The use of membrane-based technologies has been applied for water treatment applications; however, the limitations of conventional polymeric membranes have led to the addition of inorganic fillers to enhance their performance. In recent years, nanocomposite membranes have greatly attracted the attention of scientists for water treatment applications such as wastewater treatment, water purification, removal of microorganisms, chemical compounds, heavy metals, etc. The incorporation of different nanofillers, such as carbon nanotubes, zinc oxide, graphene oxide, silver and copper nanoparticles, titanium dioxide, 2D materials, and some other novel nano-scale materials into polymeric membranes have provided great advances, e.g., enhancing on hydrophilicity, suppressing the accumulation of pollutants and foulants, enhancing rejection efficiencies and improving mechanical properties and thermal stabilities. Thereby, the aim of this work is to provide up-to-date information related to those novel nanocomposite membranes and their contribution for water treatment applications.

In this work, PVDF homopolymer was blended with PVDF-co-HFP copolymer and studied in terms of morphology, porosity, pore size, hydrophobicity, permeability, and mechanical properties. Different solvents, namely N-Methyl-2 pyrrolidone (NMP), Tetrahydrofuran (THF), and Dimethylformamide (DMF) solvents, were used to fabricate blended PVDF flat sheet membranes without the introduction of any pore forming agent, through a non-solvent induced phase separation (NIPS) technique. Furthermore, the performance of the fabricated membranes was investigated for pressure and thermal driven applications. The porosity of the membranes was slightly increased with the increase in the overall content of PVDF and by the inclusion of PVDF copolymer. Total PVDF content, copolymer content, and mixed-solvent have a positive effect on mechanical properties. The addition of copolymer increased the hydrophobicity when the total PVDF content was 20%. At 25% and with the inclusion of mixed-solvent, the hydrophobicity was adversely affected. The permeability of the membranes increased with the increase in the overall content of PVDF. Mixed-solvents significantly improved permeability.

Growing energy demand associated with improved living standards and rising population has increased the consumption of petroleum-based energy sources. To bridge the gap between demand and supply of petroleum-based energy resources, enhanced oil recovery and exploration of new nonconventional resources including shale gas, coal bed methane gas, and tight gas have gained popularity. These new techniques, however, use relatively fresh water and produce huge volumes of highly contaminated produced water. From compositional and potential treatment options, bilge water can also be included in the category of produced water. This work provides an overview of the investigations carried out for the removal of oil and greases using a membrane bioreactor and various other membrane operations. An analysis of a current and future scenario of produced water generated through conventional and nonconventional sources of energy and the perspective of produced water treatment in Saudi Arabia are also given. Finally, a cost estimation for the treatment of produced water using membrane operations is discussed.

Membrane bioreactors (MBRs) represent the best available technology for municipal and wastewater treatment, as confirmed by the number of wastewater treatment plants based on MBRs in operation worldwide. However, MBRs are not able to effectively reject some substances, like low molecular weight organic compounds found in wastewaters. Therefore, further improvements are needed. In this respect, coupling MBRs with high-retention membrane processes, like reverse osmosis (RO) and membrane distillation (MD), was investigated in the past years. In this paper, the main MBR features and their commercial development are presented. Their performance when coupled with RO and with MD units is discussed, as well as limitations toward a large-scale implementation, with particular emphasis on the further research needed in the field. Finally, MBR-RO and MBR-MD integrated systems are compared in terms of the most significant parameters. Actions to take in order to overcome linked issues are also proposed.