Increasing Loading Rate Research Articles

Evolution of quorum sensing process and their regulatory role on biochemical metabolism during the organic loading rate increase in dry anaerobic digestion

The organic loading rate (OLR) is a critical parameter affecting the stability of dry anaerobic digestion (AD) of kitchen waste (KW), and significantly impacting the variations in physicochemical parameters and microbial communities. However, the evolution of quorum sensing (QS) and their role on anaerobic biochemical metabolism during the increase in OLR in dry AD remain unknown. Therefore, this study systematically elucidated the matter through multi-omics analysis based on a pilot-scale dry AD of KW. The results demonstrated that fluctuations in the OLR significantly influenced the microbial QS in dry AD. When the OLR ≤4.0 g·VS/L·d, the system operated stably, and methane production increased. The enrichment of Proteobacteria was crucial for sustaining high levels of functional genes associated with various types of QS, including acyl-homoserine lactones (AI-1), autoinducer-2 (AI-2), autoinducer-3 (AI-3), and gamma-aminobutyric acid (GABA). This enabled cooperative communication among microbes under low OLR. Furthermore, most genes associated with these QS processes positively affected hydrolysis, acidogenesis, and methanogenesis. When the OLR increased to 6.0 g·VS/L·d, the fatty acids and hydrogen partial pressure increased significantly. The autoinducing peptides (AIP)-type became the predominant QS and was positively correlated with fatty acids abundance. Syntrophaceticus and Syntrophomonas may promote syntrophic oxidation of acetate at high OLR through AIP-type QS. These findings provided new insights into the QS processes of microbes during dry AD of KW and a theoretical foundation for optimizing biochemical metabolic processes in dry AD through QS.

Improvement of Anammox Particle Size Distribution in a Reactor Fed with Real Effluent Using Flow Rate as a Strategy for Loading Rate Increase

Improvement of Anammox Particle Size Distribution in a Reactor Fed with Real Effluent Using Flow Rate as a Strategy for Loading Rate Increase

Experimental and numerical study on the loading rate dependent tensile behavior of carbon fiber/epoxy interface

A series of experiments and simulations were performed to explore the effect of loading rate on the tensile behavior of carbon fiber/epoxy composite interface via the fiber bundle tensile method. Varying velocities were used to test the stress‒time and stress‒displacement curves of the samples, and a high-speed camera was used to study the in situ failure behavior of the carbon fiber/epoxy interface. Increasing the loading rate from 5 × 10−6 m/s to 12.0 m/s leds to an increase in the interfacial tensile strength from 6.1 ± 0.9 MPa to 16.4 ± 0.3 MPa, an increase in the interfacial stiffness from 1.58 ± 0.3 N/m to 17.4 ± 3.1 N/m, and a decrease in the fracture displacement from 0.23 ± 0.03 mm to 0.10 ± 0.01 mm. Optical microscopy analysis revealed rougher crack surfaces at higher loading rates. The fracture mode of interface transitioned from fiber breakage and pull-out to brittle matrix cracking with increasing loading rate. The finite element method was employed to verify the effectiveness of the fiber bundle tensile method with a split Hopkinson tension bar and study the failure behavior of the interface under dynamic loading. The simulation results showed that the calculated failure stress was 20 % lower than the actual value, and the cohesive layer was found to have greater stress at the edge region. This investigation deepens the understanding of the effects of the loading rate on the interfacial tensile behaviors of carbon fiber/epoxy composites.

Experimental study on the mechanical characteristics of weakly cemented mudstone under different loading rates

With the gradual shift of coal mining to the western coal mining region of China, floor heave in weakly cemented mudstone roadways has become an issue affecting the safety and efficiency of coal mine production. Additionally, different mining rates can lead to fluctuating support stresses on the roof and floor of weakly cemented mudstone roadways. Therefore, obtaining a comprehensive understanding of the mechanical properties of weakly cemented mudstone at different loading rates is conducive to improving the issue of floor heave in such roadways and provides a theoretical basis for further study. In this context, a series of uniaxial mechanical tests with concurrent acoustic emission monitoring were conducted on specimens of weakly cemented mudstone under various loading rates (0.005, 0.01, 0.05, and 0.1 mm/s). The stress‒strain and acoustic emission response curves were obtained to effectively characterize the strength, deformation, damage, macroscale instability, and crack propagation characteristics of the mudstone under the influence of loading rate effects. The research results support the following findings: (1) With increasing loading rate, the peak strength and elastic modulus of weakly cemented mudstone significantly increase, while the peak axial strain and peak radial deformation significantly decrease. (2) With increasing loading rate, the stress required to trigger the expansion of weakly cemented mudstone gradually increases, and a significant power-law relationship arises between the strain of the mudstone at the start of expansion and the loading rate. (3) With increasing loading rate, the acoustic emission ringing count of weakly cemented mudstone increases: The failure of weakly cemented mudstone changes from small-range progressive failure to sudden failure, and the failure mode transitions from shear failure to tensile‒shear composite failure. (4) The studied mudstone damage variables increase with increasing loading rate, following an approximate exponential function. The conclusions obtained in this work can provide a theoretical basis for the evolution mechanism and control of floor heave in deep roadway mining.

Study on the Tensile Failure Characteristics and Energy Calculation Model of Coal Seam Hard Roof Considering the Mining Speed

To reveal the influence mechanism of mining speed on roof fracture-type rockburst, the Brazilian split technique combined with acoustic emission monitoring technology was employed to study the effects of loading rates on the tensile failure characteristics and acoustic emission parameters of coal series sandstone. The linear relationship between the tensile strength of the samples and the change rate of tensile stress was determined. The mining speed was introduced into the mechanical model of initial and cyclic fracture of the hard roof, and the quantitative relationship between the maximum rate of change of tensile stress within the hard roof and the mining speed was derived. Based on this, a computational model for the bending elastic energy of the hard roof during initial and cyclic fractures, considering the mining speed, was established. The main findings are as follows: As the loading rate increases, the distribution range of acoustic emission energy in sandstone Brazilian split samples before failure widens, with a significant rise in acoustic emission ring-down counts and energy at failure. At lower loading rates, acoustic emission events primarily occur near sample failure, whereas at higher rates, they mostly happen in the early loading stage. The higher the mining speed, the less opportunity there is for internal micro-fractures to develop and expand before the hard roof fractures, which macroscopically results in increased tensile strength and a larger amount of energy released at the moment of fracture. Bending elastic energy rises approximately linearly with mining speed, and the thicker the hard roof, the more sensitive the bending elastic energy is to changes in mining speed. This effect is even more pronounced during cyclic fractures. Optimizing mining speed is crucial for preventing roof fracture-type rockbursts, especially in mining workfaces with thick and hard roofs.

Damage Evolution and Fractal Characteristics of Granite under the Influence of Temperature and Loading

To study the damage characteristics and evolution law of granite under the influence of temperature and loading rate, uniaxial compression tests at different loading rates were performed for granite samples at 30 °C, 40 °C, 60 °C, and 80 °C. The damage characteristics and evolution law of granite were studied in conjunction with acoustic emission ringing, acoustic emission b values, acoustic emission signaling constellations, and fractal dimensions. The results showed the following: (1) At a low loading rate (0.005 mm/s), the peak stress of the granite increases gradually as the temperature increases. At high loading rates (0.01 mm/s and 0.02 mm/s), the peak stress of the granite first decreases, then increases as the temperature increases. The elastic modulus at different loading rates decreases first, then increases as the temperature increases. The elastic modulus of the granite is the lowest at 40 °C; (2) At the same temperature, specimens subjected to higher loading rates exhibit accelerated internal damage progression, with a precipitous decrease in the b-value occurring earlier. At a loading rate of 0.005 mm/s, the total number of acoustic emission ring-down events is at least 1.7 times greater than that at other loading rates, indicating a more complex development of internal cracks in the granite specimens. Moreover, as the temperature increases under a constant loading rate, the concentration of acoustic emission ring-downs intensifies during the unstable crack development and failure phases, accompanied by progressively larger fluctuations in the b-value; (3) Under the same temperature conditions, the acoustic emission signals in the specimens loaded at 0.005 mm/s and 0.01 mm/s propagate from one end to the other. At 0.02 mm/s, emissions appear simultaneously at both ends of the specimen and converge toward the center. The proportion of damage and energy associated with compression differs with temperature; at 30 °C and 40 °C, damage and energy are concentrated in the early phase of compression, whereas at 60 °C and 80 °C, they are more significant during the later stages; and (4) The fractal dimension of the granite specimens generally decreases, then undergoes a phase of fluctuating growth, followed by a decline. With increasing loading rates at a constant temperature, the compaction of the granite specimens decreases; the orderliness of the crack patterns gradually increases. As the temperature increases, the distribution of cracks during the compaction and failure phases becomes more orderly. During the crack initiation and development phases, the dispersion of cracks and the formation of crack networks are more pronounced. These findings provide a theoretical reference for understanding the microscale damage and failure mechanisms of granite under varying loading rates and temperatures.

Effect of temperature on damage mechanism and fracture behavior of LiH ceramic under 3-point bending at different loading rates

The damage mechanism and fracture behavior of lithium hydride (LiH) ceramic are key to its design and application at elevated temperature in nuclear engineering. LiH ceramic is tested in a loading rate range of 0.001–2 mm/min from room temperature (RT) to 600 °C using digital image correlation (DIC) method combined with high-speed photography. At low temperature (up to 300 °C), LiH ceramic undergoes brittle fracture. At high temperature (up to 600 °C), LiH ceramic undergoes creep fracture at low loading rate and ductile fracture at high loading rate. The main crack growth rate of LiH ceramic with ductile fracture is higher than that of LiH ceramic with creep fracture, and is lower than that of LiH ceramic with brittle fracture. With the change of temperature and loading rate, three damage mechanisms, fatigue damage corresponding to SCG of inherent flaws, creep damage represented by creep microcracks and ductile damage symbolled by dimples, occur simultaneously and show competitive characteristics, one of which dominates the failure. At low loading rate, there is a transition of the dominant damage mechanism from fatigue to creep damage with increasing temperature. At high temperature, the dominant damage mechanism changes from creep to ductile damage with the increase of loading rate.

Crack propagation characteristics of coal body around the borehole under different loading rates

The loading rate is a crucial factor influencing the deformation and fracture of the coal body around a borehole. The uniaxial compression tests and digital image correlation methods were adopted to scrutinize the mechanical parameters, failure modes, and lateral strains of specimens. A comprehensive analysis of crack propagation characteristics under different loading rates was conducted. Based on the cohesion model, the intrinsic interplay between crack propagation characteristics and loading rates was elucidated. Combined with the actual situation on site, the treatment method of gas anomaly in high recovery rate working face is given. With an increase in loading rate, the peak strength, peak strain, and the initial stress level of cracks gradually increased and tended to stabilize. The elastic modulus exhibited an initial increase followed by a decrease. The failure mode transitioned from shear to tensile, and the fracture process became more intense. Tensile crack propagation was divided into four stages, with the first three stages characterized by “closed-open-closed” patterns. In the fourth stage, lateral strains fluctuated between positive and negative values at high loading rates, exhibiting high-strength nonlinearity, the accumulation of deformation energy density is “rupture → rupture again”. Due to the influence of cohesion, tensile crack propagation at low loading rates was hindered, resulting in K1 = 0 at the tensile crack tip. Under high loading rates, K1 > 0, leading to extensive tensile failure in the internal load-bearing structure. At the same time, combined with the abnormal situation of gas in the working face with high mining rate, specific solutions are put forward.

Modeling and evaluation of the fracture resistance of alkali-resistant glass fibre reinforced concrete under different loading rates

Alkali-resistant glass fibre reinforced concrete (AR-GFRC) has garnered significant interest due to its economic and environmental friendliness. Given the critical importance of evaluating the crack resistance of AR-GFRC under dynamic loading conditions and the size effect inherent in determined fracture parameters using traditional methods, this study aims to propose an analytical approach based on the boundary effect model. The goal is to predict the realistic dynamic tensile strength (ft) and fracture toughness (KIC) while elucidating the rate sensitivity of fracture resistance. Three-point bending tests were conducted on AR-GFRC with three different fibre volumes to investigate dynamic fracture behaviors under varying loading rates. By introducing discrete parameter and the microstructure characteristic parameter that account for material discontinuity and heterogeneity, the realistic dynamic ft and KIC of AR-GFRC can be directly obtained as closed-form solutions upon determining the maximum fracture load from the tests. The results revealed a substantial increase in ft and KIC with an improvement in the loading rate. However, due to relatively weakened fibre activities, the enhancement of dynamic fracture resistance decreases with the increase in fibre content and loading rate.

Optimization of mixed cargo allocation and stowage with heterogeneous vehicles

In order to solve the problem of low efficiency and high loading costs in business logistics and distribution operations, this paper classifies non-standard cargoes based on their spatial and temporal characteristics. Based on this, a dual-layer planning model for multi-vehicle cargoes loading and transportation is constructed to jointly optimize the loading process. This paper designs a space-inspired heuristic algorithm to solve the model and verifies the feasibility of the model. The results show that compared to a single vehicle type, the joint optimization of multi-vehicle combinations for loading and transportation has stronger adaptability and can better accommodate changes in cargo volume. Compared to the single vehicle type, not only did the loading rate increase by 18%, but also effectively reduced the transportation cost by 3%. Different proportions of spatial and temporal characteristic cargoes have different effects on the loading and transportation. Adjusting the proportion of cargoes that can be placed on both upper and lower layers to 50% can better utilize transportation resources such as vehicles. Increasing the proportion of urgent cargoes can improve the economic efficiency of loading and transportation.

Cyclic loading and unloading strain equations and damage evolution of gypsum specimens considering damping effects

This study aims to establish a strain instanton equation and damage factor evolution law for gypsum specimens by considering damping. First, damping energy is calculated based on the single-degree-of-freedom vibration model, and the instantaneous strain equation is obtained based on the stress balance equation. Second, the dissipation energy is divided into damping and damage energies, and a damage-factor correction algorithm is obtained. Third, cyclic loading and unloading tests were performed at different loading rates and stress amplitudes to verify the accuracy of the strain equation. Finally, the specimens’ magnitude curves and crack characteristics were monitored using moment–tensor acoustic emission simulations. The factors influencing the damping energy and strain equations, energy and damage evolution laws of the specimens, and damage patterns of the specimens at different loading rates were analysed. The results show that the instantaneous strain equation and the modified damage factor considering the damping effect can effectively reflect the deformation law and damage state of the specimens. In contrast, the damage to the specimens in the lower limit of the variable stress experiment was lower than that in the lower limit of the constant stress experiment. As the loading rate increases, the damage energy density of the specimen decreases, and the damage factor within a single cycle gradually decreases. As the loading rate increases, the number of crack events in the model increases significantly, size becomes more uniform, and sequentially exhibits dense and sparse distribution patterns, percentage of shear cracks decreases significantly, number of mixed cracks increases significantly, brittle behaviour of the specimen becomes obvious, and a complete damage state is attained known as the ‘crushed’ state. This study provides a theoretical reference for damage assessments of viscoelastic–plastic materials subjected to perturbing loads.

Viscoelastic Model of Fiber Concrete under Dynamic Loading Considering the Effect of Initial Stresses

Statement of the problem. The objective of the study was to identify the peculiarities of the stress-strain state of fiber concrete under two-stage static-dynamic loading and to develop a variant of a nonlinear viscoelastic model of concrete reinforced with steel fiber. Results. The paper presents the results of experimental tests of fiber-concrete prisms under quasi-static, dynamic and static-dynamic loading conditions. On the basis of the analysis of experimental data it is established that at dynamic loading there is an upward shift of the boundary of macrocrack formation. A nonlinear viscoelastic model of fiber concrete is proposed and compared with experimental data, taking into account the effect of the initial stress level caused by the service load. The parametric study performed using this model shows that as the loading rate increases, a more intensive dynamic hardening of concrete is observed. Conclusions. The proposed viscoelastic model of fiber concrete allows to estimate the ultimate strength and corresponding strain under static-dynamic mode of loading due to an accidental action caused by the collapse of one of the load-bearing members of the structural system of the building.

A model predicting mechanical properties of asphalt mixtures considering void ratio and loading conditions

The void ratio is an essential parameter in asphalt mixture design, which significantly affects asphalt mixtures' mechanical properties and road performance. The prediction model for mechanical properties will be established based on the Computed tomography (CT) scanning, strength, and fatigue test results in this research to reveal the relationship between the asphalt mixtures' mechanical properties and void ratio. Firstly, the voids' transverse and longitudinal distribution characteristics in asphalt mixtures of different gradations were investigated based on CT scanning. Then, the influences of void ratio, loading rates on the strength, and the impacts of void ratio and stress levels on the fatigue life were investigated by conducting indirect tensile tests. Finally, the mechanical properties prediction model was established for void ratio and loading conditions. Further, the feasibility of the model is verified in conjunction with existing research results. The results show that the void ratio calculated based on CT scanning is about 1.15 times the measured void ratio in the water weight method. The number of voids was uniformly distributed in the range of 15 mm∼50 mm in height and 10 mm∼40 mm in radius of the specimen. The asphalt mixtures' strength decreases with increasing void ratio and increases with increasing loading rate. The asphalt mixtures' fatigue life declines with increasing void ratio and stress level. The correlation coefficients of the established strength and fatigue prediction models were 0.963 and 0.976, respectively. The relative error between the measured strength, fatigue life, and predicted results is about 10.75% and 11.27%, respectively. This research provides a basis for designing high-performance asphalt mixtures by establishing the relationship between asphalt mixtures' microscopic and mechanical characteristics.

Experimental Study on the Performance of Glass/Basalt Fiber Reinforced Concrete Unidirectional Plate under Impact Load

Fiber-reinforced composite materials have emerged as essential solutions for addressing the durability challenges of traditional reinforced concrete, owing to their lightweight nature, high strength, ease of construction, superior tensile capacity, robust corrosion resistance, and excellent electromagnetic insulation properties. This paper delves into the influence of loading rate and fiber bar type on the mechanical characteristics of concrete one-way plates through impact experiments on such plates fitted with glass/basalt fiber bars at varying drop weight heights. The test results reveal a direct correlation between increasing loading rates and escalating damage in fiber-reinforced concrete one-way plates, reflected in the progressive rise in peak deflection and residual displacement at the mid-span of the specimens. Notably, when subjected to higher impact loads, glass fiber-reinforced concrete specimens exhibit amplified deformation and intricate crack formations, consequently diminishing the overall deformation resistance of the plate. Furthermore, glass/basalt fiber-reinforced composites demonstrate notable vibration damping qualities, characterized by substantial residual displacement, minimal rebound, and rapid decay following vibration stimulation. Overall, glass fiber-reinforced one-way plates display marginally superior impact resistance compared to their basalt fiber-reinforced counterparts.

Impact fatigue behavior of laser metal deposition 316L stainless steel with an automated impact fatigue system based on split Hopkinson bar technique

Repeated impact subjecting on the key components of equipment is always characterized by extremely high loading rate loading, while plastic deformation of most metals depends on loading rate. To ensure the reliability and security of these components, it is necessary to understand the loading rate effect on the fatigue performance. In this study, an automated impact fatigue system based on split Hopkinson bar technique was newly developed to investigate the materials’ impact fatigue behavior. Impact fatigue behavior and non-impact fatigue behavior of laser metal deposition 316L stainless steel were analyzed. The fatigue life decreases with the increasing loading rate, implying the significant loading rate dependence. The compression and fracture toughness tests combined with fractography analysis at high and low loading rates were also conducted to reveal the underlying mechanism of the difference between impact and non-impact fatigue life. Finally, microstructure of the laser metal deposition 316L stainless steel after impact and non-impact fatigue was characterized. It can be concluded that the fatigue crack is apt to initiate under impact fatigue due to the high density of dislocation entanglement, while under non-impact fatigue, a large number of twins are beneficial to delay the fatigue crack initiation.

Bacterial community composition and diversity under increasing loading rates in reed wetland for sludge treatment

Efficient and sustainable sludge management is a significant environmental and health challenge. Sludge-treatment reed beds (STRBs) are widely recognized as a cost-effective, highly efficient, and environmentally friendly solution for sludge treatment and dewatering. This study investigated the bacterial community composition and diversity in pilot-scale STRBs operating at different sludge loading rates (75, 100, and 125 ​kg ​m2 year−1). 16S rRNA V4 DNA sequencing was used to assess the diversity of the bacterial communities within the sludge samples. The relative abundance of prokaryotic taxa was affected by all treatments. As the sludge loads increased, the Shannon entropy and evenness diversity also increased for the STRBs and unplanted beds. Interestingly, the presence of reeds resulted in significantly lower Shannon and evenness indices than unplanted beds, regardless of the sludge. Additionally, the correlation network analysis revealed distinct microbial clusters with distinct responses to reeds and sludge loads. Principal component analysis evidenced an association between cluster 5 and organic matter decomposition, primarily at higher sludge doses, while clusters 4 and 6 were related to sludge decomposition at lower doses. Additionally, cluster 4 was associated with nutrient removal. The formation of distinct microbial niches was linked to sludge stabilization and nutrient removal and was influenced by both sludge loading rates and the presence of reeds. Future research can leverage these findings to innovate pollutant removal and ecosystem services for sludge treatment, thus advancing sustainable sludge management and environmental preservation.

An investigation of a process for selective biogas desulfurization and autotrophic denitrification in a membrane supported reactor

A lab-scale dense polydimethylsiloxane (PDMS) membrane bioscrubber (MBS) was used for selective removal of highly toxic H2S from biogas under autotrophic conditions for the first time. The performance of MBS was evaluated under the effects of sulfide loadings, pH, and hydraulic retention time (HRT). The results showed that gradual increase in sulfide loading rate from 131 to 316 g/m3.d boost S/N ratios 1.9–4.0, on average sulfide oxidation efficiencies higher than 95% were achieved. The S/N ratios were determinant on the formation of oxidation products, but not on the H2S gas removal efficiency. The transition of HRT significantly affected the denitrification rather than the sulfide oxidation, when HRT reduced from 24 to 12 h the nitrate removal efficiency suddenly dropped from 98% to 70%. Increasing the pH values from 7.0 to 9.0 also decreased the sulfide oxidation efficiency from 97±0.5–92±1.1%. Denitrification efficiency > 96% was observed between pH value of 7.0 and 8.0, whereas at pH 9.0 dropped rapidly to 82%. In the whole experiment time there was no membrane-induced problem that adversely affected the system performance. Over-all the developed anoxic dense MBS successfully employed for selective removal of 10,000 ppm H2S and nitrate concurrently with low chemical consumption, possibility for recovery of elemental sulfur, enhanced CH4 calorific value and eliminating the risks of explosion and dilution of biogas. The current work showed the PDMS MBS system is a promising alternative way in biological nitrogen removal and biogas desulfurization under anoxic conditions. Its application in real scale would have high economic importance.

Energy consumption during transient operation of coal-fired generating units with cold end system back pressure regulation

The dynamic characteristics of key parameters were investigated in this study, which reflected the operational flexibility and efficiency of thermal power units during load regulation. A refined model of the cold end of the unit was proposed. Simultaneously, an innovative exploration was conducted into the coordinated achievement of flexible load regulation and the promotion of energy-efficient operations. Two variables, the variable load rate and cooling water flow, were selected, and the continuous dynamic characteristics of unit energy consumption during load adjustment were determined. The ratio of total variable load coal consumption to load regulation and variable load time was defined as the average regulated coal consumption BZ, which was introduced to enhance the intuitive evaluation of flexibility and efficiency. It was shown that with the increase in variable load rate, there was a decrease observed in the total coal consumption during the variable load process. This trend was consistent with earlier publications. Concurrently, a reduction in cooling water flow had resulted in an increase in power generation coal consumption and a decrease in coal consumption for circulating cooling water pumps. The elevated rate of load variation was attributed to the increased flow of cooling water. A decrease of 14.9 % in back pressure was noted with the increase in the flow of the cooling water. As a result of this reduction in back pressure, the coal consumption rate for power generation was decreased by 1.334 g/kWh, reflecting a decrease of 0.43 %. Additionally, a reduction in total coal consumption of 0.16 t during variable load operation was witnessed, while a 1.97 % increase in the variable load rate was recorded. The optimal flexibility and coal-saving effect were achieved under the conditions of 30 MW/min and 60000 t/h, with ΔBZ = −50 g/(MW·s). Finally, the feasibility of the proposed scheme was verified through the case of a 350 MW unit.

Piezoresistive performance of cement-based composites with two-dimensional MXene subjected to various loading conditions and water content

Two-dimension MXene was applied in cement to fabricate MXene cement-based sensor used in structural health monitoring. The effect of MXene content on the piezoresistive performance of MXene cement-based composites (MCBC) was investigated. The fractional change in resistivity (FCR) under different loading rate, water content and failure load were also measured. Microanalysis results proves that MXene can construct electrical network in cement composites. The results demonstrated that the stress sensitivity has a maximum at 1.0 wt% MXene content. When loading rate increases, the sensitivities of composites decrease linearly, while the water content increases, the decrease of sensitivities is not completely linear. The relationship between compressive stress and fractional change in resistivity conforms to quadratic polynomial under failure load.

Anaerobic co-digestion of municipal mixed sludge and mango peel biowaste: Performance and stability analysis for different ratios

In an urban context, municipal mixed sludge (MMS) and fruit and vegetable waste (FVW) are becoming the major organic solid wastes in human society. Thus, anaerobic digestion as a low carbon energy strategy to minimize their environmental polluting risk was studied. To overcome the drawbacks of anaerobic digestion of MMS, an alternative approach is proposed, involving the addition of increasing proportions of mango peel pulp (MPP) as a co-substrate. Different ratios of MMS:MPP (v:v) were studied: 80:20 (T1), 70:30 (T2), 60:40 (T3). The increase in the organic loading rate was well incorporated by the reactor's biomass activity, and it had no negative effects on the reactor stability and performance operational parameters. Results indicated that the addition of MPP had a beneficial effect on specific methane production, where the highest value was registered in T2 (0.47 L CH4/g VS added), with a 1.8-fold increase in this operational parameter. Moreover, bioenergy recovery within the same trial followed the same profile, representing a two-fold increment.