Evaluation of the shear stability of aerobic granular sludge from a pilot-scale membrane bioreactor: Establishment of a quantitative method.

This work established a quantitative method to access the shear stability of aerobic granular sludge (AGS) and validated its feasibility by using the mature AGS from a pilot-scale (50 tons/day) membrane bioreactor (MBR) for treating real municipal wastewater. The results showed that the changing rate (ΔS) of the peak area (S) of granule size distribution (GSD) exhibited an exponential relationship (R2≥0.76) with the shear time (y=a-b·cx), which was a suitable indicative index to reflect the shear stability of different AGS samples. The limiting granule size (LGS) was defined and proposed to characterize the equilibrium size for AGS after being sheared for a period of time, whose value in terms of Dv50 showed high correlation (R2=0.92) with the parameter a. The free Ca2+ (28.44-34.21 mg/L) in the influent specifically interacted with polysaccharides (PS) in the granule's extracellular polymeric substance (EPS) as a nucleation site, thereby inducing the formation of Ca precipitation to enhance its Young's modulus, while Ca2+ primarily interacted with PS in soluble metabolic product (SMP) during the initial granulation process. Furthermore, the Young's modulus significantly affected the parameter a related to shear stability (R2=0.99). Since the parameter a was more closely related (R2=1.00) to ΔS than that of the parameter b or c, the excellent correlation (R2=0.99) between the parameter a and the wet density further verified the feasibility of this method.

Transcriptomic profiling of human mesenchymal stem cells using a pulsed electromagnetic-wave motion bioreactor system for enhanced osteogenic commitment and therapeutic potentials.

Traditional bioreactor systems involve the use of three-dimensional (3D) scaffolds or stem cell aggregates, limiting the accessibility to the production of cell-secreted biomolecules. Herein, we present the use a pulse electromagnetic fields (pEMFs)-assisted wave-motion bioreactor system for the dynamic and scalable culture of human bone marrow-derived mesenchymal stem cells (hBMSCs) with enhanced the secretion of various soluble factors with massive therapeutic potential. The present study investigated the influence of dynamic pEMF (D-pEMF) on the kinetic of hBMSCs. A 30-min exposure of pEMF (10V-1Hz, 5.82 G) with 35 oscillations per minute (OPM) rocking speed can induce the proliferation (1 × 105 â†’ 4.5 × 105) of hBMSCs than static culture. Furthermore, the culture of hBMSCs in osteo-induction media revealed a greater enhancement of osteogenic transcription factors under the D-pEMF condition, suggesting that D-pEMF addition significantly boosted hBMSCs osteogenesis. Additionally, the RNA sequencing data revealed a significant shift in various osteogenic and signaling genes in the D-pEMF group, further suggesting their osteogenic capabilities. In this research, we demonstrated that the combined effect of wave and pEMF stimulation on hBMSCs allows rapid proliferation and induces osteogenic properties in the cells. Moreover, our study revealed that D-pEMF stimuli also induce ROS-scavenging properties in the cultured cells. This study also revealed a bioactive and cost-effective approach that enables the use of cells without using any expensive materials and avoids the possible risks associated with them post-implantation.

Exploring New Horizons: Advancements in Cartilage Tissue Engineering Under Space Microgravity.

Novel investigations of how microgravity affects cellular and tissue development have recently been made possible by the multidisciplinary fusion of tissue engineering and space science. This review examines the intersection of cartilage tissue engineering (CTE) and space science, focusing on how microgravity affects cartilage development. Space microgravity induces distinct physiological changes in chondrocytes, including a 20-30% increase in cell diameter, a 1.5- to 2-fold increase in proliferation rates, and up to 3-fold increases in chondrogenic markers such as SOX9 and collagen type II. These cellular alterations impact extracellular matrix composition and tissue structure. Space-optimized bioreactors using dynamic culture methods replicate physiological conditions and enhance tissue growth, but the absence of gravity raises concerns about the mechanical properties of engineered cartilage. Key research areas include the role of growth factors in cartilage development under microgravity, biocompatibility and degradation of scaffold materials in space, and in situ experiments on space stations. This review highlights the opportunities and challenges in leveraging microgravity for CTE advancements, emphasizing the need for continued research to harness space environments for therapeutic applications in cartilage regeneration. The multidisciplinary fusion of tissue engineering and space science opens novel avenues for understanding and improving cartilage tissue engineering, with significant implications for the future of biomedical applications in space and on Earth.

Synergic treatment of domestic wastewater and food waste in an anaerobic membrane bioreactor demo plant: Process performance, energy consumption, and greenhouse gas emissions.

Ambient operation and large-scale demonstration have limited the implementation and evaluation of anaerobic membrane bioreactors (AnMBRs) for low-strength wastewater treatment. Here, we studied these issues at an AnMBR demo plant that treats domestic wastewater and food waste together at ambient temperatures (7-28 °C). At varied hydraulic retention times (HRTs, 8-42 h), the AnMBR achieved a COD removal efficiency and biogas production of 80.4% ± 3.9% and 66.5 ± 9.4 NL/m3-Influent, respectively. Moreover, a stable high membrane flux of 14.4 L/m2/h was reached. The electric energy consumption for the AnMBR operation was 0.269-0.433 kW·h/m3, and 49.4%-91.3% could be compensated by the electric energy produced from methane production. At an HRT of 10 h, the AnMBR system demonstrated an impressively low net electric energy consumption of merely 0.05 kW·h/m3, resulting in a net greenhouse gas emission of 0.015 CO2-eq/m3, cutting 85% compared to the conventional activated sludge process. Achievements in this study provide key parameters for the ambient operation of AnMBR and demonstrate that AnMBR is an energy-saving and low-carbon solution for low-strength wastewater treatment.

Selenium and concomitant anions removal in a fixed bed bioreactor to satisfy drinking water regulations and subsequent stability check of selenium-laden biosludge.

This is the first successful report on selenium bio-attenuation to satisfy drinking water regulations as per Indian Standards (10 µg/L) in the presence of concomitant nitrate and sulfate from water sources utilizing a fixed bed bioreactor. The bioreactor was immunized with blended microbial culture and worked in downflow mode under anoxic conditions at 30±2°C for around 190 days under varying influent selenate (100 - 500 µg/L as selenium), nitrate (50 mg/L), sulfate concentrations (as per selenium removal) and necessary dose of acetic acid (as COD, a carbon source) in synthetic groundwater, operated at an empty bed contact time (EBCT) of 45 - 120 min. After supplying an adequate dosage of sulfate and alteration of EBCT, selenium was found to comply with drinking water regulations and nitrate was completely removed. X-ray diffraction and transmission electron microscopy analyses depicted nanocrystalline selenium sulfides (SeS and SeS2) formation as the possible mechanisms of selenium removal. Extended toxicity characteristic leaching procedure (TCLP) extractions confirmed a maximum selenium leaching of 52 and 282 µg/L during anoxic and oxic extractions, respectively. Long-term column leaching (> 3-month equilibration) under aerobic conditions at pH 7 confirmed the produced precipitate to be essentially stable (∼ 0.14% Se leaching). This work exhibits the synchronous bioremoval of selenium and its co-anions from contaminated water complying with drinking water standards, and leaving a stable and non-hazardous selenium-laden biosludge.

Intra- and extracellular real-time analysis of perfused fibroblasts using an NMR bioreactor: A pilot study.

INTRODUCTION: Metabolomic discrimination of different mitochondrial defects is challenging. We describe an NMR-based bioreactor allowing real-time intra- and extracellular metabolic investigation of perfused fibroblasts. OBJECTIVES: The objective of this study is (I) determining whether metabolic investigations of perfused fibroblasts overall and separated for intra- and extracellular contributions by real-time NMR allows for discrimination of different representative mitochondrial defects in a feasibility study and (II) gaining insight into physiological consequences of mitochondrial dysfunction in basal condition and during glycolysis inhibition. METHODS: Overall, intra- and extracellular metabolomes of malate dehydrogenase 2 (MDH2), pyruvate dehydrogenase (PDH), complex I (CI) deficient fibroblasts, and control fibroblasts were investigated under standard culture conditions and under glycolysis inhibition. In addition to "overall" metabolite quantification, intra- and extracellular metabolic contributions were separated based on diffusion rate differences. RESULTS AND DISCUSSION: Overall metabolites: Chemometric analysis of the entire metabolome revealed good separation between control, PDH and MDH2, while CI was less well separated. However, mixed intra- and extracellular changes complicated interpretation of the cellular metabolism. Intra- and extracellular metabolites: Compartment specific chemometrics revealed possibly augmenting metabolomic separation between control and deficient cell lines under basal and inhibition condition. All mitochondrial defects exhibited upregulation of glycolytic metabolism compared to controls. Inhibition of glycolysis resulted in perturbations of other metabolic pathways such as glutaminolysis, alanine, arginine, glutamate, and proline metabolism. MDH2 showed upregulation of alanine and glutamate metabolism, while the CI defect revealed lower intracellular arginine and downregulation of glutamate and arginine-dependent proline synthesis. CONCLUSION: Discrimination of intra- and extracellular metabolic contributions helps understanding the underlying mechanisms of mitochondrial disorders, uncovers potential metabolic biomarkers, and unravels metabolic pathway-specific adaptations in response to metabolic perturbations.

Unveiling the impacts of salts on halotolerant bacteria during filtration: A new perspective on membrane biofouling formation in MBR treating high-saline organic wastewater.

In recent decades, membrane bioreactor (MBR) has been prevalently employed to treat high-saline organic wastewater, where the halotolerant microorganisms should be intensively utilized. However, limited works were devoted to investigating the biofouling characteristics from the perspective of the relationship between halotolerant bacteria and salts. This work filled the knowledge gap by exploring the biofouling formation mechanisms affected by high salinity. The results showed that the amount of negative charge on halotolerant bacteria surface was significantly reduced by high content of NaCl, probably leading to the obvious cell agglomeration. Despite the normal proliferation, the halotolerant bacteria still produced substantial EPS triggered by high salinity. Compared with the case of control without salt addition, the enhanced biofouling development was observed under high-saline conditions, with the fouling mechanism dramatically transformed from cake filtration to intermediate blocking. It was inferred that the halotolerant bacteria initially adhered on membrane created an extra filter layer, which contributed to the subsequent NaCl retention, resulting in the simultaneous occurrences of pore blockage and cake layer formation because of NaCl deposition both on membrane pores as well as on biofilm layer. Under high-saline environment, remarkable salt crystallization occurred on the biofilm layer, with more protein secreted by the attached halotolerant bacteria. Consequently, the potential mechanisms for the enhanced biofouling formation influenced by high salinity were proposed, which should provide new insights and enlightenments on fouling control strategies for MBR operation when treating high-saline organic wastewater.

Enhancing the membrane bioreactor efficiency: The impact of rotating membrane modules and aeration strategies on the transmembrane pressure.

The study analyses the performance of a pilot plant using a rotating hollow fibre (HF) membrane bioreactor system. The experiments evaluated the effect of operational parameters such as rotational speed, aeration strategies, and maintenance cleaning (MC) procedures on the efficiency of the system, in particular transmembrane pressure (TMP) and filtrate quality. The results indicate that the rotating membrane module reduces TMP increase and can operate for 48 days with satisfactory performance, even without aeration. This has the potential to significantly improve efficiency, resulting in significant energy savings. In addition, two MC methods, clean in air and clean in place, were tested and found to be efficient for weekly MC. It was observed that operating without aeration during colder seasons may not be effective. Therefore, adaptive strategies are needed to address seasonal temperature variations.

Analytical and computational studies predict negligible risk of cell death from eddy generation off flat surfaces in cell culture flow systems.

Cell-based therapies represent the current frontier of biomedical innovations, with the technologies required underpinning treatments as broad as CAR-T cell therapies, stem cell treatments, genetic therapies and mRNA manufacture. A key bottleneck in the manufacturing process for each of these lies in the expansion of cells within a bioreactor vessel, requiring by far the greatest share of time for what are often time-critical therapies. While various designs, culture feeding and mixing methods are employed in these bioreactors, a common concern among manufacturers and researchers lies in whether shear stresses generated by culture media flow will damage cells and inhibit expansion. This study develops an analytical tool to link macro-scale measures of flow to risk of cell death using relationships with eddy size and dissipation rates, from eddies generated off flat surfaces. This analytical tool was then employed using computational fluid dynamics (CFD) to replicate a range of generic bioreactor geometries and flow conditions. We found that no combination of flow condition or design parameter was predicted by the tool to cause cell death within eddies, indicating negligible risk of cell death due to eddy formation within cell culture systems. While this requires experimental validation, and does not apply when cells are expanded using microcarriers, this tool nonetheless provides reassurance and accessible prediction of bioreactor design parameters that could result in cell death. Finally, our findings show that bioreactor design can be tailored such that the shear stress stimulation of cells can be selectively altered through small changes in flow rate.

Orthophosphate uptake onto woodchips in denitrifying bioreactors is enhanced by anoxic-(anaerobic-)oxic cycling.

Woodchips are widely used as a low-cost and renewable organic carbon source for denitrifying biofilms in passive nutrient removal systems. One limitation of wood-based biofiltration systems is their relatively poor removal of phosphorus (P) from subsurface drainage and stormwaters, necessitating the use of additional filter media when co-treatment of nitrogen (N) and P is required. Here, we show that anoxic-oxic cycling of woodchip media, which enhances nitrate (NO3-) removal by increasing the mobilization of organic carbon from wood, also improves orthophosphate (Pi) uptake onto woodchips. Orthophosphate removal rates in flow-through woodchip columns ranged from 0 to 34.9 µg PO43- L-1 h-1 under continuously-saturated (anoxic) conditions, and increased to 17.5 to 71.9 µg PO43- L-1 h-1 in columns undergoing drying-rewetting (oxic-anoxic) cycles. The highest Pi removal efficiencies were observed in the first 20 h after reactors were re-flooded, and were concurrent with maxima in polyphosphate kinase (ppk) gene expression by the polyphosphate accumulating organisms (PAOs) Accumulibacter spp. and Pseudomonas spp. Batch experiments confirmed that anoxic-anaerobic-oxic pre-incubation conditions led to orthophosphate uptake onto woodchips as high as 74.9 ± 0.8 mg PO43-/kg woodchip, and batch tests with autoclaved woodchips demonstrated that Pi uptake was due to biological processes and not adsorption. NO3- removal in batch tests was also greatest under oxic incubation conditions, attributed to greater carbon availability in hypoxic to anoxic zones in woodchip biofilms. While further research is needed to elucidate the mechanisms controlling enhanced Pi uptake by woodchip biofilms under anoxic-(anaerobic-)oxic cycling, these results suggest a role for enhanced Pi uptake by PAOs in a nature-based system for treatment of nonpoint source nutrients.

Functionalized Metal-organic Framework for NADH Regeneration by Hydrogen in a Redox Flow Bioreactor.

The electrochemical regeneration of reduced nicotinamide adenine dinucleotide (NADH) using [Rh(Cp*)(bpy)Cl]+ holds significant promise for the industrial synthesis of chiral chemicals. However, challenges persist due to the high consumption of NADH and the limited efficiency of its cyclic regeneration, which currently hinder widespread application. To address these obstacles, based on in-situ growth of 3D ordered metal-organic framework (NU-1000) on the surface of graphite felt, [Rh(Cp*)(bpy)Cl]+ were immobilized on the Zr6 nodes of NU-1000 by solvent-assisted ligand incorporation (SALI), and applied in a flow bioreactor. Moreover, we employ a gas diffusion electrode (GDE) to oxidize H2, providing a clean proton source for the electrochemical regeneration of NADH. Consequently, highly efficient enzymatic electrocatalytic synthesis of L-lactate was achieved when coupled with L-lactate dehydrogenases (LDH) as a model reaction, and the total turnover number (TTN) reached 19600 and 1750 for [Rh(Cp*)(bpy)Cl]+ and NAD+ after 48 h, corresponding to a high turnover frequency (TOF) of 2350 h-1 and 210 h-1 for [Rh(Cp*)(bpy)Cl]+ and NAD+, respectively. This work provides new insights for the construction of efficient enzymatic electrosynthesis systems in industrial production.

Biofunctionalization of Cellulose Microcarriers Using a Carbohydrate Binding Module Linked with Fibroblast Growth Factor for the Expansion of Human Umbilical Mesenchymal Stromal Cells in Stirred Suspension Bioreactors.

Mesenchymal stromal cells (MSCs) have the potential to be used as autologous or allogenic cell therapy in several diseases due to their beneficial secretome and capacity for immunomodulation and differentiation. However, clinical trials using MSCs require a large number of cells. As an alternative to traditional culture flasks, suspension bioreactors provide a scalable platform to produce clinically relevant quantities of cells. When cultured in bioreactors, anchorage-dependent cells like MSCs require the addition of microcarriers, which provide a surface for cell attachment while in suspension. The best performing microcarriers are typically coated in animal derived proteins, which increases cellular attachment and proliferation but present issues from a regulatory perspective. To overcome this issue, a recombinant fusion protein was generated linking basic fibroblast growth factor (bFGF) to a cellulose-specific carbohydrate binding module (CBM) and used to functionalize the surface of cellulose microcarriers for the expansion of human umbilical MSCs in suspension bioreactors. The fusion protein was shown to support the growth of MSCs when used as a soluble growth factor in the absence of cellulose, readily bound to cellulose microcarriers in a dose-dependent manner, and ultimately improved the expansion of MSCs when grown in bioreactors using cellulose microcarriers. The use of CBM fusion proteins offers a simple method for the surface immobilization of growth factors to animal component-free substrates such as cellulose, which can be used alongside bioreactors to increase growth factor lifespan, decrease culture medium cost, and increase cell production in the manufacturing of therapeutic cells.

Determining Which Hydrostatic Pressure Regimes Promote Osteogenesis in Human Mesenchymal Stem Cells.

BACKGROUND: Compressive loading of bone causes hydrostatic pressure changes which have been proposed as an osteogenic differentiation stimulus for mesenchymal stem cells (hMSCs). We hypothesised that hMSCs are adapted to differentiate only in response to cyclic hydrostatic pressures above critical thresholds of magnitude and frequency which correspond to physiological levels of anabolic bone loading. METHODS: Using a pneumatic-hydrostatic bioreactor, we applied hydrostatic pressure regimes to human hMSCs in 3D collagen hydrogel cultures for 1 h/day over 28 days to determine which levels of pressure and frequency stimulated osteogenesis in vitro. RESULTS: Stimulation of the 3D cultures with 0-280 kPa cyclic hydrostatic pressure at 1 Hz resulted in up to 75% mineralisation in the hydrogel (without exogenous growth factors), whilst static culture or variations of the regime with either constant high pressure (280 kPa, 0 Hz), low-frequency (0.05 Hz, 280 kPa) or low-magnitude (70 kPa, 1 Hz) stimulation had no osteogenic effects (< 2% mineralisation). Nuclear translocation of YAP was observed following cyclic hydrostatic pressure in mature MLO-A5 osteoblasts but not in hMSCs, suggesting that cyclic hydrostatic pressure activates different mechanotransduction pathways in undifferentiated stem cells and committed osteoblasts. CONCLUSIONS: Hydrostatic pressure is a potent stimulus for differentiating MSC into highly active osteoblasts and may therefore be a versatile tool for translational cell engineering. We have demonstrated that there are minimum levels of force and frequency needed to trigger osteogenesis, i.e. a pressure 'switch', which corresponds to the physiological forces experienced by cells in their native mesenchymal niche. The mechanotransduction mechanisms underpinning these effects are the subject of further study.

Stratified structure of membrane clogs observed in full scale cross-flow tubular ultrafiltration (UF) system: Fouling characterization and a proposed two-stage formation mechanism.

Membrane fouling remains a significant challenge in wastewater treatment, hindering both efficiency and lifespan. This study reports a distinct phenomenon of stratified membrane clogging observed in a full-scale cross-flow tubular ultrafiltration (UF) system treating sludge anaerobic digestion (AD) reject water. The distinct stratified structure, comprising inner and outer layers within the cake layer, has not been previously described. This research involved characterizing the filtration performance, analyzing membrane clog composition, and proposing a two-stage formation mechanism for the stratified clogs. It was revealed that higher inorganic and lower organic content in the outer layer compared to the inner layer. Acid and alkali treatments demonstrated the effectiveness of combined cleaning strategies. A mathematical model was developed to determine the critical conditions for stratified clog formation, influenced by membrane flux and cross-flow velocity (CFV). It is proposed that outer layer forms through long-term selective deposition, while the inner layer results from short-term dewatering within limited tubular space. High CFV (>2.5 m/s) prevents inner layer formation. Critical conditions for stratification occur at a flux of 18 L/m2/h with a CFV of 0.1 m/s or 65 L/m2/h with a CFV of 0.35 m/s. This study contributes a novel understanding of stratified membrane clogging, proposing a two-stage formation mechanism and identifying critical conditions, which provides insights for effective fouling control strategies and maintenance of operational efficiency for membrane systems.

Study on membrane fouling mechanisms and mitigation strategies in a pilot-scale anaerobic membrane bioreactor (P-AnMBR) treating digestate.

Anaerobic Membrane Bioreactor (AnMBR) are employed for solid-liquid separation in wastewater treatment, enhancing process efficiency of digestion systems treating digestate. However, membrane fouling remains a primary challenge. This study operated a pilot-scale AnMBR (P-AnMBR) to treat high-concentration organic digestate, investigating system performance and fouling mechanisms. P-AnMBR operation reduced acid-producing bacteria and increased methane-producing bacteria on the membrane, preventing acid accumulation and ensuring stable operation. The P-AnMBR effectively removed COD and VFA, achieving removal rates of 82.3 % and 92.0 %, respectively. Higher retention of organic nitrogen and lower retention of ammonia nitrogen were observed. The membrane fouling consisted of organic substances (20.3 %), predominantly polysaccharides, and inorganic substances (79.7 %), primarily Mg ions (10.1 %) and Ca ions (4.5 %). To reduce the increased transmembrane pressure (TMP) caused by fouling (a 10.6-fold increase in filtration resistance), backwash frequency experiment was conducted. It revealed a 30-min backwash frequency minimized membrane flux decline, facilitating recovery to higher flux levels. The water produced amounted to 70.3 m³ over 52 days. The research provided theoretical guidance and practical support for engineering applications, offering practical insights for scaling up P-AnMBR.

Development of Stephania tetrandra S. MOORE hairy root culture process for tetrandrine production.

Tetrandrine, a bioactive active compound mainly found in the roots of Stephania tetrandra, exhibits various pharmacological properties. In vitro hairy root (HR) culture may serve as a promising solution for the extraction of tetrandrine, overcoming the limitations of natural cultivation. The present study describes the consistent production of tetrandrine from S. tetrandra hairy roots induced by different strains of Agrobacterium rhizogenes. Cultivation in woody plant medium (WPM) resulted in the highest HR biomass (0.056 g/petri-dish) and tetrandrine content (7.28 mg/L) as compared to other media. The maximum HR biomass (6.95 g dw/L) and tetrandrine production (68.69 mg/L) were obtained in the fifth week of cultivation. The presence of ammonium nitrate (800 mg/L), calcium nitrate (1156 mg/L), sucrose (20 g/L) and casein (2 g/L) enhanced the tetrandrine production. Moreover, the fed-batch cultivation demonstrated that the NH4NO3 (1200 mg/L) was an important growth limiting factor that yielded the highest tetrandrine amount (119.59 mg/L). The cultivation of hairy roots in a mist trickling bioreactor for eight weeks was less (26.24 mg/L) than in the flask. Despite a lower tetrandrine yield observed in bioreactors compared to flask cultures, refining the growth medium and fine-tuning bioreactor operations hold promise for boosting tetrandrine yield.

Exploring Aeration Strategies for Enhanced Simultaneous Nitrification and Denitrification in Membrane Aerated Bioreactors: A Computational Approach.

In this study we employ computational methods to investigate the influence of aeration strategies on simultaneous nitrification-denitrification processes. Specifically, we explore the impact of periodic and intermittent aeration on denitrification rates, which typically lag behind nitrification rates under identical environmental conditions. A two-dimensional deterministic multi-scale model is employed to elucidate the fundamental processes governing the behavior of membrane aerated biofilm reactors (MABRs). We aim to identify key factors that promote denitrification under varying aeration strategies. Our findings indicate that the concentration of oxygen during the off phase and the duration of the off interval play crucial roles in controlling denitrification. Complete discontinuation of oxygen is not advisable, as it inhibits the formation of anaerobic heterotrophic bacteria, thereby impeding denitrification. Extending the length of the off interval, however, enhances denitrification. Furthermore, we demonstrate that the initial inoculation of the substratum (membrane in this study) influences substrate degradation under periodic aeration, with implications for both nitrification and denitrification. Comparison between continuous and periodic/intermittent aeration scenarios reveals that the latter can extend the operational cycle of MABRs. This extension is attributed to relatively low biofilm growth rates associated with non-continuous aeration strategies. Consequently, our study provides a comprehensive understanding of the intricate interplay between aeration strategies and simultaneous nitrification-denitrification in MABRs. The insights presented herein can contribute significantly to the optimization of MABR performance in wastewater treatment applications.

Advanced temperature control in ethanol fermentation using a PSO-PID controller with split-range control strategy.

Global energy demand is experiencing a notable surge due to growing energy security. Renewable energy sources, like ethanol, are becoming more viable. In the present study, the application of a PSO-PID (Particle Swarm Optimization - Proportional Integral Derivative) controller with a split-range control strategy was suggested for the regulation of temperature within the fermentation system. To optimize performance, a POS-PID controller with a split-range arrangement utilizing two control valves for hot and cold utilities was constructed. The study began by examining the open-loop dynamic response of the system to inlet temperature and concentration disturbances during ethanol production fermentation. Subsequently, a transfer function model was developed through linearization at the steady-state operating point. The split-range controller structure, implemented by optimizing the PSO-PID controller parameters using PSO, effectively demonstrated temperature control in simulations of a nonlinear model. In this investigation, the ethanol fermentation system was modeled as a CSTR using a modified Monod equation for microbial growth kinetics. Various dynamic behavioral disturbances were explored and verified in the model with plant data in this study. The simulation model results were validated through plant data. The proposed method showed superior closed-loop performance with respect to errors, with the actuators proving to be effective than other reported methods for temperature control.

Developments of electrospinning technology in membrane bioreactor: A review.

The necessity for effective wastewater treatment and purification has grown as a result of the increasing pollution issues brought on by industrial and municipal wastewater. Membrane bioreactor (MBR) technology stands out when compared to other treatment methods because of its high efficiency, environmental friendliness, small footprint, and ease of maintenance. However, the development and application of membrane bioreactors has been severely constrained by the higher cost and shorter service life of these devices brought on by membrane biofouling issues resulting from contaminants and bacteria in the water. The nanoscale size of the electrospinning products provides unique microstructure, and the technology facilitates the production of structurally different membranes, or the modification and functionalization of membranes, which makes it possible to solve the membrane fouling problem. Therefore, many current studies have attempted to use electrospinning in MBRs to address membrane fouling and ultimately improve treatment efficacy. Meanwhile, in addition to solving the problem of membrane fouling, the fabrication technology of electrospinning also shows great advantages in constructing thin porous fiber membrane materials with controllable surface wettability and layered structure, which is helpful for the performance enhancement of MBR and expanding innovation. This paper systematically reviews the application and research progress of electrospinning in MBRs. Firstly, the current status of the application of electrospinning technology in various MBRs is introduced, and the relevant measures to solve the membrane fouling based on electrospinning technology are analyzed. Subsequently, some new types of MBRs and new application areas developed with the help of electrospinning technology are introduced. Finally, the limitations and challenges of merging the two technologies are presented, and pertinent recommendations are provided for future research on the use of electrospinning technology in membrane bioreactors.

Treatment of Synthetic Wastewater Containing Polystyrene (PS) Nanoplastics by Membrane Bioreactor (MBR): Study of the Effects on Microbial Community and Membrane Fouling.

The persistent presence of micro- and nanoplastics (MNPs) in aquatic environments, particularly via effluents from wastewater treatment plants (WWTPs), poses significant ecological risks. This study investigated the removal efficiency of polystyrene nanoplastics (PS-NPs) using a lab-scale aerobic membrane bioreactor (aMBR) equipped with different membrane types: microfiltration (MF), commercial ultrafiltration (c-UF), and recycled ultrafiltration (r-UF) membranes. Performance was assessed using synthetic urban wastewater spiked with PS-NPs, focusing on membrane efficiency, fouling behavior, and microbial community shifts. All aMBR systems achieved high organic matter removal, exceeding a 97% COD reduction in both the control and PS-exposed reactors. While low concentrations of PS-NPs did not significantly impact the sludge settleability or soluble microbial products initially, a higher accumulation increased the carbohydrate concentrations, indicating a protective bacterial response. The microbial community composition also adapted over time under polystyrene stress. All membrane types exhibited substantial NP removal; however, the presence of nano-sized PS particles negatively affected the membrane performance, enhancing the fouling phenomena and increasing transmembrane pressure. Despite this, the r-UF membrane demonstrated comparable efficiency to c-UF, suggesting its potential for sustainable applications. Advanced characterization techniques including pyrolysis gas chromatography/mass spectrometry (Py-GC/MS) were employed for NP detection and quantification.