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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.

Forward osmosis technology is one of the most rapidly developing processes of desalination and water treatment. The transport of boron in forward osmosis (FO) using various FO membranes was investigated in this study. Three specific membranes — an FTS H2O™ membrane, a PSU membrane and an Aquaporin Inside™ membrane — were applied to study the impact of the feed solution (FS) pH, boron concentration, and draw solution (DS) concentration on boron solute flux, boron rejection and water flux. The results indicated an increment in boron solute flux with increasing DS and boron concentration but a reduction with increasing FS pH. Moreover, increasing the FS pH from 4 to 10 enhanced the rejection rate of boron from 12% to 90% for the FTS H2O™ membrane, from 8% to 84% for the PSU membrane and from 8% to 76% for the Aquaporin Inside™ membrane. With increment in the DS concentration from 0.5 to 3 M, the rejection rate of boron increased from 20% to 54% for the FTS H2O™ membrane, from 14% to 50% for the PSU membrane and from 8% to 40% for the Aquaporin Inside™ membrane. Apparently, increasing the boron concentration in the FS did not have a significant effect on boron rejection. The boron rejection rate was approximately 20–30% for the Aquaporin Inside™ membrane, 32–40% for the FTS H2O™ membrane and 25–35% for the PSU membrane.

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.

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.