Loading Rate Research Articles

Compaction method and specimen geometry effect on the fracture properties of asphalt concrete in the SCB test at intermediate temperature

ABSTRACT Recent research using the semicircular bending (SCB) test with 100 mm diameter specimen cored from gyratory compacted samples demonstrated the suitability of this sample size for testing dense graded asphalt mixes with a nominal maximum aggregate size (NMAS) of up to 19 mm. Alongside the gyratory compactor, the Marshall compactor remains part of current specifications in many countries, including ASTM international standards. The Marshall compactor uses a 4-inch (101.6 mm) mould, which is slightly larger than the gyratory compactor’s 100 mm mould, and employs a different compaction effort, resulting in different aggregate orientation. This study investigates potential differences in the fracture properties of SCB test specimens compacted using different methods. Sample thicknesses of 30 , 40 , and 50 mm were evaluated in the SCB test at 25°C under a monotonic loading rate of 1 mm/min. A total of 81 specimens were prepared from three asphalt mixes with NMAS of 14 mm and 20 mm, including two dense graded asphalt mixes and one stone mastic asphalt mix. The fracture properties, including fracture energy, fracture toughness, and cracking resistance index (CRI) were evaluated. The study found that the repeatability, evaluated via the coefficient of variation, ranged from 1.1% to 21.7%, with an average value of 8.3%. A directly proportional relation was observed for indexes from the 100 mm and 150 mm samples using the gyratory compactor. The Marshall compactor specimens yielded higher fracture toughness and fracture energy values, while the CRI values were approximately 1.23 times those obtained from the gyratory compactor. This result shows that different compaction methods have direct effect on the fracture properties of SCB test specimens, emphasising the importance of considering compaction methods for the SCB test when determining the threshold value of cracking resistance for asphalt mixes, especially in the balanced mix design for asphalt mixes.

Influence of Heat Treatment on the Mechanical Properties of Fine-Grained Granite under Dynamic Impact Loading

In order to study the influence of heat treatment on the dynamic properties of fine-grained granite, an improved split Hopkinson pressure bar (SHPB) system was used to conduct impact compression tests on the granite specimens treated at 20~1000 °C under three loading rates. The experimental results show that the shape of the impact stress–strain curve is affected by the loading rate and heat treatment temperature. Under the same loading rate, the average strain rate, peak strain, and maximum strain of granite specimen exhibit a trend of “slow increasing (20~200 °C)—slow decreasing (200~400 °C)—slow increasing (400~500 °C)”. The peak stress and elastic modulus show the opposite trend. The average strain rate, peak strain, and maximum strain of the granite specimen treated at 600 °C increase significantly. The peak stress and elastic modulus decrease significantly. Within the heat treatment temperature range of 600~800 °C, the dynamic properties of granite deteriorate slowly. The average strain rate, peak strain, and maximum strain of the granite specimens treated at 900 °C and 1000 °C increase sharply, while the peak stress decreases sharply. Within the heat treatment temperature range of 600–1000 °C, the elastic modulus of the granite specimen shows an approximately linear decreasing trend. There are no changes in the mineral composition of granite within the heat treatment temperature range of 20–1000 °C. After heat treatment at 600 °C, the width of internal cracks in granite increases significantly. The width of internal cracks in the heat-treated granites at 900 °C and 1000 °C increases sharply. The change in the dynamic properties of granite is determined by the internal microstructure of the heat-treated granite at different temperatures.

Mechanistic Pavement Modeling of Typical Brazilian Pavements: Cohesive Zone Fracture Modeling and Continuum Damage Modeling

Pavement performance evaluation with respect to fatigue cracking has seen a major shift toward more rigorous mechanistic models that can capture the complex damage response of the mixtures more accurately. This study utilized two mechanistic methods (cohesive zone [CZ]-based fracture modeling and continuum damage [CD] modeling) to study the cracking behavior of asphalt mixtures and subsequently predict the damage-associated performance of pavements. A Superpave mixture designed for Brazilian highway conditions was selected to evaluate the two modeling approaches for the performance of the mixture when utilized as a surface course within typical Brazilian highway pavements. The mixture was first evaluated for its linear viscoelastic properties, and then the damage characteristics of the mixture were obtained through two different experiments: the semi-circular bending (SCB) beam test and the cyclic fatigue (CF) test. The SCB tests performed at different loading rates were used to obtain the model parameters of the nonlinear viscoelastic CZ model with a Gaussian damage evolution criterion, while the CF tests were performed at different strain amplitudes, and the mixture-specific damage characteristic curve and the fatigue failure criterion were obtained using the simplified-viscoelastic continuum damage model. From a design perspective, three pavement structures that varied in geometry (pavement layer thickness) and underlying layer properties were selected while retaining the same asphalt mixture. The three pavement scenarios were evaluated for the fatigue cracking performance from each of the mechanistic modeling methods. The results indicate that both methods rank the performance of the pavement structures in a similar manner, while the damage initiation and progression were seen to be different because of the different mechanics in modeling cracks.

Uncovering efficient operational strategies for simultaneous anammox and heterotrophic denitrification (SAD) granular process at different nitrogen loadings: A model-based evaluation

The simultaneous anammox and denitrification granular process effectively removes nitrogen and organic matter, but its optimization for variable nitrogen loading rates (NLRs) is challenging due to regulatory complexities and delays. This study developed and evaluated a modified model to determine an effective operational strategy, using data from batch tests and long-term experiments. Simulations revealed a spatial cross-distribution of anammox bacteria and heterotrophic denitrification bacteria (HDB) within the granules, and HDB tended to grow on the surface. Higher NLRs (from 0.35 to 14.06 kg N (m3·d)−1) extended the time to reach steady state, limiting the treatment capacity to 7.73 kg N (m3·d)−1 at NH4+-N/NO2−-N/COD = 1:1.32: 0.5. At different influent NH4+-N concentrations (NH4+-NInf: 40, 150, and 300 g N m−3), single-factor simulations showed that optimal nitrogen removal and granular stability were achieved at specific NO2−-N/NH4+-N ratios (1.2–1.3), C/N ratios (1.2–0.8), and particle sizes (500–1000 μm). Adjusting the NO2−-N/NH4+-N (1.0–1.6) and C/N ratios (0.2–1.2) zones synergistically improved the operational efficiency (TN removal efficiency >90 %). Notably, elevated NH4+-NInf amplified single-factor effects, complicating efficient optimization. These insights significantly inform the process design and operation in varying NLR wastewater contexts.

Effect of functionalization on adsorption and thermal property of graphene nanosheet/paraffin composite

Functionalization of graphene nanosheet (GNS) is found to be useful for improving the thermal property of materials. However, the mechanism responsible for the enhancement is still open. In this article, molecular dynamic simulation is adopted to investigate the effects of four functionalized groups, including -COOH, -NH2, -OH, and -CH3, on the adsorption and thermal properties of GNS/paraffin (PA) composites. The results show that it forms a spherical structure after GNS absorbs in PA. The loading rate of the systems follows the order: GNS-COOH/PA > GNS-NH2/PA > GNS-OH/PA > GNS-CH3/PA > GNS/PA, which is determined by the adsorption free energy. Due to the functionalization, the latent heats of the composites undergo a significant change and the thermal conductivities are significantly enhanced. GNS-OH/PA exhibits the most substantial improvement with the latent heat increasing by 11.2% and the thermal conductivity increasing by 107.4% compared to GNS/PA. The study demonstrates the potential of these composites for energy storage applications, highlighting the improved performance through functionalization.

Low-cost, reliable, and highly efficient removal of COD and total nitrogen from sewage using a sponge-filled trickling filter

ABSTRACT Development of low-cost and reliable reactors demanding minimal supervision is a need-of-the-hour for sewage treatment in rural areas. This study explores the performance of a multi-stage sponge-filled trickling filter (SPTF) for sewage treatment, employing polyethylene (PE) and polyurethane (PU) media. Chemical oxygen demand (COD) and nitrogen transformation were evaluated at hydraulic loading rates (HLRs) ranging from 2 to 6 m/d using synthetic sewage as influent. At influent COD of ∼350 mg/L, PU-SPTF and PE-SPTF achieved a COD removal of 97% across all HLRs with most of the removal occurring in the first segments. Operation of PE-SPTF at an HLR of 6 m/d caused substantial wash-out of biomass, while PU-SPTF retained biomass and achieved effluent COD < 10 mg/L even at HLR of 8–10 m/d. The maximum Total Nitrogen removal by PE-SPTF and PU-SPTF reactors was 93.56 ± 1.36 and 92.24 ± 0.66%, respectively, at an HLR of 6 m/d. Simultaneous removal of ammonia and nitrate was observed at all the HLRs in the first segment of both SPTFs indicating ANAMMOX activity. COD removal data, media depth, and HLRs were fitted (R2 > 0.99) to a first-order kinetic relationship. For a comparable COD removal, CO2 emission by PU-SPTF was 3.5% of that of an activated sludge system.

Performance evaluation of a hybrid treatment system for the treatment of grey water

ABSTRACT The performance of a combined up-flow submerged aerated biological filter (SABF) and photocatalytic process (PC) for the treatment of grey water was studied. The removal of COD, hardness, alkalinity, and turbidity was considered. The removal efficiency of SABF using organic and inorganic packing materials was evaluated. The combined SABF and PC removed 100% of COD, up to an organic loading rate (OLR) of 0.21 ± 0.05 kg/m3/day at 12 h HRT, irrespective of the packing media. The fibrous outer shell of coconut fibres favoured turbidity removal, but both the organic and inorganic packing materials showed equal performance in the removal of physicochemical parameters of the grey water.

In-situ biological biogas upgrading using upflow anaerobic polyfoam bioreactor: Operational and biological aspects.

A high rate upflow anaerobic polyfoam-based bioreactor (UAPB) was developed for lab-scale in-situ biogas upgrading by H2 injection. The reactor, with a volume of 440 mL, was fed with synthetic wastewater at an organic loading rate (OLR) of 3.5 g COD/L·day and a hydraulic retention time (HRT) of 7.33 h. The use of a porous diffuser, alongside high gas recirculation, led to a higher H2 liquid mass transfer, and subsequently to a better uptake for high CH4 content of 56% (starting from 26%). Our attempts to optimize both operational parameters (H2 flow rate and gas recirculation ratio, which is the total flow rate of recirculated gas over the total outlet of gas flow rate) were not initially successful, however, at a very high recirculation ratio (32) and flow rate (54 mL/h), a significant improvement of the hydrogen consumption was achieved. These operational conditions have in turn driven the methanogenic community towardthe dominance of Methanosaetaceae, which out-competed Methanosarcinaceae. Nevertheless, highly stable methane production rates of 1.4-1.9 L CH4/Lreactor.day were observed despite the methanogenic turnover. During the different applied operational conditions, the bacterial community was especially impacted, resulting in substantial shifts of taxonomic groups. Notably, Aeromonadaceae was the only bacterial group positively correlated with increasing hydrogen consumption rates. The capacity of Aeromonadaceae to extracellularly donate electrons suggests that direct interspecies electron transfer (DIET) enhanced biogas upgrading. Overall, the proposed innovative biological in-situ biogas upgrading technology using the UAPB configuration shows promising results for stable, simple, and effective biological biogas upgrading.

Source separation and anaerobic co-digestion of blackwater and food waste for biogas production and nutrient recovery

ABSTRACT Anaerobic co-digestion of source-separated blackwater (BW) and food and kitchen waste (FW) offers decentralized circular economy solutions by enabling local production of biogas and nutrient-rich byproducts. In this study, a 2 m3 pilot-scale continuously stirred tank reactor (CSTR) operated under mesophilic conditions was utilized for co-digestion of BW and FW. The process obtained a CH4 yield of 0.7 ± 0.2 m3/kg influent-volatile solid (VS), reaching a maximum yield of 1.1 ± 0.1 m3/kg influent-VS, with an average organic loading rate of 0.6 ± 0.1 kg-VS/m3/d and HRT of 25 days. The CH4 production rate averaged 0.4 ± 0.1 m3/m3/d, peaking at 0.6 ± 0.1 m3/m3/d. Treatment of digestate through flocculation followed by sedimentation recovered over 90% of ammonium nitrogen and potassium, and 80–85% of total phosphorus in the liquid fraction. This nutrient-rich liquid was used to cultivate Chlorella vulgaris, achieving a biomass concentration of 1.2 ± 0.1 g/L and 85 ± 3% and 78 ± 5% ammonium nitrogen and phosphorus removal efficiency, respectively. These findings not only highlight the feasibility of anaerobic co-digestion of source-separated BW and FW in local biogas production but also demonstrate the potential of microalgae cultivation as a sustainable approach to converting digestate into nutrient-rich algae biomass.

Comparative study on pharmacokinetics of extract from Bufonis venenum and its liposomes

Bufadienolides and indolealkylamines, the primary active components in Bufonis venenum, have rapid clearance from the body with a short half-life, leading to low bioavailability. Moreover, Bufadienolides and indolealkylamines are associated with serious adverse effects. In order to reduce the toxicities, minimize the adverse effects and simultaneously load lipophilic bufadienolides and hydrophilic indolealkylamines with satisfactory drug loading and encapsulation rate, we prepared Bufonis venenum extract-liposomes (BVE-LP). To compare the pharmacokinetic differences between Bufonis venenum extract (BVE) and its liposomes, ultra-high performance liquid chromatography-tandem mass spectrometry (UPLC-MS/MS) assay was established to simultaneously detect the 12 chemical components in rat plasma. Results of pharmacokinetic study in SD rats showed that the highest exposure based on the area under the plasma concentration-time curve (AUC0-t) was obtained by 5-hydroxytryptamine with a mean value of 267.097 μg/L*h in BVE-LP group, which was 72.36 % higher as compared to that obtained in Bufonis venenum extract (BVE) group with a mean value of AUC0-t of 154.966 μg/L*h. The exposure (AUC0-t) of desacetylcinobufotalin, desacetylcinobufagin, arenobufagin and telocinobufagin in BVE-LP group was 111.89 %, 94.13 %, 134.08 %, and 92.94 % higher when compared to that in BVE group. With the employment of liposomes, there was an obvious decrease in the clearance of bufotenidine, desacetylcinobufotalin, gamabufotalin, arenobufagin, and telocinobufagin. The terminal half life (t1/2) of desacetylcinobufotalin, gamabufotalin, arenobufagin, and telocinobufagin in BVE-LP group was increased by 185.96 %, 292.64 %, 196.78 % and 131.29 % when compared to that in BVE group. All the results above indicated that a slower elimination rate and more exposure of some bufadienolides and indolealkylamines was obtained by BVE-LP when compared to BVE group, which verified BVE-LP could provide a therapeutic option for effective delivery of Bufonis venenum in clinical. Data availabilityThe data will be shared on reasonable request to the corresponding author.

Multi-criteria analysis of the continuous operation of a membrane photobioreactor to treat sewage: Modeling and sensitivity analysis

Microalgae-based wastewater remediation is aligned with circular economy principals but successful large-scale facilities are scarce due to the limited knowledge of the interactions between all relevant variables and the scarce development of control and automation systems. Machine learning (ML) methods have the potential predict performance in microalgae photobioreactors, with the aim to optimize it. Some attempts have been performed under controlled lab conditions which prevents the direct application of their results to industrial scale. This study aims to develop ML models for the prediction of nutrient removal, biomass production and photosynthetic efficiency using a database obtained from 1.5-y operation of a pilot-scale membrane photobioreactor (MPBR) that treated sewage. A total of 14 inputs and 6 outputs were selected. Random forests (RF), boosted trees (BT), multilayer perceptron (MLP), support vector machine methods (SVM) were tested. The lowest prediction errors were obtained with the MLP model, allowing the developed tool to be used as an alternative to mechanistic models. Large ranges of data were used, considering the variability of factors in the diurnal cycle whose influence on the variability of the data is usually neglected. Using global sensitivity analysis (GSA), input-output relationships were verified, reflecting relevant number of variables showing significant values of Shapley Indices. Additionaly, partial dependence plots showed both linear and nonlinear depending on the selected inputs and outputs. Finally, using ML models, multi-criteria optimization of operating parameters was performed for two variants: a) optimization of operating parameters (HRT, SRT, and air flowrate (Fair)); and b) optimization of operating parameters and influent nutrient loads (HRT, SRT, Fair, nitrogen and phosphorus loading rates).

In-situ biomethanation of high CO content syngas in agricultural biogas digesters

To meet global energy demands, syngas with high CO content (>50 %) generated from hydrothermal gasification of agricultural residues or wood, could be utilized as a co-substrate in anaerobic digestion (AD) processes for conversion into CH4. This study investigated in-situ biomethanation using synthetic gas (55 % CO, 35 % H2, and 15 % CO2), mimicking wood gasification syngas, during AD of cow manure, the most abundant agricultural waste. A continuously stirred tank reactor (CSTR) served as a control and was fed only cow manure, while the other two reactors were fed syngas with or without gas recirculation at different gas loading rates (GLRs).In-situ syngas injection in AD of cow manure at GLRs ≤0.3 L LRV−1 d−1 improved overall CH4 productivity compared to the control (0.35 ± 0.1 vs. 0.29 ± 0.1 L LRV−1 d−1), though the CH4 content (45 ± 5 %) was lower than the control reactor (62 ± 3 %), indicating a need for biogas upgrading. Gas recirculation enabled higher CO and H2 conversion efficiencies of 99–100 % but considerably decreased CH4 productivity from cow manure. In-situ biomethanation enhanced the relative abundance of hydrogenotrophic methanogens, highlighting their role in syngas conversion to CH4.

Characterization on fibre kinking fracture of laminated composites under combined compression and shear at high loading rate

This paper presented a novel method to characterize the fracture toughness and cohesive law of laminated composites under combined compression and shear at high loading rate. Compact compression specimens with off-axis fibres which introduce the in-plane shear stresses were conducted on the uniaxial bidirectional electromagnetic Hopkinson bar system and the displacement field and strain field were recorded by the high-speed camera for the digital image correlation analysis and J-integral calculation. The results reveal that the in-plane shear stresses bring the increase of fracture toughness at crack initiation and propagation and advance the damage initiation of the specimens. The fracture surfaces indicate that the shear stresses cause the fibre bundles' shear failure during the formation of the kink band, accompanied by more energy dissipation with the increase of off-axis angle.

In-plane crashing behavior and energy absorption of graded re-entrant honeycombs reinforced by catenary

Re-entrant honeycombs have demonstrated promising applications in engineering fields attributed to better manufacturability and adaptability. Herein, the reinforced re-entrant honeycombs (RRH) with thickness and reinforced strut gradients are proposed, respectively, and their in-plane energy absorption is investigated through experiment, theoretical analysis, and simulation. Metallic specimens of uniform and graded RRH are manufactured through a step-by-step method. The deformation mode and plateau stress (PS) of these specimens are significantly influenced by both thickness and catenary gradients. Two PSs of RRH specimens are predicted theoretically with a relative error of less than 7.0 %. Subsequently, the deformation mode and energy absorption of uniform and graded RRH, subjected to varying load rates, are investigated thoroughly with a numerical method verified against the experimental data. The results show that both thickness and catenary gradients can inspire multi-step deformation mode and prevent instability deformation. Compared to uniform RRH (U-RRH), the specific energy absorptions (SEA) of thickness gradient (TG)-123 (123 represents that the thicknesses from impact end to fixed end are t1, t2, t3) and TG-213 are enhanced by 52.2 % and 49.8 %, respectively, under quasi-static compression, the SEA of TG-132 and TG-123 are raised by 41.6 % and 20.2 %, respectively, under low-velocity impact, and the SEA of strut gradient (SG)-123 is 66.7 % higher than that of U-RRH under high-velocity impact. More significant auxetic deformation does not always mean better energy absorption because there is also an increased tendency of global instability and earlier densification points. This work provides a novel approach to designing high-energy absorption honeycombs with low structural complexity.

Application of polyethylene glycol 8000 as plasticizer for the development of ellagic acid and Eudragit® EPO based solid dispersions using hot melt extrusion.

Solid dispersion formation by Hot melt extrusion (HME) is a widely used formulation strategy to improve the solubility and bioavailability of poorly water-soluble drugs. Despite this, they are limited by various factors such as drug-excipient miscibility, poor stability, limited drug loading and extrudability of physical drug-excipient mixtures. In this work, polyethylene glycol 8000 (PEG 8000) was used as a plasticizer for the manufacture of ellagic acid solid dispersions (EASD) with high drug loading. Indeed, EA is a polyphenolic active compound with antimalarial and other promising therapeutic activities. However, its low solubility and low permeability limit its therapeutic use. Solid dispersions formation may overcome this challenge, but its high melting point negatively influences the extrudability of its binary physical mixtures with a high drug loading rate, hence the need to use a plasticizer. Thus, five formulations consisting of EA, Eudragit® EPO and PEG 8000 in the ratio of 15:75:10 (F1), 20:70:10 (F2), 25:65:10 (F3), 15:80:5 (F4) and 20:85:5 (F5) % w/w, respectively, have been extruded, four of which were successful. The extrudates were evaluated by X-ray powder diffraction, FTIR spectroscopy and in vitro dissolution tests. Based on the results of these tests, the F5 formulation was identified as the most promising. Indeed, after 15 min of dissolution test, the dissolution rate of ellagic acid from the formulations was 62.67±3.10%, 58.74±7.23 %, 88.75±3.02% and 83.47±4.40% respectively for formulation F1, F2, F4 and F5. Moreover, the results of the FTIR spectroscopy analyses showed stronger interactions between the different constituents in the F4 and 5 formulations compared to the F1 and 2 formulations. Extruded materials of the F5 formulation, characterized by solid state nuclear magnetic resonance (ssNMR) spectroscopy and subjected to stability studies, showed good physical stability for twelve months under real-time stability study conditions and for six months under accelerated conditions.

GSH-responsive bithiophene Aza-BODIPY@HMON nanoplatform for achieving triple-synergistic photoimmunotherapy

Photoimmunotherapy represents an innovative approach to enhancing the efficiency of immunotherapy in cancer treatment. This approach involves the fusion of immunotherapy and phototherapy (encompassing techniques like photodynamic therapy (PDT) and photothermal therapy (PTT)). Boron-dipyrromethene (BODIPY) has the potential to trigger immunotherapy owing to its excellent PD and PT efficiency. However, the improvements in water solubility, bioavailability, PD/PT combined efficiency, and tumor tissue targeting of BODIPY require introduction of suitable carriers for potential practical application. Herein, a disulfide bond-based hollow mesoporous organosilica (HMON) with excellent biocompatibility and GSH-responsive degradation properties was used as a carrier to load a bithiophene Aza-BODIPY dye (B5), constructing a sample chemotherapy reagent-free B5@HMON nanoplatform achieving triple-synergistic photoimmunotherapy. HMON, involving disulfide bond, is utilized to improve water solubility, tumor tissue targeting, and PD efficiency by depleting GSH and enhancing host-guest interaction between B5 and HMO. The study reveals that HMON’s large specific surface area and porous properties significantly enhance the light collection and oxygen adsorption capacity. The HMON’s rich mesoporous structure and internal cavity achieved a loading rate of B5 at 11 %. It was found that the triple-synergistic nanoplatform triggered a stronger anti-tumor immune response, including tumor invasion, cytokine production, calreticulin translocation, and dendritic cell maturation, eliciting specific tumor-specific immunological responses in vivo and in vitro. The BALB/c mouse model with 4T1 tumors was used to assess tumor suppression efficiency in vivo, showing that almost all tumors in the B5@HMON group disappeared after 14 days. Such a simple chemotherapy reagent-free B5@HMON nanoplatform achieved triple-synergistic photoimmunotherapy.

Unique stick–slip crack dynamics of double-network hydrogels under pure-shear loading

In this work, we have found that a prenotched double-network (DN) hydrogel, when subjected to tensile loading in a pure-shear geometry, exhibits intriguing stick-slip crack dynamics. These dynamics synchronize with the oscillation of the damage (yielding) zone at the crack tip. Through manipulation of the loading rate and the predamage level of the brittle network in DN gels, we have clarified that this phenomenon stems from the significant amount of energy dissipation required to form the damage zone at the crack tip, as well as a kinetic contrast between the rapid crack extension through the yielding zone (slip process) and the slow formation of a new yielding zone controlled by the external loading rate (stick process).

Elucidating the role of organic loading rate on the performance and microbial dynamics of a novel continuous-flow aerobic granular sludge reactor

Aerobic granular sludge technology operated in continuous-flow reactors enables the upgrading of existing conventional wastewater treatment plants. The viability of applying this technology at full-scale increases with the simplicity of the bioreactor design. Hence, in contrast to previous research carried out in complex configurations, this study is based on evaluating the capacity of a novel single-chamber continuous-flow bioreactor to operate at different loads found in domestic sewage, highlighting that this configuration combines and joins the advantages of activated sludge and granular sludge technologies. At organic loading rates ranging from 0.45 to 1.85 kg COD•m−3•d−1, the reactors achieved high performance, removing >80 % of the chemical oxygen demand, regardless influent characteristics. The trend of ammonium removal rates was risen over operational time. Moreover, the granular size and biomass concentration increased with the organic loading rate. Changes in the influent did not compromise the structure of the granules. Microbiota studies showed a high diversity in communities at lower organic loading rates, whereas a strong microbial competition was detected at high loading rates, linking with lower evenness. Phylotypes belonging to Hypocreales played a key role in mature granules.

The impact of loading rate on chloride induced stress corrosion cracking of 304L stainless steel

Abstract The influence of applied loading rate (dK/dt) on stress corrosion cracking (SCC) behavior in annealed 304L stainless steel immersed in 4.7 M MgCl2 solution was assessed at varying temperatures from 23 °C to 70 °C. Measured crack growth rates obtained under rising K loading (dK/dt > 0) are compared to those obtained during static K testing. A rising K-based loading protocol was found to yield more conservative crack growth rates across all temperatures, with the variation in crack growth rates (and therefore the dependence in loading rate) decreasing with increasing environmental severity.

Comparative analysis of operating efficiency for two sewage treatment processes

To decrease pollutant effluent levels in sewage plants, in order to improve the pollutant control capacity, the removal efficiencies for COD, TP, TN, and NH3-N in two sewage plants located in Guangzhou were compared and analyzed. The correlation among influent carbon and nitrogen ratios, water loading rate, and total nitrogen removal rate were examined to enhance the nitrogen removal. The CASS process in Plant I had slightly higher TN (81.85%) and TP (98.38%) removal rates than those in Plant II (80%). Plants I and II achieved COD removal rates of 95.51% and 96.44%, respectively, and NH3-N removal rates of 99.08% and 99.34%, respectively. Correlation analysis showed that only the influent loading rate of Plant I had a moderate correlation with the total nitrogen removal rate, while the other factors only had a weak correlation. Therefore, the total nitrogen removal rate is influenced by multiple factors.