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A rotating biological contactor (RBC) is a type of attached-growth biological wastewater treatment system and a widely used biological wastewater treatment technology. It employs a series of rotating discs to support microbial growth and promote the removal of pollutants from wastewater. RBC is widely recognized for its simplicity of design, high reliability, and low energy consumption. It has been used in various applications, from small-scale decentralized systems to large municipal wastewater treatment plants. The current review provides an overview of RBC bioreactors, design parameters, and the factors that influence biological performance, such as hydraulic retention time, sludge retention time, organic loading rate, disc rotational speed, and temperature. The review also highlights the advantages and disadvantages of RBCs compared with other wastewater treatment technologies and discusses their role in sustainable environmental performance. The future prospects of RBC are also discussed, including integration with other technologies, such as membrane filtration and potential use in resource recovery. The review explores the application of RBC in decentralized wastewater treatment and the potential to provide sustainable solutions for wastewater management in rural and remote areas. Overall, RBC remains a promising option for effective and efficient wastewater treatment, particularly in situations where simplicity, reliability, and low energy consumption are desired. [ABSTRACT FROM AUTHOR]

The water resource crisis and concerns with environmental pollution prompt the necessity to upgrade conventional wastewater treatment processes. The microalgae-based wastewater treatment process has shown many advantages that can fulfill the stricter demands for improved wastewater treatment. Microalgae cultivation can be carried out in different photobioreactors and under different operational conditions. The cultivation of the microalgae biomass provides the bioremediation of some targeted pollutants through uptake/digestion or biosorption, resulting in treated effluent and the production of biomass. This paper reviews the progress in microalgae-biotechnology for industrial wastewater treatment. A brief overview of microalga types/classification, the cultivation photobioreactors type, and conditions was first provided. Next, a comprehensive review of the bioremediation of industrial wastewater, including distillery, heavy metals, textiles, and emerging contaminants, was provided. Finally, perspectives on the potential scale-up of the technology and some critical considerations were also discussed. [ABSTRACT FROM AUTHOR]

Our world is facing continued challenges of environmental and ecological pollutions due to human and industrial activities. One of the major threats is oily wastewater mainly discharged from oil fields, refineries, automobile, palm oil industries, and many others. Membrane-based technology offers an almost complete separation of oil from water. However, the technology is facing the challenge of maintaining performance over long periods of operation caused by membrane fouling as a result of interaction between oil droplets and the membrane surface. This attracts research interest mainly on developing customized polymeric, ceramic well as a metallic-based membrane material for improved performance. This paper reviews the recent advances of membrane material developments with the focus on methods of improving the surface chemistry, structure, and hydrodynamics and their implication on the filtration performances. [ABSTRACT FROM AUTHOR]

• A new process of membrane integrated rotating biological contactor is introduced. • Membrane placement near the disk rotation helps to control membrane fouling. • The system allows inherent fouling control thus reduces costs for fouling control. • Low membrane-to-disk gap and high disk rotation enhance membrane permeability. • The energy consumption can reach one fourth of membrane bioreactor. Membrane fouling is a major bottleneck of almost all pressure-driven membrane filtration processes that limits their widespread applications. Improvement of hydrodynamics conditions is one of the most effective methods for membrane fouling control. This paper assesses a rotating biological contactor (RBC) integrated with membrane (RBC-MI) filtration that potentially offers inherent membrane fouling control as well as enhances biological performance, in which the membrane is placed inside the RBC bioreactor. Results show that the RBC-MI system achieves 84% of COD, 96.7% ammonium, 74% total nitrogen, 89% total phosphorus, and 96% turbidity removals. The integration of membrane placed inside the bioreactor doubles the permeability as compared to the external placement. Higher hydraulic performance is achieved at the low membrane-to-disk gap and higher disk rotational speed. The energy analysis shows that the RBC-MI consumes only 0.18 kWhm−3 signifying its viability as promission option to the energy-intensive conventional treatment systems. [ABSTRACT FROM AUTHOR]

A rotating biological contactor (RBC) offers a low energy footprint but suffers from performance instability, making it less popular for domestic wastewater treatment. This paper presents a study on an RBC integrated with membrane technology in which membrane filtration was used as a post-treatment step (RBC–ME) to achieve enhanced biological performance. The RBC and RBC–ME systems were operated under different hydraulic retention times (HRTs) of 12, 18, 24, and 48 h, and the effects of HRT on biological performance and effluent filterability were assessed. The results show that RBC–ME demonstrates superior biological performance than the standalone RBC. The RBC–ME bioreactor achieved 87.9 ± 3.2% of chemical oxygen demand (COD), 98.9 ± 1.1% ammonium, 45.2 ± 0.7% total nitrogen (TN), and 97.9 ± 0.1% turbidity removals. A comparison of the HRTs showed that COD and TN removal efficiency was the highest at 48 h, with 92.4 ± 2.4% and 48.6 ± 1.3% removal efficiencies, respectively. The longer HRTs also lead to better RBC effluent filterability. The steady-state permeability increased respectively by 2.4%, 9.5%, and 19.1% at HRTs of 18, 24, and 48 h, compared to 12 h. Our analysis of membrane fouling shows that fouling resistance decreased at higher HRTs. Overall, RBC–ME offered a promising alternative for traditional suspended growth processes with higher microbial activity and enhanced biological performance, which is in line with the requirements of sustainable development and environment-friendly treatment. [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]

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]

• Discuss on electrospun nanofiber membrane and membrane modification. • Discuss on produced water and its conventional treatment. • Elaborate on the basic concept and parameters which affect electrospinning. • Summarize previous application of membrane modification for produced water treatment. Produced water is the largest wastewater generated in oil and gas industry and its handling has become a significant issue of environmental concern. Due to its massive production, it has caught the attention of the researchers to find the most effective solution. As the front-runner of advanced fiber materials, electrospun nanofiber membrane (NFM) has high potential for oily wastewater treatment since it offers promising properties such as huge surface area, high porosity, tuneable wettability, great permeability and small basis weight. However, fouling issue and low mechanical strength of NFM will mitigate membrane performance over time. Therefore, membrane surface modification methods are applied to reduce fouling and promote crosslinking of nanofibers to improve the mechanical strength of membrane. In this review, it highlights and summarizes the research and development starting from the design concepts and the synthesis of nanofiber membranes and how membrane modification is important for effective oil/water separation. [ABSTRACT FROM AUTHOR]

Integrated fixed-film activated sludge (IFAS) process is considered as one of the leading-edge processes that provides a sustainable solution for wastewater treatment. IFAS was introduced as an advancement of the moving bed biofilm reactor by integrating the attached and the suspended growth systems. IFAS offers advantages over the conventional activated sludge process such as reduced footprint, enhanced nutrient removal, complete nitrification, longer solids retention time and better removal of anthropogenic composites. IFAS has been recognized as an attractive option as stated from the results of many pilot and full scales studies. Generally, IFAS achieves >90% removals for combined chemical oxygen demand and ammonia, improves sludge settling properties and enhances operational stability. Recently developed IFAS reactors incorporate frameworks for either methane production, energy generation through algae, or microbial fuel cells. This review details the recent development in IFAS with the focus on the pilot and full-scale applications. The microbial community analyses of IFAS biofilm and floc are underlined along with the special emphasis on organics and nitrogen removals, as well as the future research perspectives. Image 1 • Recent progress of integrated fixed-film activated sludge (IFAS) process is reviewed. • IFAS process is an effective upgrade of existing conventional activated sludge system. • IFAS process can be retrofitted to improve nitrification in partial nitritation anammox. • IFAS process can incorporate energy generation through algae and microbial fuel cells. • IFAS process offers low sludge production, low energy foot-print and cost saving. [ABSTRACT FROM AUTHOR]

During the production of oil and gas, a large amount of oily wastewater is generated, which would pollute the environment if discharged without proper treatment. As one of the most promising treatment options, membrane material used for oily wastewater treatment should possess desirable properties of high hydraulic performance combined with high membrane fouling resistance. This project employs the vapor induced phase separation (VIPS) technique to develop a hydrophilic polyvinylidene fluoride (PVDF) membrane with polyethylene glycol (PEG) as an additive for produced water treatment. Results show that thanks to its slow nonsolvent intake, the VIPS method hinders additive leaching during the cast film immersion. The results also reveal that the exposure of the film to the open air before immersion greatly influences the structure of the developed membranes. By extending the exposure time from 0 to 30 min, the membrane morphology change from typical asymmetric with large macrovoids to the macrovoid-free porous symmetric membrane with a granular structure, which corresponds to 35% increment of steady-state permeability to 189 L·m−2h−1bar−1, while maintaining >90% of oil rejection. It was also found that more PEG content resides in the membrane matrix when the exposure time is extended, contributes to the elevation of surface hydrophilicity, which improves the membrane antifouling properties. Overall results demonstrate the potential of VIPS method for the fabrication of hydrophilic PVDF membrane by helping to preserve hydrophilic additive in the membrane matrices. [ABSTRACT FROM AUTHOR]

A membrane bioreactor enhances the overall biological performance of a conventional activated sludge system for wastewater treatment by producing high-quality effluent suitable for reuse. However, membrane fouling hinders the widespread application of membrane bioreactors by reducing the hydraulic performance, shortening membrane lifespan, and increasing the operational costs for membrane fouling management. This study assesses the combined effect of membrane surface corrugation and a tilted panel in enhancing the impact of air bubbling for membrane fouling control in activated sludge filtration, applicable for membrane bioreactors. The filterability performance of such a system was further tested under variable parameters: Filtration cycle, aeration rate, and intermittent aeration. Results show that a combination of surface corrugation and panel tilting enhances the impact of aeration and leads to 87% permeance increment. The results of the parametric study shows that the highest permeance was achieved under short filtration–relaxation cycle of 5 min, high aeration rate of 1.5 L/min, and short switching period of 2.5 min, to yield the permeances of 465 ± 18, 447 ± 2, and 369 ± 9 L/(m2h bar), respectively. The high permeances lead to higher operational flux that helps to lower the membrane area as well as energy consumption. Initial estimation of the fully aerated system yields the energy input of 0.152 kWh/m3, much lower than data from the full-scale references of <0.4 kWh/m3. Further energy savings and a lower system footprint can still be achieved by applying the two-sided panel with a switching system, which will be addressed in the future. [ABSTRACT FROM AUTHOR]

Membrane fouling is seen as the main culprit that hinders the widespread of membrane application in liquid-based filtration. Therefore, fouling management is key for the successful implementation of membrane processes, and it is done across all magnitudes. For optimum operation, membrane developments and surface modifications have largely been reported, including membrane surface patterning. Membrane surface patterning involves structural modification of the membrane surface to induce secondary flow due to eddies, which mitigate foulant agglomeration and increase the effective surface area for improved permeance and antifouling properties. This paper reviews surface patterning approaches used for fouling mitigation in water and wastewater treatments. The focus is given on the pattern formation methods and their effect on overall process performances. [ABSTRACT FROM AUTHOR]

Water reuse for drinking, irrigation, district cooling, process heating/cooling, landscaping, etc. remains pivotal to water security and sustainability. Advanced oxidation processes (AOPs) are at the heart of the industrial wastewater treatment especially for the removal of contaminants of emerging concern. Recent studies conducted to advance AOP technologies for the degradation of industrial wastewater pollutants generally encompass seven areas, namely artificial neural networks (ANNs), sustainability, plasma activation, catalyst structures, AOP-Bioremediation, and membrane-based AOPs. This review presents the advancements in AOPs for oxidation and removal of a wide range of contaminants of emerging concern from water. Detailed discussions and a critical examination of recently published works are presented in this article. Many of the reports have recorded technical progress in the form of: improved energy efficiency through the use of low-energy and renewable energy sources, successful prediction of process performance and process control, improved light capturing capabilities through plasmonic effect, successful integration with biological treatment methods and membrane filtration. In spite of this progress, a number of challenges still persist such as lack of appropriate ANN modeling structures, impractical spatial and temporal scales of investigation (i.e. scales that are too low for real operations), and membrane fouling in membrane-based AOPs. These challenges and the strategies for addressing them are discussed in this article. [ABSTRACT FROM AUTHOR]