Influence of foulant particle shape on membrane fouling in dead-end microfiltration

Advancements in membrane technology for efficient POME treatment: A comprehensive review and future perspectives

The treatment of POME related contamination is complicated due to its high organic contents and complex composition. Membrane technology is a prominent method for removing POME contaminants on account of its efficiency in removing suspended particles, organic substances, and contaminants from wastewater, leading to the production of high-quality treated effluent. It is crucial to achieve efficient POME treatment with minimum fouling through membrane advancement to ensure the sustainability for large-scale applications. This article comprehensively analyses the latest advancements in membrane technology for the treatment of POME. A wide range of membrane types including forward osmosis, microfiltration, ultrafiltration, nanofiltration, reverse osmosis, membrane bioreactor, photocatalytic membrane reactor, and their combinations is discussed in terms of the innovative design, treatment efficiencies and antifouling properties. The strategies for antifouling membranes such as self-healing and self-cleaning membranes are discussed. In addition to discussing the obstacles that impede the broad implementation of novel membrane technologies in POME treatment, the article concludes by delineating potential avenues for future research and policy considerations. The understanding and insights are expected to enhance the application of membrane-based methods in order to treat POME more efficiently; this will be instrumental in the reduction of environmental pollution.

Gaining comprehensive insight into the effect of electrocoagulation integrated in a membrane bioreactor on the detergent manufacturing plant wastewater treatment and membrane fouling

This study evaluated the integration of electrocoagulation into a lab-scale membrane bioreactor (EC-MBR) for treating wastewater from a detergent manufacturing plant. The EC-MBR system achieved a higher chemical oxygen demand (COD) and anionic surfactant removal efficiencies of 95.1% and 99.7% compared to 93.3% and 98.7% in the MBR system, respectively. Sludge volume index and mixed liquor supernatant turbidity revealed superior sludge settling and flocculation ability, respectively, in the EC-MBR system compared to the MBR system. Membrane fouling was less severe in the EC-MBR system, linked to reduced concentrations of soluble microbial products and loosely bond extracellular polymeric substances, especially their protein to carbohydrate ratio, as well as increased particle size in the mixed liquor. Fourier transform infrared spectroscopy (FTIR) analysis indicated that the membrane cake layer was mainly composed of protein and carbohydrate. Scanning electron microscopy (SEM) revealed microbial clusters in the MBR system composed of rod- and oval-shaped bacteria, while the EC-MBR system primarily showed spherical microbial structures. The EC-MBR system demonstrated low energy consumption (1.75 kWh m-³) and operating costs ($0.55 m-³), highlighting its efficiency and cost-effectiveness for sustainable wastewater management.

A comprehensive study on the effects of electrocoagulation integrated in a membrane bioreactor treating sunflower oil refinery wastewater on treatment performance, biological properties, and fouling behavior

This study evaluated the effects of electrocoagulation integrated in a laboratory-scale membrane bioreactor (MBR), namely EC-MBR, on the treatment performance, activated sludge morphological characterization, and membrane fouling of MBR treating actual sunflower oil refinery wastewater. The EC-MBR system exhibited significantly higher chemical oxygen demand (COD) and oil and grease (O&G) removal efficiency compared to the MBR system. Additionally, both systems achieved excellent turbidity removal, with a percentage above 99%. The membrane fouling rate was higher in the EC-MBR system compared to the MBR system. Despite the decrease in the soluble microbial product (SMP) and extracellular polymeric substance (EPS) concentration in the EC-MBR system, especially their protein fraction, the significant increase in MLSS and carbohydrates/protein ratio, and the decrease in the mixed liquor and the cake layer particles size were the main membrane fouling factors. The membrane fouling resistance distribution showed that the EC-MBR system had a higher percentage of pore blocking resistance compared to the MBR. FTIR analysis identified a greater proportion of carbohydrate compounds in the cake layer of the EC-MBR system. SEM images revealed dense microbial clusters, mainly rod- and oval-shaped bacteria, in the EC-MBR system. Furthermore, EDX analysis detected elements such as Ca, K, O, Al, and P in both systems, with the EC-MBR system showing a higher Al content. The EC-MBR system showed low energy consumption (0.431 kWh m-3) and total operating costs ($0.90 m-3), showcasing its effectiveness and affordability for sustainable wastewater management.

Mechanism of Silica Nanoparticle-Induced Particulate Fouling in Vacuum Membrane Distillation

Membrane distillation (MD) is a process driven by the vapor pressure difference dependent on temperature variation, utilizing a hydrophobic porous membrane. MD operates at low pressure and temperature, exhibiting resilience to osmotic pressure. However, a challenge arises as the membrane performance diminishes due to temperature polarization (TP) occurring on the membrane surface. The vacuum MD process leverages the application of a vacuum to generate a higher vapor pressure difference, enhancing the flux and mitigating TP issues. Nevertheless, membrane fouling leads to decreased performance, causing membrane wetting and reducing the ion removal efficiency. This study investigates membrane fouling phenomena induced by various silica nanoparticle sizes (400, 900, and 1300 nm). The patterns of membrane fouling, as indicated by the flux reduction, vary depending on the particle size. Distinct MD performances are observed with changes in the feed water temperature and flow rate. When examining the membrane fouling mechanism for particles with a porosity resembling actual particulate materials, a fouling form similar to the solid type is noted. Therefore, this study elucidates the impact of particulate matter on membrane fouling under diverse conditions.

The impact of PET microplastic fibres on PVDF ultrafiltration performance - A short-term assessment of MP fouling in simple and complex matrices

Wastewater treatment plants (WWTPs) are key components for the capture of microplastics (MPs) before they are released into natural waterways. Removal efficiencies as high as 99% may be achieved but sub-micron MPs as well as nanoplastics have been overlooked because of analytical limitations. Furthermore, short MP fibres are of concern because of their low capture rate as well as the lack of understanding of their influence on purification system efficiency. This study has investigated the impact of poly(ethylene terephthalate) (PET) short nanofibres on the performance of polyvinylidene fluoride (PVDF) ultrafiltration membranes during cross-flow operation. Model MP fibres with an average length of 10 ± 7 μm and a diameter of 142 ± 40 nm were prepared via a combination of electrospinning and fine cutting using a cryomicrotome. The manufactured MPs were added to both pure and synthetic domestic wastewater at a concentration of 1 mg.L^-1 to determine their impact on the performance of PVDF ultrafiltration membranes. The results show that PET fibres attach to the membrane in a disorganised manner with low pore coverage. The water flux was decreased by 8% for MPs in pure water and no noticeable effect in wastewater after 3 days of filtration. Additionally, the nutrient removal efficiency of the membrane was not altered by the presence of PET MPs. These findings show that MP fibres do not significantly influence the early stages of filtration for a standard concentration of MPs in wastewater treatment plant studies.