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.

Effects of salinity and betaine addition on anaerobic granular sludge properties and microbial community succession patterns in organic saline wastewater.

In this study, the effects of different salinity gradients and addition of compatible solutes on anaerobic treated effluent water qualities, sludge characteristics and microbial communities were investigated. The increase in salinity resulted in a decrease in particle size of the granular sludge, which was concentrated in the range of 0.5-1.0 mm. The content of EPS (extracellular polymeric substances) in the granular sludge gradually increased with increasing salinity and the addition of betaine (a typical compatible solute). Meanwhile, the microbial community structure was significantly affected by salinity, with high salinity reducing the diversity of bacteria. At higher salinity, Patescibacteria and Proteobacteria gradually became the dominant phylum, with relative abundance increasing to 13.53% and 12.16% at 20 g/L salinity. Desulfobacterota and its subordinate Desulfovibrio, which secrete EPS in large quantities, dominated significantly after betaine addition.Their relative abundance reached 13.65% and 7.86% at phylum level and genus level. The effect of these changes on the treated effluent was shown as the average chemical oxygen demand (COD) removal rate decreased from 82.10% to 79.71%, 78.01%, 68.51% and 64.55% when the salinity gradually increased from 2 g/L to 6, 10, 16 and 20 g/L. At the salinity of 20 g/L, average COD removal increased to 71.65% by the addition of 2 mmol/L betaine. The gradient elevated salinity and the exogenous addition of betaine played an important role in achieving stability of the anaerobic system in a highly saline environment, which provided a feasible strategy for anaerobic treatment of organic saline wastewater.

Effect of gradual increase of salt on performance and microbial community during granulation process.

Salinity was considered to have effects on the characteristics, performance microbial communities of aerobic granular sludge. This study investigated granulation process with gradual increase of salt under different gradients. Two identical sequencing batch reactors were operated, while the influent of Ra and Rb was subjected to stepwise increments of NaCl concentrations (0-4 g/L and 0-10 g/L). The presence of filamentous bacteria may contribute to granules formed under lower salinity conditions, potentially leading to granules fragmentation. Excellent removal efficiency achieved in both reactors although there was a small accumulation of nitrite in Rb at later stages. The removal efficiencies of chemical oxygen demand (COD), total nitrogen (TN), and total phosphorus (TP) in Ra were 95.31%, 93.70% and 88.66%, while the corresponding removal efficiencies in Rb were 94.19%, 89.79% and 80.74%. Salinity stimulated extracellular polymeric substances (EPS) secretion and enriched EPS producing bacteria to help maintain the integrity and stability of the aerobic granules. Heterotrophic nitrifying bacteria were responsible for NH4+-N and NO2--N oxidation of salinity systems and large number of denitrifying bacteria were detected, which ensure the high removal efficiency of TN in the systems.

Engineered Shape-Morphing Transitions in Hydrogels Through Suspension Bath Printing of Temperature-Responsive Granular Hydrogel Inks.

4D printing of hydrogels is an emerging technology used to fabricate shape-morphing soft materials that are responsive to external stimuli for use in soft robotics and biomedical applications. Soft materials are technically challenging to process with current 4D printing methods, which limits the design and actuation potential of printed structures. Here, a simple multi-material 4D printing technique is developed that combines dynamic temperature-responsive granular hydrogel inks based on hyaluronic acid, whose actuation is modulated via poly(N-isopropylacrylamide) crosslinker design, with granular suspension bath printing that provides structural support during and after the printing process. Granular hydrogels are easily extruded upon jamming due to their shear-thinning properties and their porous structure enables rapid actuation kinetics (i.e., seconds). Granular suspension baths support responsive ink deposition into complex patterns due to shear-yielding to fabricate multi-material objects that can be post-crosslinked to obtain anisotropic shape transformations. Dynamic actuation is explored by varying printing patterns and bath shapes, achieving complex shape transformations such as 'S'-shaped and hemisphere structures. Furthermore, stepwise actuation is programmed into multi-material structures by using microgels with varied transition temperatures. Overall, this approach offers a simple method to fabricate programmable soft actuators with rapid kinetics and precise control over shape morphing.

Uncommon and Unusual Variants of Autoimmune Bullous Diseases.

Background: Autoimmune blistering diseases (AIBDs) are a type of dermatosis with antibodies produced against various structural proteins of the epidermis or dermoepidermal junction. AIBDs are broadly divided into intraepidermal and subepidermal types. Apart from the common AIBDs, there is an array of uncommon AIBDs. Objective: To discuss uncommon variants of AIBDs so that the readers are updated about them. Methods: In this review, we have discussed uncommon and unusual variants like pemphigus herpetiformis, IgA pemphigus, paraneoplastic pemphigus, induced pemphigus, IgG/IgA pemphigus, oral lichenoid pigmentation in pemphigus, pemphigus acanthoma, and follicular pemphigus. Rarer variants of the pemphigoid group of disorders include anti-laminin 332 pemphigoid, mixed linear IgA/IgG pemphigoid, anti-p200 pemphigoid, Brunsting-Perry pemphigoid, IgM pemphigoid, granular C3 pemphigoid, anti-p105 pemphigoid, ORF-induced anti-laminin 332 pemphigoid, and acral purpura in dermatitis herpetiformis. Conclusion: This review will help in early diagnosis and treatment of uncommon and unusual variants of AIBDs.

Two-scale concurrent simulations for crack propagation using FEM-DEM bridging coupling.

The Discrete element method (DEM) is a robust numerical tool for simulating crack propagation and wear in granular materials. However, the computational cost associated with DEM hinders its applicability to large domains. To address this limitation, we employ DEM to model regions experiencing crack propagation and wear, and utilize the finite element method (FEM) to model regions experiencing small deformation, thus reducing the computational burden. The two domains are linked using a FEM-DEM coupling, which considers an overlapping region where the deformation of the two domains is reconciled. We employ a "strong coupling" formulation, in which each DEM particle in the overlapping region is constrained to an equivalent position obtained by nodal interpolation in the finite element. While the coupling method has been proved capable of handling propagation of small-amplitude waves between domains, we examine in this paper its accuracy to efficiently model for material failure events. We investigate two cases of material failure in the DEM region: the first one involves mode I crack propagation, and the second one focuses on rough surfaces' shearing leading to debris creation. For each, we consider several DEM domain sizes, representing different distances between the coupling region and the DEM undergoing inelasticity and fracture. The accuracy of the coupling approach is evaluated by comparing it with a pure DEM simulation, and the results demonstrate its effectiveness in accurately capturing the behavior of the pure DEM, regardless of the placement of the coupling region. Supplementary Information: The online version contains supplementary material available at 10.1007/s40571-024-00788-x.

Macroscopic Assembly of Materials with Engineered Bacterial Spores via Coiled-Coil Interaction.

Herein, we report macroscopic materials formed by the assembly of engineered bacterial spores. Spores were engineered by using a T7-driven expression system to display a high density of pH-responsive self-associating proteins on their surface. The engineered surface protein on the spore surface enabled pH-dependent binding at the protein level and enabled the assembly of granular materials. Mechanical properties remained largely constant with changing pH, but erosion stability was pH-dependent in a manner consistent with the pH-dependent interaction between the engineered surface proteins. Our finding utilizes synthetic biology for the design of macroscopic materials and illuminates the impact of coiled-coil interaction across various length scales.

Deciphering anammox response characteristics and potential mechanisms to polyethylene terephthalate microplastic exposure.

Microplastics (MPs) are frequently detected in the wastewater. Herein, the short-term and long-term effects of polyethylene terephthalate (PET) MPs on anammox granular sludge were investigated and the potential response mechanisms were analyzed. Results showed that although short-term exposure of anammox granular sludge to PET-MPs induced a stress response, the nitrogen removal performance was not significantly affected. By contrast, long-term exposure to PET-MPs inhibited nitrogen removal performance with increased exposure time and PET-MP concentration. The total nitrogen removal efficiency (TNRE) decreased by 28.7 % when sludge was exposed to 200 mg/L of PET-MPs. However, the anammox activity recovered with prolonged operation time, and approximately 87 % of the initial TNRE was recovered after three months. Microbial community evolution and metabolic exchange variations were the potential response mechanisms of anammox granular sludge to PET-MP exposure, with PET-MP exposure decreasing the anammox bacteria growth rate and relative symbiotic bacterial abundance in the anammox consortia and hindering cross-feeding pathways. The findings of this study provide novel insight into anammox behavior when treating wastewater containing PET-MPs.

Sludge size affects sorption of organic micropollutants in full-scale aerobic granular sludge systems.

Aerobic granular sludge (AGS) is gaining popularity as an alternative to activated sludge for wastewater treatment. However, little information is available on AGS regarding the removal of organic micropollutants (OMPs) through sorption. In this study, the sorption behavior of 24 OMPs at environmentally relevant concentrations (1 µg/L) was investigated in six sludge fractions of varying sizes (>4 mm, 2-4 mm, 1-2 mm, 0.6-1 mm, 0.2-0.6 mm, and <0.2 mm) from a full-scale AGS reactor using batch experiments. Sorption was significant (removal efficiency >40 %) for 10 OMPs, including 4 zwitterionic and 6 positively charged pharmaceuticals, indicating the importance of electrostatic interaction for OMP sorption in AGS systems. Larger granules exhibited a higher sorption coefficient and capacity than smaller AGS fractions, probably due to increased extracellular polymeric substance content for larger granules. Equilibrium OMP sorption was only reached after 72 h in granules larger than 2 mm, indicating an effect of longer diffusion distance for OMPs into larger granules. Additionally, compared to activated sludge, AGS demonstrates a similar or even slightly higher sorption capacity for 10 OMPs at 1 µg/L. Overall, this study is the first to investigate the sorption behavior of six AGS size fractions for OMPs at environmentally relevant concentrations (1 µg/L) and propose the possible roles of different-sized sludge in OMP sorption in the full-scale AGS reactor.

Modeling of the effect of gradation and compaction characteristics on the california bearing ratio of granular materials for subbase and landfill liner construction.

The California bearing ratio (CBR) of a granular materials are influence by the soil particle distribution indices such as D10, D30, D50, and D60 and also the compaction properties such as the maximum dry density (MDD) and the optimum moisture content (OMC). For this reason, the particle packing and compactibility of the soil play a big role in the design and construction of subbases and landfills. In this research paper, experimental data entries have been collected reflecting the CBR behavior of granular soil used to construct landfill and subbase. The database was utilized in the ratio of 78-22% to predict the CBR behavior considering the artificial neural network (ANN), the evolutionary polynomial regression (EPR), the genetic programming (GP), Extreme Gradient Boosting (XGBoost), Random Forest (RF) and the response surface methodology (RSM) intelligent learning and symbolic abilities. The relative importance values for each input parameter were carried out, which indicated that the (CBR) value depends mainly on the average particle size (D30, 50 & 60). They showed a combined influence index of 66% of the considered parameters in the model exercise. This further shows the importance and structural influence of the particles within the D50 and D60 range in a granular material consistency in the design and construction purposes. Performance indices were also used to study the ability of the models. The ANN model showed the best performance with accuracy of 88%, then GP, EPR and RF with almost the same accuracies of 85% and lastly the XGBoost with accuracy of 81%. Also, the RSM produced an R2 of 0.9464 with a p-value of less than 0.0001. These values show that the ANN produced the decisive model with the superior performance indices in the forecast of CBR of granular material used as subbase and waste compacted earth liner material. The results further show that optimal performance of the CBR depended on D50 and D60 for the design of subgrade, subbase, and liner purposes and also during the performance monitoring phase of the constructed flexible pavement foundations and compacted earth liners.

Partitioned granular sludge coupling with membrane-aerated biofilm reactor for efficient autotrophic nitrogen removal.

The partial nitritation-anammox process based on a membrane-aerated biofilm reactor (MABR) faces several challenges, such as difficulty in suppressing nitrite-oxidizing bacteria (NOB), excessive effluent nitrate, and ineffective synergy between denitrification and anammox bacteria. Therefore, a novel partitioned granular sludge coupling with MABR (G-MABR) was constructed. The chemical oxygen demand (COD) and nitrogen removal efficiency were 88.8 ±â€¯1.8 %-92.6 ±â€¯1.2 % and 88.8 ±â€¯1.5 %-93.6 ±â€¯0.7 %, respectively. The COD was mainly lowered in the lower granular sludge-zone, while nitrogen was removed in the upper MABR-zone. NOB was significantly suppressed in the MABR-zone due to competition for substrate with denitrifying bacteria and anammox bacteria. This partitioned configuration reduced the C/N ratio in the MABR-zone, thus facilitating autotrophic nitrogen removal. Both partial nitrification and denitrification provided nitrite for anammox bacteria in granular sludge, whereas partial nitrification mainly supplied nitrite to the anammox bacteria in membrane biofilms.

Inhibition of denitrification and enhancement of microbial interactions in the AGS system by high concentrations of quinoline.

Quinoline represents a highly toxic and structurally stable nitrogen-containing heterocyclic compound in coking wastewater, posing a potential threat to human beings and the ecological environment. In this study, we investigated the impact of gradually elevating quinoline concentration on pollutant removal efficiency, sludge characteristics, microbial community and their interactions in the aerobic granular sludge (AGS) system. The results demonstrated that AGS was capable of effectively degrading quinoline, with a final removal rate of 90 mg/L quinoline reaching 98.54 ± 0.28%. Notably, the denitrification process was significantly impeded in the presence of 90 mg/L quinoline, with the Phase D effluent displaying a notably high NO3--N concentration of 37.09 ± 21.81 mg/L, primarily attributed to the reduced abundance of norank_f_A4b bacteria. As the quinoline concentration increased, the sludge particle size diminished from 3.46 to 2.60 mm, while the settling performance deteriorated significantly, escalating from 31.29 ± 1.63 mL/g to 62.32 ± 2.87 mL/g. Meanwhile, the protein (PN) content in EPS gradually increased (from 19.87 ± 0.88 mg/g MLVSS to 51.22 ± 3.21 mg/g MLVSS), while the polysaccharide (PS) content fluctuated. Quinoline profoundly modified microbial community composition and structure, with deterministic processes dominating community assembly. Network analysis indicated intensified and complex microbial interactions at 90 mg/L quinoline, characterized by significantly higher positive correlations. In addition, rare taxa (RT) dominated the network nodes, with 74 of 93 key species belonging to RT, highlighting their pivotal roles in sustaining system functions and strengthening microbial connections. This study provides new insights into the effects of quinoline on microbial community structure and interactions in AGS system.

Surface-Adhered Microbubbles Enhance the Resistance of ANAMMOX Granular Sludge to Sulfamethoxazole Stress.

The granule-based anammox process has been reported to be more resistant to the stress of antibiotics; however, the underlying resistance mechanism is still not fully understood. In this study, we found that more microbubbles stably adhered to the surface layer of anammox granular sludge (AnGS, Gs) operating under long-term sulfamethoxazole (SMZ) stress of 2 mg/L, compared to that in the control reactor (Gc). The difference in covering content can be up to over three times (1.0 ± 0.1% vs 0.3 ± 0.0%). Batch tests showed that the coverage ratio of microbubbles on Gs reached approximately 32.5%, which significantly reduced SMZ transfer into AnGS due to the adsorption of SMZ by bubbles, thus alleviating the inhibition of anammox bacterial activity by 36.5%. The adhesion force between the microbubbles and the surface layer of Gs was found to be largely enhanced by 75.0% compared to that of Gc. The increased hydrophobicity of surface layer due to the increased extracellular polymer substance (EPS, mainly proteins) content, and the larger capillary force of surface layer, owing to the unique micronano structure, were identified as key factors responsible for the stable adhesion of microbubbles on the Gs. Consequently, this study demonstrated the vital roles of the surface-adhered microbubbles in resisting the stress of SMZ and shed light on the regulation and development of robust granule-based anammox processes.

Antiferromagnetic Nanoscale Bit Arrays of Magnetoelectric Cr2O3 Thin Films.

Magnetism of oxide antiferromagnets (AFMs) has been studied in single crystals and extended thin films. The properties of AFM nanostructures still remain underexplored. Here, we report on the fabrication and magnetic imaging of granular 100 nm-thick magnetoelectric Cr2O3 films patterned in circular bits with diameters ranging from 500 down to 100 nm. With the change of the lateral size, the domain structure evolves from a multidomain state for larger bits to a single domain state for the smallest bits. Based on spin-lattice simulations, we show that the physics of the domain pattern formation in granular AFM bits is primarily determined by the energy dissipation upon cooling, which results in motion and expelling of AFM domain walls of the bit. Our results provide a way toward the fabrication of single domain AFM-bit-patterned memory devices and the exploration of the interplay between AFM nanostructures and their geometric shape.

Removal-Free and Multicellular Suspension Bath-Based 3D Bioprinting.

Suspension bath-based 3D bioprinting (SUB3BP) is effective in creating engineered vascular structures. The transfer of oxygen and nutrients via engineered vascular networks is necessary for tissue or organ survival and integration following transplantation. Existing SUB3BP techniques face challenges in fabricating hierarchical structures with multicellular organization, including issues related to suspension bath removal, restricted material choices, and low accuracy. A next-generation SUB3BP technique that is removal-free and multicellular is presented. A simple, storable, stable, and scalable starch hydrogel design leverages the diverse spectrum of hydrogels available for use in SUB3BP. Starch granules (8.1 µm) create vascular structures with minimal surface roughness (2.5 µm) that simulate more natural vessel walls compared to prior research. The development of cells and organoids, as well as the bioprinting of multicellular skin models with vasculature, demonstrates that starch suspension baths eliminate the removal process and have the potential for fabricating artificial tissue with a hierarchical structure and multicellular distribution.

Continuous self-circulating up-flow granular sludge fluidized bed process treating low-strength real municipal wastewater at high hydraulic loads.

Conditions conducive to aerobic granular sludge (AGS) growth and maintenance are very difficult to realize in continuous-flow biological treatment processes. This study conducted a continuous-flow self-circulating up-flow granular sludge fluidized bed (Zier process) treating real urban wastewater approximately one year. The substantial self-circulating multiple times (RSCMT, 8-15 times) and up-flow velocity (8-15 m/h) generated by aeration, the only power equipment in Zier process, facilitated pollutant removal, particle granulation and stabilization. With hydraulic retention time of 5 h, RSCMT of 9.3-14.4 times and chemical oxygen demand (COD)/total nitrogen (TN) ratio of 5.9 ±â€¯1.0, the effluent COD, ammonia nitrogen and TN were 28.6 ±â€¯7.7, 1.1 ±â€¯1.2, and 13.3 ±â€¯1.7 mg/L, respectively. The median particle size was 150-250 µm and effluent suspended solids concentration was 33.4 ±â€¯14.5 mg/L. It is unnecessary to set up sludge reflux which simplifies the subsequent mud-water separation facilities. The Zier process provides a new process structure for implementation of continuous-flow AGS process.

A Simplified Calibration Procedure for DEM Simulations of Granular Material Flow.

The discrete element method (DEM) has emerged as an essential computational tool in geotechnical engineering for the simulation of granular materials, offering significant advantages over traditional continuum-based methods such as the finite element method (FEM) and the finite difference method (FDM). The DEM's ability to model particle-level interactions, including contact forces, rotations, and particle breakage, allows for a more precise understanding of granular media behavior under various loading conditions. However, accurate DEM simulations require meticulous calibration of input parameters, such as particle density, stiffness, and friction, to effectively replicate real-world behavior. This study proposes a simplified calibration procedure, intended to be conducted prior to any granular material flow DEM modeling, based on three fundamental physical tests: bulk density, surface friction, and angle of repose. The ability of these tests, conducted on dry quartz sand, to accurately determine DEM micromechanical parameters, was validated through numerical simulation of cylinder tests with varying height-to-radius ratios. The results demonstrated that this calibration approach effectively reduced computational complexity while maintaining high accuracy, with validation errors of 0% to 12%. This research underscores the efficacy of simplified DEM calibration methods in enhancing the predictive reliability of simulations, particularly for sand modeling in geotechnical applications.