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This work shows the concept of a simple, single-step, partial pyrolysis approach to prepare inorganic composite hollow fibers at low temperature conditions. Two series of robust, photocatalytic and high-performance membranes were synthesized by changing the pyrolysis temperature (Series 1: 500–600 °C for 8 h) and time (Series 2: 550 °C for 3–12 h), leading to the formation of a composite matrix consisted of carbonaceous char and titania nanoparticles. Chemical composition, phase of crystallinity, mechanical strength, textural characteristics, morphology and photocatalytic activity of the hollow fibers were comprehensively characterized. Mechanical strength of the hollow fibers was found to directly attribute to the amount of char and porosity. Hollow fibers, prepared using 8 h at 550 and 575 °C or 6 h at 550 °C condition, displayed a good balance between the highest mechanical strength of 52 MPa and photo-degradation of 90.4% of acid orange 7 under ultra-violet light. This was attributed to the optimization of degree of char derived from the binder and the exposure of anatase titania nanoparticles on the hollow fiber surface made available for photo-oxidation. This work offers the opportunity for future development of a fully integrated photocatalysis and membrane operation for wastewater treatment applications. [ABSTRACT FROM AUTHOR]

Carbonised template silica membranes were synthesised and investigated for water desalination for brackish (0.3 wt%), sea water (3.5 wt%) and brine (7.5 wt%) NaCl solutions at temperatures range from 22 to 60 °C. The membranes were prepared by a two-step base catalysed sol–gel method using tetraethyl orthosilicate TEOS as the silica precursor and triblock copolymer of Pluronic ® P123 as the templating agent. The P123 silica membranes calcined under vacuum only produced high quality membranes by the interlayer-free method. The membranes were stable during testing of up to 250 h under different thermal and salt concentration solutions, always delivering very high salt rejections >99.5%. It was found that by increasing the template concentration in the silica matrix from 5 to 50 wt%, salt concentration polarisation was greatly reduced. As such, high water fluxes were measured up to 8.5 kg m −2 h −1 for brackish water and 6.6 kg m −2 h −1 for brine water. [ABSTRACT FROM AUTHOR]

Membrane fouling is a major drawback of almost all pressure-driven membrane processes that limit their widespread application. This study compares the biological and the hydraulic performances of polyvinylidene fluoride (PVDF) and polysulfone (PSF) membranes when used as external filtration for polishing of a rotating biological contactor (RBC) effluent and as an integrated part in a membrane rotating biological contactor (MRBC). MRBC is an upgrade of the conventional RBC, in which the disk rotations are used not only to provide biological aeration but also as an inherent mechanism for membrane fouling control. Results showed that high biological performances were achieved irrespective of the membrane materials. The steady-state permeabilities of the membranes in MRBC are higher than external filtration by 92.4% and 19.7% for the PVDF and PSF membrane respectively. In the MRBC, smaller membrane-to-disk gaps and high disk rotational speed improve permeability for both membranes reaching the values of 297 and 173 L/(m2 h bar) for PVDF and PSF membranes, respectively. Full-scale energy consumption projection results show that the MRBC consumes only one-fourth of the energy of a referenced membrane bioreactor. The PVDF membrane outperforms PSF membrane thanks to the effective fouling control that maximize the throughput of a lower intrinsic resistance of the PVDF membrane. It implies that apart from membrane material, other operational parameters can still be optimized to further enhance the MRBC performance. ga1 • This study explores the effect of membrane properties in MRBC. • Operation inside of bioreactor enhance permeability irrespective of membrane. • Combination of disk rotation and small gap reaches permeability of 297 L/(m2 h bar). • MRBC with high throughput membrane has a very low energy input of 0.18 kWh/m3. [ABSTRACT FROM AUTHOR]

The construction and modification of a Graphene Oxide (GO) membrane, incorporating polyvinyl alcohol (PVA) cross-linked with maleic acid (MA) and supported by a nylon membrane, have been successfully completed. Systematic variations in PVA and MA concentrations were conducted to achieve membranes with favorable characteristics, stability, and excellent desalination performance. Optimization studies utilizing the Central Composite Design (CCD) revealed that the most optimal desalination results were obtained with 10 mL of PVA (0.1 mg mL−1) and 0.9 M of MA (GO-MA 0.9 -PVA 10 /Nylon membrane). Experimental findings demonstrated that the inclusion of PVA and MA resulted in an increased interlayer distance of GO and enhanced membrane stability. The addition of PVA increases GO membrane hydrophilicity, while the addition of MA reduces membrane hydrophilicity. The GO-MA 0.9 -PVA 10 /Nylon membrane exhibited the highest desalination performance, boasting a rejection value exceeding >99.9% and a permeance of 18.76 kg m−2.h−1 under 1% NaCl feed at a temperature of 50 °C. This membrane demonstrated consistent desalination performance stability over an extended period of up to 70 h. Moreover, it exhibited durability through 8 cycles of 24-h usage with washing treatment. In conclusion, the GO-MA 0.9 -PVA 10 /Nylon membrane is strongly recommended for practical applications, outperforming other membrane options based on the comprehensive evaluation of its stability and desalination efficiency. [Display omitted] • Polyvinyl alcohol intercalated graphene oxide membrane crosslinked maleic acid was successfully prepared. • The membrane composition (PVA and MA) is adjusted using CCD. • The addition of PVA and MA increases the stability and desalination ability. • GO-MA 0.9 -PVA 10 /Nylon membrane showed the best desalination results (rejection >99% and permeance 18.76 kg m−2.h−1. [ABSTRACT FROM AUTHOR]

Membrane filtration exhibits excellent separation performance for water and wastewater treatment but is still limited by the membrane fouling. This study presents a novel membrane rotating biological contactor (MRBC) that combines a conventional rotating biological contactor (RBC) with membrane filtration. MRBC combines conventional RBC with the membrane filtration placed in between two adjacent rotating disks to offer inherent control over membrane fouling. The disks rotations provide some degree of foulant removal, maintain membrane permeability, and potentially save a substantial amount of energy. The biological and hydraulic performance of MRBC was compared with a series of RBC and external membrane filtration (RBC + ME) where the membrane is treated as a post-treatment unit. Results show that the MRBC enhances not only the biological performance but also offers advantages for inherent membrane fouling control through the rotation of the disk. Membrane fouling control primarily originates from the enhanced shear rate from higher disk rotation and minimum membrane-to-disk gap. The hydraulic performance is 92.4% higher than literature, which further enhanced at smaller membrane-to-disk gaps and higher disk rotations. The highest steady-state permeability of 297 L/(m2.h.bar) and 288 L/(m2.h.bar) results at 40 rpm disk rotational speed and 0.5 cm membrane-to-disk gap, respectively. A projected full-scale MRBC consumes 0.18 kWh/m3 permeate, one-fourth of the energy for the referenced MBR system thanks to the active role of disks rotation for membrane fouling control which eliminates the need of extensive aeration like in the traditional MBRs. MRBC offers a promising alternative for traditional wastewater treatment as a low energy foot-print process, which is in line with the requirements of sustainable development and promotes the development of cleaner production. Image 1 • The proof of concept of membrane rotating biological contactor (MRBC) is reported. • It utilizes the disk rotations to dissolve oxygen and to control membrane fouling. • High rotation speeds and small gaps offer high permeability of up to 297 L/(m2.h.bar). • The energy consumption of the MRBC is merely 0.18 kWh/m3. [ABSTRACT FROM AUTHOR]