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Several Membrane Distillation (MD) technologies have been employed to remove boron from various concentrations. In this study, Vacuum Membrane Distillation (VMD), Permeate Gap Membrane Distillation (PGMD), and Air Gap Membrane Distillation (AGMD) are examined to evaluate their effectiveness when combined with several boron concentrations (1.5, 7 and 30 ppm) and operating parameters (circulation rate from 0.9 L/min to 5 L/min, feed temperature from 40 to 70 &deg, C, and pH from 3&ndash, 11). Those concentrations of boron are selected on the basis of the concentration of boron in the permeate side of the single-pass reverse osmosis (RO) system, Arabian Gulf, and contaminated brackish water. Moreover, synthetic seawater is treated to assess MD technologies&rsquo, effectiveness. A high removal efficiency of boron is accomplished by MD. AGMD, PGMD, and VMD are promising methods for the desalination industry. AGMD shows excellent boron removal, which was above 99% with a wide ranging concentration. In addition, VMD demonstrates good permeate flux compared to the other MD technologies, which were about 5.8 kg/m2&middot, h for synthetic seawater. Furthermore, there is no noteworthy influence of the pH value on the boron removal efficiency.

Nowadays, integrated microfiltration (MF) membrane systems treatment is becoming widely popular due to its feasibility, process reliability, commercial availability, modularity, relative insensitivity in case of wastewater of various industrial sources as well as raw water treatment and lower operating costs. The well thought out, designed and implemented use of membranes can decrease capital cost, reduce chemical usage, and require little maintenance. Due to their resistance to extreme operating conditions and cleaning protocols, ceramic MF membranes are gradually becoming more employed in the drinking water and wastewater treatment industries when compared with organic and polymeric membranes. Regardless of their many advantages, during continuous operation these membranes are susceptible to a fouling process that can be detrimental for successful and continuous plant operations. Chemical and microbial agents including suspended particles, organic matter particulates, microorganisms and heavy metals mainly contribute to fouling, a complex multifactorial phenomenon. Several strategies, such as chemical cleaning protocols, turbulence promoters and backwashing with air or liquids are currently used in the industry, mainly focusing around early prevention and treatment, so that the separation efficiency of MF membranes will not decrease over time. Other strategies include combining coagulation with either inorganic or organic coagulants, with membrane treatment which can potentially enhance pollutants retention and reduce membrane fouling.

The research efforts on the development of ideal forward osmosis membranes with high water flux and low reverse salt flux have been devoted in the recent years. In this study, thin film composite polyamide forward osmosis membranes were prepared. The porous polysulfone (PSU), polyphenylsulfone (PPSU), and polyethersulfone (PESU) substrates used in this study were prepared by the phase inversion process, and the active rejection layer was prepared by interfacial polymerization. All the membranes showed highly asymmetric porous structures with a top dense upper layers and finger-like porous substrates with macro voids in the bottom layer. The addition of 3 % lithium chloride (LiCl) to the membrane substrates resulted in an increase in both the water flux and reverse salt flux. PSU and PESU showed the highest water flux when the active layer faced the feed solution (AL-FS), while the largest water flux was obtained when the active layer faced the draw solution (AL-DS). For all the membranes, the water flux under the AL-DS orientation was higher than that under the AL-FS orientation.

Synthetic solutions assimilating irrigated groundwater containing varying concentrations of humic acid (10 mg/L), saline (10&ndash, 35 g/L) and metal agents (5&ndash, 10 mg/L), were processed through a ceramic microfiltration membrane (Sterilox Ltd., 0.5 &mu, m). This was done with enrichment schemes using polymeric coagulants (PDADMAC) applied to enhance the removal of the above-mentioned pollutants. The study was conducted with the scope of investigating the feasibility of sequential and hybrid coagulation and microfiltration as a method of choice for drinking water treatment. Membrane microfiltration is easily scalable into various arrangements, allowing versatility in operation and enrichment schemes, with a relatively lower cost which other treatment practices do not allow. The highest humic acid removal, 91.11% was achieved with hybrid coagulation.

Synthetic industrial wastewater samples containing mercury (Hg), arsenic (As), and lead (Pb) ions in various concentrations were prepared and treated by air gap membrane distillation (AGMD), a promising method for heavy metals removal. Three different membrane pore sizes (0.2, 0.45, and 1 &mu, m) which are commercially available (TF200, TF450, and TF1000) were tested to assess their effectiveness in combination with various heavy metal concentrations and operating parameters (flow rate 1&ndash, 5 L/min, feed temperature 40&ndash, 70 &deg, C, and pH 2&ndash, 11). The results indicated that a high removal efficiency of the heavy metals was achieved by AGMD. TF200 and TF450 showed excellent membrane removal efficiency, which was above 96% for heavy metal ions in a wide range of concentrations. In addition, there was no significant influence of the pH value on the metal removal efficiency. Energy consumption was monitored at different membrane pore sizes and was found to be almost independent of membrane pore size and metal type.

Membrane distillation (MD) is a promising technology for treating saline water and wastewater with high rejection factors, which cannot be accomplished by conventional technologies. MD is a thermally driven separation process in which only the vapor molecules pass through a microporous hydrophobic membrane. The driving force in the MD process is the vapor pressure difference induced by the temperature difference across the membrane surface. This chapter provides a comprehensive study of MD. The first part gives an introduction, including general information about water problems, existing water technology, and historical review for MD. MD configuration and modules, membrane properties, and membrane characterization will be illustrated in the second and third parts. The transport phenomena relating to mass and heat transfer for different MD types are also presented. Operating parameters and MD application are covered in this chapter.

An experimental study is used to examine the effect of high concentration of several salts, i.e., NaCl, MgCl 2 , Na 2 CO 3 and Na 2 SO 4 on permeate flux and rejection factor by air gap membrane distillation (AGMD). A comparative study involving three different membrane pore sizes (0.2, 0.45 and 1.0 μm) were performed to investigate the influence of pore size on energy consumption, permeate flux and rejection factor. The permeate flux decline is higher than that predicted from the vapour pressure reduction. Furthermore, the energy consumption was monitored at different membrane pore size and was found to be increased when the concentration increased.

Water treatment is a strategic solution to resolve the water shortage in agriculture and industrial sectors in Saudi Arabia. Rainfall which is not a reliable water source varies from 50 mm in most of the country to 500 mm per year in the southwest region. Lack of incentive and poor water treatment level were the main challenges in the water treatment industry. The water consumption in 2018; around 3360 million m3, was almost 70% higher than it was in 2007. Similarly, the total municipal wastewater increased steadily and it is predicted to rise dramatically between 2025 and 2050 to reach 5090 million m3. Treated water rose by nearly 200 % between 2007 and 2018 and is expected to grow annually by 4% between 2025 to 2050.

Air Gap Membrane Distillation (AGMD) has been implemented to treat produced water. The permeate fluxes, rejection factor and energy consumption for three different membranes, TF200, TF450 and TF1000, with pore sizes of 0.2, 0.45 and 1 μm, respectively, are measured at different operating parameters. The influence of membrane pore size is investigated for the produced water. Also, the effect of feed flow rate, coolant temperature and feed temperature on permeate flux is studied. The flux increases as the feed temperature and flow rate increase, and declines as the coolant temperatures increase. Moreover, the energy consumption was measured at different pore size and was found to be independent of membrane pore size.

article i nfo Membrane Distillation (MD) is a thermally-driven separation process, in which only vapour molecules trans- fer through a microporous hydrophobic membrane. The driving force in the MD process is the vapour pres- sure difference induced by the temperature difference across the hydrophobic membrane. This process has various applications, such as desalination, wastewater treatment and in the food industry. This review addresses membrane characteristics, membrane-related heat and mass transfer concepts, fouling and the effects of operating condition. State of the art research results in these different areas will be pre- sented and discussed.

Air Gap Membrane Distillation, using a high concentration of NaCl, MgCl 2 , Na 2 CO 3 , and Na 2 SO 4 , is implemented in this study. Permeate fluxes are measured for different feed concentrations and membrane pore sizes (0.2 and 0.45 μm). The flux declines as the concentration of salt increases, and increases as the pore size increases. The TF200 membrane showed excellent hydrophobicity compared to TF450. Moreover, the energy consumption was measured at different salt concentrations for the different membrane sizes, and was found to be independent of membrane pore size, salt type and salt concentration in the feed solution.

Air Gap Membrane Distillation (AGMD) has been implemented for four different salts. The permeate fluxes of sodium chloride (NaCl), magnesium chloride (MgCl2), sodium carbonate (Na2CO3), and sodium sulphate (Na2SO4) are measured at different feed concentrations and different operating parameters using Polytetrafluoroethylene (TF200) membrane. The influence of membrane pore size is investigated for the different salts. Also, the effect of feed concentration, feed temperature, coolant temperature and feed flow rate on permeate flux is studied. The flux declines as the concentration of salt and coolant temperatures increase, and increases as the feed temperature and flow rate increase. Moreover, the energy consumption was measured at different salt concentrations for the different membrane pore size and was found to be independent of membrane pore size, and salt type.