO) process was investigated for power generation using different types of membranes. Polyamide (PA) and cellulose triacetate (CTA) membranes were used in the first and second stage of the PRO process to improve the process performance due to the high water permeability of PA membranes. A comparison between dual stage PA–CTA and CTA–CTA membrane systems were carried out using seawater as a draw solution, while fresh water and wastewater effluent were the feed solution in the first and second stage of the process. The impact of draw solution flow rate on the process performance was evaluated. The performance of first and second stage of the PRO process increased by 11.5 and 28.6%, respectively, when the draw solution flow rate increased by a factor of 2.5. In return, there was a negligible increase in the total specific power consumption of the PRO process. In general, power consumption of the dual stage PRO process was as low as 0.3 kWh/m3. Furthermore, the results showed that the performance of the dual stage PRO process increased with increasing seawater salinity from 32 to 50 g/L due to the higher net driving pressure across the membrane. Finally, power generation in the PA–CTA system was up to 33% higher than that in the CTA–CTA system.

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.

AbstractTwo-stage forward osmosis (FO)–reverse osmosis (RO)/BWRO and conventional RO/BWRO processes were evaluated for saline water treatment. Three different salts, NaCl, MgCl2and MgSO4, were used as a draw solution. The performance of FO, RO and BWRO regeneration processes was simulated using predeveloped software. The simulation results showed that the water and solute flux across the FO membrane decreased with increasing the FO recovery rate. The highest water flux was in case of 1.2 mol NaCl draw solution for seawater desalination. The total power consumption for seawater desalination was lower in the RO process than in the FO–RO process. However, as the RO recovery rate increased, the difference in total power consumption between the conventional RO process and 0.65 mol MgCl2FO–RO processes was insignificant. In case of brackish water desalination, the lowest specific power consumption and permeate TDS were in case of the conventional BWRO process and then followed by 0.32 mol MgSO4, 0.22 mol MgCl2and 0.33 mol NaCl FO-BWRO processes. However, the specific power consumption of RO-BWRO process dropped to less than that in the conventional BWRO process when NF membrane was used for MgSO4regeneration and water extraction. In general, the high recovery rate can be achieved by the FO–RO/BWRO process which is particularly important especially in case of inland desalination.

Two-stage forward osmosis (FO)–reverse osmosis (RO)/BWRO and conventional RO/BWRO processes were evaluated for saline water treatment. Three different salts, NaCl, MgCl2and MgSO4, were used as a draw solution. The performance of FO, RO and BWRO regeneration processes was simulated using predeveloped software. The simulation results showed that the water and solute flux across the FO membrane decreased with increasing the FO recovery rate. The highest water flux was in case of 1.2 mol NaCl draw solution for seawater desalination. The total power consumption for seawater desalination was lower in the RO process than in the FO–RO process. However, as the RO recovery rate increased, the difference in total power consumption between the conventional RO process and 0.65 mol MgCl2FO–RO processes was insignificant. In case of brackish water desalination, the lowest specific power consumption and permeate TDS were in case of the conventional BWRO process and then followed by 0.32 mol MgSO4, 0.22 mol MgCl2and 0.33 mol NaCl FO-BWRO processes. However, the specific power consumption of RO-BWRO process dropped to less than that in the conventional BWRO process when NF membrane was used for MgSO4regeneration and water extraction. In general, the high recovery rate can be achieved by the FO–RO/BWRO process which is particularly important especially in case of inland desalination.

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.

AbstractThe main objective of this study is to understand the operation mechanisms of reverse osmosis (RO) membrane and optimization of the operating mechanisms of the RO system in order to reduce the membrane fouling and/or energy requirements. Typically, the high-pressure RO membrane vessel is loaded with membrane elements having the same flux and salt rejection rate. It has been conceived that when different types of RO elements are loaded into the pressure vessel in a special arrangement according to their permeability and salt rejection rate, this arrangement has the potential for reducing the energy consumption of the RO plant. Here, a conceptual design is introduced to describe this new idea. The effects of feed salinity and temperature were investigated in this paper using the reverse osmosis system analysis filmtec membrane design software. A two pass membrane treatment process was designed for desalting seawater at different salinities varied from 35,000 ppm to 43,000 ppm. The results showed a net energy saving from 2.5 to 3% (depends on the feed salinity) could be achieved. The effect of the feed temperature was also investigated, and the new design was found to be more energy efficient. Membrane scaling was also investigated in this study, and it was found that the new membrane arrangement design was less efficient than old design at feed salinity 35,000 ppm and vice versa at feed salinity 45,000 ppm. This was attributed to the use of high membranes permeabilities in the new design.

The main objective of this study is to understand the operation mechanisms of reverse osmosis (RO) membrane and optimization of the operating mechanisms of the RO system in order to reduce the membrane fouling and/or energy requirements. Typically, the high-pressure RO membrane vessel is loaded with membrane elements having the same flux and salt rejection rate. It has been conceived that when different types of RO elements are loaded into the pressure vessel in a special arrangement according to their permeability and salt rejection rate, this arrangement has the potential for reducing the energy consumption of the RO plant. Here, a conceptual design is introduced to describe this new idea. The effects of feed salinity and temperature were investigated in this paper using the reverse osmosis system analysis filmtec membrane design software. A two pass membrane treatment process was designed for desalting seawater at different salinities varied from 35,000 ppm to 43,000 ppm. The results showed a net energy saving from 2.5 to 3% (depends on the feed salinity) could be achieved. The effect of the feed temperature was also investigated, and the new design was found to be more energy efficient. Membrane scaling was also investigated in this study, and it was found that the new membrane arrangement design was less efficient than old design at feed salinity 35,000 ppm and vice versa at feed salinity 45,000 ppm. This was attributed to the use of high membranes permeabilities in the new design.

We report first-principles calculations, using the full potential linear augmented plane wave method, on six lead halide semiconductors, namely, CH3NH3PbI3, CH3NH3PbBr3, CsPbX3(X = Cl, Br, I), and RbPbI3. Exchange is modeled using the modified Becke–Johnson potential. With an appropriate choice of the parameter that defines this potential, an excellent agreement is obtained between calculated and experimental band gaps of the six compounds.

Electrochemical processes can provide valuable contributions to the protection of the environment through implementation of effluent treatment and production-integrated processes for the minimization of waste and toxic compounds. The performance of a novel pilot scale, fixed bed flow-through cell, consisting of stainless steel tubes bundle cathode, in the removal of cadmium was investigated in the batch re-circulation mode; utilizing the potential results obtained from rotating disc electrode experiments in batch mode. The studied electrochemical reaction was the cathodic reduction of Cd2+using 0.5M sodium sulphate as supporting electrolyte. The analyzed parameters were different electrolyte pH, different initial Cd2+concentrations, and different Reynolds numbers. The tubes bundle consisted of 920 tubes of 0.6 cm outer diameters. The overall empirical mass transfer correlation was found to be: Sh = 0.51 Re0.859Sc1/3for 5 < Re < 20 and Sc = 649. Experimental results, analysis and correlations showed good performance of the cell and proved its adequacy in the removal of Cd2+from simulated effluents.

Electrochemical processes can provide valuable contributions to the protection of the environment through implementation of effluent treatment and production-integrated processes for the minimization of waste and toxic compounds. The performance of a novel pilot scale, fixed bed flow-through cell, consisting of stainless steel tubes bundle cathode, in the removal of cadmium was investigated in the batch re-circulation mode; utilizing the potential results obtained from rotating disc electrode experiments in batch mode. The studied electrochemical reaction was the cathodic reduction of Cd2+using 0.5 M sodium sulphate as supporting electrolyte. The analyzed parameters were different electrolyte pH, different initial Cd2+concentrations, and different Reynolds numbers. The tubes bundle consisted of 920 tubes of 0.6 cm outer diameters. The overall empirical mass transfer correlation was found to be: Sh = 0.51 Re0.859Sc1/3for 5 < Re < 20 and Sc = 649. Experimental results, analysis and correlations showed good performance of the cell and proved its adequacy in the removal of Cd2+from simulated effluents.

In the petroleum industries, high electric fields are used in the separation of aqueous drops from an oil phase. However, high electric fields can also deform and break up the drops. Under a high uniform electric field, a drop is usually a prolate spheroid, but it can also be of different forms such as a lamella penetrating into the continuous phase, or a drop with a flat surface on one side and a cone on the other side. The deformed drop shape depends greatly on the electrical conductivity, viscosity, surface tension and density of both liquid phases. Droplets can be produced from a prolate drop head, while the tail has a lamella penetrating into the continuous phase. The onset of drop break-up occurs at an electric field strength of between 300 and 350kV/m, corresponding to an electric Weber number of between 0.06 and 0.13. The current Weber number needs some modifications before it can be fully applied to characterise the onset of drop break-up. However, the form of the applied electric field is important. With pulsed dc fields, drop deformation and detachment rates are influenced by the field strength and the pulsing frequency.

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

One of the most important problems for diesel engines is the emissions of nitrogen oxides (NOx) and smoke, the use of emulsification technology is one of the most influential ways to control this emissions. In this present work Aluminum oxide (Al2O3) are blended by rotary-stator homogenizer at three different levels (50,100,150 ppm) with prepared Nano-emulsion at optimum composition and circumstances that are analyzed experimentally by Design Expert software. Alumina nanoparticle with its high thermal conductivity (30[?]1 Wm K[?]1 compare to diesel and high calorific value which helps to promote more internal combustion due to making higher thermal efficiency. Direct injection (DI), water cooled four cylinders, in-line, natural aspirated Fiat diesel engine was used and run at a constant speed (1500 rpm) and constant fuel injection pressure (400 bars) with varying the operation load. Multigas analyzer model 4880 was used to measure the concentration of the emission gases such as NOx, unburned total hydrocarbon HC, CO2 and CO. The engine exhaust smoke emissions were measured using the AVL-415 smoke meter. Based on these observations, the rate of CO and NOx would be reduced significantly up to 24 and 5.8 %, at 150ppm to net diesel respectively, noting that the net smoke of diesel would undergo the highest change (up to 26.5 %). The results also indicate a 6.97 % fuel consumption reduction accompanied with 6.2 % improvement in the thermal efficiency, utilizing Al2O3 nanoparticles in blended in Nano-emulsion. Enhancement in break thermal efficiency (BTE), reduction in (NOx) and smoke are noticed after mixing Al2O3 into prepared nano-emulsion.

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.

A new O-ring flat sheet membrane module design was used to investigate the performance of Vacuum Membrane Distillation (VMD) for water desalination using two commercial polytetrafluoroethylene (PTFE) and polyvinylidene fluoride (PVDF) flat sheet hydrophobic membranes. The design of the membrane module proved its applicability for achieving a high heat transfer coefficient of the order of 103 (W/m2 K) and a high Reynolds number (Re). VMD experiments were conducted to measure the heat and mass transfer coefficients within the membrane module. The effects of the process parameters, such as the feed temperature, feed flow rate, vacuum degree, and feed concentration, on the permeate flux have been investigated. The feed temperature, feed flow rate, and vacuum degree play an important role in enhancing the performance of the VMD process; therefore, optimizing all of these parameters is the best way to achieve a high permeate flux. The PTFE membrane showed better performance than the PVDF membrane in VMD desalination. The obtained water flux is relatively high compared to that reported in the literature, reaching 43.8 and 52.6 (kg/m2 h) for PVDF and PTFE, respectively. The salt rejection of NaCl was higher than 99% for both membranes.