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Production of fermentable sugars from renewable lignocellulosic biomass could provide a sustainable substrate for biofuel production by microbial fermentation. However, the inherent structure of lignocellulose largely hinders enzymatic saccharification efficiency to obtain sugars, thus the development of efficient pretreatment methods to reduce biomass recalcitrance is an important issue. In this study, the effects of two typical processes including hydrothermal (HTP) and citric acid pretreatments (CAP) on the enzymatic hydrolysis yield of reed biomass were investigated. The results indicate that, when performing HTP at 180 °C for 120 min to deconstruct reed, the pretreated biomass led to a higher glucose yield of 87.1% after 72 h enzymatic hydrolysis with cellulase (10 FPU/g substrate). Furthermore, under the pretreatment conditions with 6% (w/v) citric acid, 150 °C, and 60 min, the glucose yield of pretreated reed was 63.4% after hydrolysis with cellulase (10 FPU/g substrate). In this case, adding Tween 80 (100 mg/g substrate) significantly facilitated the enzymatic saccharification activity resulting in the glucose yield of CA-pretreated reed to 84.2%. Compared with the untreated reed, the glucose yield of pretreated residues after HTP and CAP was largely improved by 4.97–5.18 folds which was mainly due to the enhanced crystallinity (50.0–53.2% vs. 45.9%). The total fermentable sugars of 34.7–34.8 g can be produced from 100 g of raw reed biomass based on the proposed HTP and CAP processes. The mechanism of enhanced enzymatic hydrolysis after pretreatments was elucidated through physicochemical characterization techniques. In summary, the proposed pretreatments show high potential application for biorefinery from renewable, abundant reed biomass. [ABSTRACT FROM AUTHOR]

Problem. The functioning of road transport in regions of long-term armed conflicts is associated with additional risks for road traffic safety. The degree of influence of additional risk factors can be investigated by analyzing traffic accident statistics in such a region. Goal. The purpose of the work is to study the impact of martial law conditions on road safety indicators in the Kharkiv region of Ukraine by comparing statistical data on accidents and road deaths due to road accidents. Methodology. To achieve the goal, the work uses methods of statistical analysis of data and construction of trends, methods of determining relative indicators of the severity of road accidents. Results. As a result of the analysis of statistical data on road accidents in the Kharkiv region, the distribution of accident rates for the period from 2019 to 2023 was obtained, which made it possible to reveal their significant differences during the period of martial law compared to previous periods. In particular, it was established that with a decrease in the total number of road accidents, there was an increase in the severity of the consequences of road accidents. This regularity was confirmed by analyzing the relative indicators of road accident severity. The identified differences in accident and death rates on the roads of the Kharkiv region in 2023 compared to the periods before the start of hostilities indicate a change in road traffic conditions. Originality. The paper investigated the impact of martial law conditions on road safety on the example of the Kharkiv region of Ukraine. As a result, the degree of influence of the risk factors that arose as a result of the deployment of the armed conflict on the increase in the level of danger for road users was established. Practical value. The obtained results can be used for planning and implementation of measures to ensure traffic safety on highways in regions that are the zone of long-term armed conflicts.

Pine nut shells, a biomass residue from the Mediterranean Pinus pinea pine nut industrial processing, were treated by microwave-assisted autohydrolysis to produce xylo-oligosaccharides. Microwave-assisted processes provide alternative heating that may reduce energy input and increase overall process efficiency. The autohydrolysis treatments were performed under isothermal and non-isothermal operations within a wide range of operational conditions (temperature/reaction times) covering several severity regimes (as measured by the log R0 severity factor). The composition of the autohydrolysis liquors was determined in terms of oligo- and monosaccharides, aliphatic acids and degradation compounds. The process was highly selective towards hemicelluloses hydrolysis and liquid streams containing a mixture of oligomeric compounds (mainly xylo-oligosaccharides) could be obtained under relatively mild operation conditions (190 °C, 30 min) with a maximal oligosaccharides' concentration of 18.48 g/L. The average polymerization degree of the obtained oligosaccharides was characterised by HPLC, showing that for the optimal conditions a mixture of oligomers with DPs from 2 to 6. [ABSTRACT FROM AUTHOR]

Hemicellulose, as a rich source of five distinct sugars, has a wide range of application prospects. The physicochemical properties of hemicellulose depend on the source and extraction method. The aim of this study was to determine the effect of hydrothermal severity on the chemical composition, extraction yield, and purity of hemicellulose. Hence, wheat straw was subjected to hydrothermal process using an experimental design with 16 runs: 140–170 °C reaction temperatures, 30—120-min reaction time, and liquor to solid ratio of 15. The pre-extracted wheat straw showed higher thermal stability compared to the untreated wheat straw. The presence of hemicelluloses in the pre-extracted wheat straw as well as recondensation of lignin over the pre-extraction stage was suggested based on the FT-IR data. The xylose content (62.35–68.13%) and lignin content (4.14–9.02%) of hemicellulose increased along with heightening the severity factor from 2.34 to 3.18. The data showed that using hydrothermal process with SF of 2.34–3.18 is an efficient method to isolate high purity hemicellulose (91–96%) including β-(1→4)-D-xylopyranosyl residues and side branches of a-L-arabinofuranosyl groups from wheat straw with possible application in developing sweeteners and thickening agents for a wide range of industrial applications such as bakery products, beverages, and pharmaceutical syrups. [ABSTRACT FROM AUTHOR]

Hydrothermal carbonization (HTC) is a widely used process for converting biomass with a wide range of moisture. Biomass selection poses challenges in producing hydrochar with desired properties because of their different constituents. In this study, we investigated the fuel properties of hydrochar of sorghum bagasse (SB) and microalgae (MA) at different severity factors (SFs = 4.08, 4.43, 5.56, 5.90, and 6.63) and their potential as alternatives to coal. The results show that during HTC, both biomasses underwent dehydration, in addition to the noticeable decarboxylation of MA. Fixed carbon increasingly developed in the SB hydrochar, in contrast to the MA hydrochar, which formed volatile hydrocarbon; thus, the MA hydrochar released heat values of 26.7–36.2 MJ·kg−1, which was higher than that of SB at 19.7–28.0 MJ·kg−1. However, owing to the stable hydrocarbons, SB hydrochar is assumed to combust more stably and ignite more decently, as indicated by its fuel ratio (0.83), approaching 0.9–1.5. Moreover, the greater number of solids recovered in SB after carbonization makes its conversion more techno-commercially viable, retaining 1.8 times more of the original energy. Conflating these fuel properties reveals that SB hydrochar (SF = 6.63) is a promising alternative to steam coal, and MA hydrochar is an attractive alternative to both steam (SF = 4.08–5.90) and coking coals (SF = 6.63). Concisely, both biomasses are practically promising as value-added hydrochars, but only SB can be developed beyond the current HTC severity owing to the thermal stability of its hydrocarbons. [ABSTRACT FROM AUTHOR]

The pretreatment step has a major role in ethanol production as it breaks the lignocellulosic material structure, which improves the digestibility in the enzymatic hydrolysis and increases the ethanol yield during fermentation. The purpose in this study was to pretreat green coconut fiber (GCF) with steam explosion (SE) to produce ethanol. Different severity factors (ranging between 2.18 and 4.24) were performed and the humidification process of the raw material before pretreatment was also evaluated. Considering that SE did not provide lignin removal nor significant improvement in enzymatic digestibility, a subsequent alkaline pretreatment was carried out to overcome these challenges. The alkaline pretreatment using NaOH increased delignification, either as a stand-alone or in the sequential pretreatment. The sequential SE/alkaline pretreatment provided higher values of hydrolysis yield (54.74%), total reducing sugars (29.17 ± 1.21 g/L), and glucose production (16.65 ± 0.82 g/L) when compared to the separated pretreatments. Thereafter, simultaneous saccharification and fermentation (SSF) and semi-simultaneous saccharification and fermentation (SSSF) strategies were evaluated using Saccharomyces cerevisiae PE2, Saccharomyces cerevisiae CAT-1, and Kluyveromyces marxianus ATCC 36,907 yeasts with different solid loadings (5, 10, and 15% w/v). The pre-saccharification step increased ethanol yield and ethanol concentration in all experiments. The highest ethanol concentration (24.88 ± 1.04 g/L) was achieved using SSSF with 15% (w/w) solid loading, while the ethanol obtained in SSF experiments was equal to 21.62 ± 0.87 g/L using the same solid loading. The sequential SE/alkaline pretreatment was a successful combination, improving sugars' production and leading to a high ethanol concentration. [ABSTRACT FROM AUTHOR]

Olive tree pruning is an abundant and renewable lignocellulosic residue, which is generally burned in the fields, causing economic costs and environmental problems. This lignocellulosic residue can be considered a suitable raw material for the production of a wide range of byproducts in a biorefinery context due to its high content of potentially fermentable carbohydrates. To take advantage of its sugar content, pretreatment is necessary to enhance the accessibility of the enzymes to the cellulosic fraction. The aim of this work is to obtain sugars contained in olive tree pruning as a substrate for the production of bioethanol by fermentation. Specifically, the production of fermentable sugars by sequential pretreatment with sulfuric acid and sodium hydroxide is studied. A two-factor rotatable composite central design temperature and catalyst concentration (H2SO4 and NaOH) has been generated, and response surface methodology has been used to discuss and optimize the responses. This work shows that under optimal pretreatment conditions (130 °C, 1.90% w/v H2SO4 and 130 °C, 1.49% w/v NaOH) of 1 kg of olive tree pruning, a solution rich in sugars (102 g of glucose and 61 g of xylose) and a solid residue generating 99 g of glucose by enzymatic hydrolysis is obtained. Moreover, applying the combined severity to the acid pretreatment, it has been determined that 20% of the olive tree pruning is fast solubilization, and it was also found that the apparent activation energy of the acid hydrolysis reaction is 85.07 kJ/mol. [ABSTRACT FROM AUTHOR]

Torrefaction pretreatment is a mild form of pyrolysis that has the potential to produce a high-quality raw material for making biofuel that serves as a replacement for coal in the bioenergy industry. Microwave-assisted torrefaction was conducted on white spruce sawdust (WSS) at temperatures of 200 °C, 250 °C, and 300 °C and retention times of 5 min, 7 min, and 9 min in an inert environment. The torrefaction process produces a solid carbon, commonly known as biochar, and condensable (torrefaction liquid (TL)) and non-condensable gases. In this study, torrefaction characteristics were investigated to observe its effects on the thermal and physiochemical properties of the pellets produced. During the torrefaction process, a significant mass loss associated with the decomposition of hemicellulose was observed. The hemicellulose content drastically reduced to approximately 1.8% and the cellulose content was reduced by approximately 10%, while the lignin gained approximately 35% as the severity increased. This led to an improvement in the higher heating value (HHV), hydrophobicity, bulk, particle density, pellet dimensional stability, and pellet density. However, the pellet tensile strength decreased as the torrefaction severity increased. Pellet tensile strength is a critical indicator of biomass pellets that expresses the force required to crush or damage a pellet. Therefore, to enhance the tensile strength of the pellets, the introduction of a binder was necessary. Torrefaction liquid and sawdust were used as additives at different proportions during pelletization. The addition of binders (torrefaction liquid and sawdust) to the pellet formulation increased the tensile strength of the torrefied WSS by approximately 50%. The OH groups in the biomass break down to a limited degree due to dehydration. This hinders the formation of H bonds, thereby increasing the chances that the pretreated biomass will become hydrophobic. The SEM graphs showed that the torrefied WSS pellets demonstrated more firmly glued surfaces with fewer pores spaces when set side by side with the raw pellets. The thermogravimetric analysis conducted showed that the torrefaction of WSS slightly reduced its thermal stability.

In recent years, fault diagnosis in the Induction Motor Drive (IMD) has been a popular and important field in the motor-drive research area. The development of control circuits for induction motors has prompted the attention of both researchers and industrialists. This paper proposes a broken bar fault diagnosis using Hilbert Transform (HT) and Artificial Neural Networks (ANN), with the drive regulated through the Indirect Field Orientation Control (IFOC). The HT obtains the spectrum of stator current, which is utilized to identify the Broken Rotor Bar (BRB) failure. The magnitude and side-band frequency of the drive are extracted using the Fast Fourier Transform (FFT), and these parameters are fed into the ANN inputs. The fault severity is computed by the ratio of mean side-band frequency amplitude to the main frequency amplitude for finding the impact of failure in the drive. ANN is used to diagnose failure with high accuracy. The tested and training results are used to attain the minimum Mean Square Errors (MSEs). The IFOC is involved in this proposed system to ensure high performance under the variable speed drives. The proposed scheme is validated in both MATLAB/Simulink and experimental platforms.

The current study explores steam explosion pre-treatment of wood sawdust to develop high-quality biofuel pellets. In order to determine optimized conditions (temperature and residence time) for steam-treated biomass, seven test responses were chosen, including bulk, particle and pellet densities as well as tensile strength, dimensional stability, ash content and higher heating value (HHV). Parameters tested for steam treatment process included the combination of temperatures 180, 200 and 220 °C and durations of 3, 6 and 9 min. Results showed that when the severity of steam pre-treatment increased from 2.83 to 4.49, most of the qualities except HHV and ash content were favorable for steam pretreated materials. The pellet density of pretreated sawdust in comparison to raw sawdust resulted in 20% improvement (1262 kg/m3 for pretreated material compared with 1049 kg/m3 for non-treated material). Another important factor in determining the best pellet quality is tensile strength, which can be as high as 5.59 MPa for pretreated pellets compared with 0.32 MPa for non-treated pellets. As a result, transportation and handling properties can be enhanced for steam pretreated biomass pellets. After optimization, the selected treatment was analyzed for elemental and chemical composition. Lower nitrogen and sulfur contents compared with fossil fuels make steam pretreated pellets a cleaner option for home furnaces and industrial boilers. High-quality pellets were produced based on optimized pre-treatment conditions and are therefore suggested for bioenergy applications.

Hydrochars obtained by hydrothermal carbonization (HTC) of Lavandula straws have been studied as an eco-friendly and economical valorization route of residual biomass from cosmetic industry into solid fuels. HTC process has been performed in a temperature range from 180 to 260 °C and retention time ranging from 1 to 20 h. The two key parameters (time and temperature) were normalized to severity factor (SF) ranging from 4.74 to 7.79, in order to compare the fuel characteristics of hydrochars according to the thermal treatment conditions. Proximate and ultimate analysis and microscopy and thermal analysis were used to characterize hydrochar surface, combustion behavior, and kinetics as a function of SF, and to compare them with those of the raw lavandin sample. Results showed that after HTC, hydrochar properties were close to sub-bituminous coal and lignite, and SF was a relevant optimization parameter for solid fuel application. In the case of Lavandula, SF = 6 was the optimal value for the HTC process. Nevertheless, in addition to SF, it is important to consider that HTC-temperature is a more influencing parameter than HTC-retention time for the fuel properties of the resulting hydrochars. [ABSTRACT FROM AUTHOR]

Cyclopeptide mushroom poisoning is responsible for 90%–95% of deaths from macrofungi ingestion. The main objectives of this study are to describe cases of cyclopeptide mushroom poisoning and to determine risk factors that may influence the severity/mortality of poisoned patients. We included all cases of amatoxin toxicity reported to two French Poison Centers from 2013 through 2019. We compared the severity with the Poison Severity Score (PSS) and the outcomes of patients using simple logistic regression and multinomial logistic regression. We included 204 cases of amatoxin toxicity. More than three‐quarters developed an increase in AST and/or ALT (78.1%), and over half developed a decrease in prothrombin ratio (<70%: 53%) and/or Factor V (<70%: 54%). One‐third developed an acute renal injury (AKI). Twelve patients (5.9%) developed post‐poisoning sequelae (persistent kidney injury more than 1 month after ingestion and liver transplant). Five patients (2.5%) received a liver transplant, and nine died (4.4%). The mean time to onset of digestive disorders was shorter in PSS2 and PSS3–4 patients (10.9 ± 3.9/11.3 ± 6.3 h) than in PSS1 patients (14 ± 6.5 h; p < 0.05). Patients who died or developed post‐poisoning sequelae had more frequent cardiovascular comorbidities compared with recovered patients (60.0% versus 29.5%; p < 0.01). [ABSTRACT FROM AUTHOR]

Soybean is a major crop used in the production of human food. The soybean hull (SH) is also known as the seed coat and it constitutes about 5–8% of the total seed on a dry weight basis, depending on the variety and the seed size. Dilute sulfuric acid was employed for the thermochemical pretreatment of SH prior to enzymatic saccharification and alcoholic fermentation. Empirical modeling of response surface, severity factor and multi-response desirability function methodology, were used to perform the process optimization. Temperature, acid concentration and reaction time were defined as operational variables, while furfural, 5-hydroxymethylfurfural and solubilized hemicellulose and cellulose were defined as response variables. Mathematical models satisfactorily described the process and optimal conditions were found at 121 °C; 2.5% w/v H2SO4 and 60 min. More than 80% and 90% of hemicelluloses and celluloses, respectively, were able to solubilize at this point. The fermentation performance of an industrial Saccharomyces cerevisiae strain was also evaluated. The glucose available in the hydrolysates was completely consumed in less than 12 h, with an average ethanol yield of 0.45 gethanol/gglucose. Thus, the thermochemical conditioning of SH with dilute sulfuric acid is a suitable operation for 2G-bioethanol production. [ABSTRACT FROM AUTHOR]

Hydrothermal carbonization (HTC) is a widely used process for converting biomass with a wide range of moisture. Biomass selection poses challenges in producing hydrochar with desired properties because of their different constituents. In this study, we investigated the fuel properties of hydrochar of sorghum bagasse (SB) and microalgae (MA) at different severity factors (SFs = 4.08, 4.43, 5.56, 5.90, and 6.63) and their potential as alternatives to coal. The results show that during HTC, both biomasses underwent dehydration, in addition to the noticeable decarboxylation of MA. Fixed carbon increasingly developed in the SB hydrochar, in contrast to the MA hydrochar, which formed volatile hydrocarbon; thus, the MA hydrochar released heat values of 26.7–36.2 MJ·kg−1, which was higher than that of SB at 19.7–28.0 MJ·kg−1. However, owing to the stable hydrocarbons, SB hydrochar is assumed to combust more stably and ignite more decently, as indicated by its fuel ratio (0.83), approaching 0.9–1.5. Moreover, the greater number of solids recovered in SB after carbonization makes its conversion more techno-commercially viable, retaining 1.8 times more of the original energy. Conflating these fuel properties reveals that SB hydrochar (SF = 6.63) is a promising alternative to steam coal, and MA hydrochar is an attractive alternative to both steam (SF = 4.08–5.90) and coking coals (SF = 6.63). Concisely, both biomasses are practically promising as value-added hydrochars, but only SB can be developed beyond the current HTC severity owing to the thermal stability of its hydrocarbons.

Operational risk assessment is a stochastic approach to quantify the operational security of power systems. In this study, the interrelation between severity factor and operational risk, two important parameters in operational risk assessment, is analyzed. Four different definitions of severity factor, based on the results from network studies, are proposed and applied, resulting in different values for the operational risk indices. The behavior of these indices is analyzed under varying operating conditions and compared with the behavior of the severity factor for individual contingencies. This study confirms the importance of the severity factor definition and shows that multiple operational risk indices are required to obtain a clear picture of the operational security of a transmission system. One risk index may increase while another decreases.

In recent years, fault diagnosis in the Induction Motor Drive (IMD) has been a popular and important field in the motor-drive research area. The development of control circuits for induction motors has prompted the attention of both researchers and industrialists. This paper proposes a broken bar fault diagnosis using Hilbert Transform (HT) and Artificial Neural Networks (ANN), with the drive regulated through the Indirect Field Orientation Control (IFOC). The HT obtains the spectrum of stator current, which is utilized to identify the Broken Rotor Bar (BRB) failure. The magnitude and side-band frequency of the drive are extracted using the Fast Fourier Transform (FFT), and these parameters are fed into the ANN inputs. The fault severity is computed by the ratio of mean side-band frequency amplitude to the main frequency amplitude for finding the impact of failure in the drive. ANN is used to diagnose failure with high accuracy. The tested and training results are used to attain the minimum Mean Square Errors (MSEs). The IFOC is involved in this proposed system to ensure high performance under the variable speed drives. The proposed scheme is validated in both MATLAB/Simulink and experimental platforms. [ABSTRACT FROM AUTHOR]

Torrefaction pretreatment is a mild form of pyrolysis that has the potential to produce a high-quality raw material for making biofuel that serves as a replacement for coal in the bioenergy industry. Microwave-assisted torrefaction was conducted on white spruce sawdust (WSS) at temperatures of 200 °C, 250 °C, and 300 °C and retention times of 5 min, 7 min, and 9 min in an inert environment. The torrefaction process produces a solid carbon, commonly known as biochar, and condensable (torrefaction liquid (TL)) and non-condensable gases. In this study, torrefaction characteristics were investigated to observe its effects on the thermal and physiochemical properties of the pellets produced. During the torrefaction process, a significant mass loss associated with the decomposition of hemicellulose was observed. The hemicellulose content drastically reduced to approximately 1.8% and the cellulose content was reduced by approximately 10%, while the lignin gained approximately 35% as the severity increased. This led to an improvement in the higher heating value (HHV), hydrophobicity, bulk, particle density, pellet dimensional stability, and pellet density. However, the pellet tensile strength decreased as the torrefaction severity increased. Pellet tensile strength is a critical indicator of biomass pellets that expresses the force required to crush or damage a pellet. Therefore, to enhance the tensile strength of the pellets, the introduction of a binder was necessary. Torrefaction liquid and sawdust were used as additives at different proportions during pelletization. The addition of binders (torrefaction liquid and sawdust) to the pellet formulation increased the tensile strength of the torrefied WSS by approximately 50%. The OH groups in the biomass break down to a limited degree due to dehydration. This hinders the formation of H bonds, thereby increasing the chances that the pretreated biomass will become hydrophobic. The SEM graphs showed that the torrefied WSS pellets demonstrated more firmly glued surfaces with fewer pores spaces when set side by side with the raw pellets. The thermogravimetric analysis conducted showed that the torrefaction of WSS slightly reduced its thermal stability. [ABSTRACT FROM AUTHOR]

The alkaline extraction of hemicelluloses from a mixture of three varieties of wheat straw (containing 40.1% cellulose, 20.23% xylan, and 26.2% hemicellulose) was analyzed considering the following complementary pre-treatments: freeze–thaw cycles, microwaves, and ultrasounds. The two cycles freeze–thaw approach was selected based on simplicity and energy savings for further analysis and optimization. Experiments planned with Design Expert were performed. The regression model determined through the response surface methodology based on the severity factor (defined as a function of time and temperature) and alkali concentration as variables was then used to optimize the process in a multi-objective case considering the possibility of further use for pulping. To show the properties and chemical structure of the separated hemicelluloses, several analytical methods were used: high-performance chromatography (HPLC), Fourier-transformed infrared spectroscopy (FTIR), proton nuclear magnetic resonance spectroscopy (1H-NMR), thermogravimetry and derivative thermogravimetry analysis (TG, DTG), and scanning electron microscopy (SEM). The verified experimental optimization result indicated the possibility of obtaining hemicelluloses material containing 3.40% glucan, 85.51% xylan, and 7.89% arabinan. The association of hot alkaline extraction with two freeze–thaw cycles allows the partial preservation of the hemicellulose polymeric structure. [ABSTRACT FROM AUTHOR]

Pretreating biomass efficiently in an environmentally friendly way is crucial for unlocking its valuable components. Among various pretreatment techniques, steam explosion (SE) has shown promising results, characterized by high efficiency, low operating energy, and reduced environmental impact. Pretreating biomass with steam SE is attractive due to its high efficiency, low operating energy, and reduced environmental impact. Nevertheless, temperature, severity factor (SF), and sample presoaking affect an SE pretreatment performance. Higher temperatures improve hydrolysis rates but produce unwanted by-products. Conversely, lower temperatures increase the amount of recalcitrant chemicals in the feedstock. Meanwhile, the SF measures the pretreatment harshness of the temperature and residence time. Higher SF results in more significant biomass fragmentation. In addition, water presoaking is critical in SE pretreatments as it allows feedstock to soak up more steam. The central aim of this review is to explore the potential of SE for the sequential recovery of multiple lignocellulosic components from biomass. This aspect has not been extensively reported in the literature. Moreover, the review assesses the subsequent processes involved in obtaining derivatives from these extracted components and optimizing SE parameters. Overall, the influence of these parameters on the extraction is complex and depends on the specific pretreatment utilized. Generally, based on reported SF required for each component, the extraction of various compounds with multiple SE pretreatments from a biomass sample is feasible in the sequence of: flavonoids and hydrocolloids are extracted first, followed by oils, then cellulose (fiber), hemicellulose and cellulose (for fermentation), and finally lignin. Future studies should focus on improving SE parameters to maximize the sequential recovery of multiple biomass components. Further exploration of this process could yield valuable biomass optimization and utilization advancements. • Reports on steam explosion treatment's effectiveness in extracting multiple components from biomass are limited. • Steam explosion treatment can be use to extract essential lignocellulosic components sequentially and individually. • The severity factor is applied to propose extraction sequences, excluding variables like acid or water soaking. • The suggested sequence for recovery is as follows: flavonoids and hydrocolloids, oils, cellulose, hemicellulose, and lignin. [ABSTRACT FROM AUTHOR]

This study aimed to evaluate the effectiveness of the marine macro-algae Ulva pertusa as a potential source of important chemicals, including 2,3-butanediol (2,3-BDO). This study examined how pretreatment conditions like liquid-to-solid ratio, reaction temperature, and reaction time influence the hydrolysis of U. pertusa biomass through hydrothermal pretreatment followed by enzymatic hydrolysis. Consequently, 23.44 g/L (12.7 % based on biomass weight) of reducing sugar was produced under hydrothermal pretreatment conditions (liquid-to-solid ratio of 6:1, reaction temperature of 165 °C, and reaction time of 15 min), followed by enzymatic hydrolysis. During hydrothermal pretreatment, the sugar concentration peaked at 3.68 g/L within the severity factor (SF) range of 3.5–4.4. During subsequent enzymatic hydrolysis, the sugar concentration remained stable until the SF reached 4.0. However, when SF exceeded 4.0, the sugar concentration rapidly decreased. The effectiveness of U. pertusa hydrolysate was evaluated via the fermentation of 2,3-BDO. Pantoea agglomerans successfully produced 2,3-BDO with a yield of 0.299 g/g-sugar from U. pertusa hydrolysate. In summary, this study demonstrated the effectiveness of U. pertusa hydrolysate as a bioresource for producing biochemicals, including 2,3-BDO. • Effectiveness of macro-algae Ulva pertusa as a possible source for 2,3-BDO production. • 23.44 g/L sugar yielded under hydrothermal pretreatment with subsequent enzymatic hydrolysis. • Hydrothermal pretreatment was optimized at 165 °C and 15 min with 6:1 L/S ratio. • Pantoea agglomerans yielded 0.299 g 2,3-BDO/g sugar from hydrolysate of U. pertusa. [ABSTRACT FROM AUTHOR]

Olive tree pruning is an abundant and renewable lignocellulosic residue, which is generally burned in the fields, causing economic costs and environmental problems. This lignocellulosic residue can be considered a suitable raw material for the production of a wide range of byproducts in a biorefinery context due to its high content of potentially fermentable carbohydrates. To take advantage of its sugar content, pretreatment is necessary to enhance the accessibility of the enzymes to the cellulosic fraction. The aim of this work is to obtain sugars contained in olive tree pruning as a substrate for the production of bioethanol by fermentation. Specifically, the production of fermentable sugars by sequential pretreatment with sulfuric acid and sodium hydroxide is studied. A two-factor rotatable composite central design temperature and catalyst concentration (H2SO4 and NaOH) has been generated, and response surface methodology has been used to discuss and optimize the responses. This work shows that under optimal pretreatment conditions (130 °C, 1.90% w/v H2SO4 and 130 °C, 1.49% w/v NaOH) of 1 kg of olive tree pruning, a solution rich in sugars (102 g of glucose and 61 g of xylose) and a solid residue generating 99 g of glucose by enzymatic hydrolysis is obtained. Moreover, applying the combined severity to the acid pretreatment, it has been determined that 20% of the olive tree pruning is fast solubilization, and it was also found that the apparent activation energy of the acid hydrolysis reaction is 85.07 kJ/mol.

Wheat bran (WB) is globally a major food industry waste, with a high prospect as a bioresource in the production of precious polyphenolic phytochemicals. In this framework, the current investigation had as objectives (i) to use ethanol organosolv treatment and study the effect of acid and alkali catalysts on releasing bound polyphenols, (ii) establish linear and quadratic models of polyphenol recovery based on severity and response surface, and (iii) examine the polyphenolic composition of the extracts generated. Using sulfuric acid and sodium hydroxide as the acid and the alkali catalyst, respectively, it was found that the correlation of combined severity factor with total polyphenol yield was significant in the acid catalysis, but a highly significant correlation in the alkali-catalyzed process was established with modified severity factor, which takes into consideration catalyst concentration, instead of pH. Optimization of the process with response surface confirmed that polyphenol release from WB was linked to treatment time, but also catalyst concentration. Under optimized conditions, the acid- and alkali-catalyzed processes afforded total polyphenol yields of 10.93 ± 0.62 and 19.76 ± 0.76 mg ferulic acid equivalents g−1 dry mass, respectively. Examination of the polyphenolic composition revealed that the alkali-catalyzed process had a striking effect on releasing ferulic acid, but the acid catalysis was insufficient in this regard. The outcome concerning the antioxidant properties was contradictory with respect to the antiradical activity and ferric-reducing power of the extracts, a fact most probably attributed to extract constituents other than ferulic acid. The process modeling proposed herein may be valuable in assessing both process effectiveness and severity, with a perspective of establishing WB treatments that would provide maximum polyphenol recovery with minimum harshness and cost. [ABSTRACT FROM AUTHOR]

The current study explores steam explosion pre-treatment of wood sawdust to develop high-quality biofuel pellets. In order to determine optimized conditions (temperature and residence time) for steam-treated biomass, seven test responses were chosen, including bulk, particle and pellet densities as well as tensile strength, dimensional stability, ash content and higher heating value (HHV). Parameters tested for steam treatment process included the combination of temperatures 180, 200 and 220 °C and durations of 3, 6 and 9 min. Results showed that when the severity of steam pre-treatment increased from 2.83 to 4.49, most of the qualities except HHV and ash content were favorable for steam pretreated materials. The pellet density of pretreated sawdust in comparison to raw sawdust resulted in 20% improvement (1262 kg/m3 for pretreated material compared with 1049 kg/m3 for non-treated material). Another important factor in determining the best pellet quality is tensile strength, which can be as high as 5.59 MPa for pretreated pellets compared with 0.32 MPa for non-treated pellets. As a result, transportation and handling properties can be enhanced for steam pretreated biomass pellets. After optimization, the selected treatment was analyzed for elemental and chemical composition. Lower nitrogen and sulfur contents compared with fossil fuels make steam pretreated pellets a cleaner option for home furnaces and industrial boilers. High-quality pellets were produced based on optimized pre-treatment conditions and are therefore suggested for bioenergy applications. [ABSTRACT FROM AUTHOR]

The increased complexity of the transmission grid can endanger the operational security of the grid. Operational risk assessment, a stochastic tool, helps to enhance security. Contingency analysis and its impact quantification are the main constituents of operational risk assessment. In this study, different graphical methods are proposed to visualize operational risk contingency-based detailed results: heat-map and risk-based contingency chart. Through the heat-map, the system operator can determine which contingencies contribute most to the operational risk and would therefore be the most threatening contingencies for operational security of the grid. The "risk-based contingency chart" allows the system operator to analyze contingency cases from the probability and impact aspect in one chart. Both tools may be used in the control room for improved operational planning. In this study of contingency analysis and various types of network studies of severity factor quantification, the IEEE 39-Bus sample network is used in Power-Factory to analyze the contingencies behavior under different operational scenarios. [ABSTRACT FROM AUTHOR]

Operational risk assessment is a stochastic approach to quantify the operational security of power systems. In this study, the interrelation between severity factor and operational risk, two important parameters in operational risk assessment, is analyzed. Four different definitions of severity factor, based on the results from network studies, are proposed and applied, resulting in different values for the operational risk indices. The behavior of these indices is analyzed under varying operating conditions and compared with the behavior of the severity factor for individual contingencies. This study confirms the importance of the severity factor definition and shows that multiple operational risk indices are required to obtain a clear picture of the operational security of a transmission system. One risk index may increase while another decreases. [ABSTRACT FROM AUTHOR]

Lab-scale torrefaction experiments of Rubberwood and Gliricidia were conducted at 250-300 oC and 30–60 min in a nitrogen environment to understand the torrefaction behavior. TGA and FTIR were used to characterize raw and torrefied biomass. In the lab-scale experiments, Rubberwood showed 16% mass loss, whereas Gliricidia showed 25% mass loss under the most severe conditions, resulting in 9% and 22% volatile drop, respectively. The higher heating value of the torrefied product increased from 18.9 MJ/kg to 21.39 MJ/kg for Rubberwood and from 19.46 MJ/kg to 22.44 MJ/kg for Gliricidia under the most severe conditions. The calculated Energy Mass Co-benefit Index (EMCI) of Rubberwood at 275 °C and 60 min or 300 °C and 45–60 min and Gliricidia at 300 °C and 60 min indicated favorable torrefaction conditions. Comparatively, Gliricidia was performing well in torrefaction. The severity factor was modified by finding the optimum fitted parameter ω, which establishes a feedstock-specific relationship between torrefaction severity and operating conditions. The normalized severity factor shows a linear correlation with the properties of torrefied biomass, which could facilitate torrefaction modeling. [ABSTRACT FROM AUTHOR]

[Display omitted] • Enzymatic hydrolysis of maize straw increased greatly by STAB+OHA pretreatment. • Lignin (77 %) and xylan (92 %) were removed by combined pretreatment at LogR 0 = 4.13. • Enhanced enzymatic hydrolysis was interpreted through various characterizations. • The interaction between the pretreatment system and lignin was observed by molecular simulation. • The STAB+OHA pretreatment mechanism was elucidated. Maize straw underwent pretreatment with stearyl trimethyl ammonium bromide (STAB) combined with ortho -hydroxybenzoic acid (OHA), and the parameters of the pretreatment process were optimized through single-factor and orthogonal experiments. The results demonstrated that 77.2 % lignin and 92.4 % xylan were removed through the combined pretreatment at the severity factor (LogR 0) = 4.13, resulting in an increase in the enzymatic hydrolysis activity to 90.8 %. After pretreatment, the crystallinity of the material elevated significantly to 63.6 %, the surface structure became rough, and the accessibility elevated to 667.4 mg/g. These positive changes jointly improved the efficiency of enzymatic hydrolysis. By-products including 3.7 g/L xylo -oligosaccharides, 1.1 g/L 5-hydroxymethylfurfural, 0.6 g/L furfural, 1.2 g/L formic acid, and 1.5 g/L acetic acid co-produced during STAB+OHA combination pretreatment. Meanwhile, the reusability experiment of up to 5 cycles confirmed the sustainable utilization of this combined pretreatment system. This pretreatment technology theoretically facilitated the diversification of fuel and chemical production. [ABSTRACT FROM AUTHOR]

Soybean is a major crop used in the production of human food. The soybean hull (SH) is also known as the seed coat and it constitutes about 5–8% of the total seed on a dry weight basis, depending on the variety and the seed size. Dilute sulfuric acid was employed for the thermochemical pretreatment of SH prior to enzymatic saccharification and alcoholic fermentation. Empirical modeling of response surface, severity factor and multi-response desirability function methodology, were used to perform the process optimization. Temperature, acid concentration and reaction time were defined as operational variables, while furfural, 5-hydroxymethylfurfural and solubilized hemicellulose and cellulose were defined as response variables. Mathematical models satisfactorily described the process and optimal conditions were found at 121 °C; 2.5% w/v H2SO4 and 60 min. More than 80% and 90% of hemicelluloses and celluloses, respectively, were able to solubilize at this point. The fermentation performance of an industrial Saccharomyces cerevisiae strain was also evaluated. The glucose available in the hydrolysates was completely consumed in less than 12 h, with an average ethanol yield of 0.45 gethanol/gglucose. Thus, the thermochemical conditioning of SH with dilute sulfuric acid is a suitable operation for 2G-bioethanol production.

The chemical and physical properties of steam-exploded pine chips were analyzed by varying the temperature (190 °C to 230 °C) and time (1.5 min to 20.0 min) of steam explosion at the same severity factor (Ro), i.e., 4.0. Then, their potential as a dietary fiber source was evaluated. Overall, the chemical properties, e.g., solid recovery, cellulose, hemicellulose, and total dietary fiber content, showed a tendency to decrease as the temperature increased as well as an increasing lignin content. The physical properties, e.g., water-holding capacity, oil-holding capacity, and swelling capacity, showed decreased values in pine chips subjected to steam explosion at a temperature of 210 °C or greater. The chemical and physical properties of the steam-exploded pine chips, which were subjected to steam explosion at different temperatures and times at the selected Ro) considerably changed, starting at a temperature of 200 °C for 11.5 min. Even with the same severity factor, the steam-exploded pine chips at a temperature of 200 °C for 11.5 min showed the greatest improvement in the physical properties, i.e., water holding capacity (8.3 g/g), oil holding capacity (6.8 g/g), and swelling capacity (4.9 mL/g). [ABSTRACT FROM AUTHOR]

On-site production of cellulases using lignocellulosic materials can improve the economic viability of biorefineries. This, however, requires the pretreatment of substrates using thermochemical conditions that can vary in severity. To understand the effect of pretreatment severity on cellulase production by Aspergillus ustus S3 on sugarcane bagasse, we applied NaOH pretreatment corresponding to 3 severity factors (SF1.32, SF1.79, and SF3.64) to generate SCB that was used as inducing substrate. The highest cellulase activity (0.681 U/mL) was obtained with the intermediate severity (SF1.79) while significantly lower activities of 0.495 and 0.539 U/mL were recorded with low (SF1.32) and high (SF3.64) severities, respectively. Chemical and structural characterization revealed that low and intermediate severities improved cellulose accessibility and cellulase titres while high severity impaired them, thus limiting substrate suitability for enzyme production. These results show that though high SFs might be desirable in other applications, moderate severities may be more appropriate for cellulase production.

The production of biofuels from lignocellulosic biomass includes a pretreatment step to alter the biomass structure and facilitate the enzymatic degradation of the polymers to obtain assimilable compounds. In this study, agave bagasse (AB) was used as a feedstock for obtaining methane, for which AB was pretreated with steam explosion and enzymatically hydrolyzed. The pretreatment conditions corresponded to severity factors (SFs) within a range from 1.65 to 2.89, while enzymatic hydrolysis was performed with enzyme loads of Cellic CTec2 within a range from 0.12 to 3.6 mgprotein g−1AB. The best global yields (including pretreatment and enzymatic hydrolysis) of total carbohydrates (TCs), glucose (GLU), xylose (XYL), and chemical oxygen demand (COD) were 0.7 g TC g−1AB, 0.12 g GLU g−1AB, 0.03 g XYL g−1AB, and 0.20 g O2 g−1AB obtained using 2.4 mgprotein g−1AB of Cellic CTec2 with agave bagasse pretreated with an SF of 2.41. The contribution of pretreatment to the global TC yield ranged from 13 to 34% for the different systems evaluated. The biochemical potential of methane (BMP) of hydrolysates (pretreatment at SF 2.41 and 2.4 mgprotein g−1AB of Cellic CTec2) was 0.284 ± 0.02 in NL CH4 g−1 COD with a COD removal of 78.4 ± 1.3. This BMP value was 40% higher than the BMP obtained in the system without enzymatic hydrolysis, indicating the impact of this step on conversion to biomethane. The results at the BMP level indicated the potential of this residue for biofuel production. [ABSTRACT FROM AUTHOR]

Steam Explosion (SE) is one of the most efficient and environmentally friendly processes for the pretreatment of lignocellulosic biomass. It is an important tool for the development of the biorefinery concept to mitigate the recalcitrance of biomass. However, the two distinct steps of SE, steam cracking and explosive decompression, leading to the breakdown of the lignocellulosic matrix have generally been studied in empiric ways and clarification are needed. This mini-review provides new insights and recommendations regarding the properties of subcritical water, process modeling and the importance of the depressurization rate.

Wheat bran (WB) is globally a major food industry waste, with a high prospect as a bioresource in the production of precious polyphenolic phytochemicals. In this framework, the current investigation had as objectives (i) to use ethanol organosolv treatment and study the effect of acid and alkali catalysts on releasing bound polyphenols, (ii) establish linear and quadratic models of polyphenol recovery based on severity and response surface, and (iii) examine the polyphenolic composition of the extracts generated. Using sulfuric acid and sodium hydroxide as the acid and the alkali catalyst, respectively, it was found that the correlation of combined severity factor with total polyphenol yield was significant in the acid catalysis, but a highly significant correlation in the alkali-catalyzed process was established with modified severity factor, which takes into consideration catalyst concentration, instead of pH. Optimization of the process with response surface confirmed that polyphenol release from WB was linked to treatment time, but also catalyst concentration. Under optimized conditions, the acid- and alkali-catalyzed processes afforded total polyphenol yields of 10.93 ± 0.62 and 19.76 ± 0.76 mg ferulic acid equivalents g−1 dry mass, respectively. Examination of the polyphenolic composition revealed that the alkali-catalyzed process had a striking effect on releasing ferulic acid, but the acid catalysis was insufficient in this regard. The outcome concerning the antioxidant properties was contradictory with respect to the antiradical activity and ferric-reducing power of the extracts, a fact most probably attributed to extract constituents other than ferulic acid. The process modeling proposed herein may be valuable in assessing both process effectiveness and severity, with a perspective of establishing WB treatments that would provide maximum polyphenol recovery with minimum harshness and cost.

The battery degradation and equivalent hydrogen consumption are of great significance in vehicle performance improvement for fuel cell hybrid electric vehicle. However, few energy management strategies proposed by previous researchers can optimize the objectives at the same time. To overcome this drawback, a battery degradation-aware energy management strategy with a driving pattern severity factor feedback correction algorithm is developed to achieve the optimal trade-off between power battery degradation and vehicle economy improvement. The proposed strategy adjusts the equivalent factor according trip distance and correct the battery power to directly address the battery degradation and vehicle economy problem. First, a cost function using weighting factor to trade off the battery degradation and vehicle economy is formulated. The severity factor based on the battery aging model with effective ampere-hour throughput is used to measure the degree of battery degradation. Then, the genetic algorithm back propagation neural network for driving pattern recognition is developed. The trip distance adaptive equivalent consumption minimization strategy is introduced to correct the equivalent factor according to the driving pattern information and the battery degradation feedback correction strategy of the severity factor integrated with driving patterns recognition is constructed. Finally, a comparison analysis study and hardware-in-the-loop experiment are conducted to validate the effectiveness of the proposed strategy. Experimental results under Urban Dynamometer Driving Schedule and Extra Urban Driving Cycle combined with the equivalent consumption minimum strategy indicate that the battery degradation feedback correction algorithm can significantly reduce the battery degradation degree while sacrificing hydrogen consumption optimization to a small extent. [ABSTRACT FROM AUTHOR]

In this study, semi-continuous anaerobic digestion of lignin-rich steam-exploded Ludwigia grandiflora (Lignin = 25.22% ± 4.6% total solids) was performed to understand better the effect of steam explosion on the substrate solubilisation and inhibitors formation during the process. Steam explosion pretreatment was performed at 180 °C for 30 min at a severity factor of 3.8 to enhance the biogas yield of the lignocellulosic biomass. The semi-continuous anaerobic digestion was performed in a continuously stirred tank reactor for 98 days at an initial hydraulic retention time of 30 days and an organic loading rate of 0.9 g-VS L−1 day−1. The performed steam explosion pretreatment caused biomass solubilisation, resulting in enhanced biogas production during the process. During the anaerobic digestion process, the average biogas yield was 265 mL g-VS−1, and the pH throughout the operation was in the optimum range of 6.5–8.2. Due to fluctuations in the biogas yield, the hydraulic retention time and organic loading rate were changed on day 42 (50 days and 0.5 g-VS L−1 day−1) and on day 49 (40 days and 0.7 g-VS L−1 day−1), and 1 M of NaOH was added to the liquid fraction of the steam-exploded L. grandiflora during the latter part of the operation to maintain the stability in the reactor. Therefore, the steam explosion pretreatment helped in the degradation of L. grandiflora by breaking the lignocellulose structure. In addition, changes in the operating conditions of the anaerobic digestion led to an increase in the biogas production towards the end of the process, leading to the stability in the CSTR. [ABSTRACT FROM AUTHOR]

On-site production of cellulases using lignocellulosic materials can improve the economic viability of biorefineries. This, however, requires the pretreatment of substrates using thermochemical conditions that can vary in severity. To understand the effect of pretreatment severity on cellulase production by Aspergillus ustus S3 on sugarcane bagasse, we applied NaOH pretreatment corresponding to 3 severity factors (SF1.32, SF1.79, and SF3.64) to generate SCB that was used as inducing substrate. The highest cellulase activity (0.681 U/mL) was obtained with the intermediate severity (SF1.79) while significantly lower activities of 0.495 and 0.539 U/mL were recorded with low (SF1.32) and high (SF3.64) severities, respectively. Chemical and structural characterization revealed that low and intermediate severities improved cellulose accessibility and cellulase titres while high severity impaired them, thus limiting substrate suitability for enzyme production. These results show that though high SFs might be desirable in other applications, moderate severities may be more appropriate for cellulase production. [ABSTRACT FROM AUTHOR]

Sludge is a serious problem due to the risks to environment. Therefore, an energy-efficient, economic-feasible and environmental sustainable measure for sludge management is urgently required, while hydrothermal carbonization (HTC) has been regarded as one promising method. In this study hydrothermal carbonization was utilized to convert organic sludge (OS) into solid carbonaceous product (hydrochar) under various reaction temperature (T = 180–240 °C) and residence time (t = 60–240 min), respectively. The reaction pressure ranged from 2.7 to 4.8MPa, depending on the reaction conditions. The obtained hydrochar was analyzed by elemental analysis, proximate analysis, SEM, FTIR, and BET, to investigate the effect of reaction parameters on the hydrochar properties, followed by discussions on potential applications of the obtained hydrochar. Obvious reduction of H/C and O/C ratio after HTC was observed, based on the Van Krevelen diagram and FTIR analysis, revealing that the dehydration and decarboxylation occurred during the HTC process. The reaction temperature was regarded as the dominant parameter affecting hydrochar characteristic, compared to residence time. The severity factor (log Ro) at the range from 4.13 to 5.90 showed good linear relationship with the ash content, volatile matter (VM), N content and H/C ratio of hydrochar, indicating that the severity factor could serve as a useful indicator for analyzing the hydrochar property. Although the surface area and porosity were improved by HTC, subsequent modification and activation should be needed to broaden the application field. Owing to the characteristic of high ash content, hydrochar derived from organic sludge might not be feasible for fuel use. Instead, the precursor of the activated carbon and low-cost adsorbent might be the potential applications, while further works should be needed to verify the feasibility.

In this work, the effect of particle size and severity factors was investigated to find the optimum condition of steam explosion pretreatment on xylan recovery of beech wood. The beech wood particles with sizes of 0.16, 1, or 2 mm were steamed at 150–210 °C for 2.5–15 min before an explosive decompression. The results showed that the maximum xylan recovery was about 10% w/w wood with low concentrations of the inhibitors, which were obtained when the particle size is 1 mm and R0 = 3.65 (190 °C, 10 min). The smallest particle size may result in overcooking of biomass, leads to easily and high degradation of hemicelluloses sugars, whereas the largest particle sizes may result in incomplete autohydrolysis in biomass and lower extractability of hemicelluloses sugars. The obtained optimum condition for xylan recovery will improve the subsequent utilization (such as in food industry and other chemical products), prior to subsequent transformation of steam explosion pretreated wood (bioethanol and pellet). [ABSTRACT FROM AUTHOR]

Two series of six wet torrefaction tests were performed using a pressurized batch reactor in order to upgrade almond-tree pruning (a largely available agricultural waste in Mediterranean areas) as a fuel. The assayed maximum temperatures were in the range of 175–300 °C, held for either 10 or 60 min. Raw almond-tree pruning and wet-torrefied solid products were systematically characterized through a wide range of analytical procedures, such as bulk density, particle size, structural and elemental composition, ash content, heating values, moisture uptake, FTIR spectra and SEM micrographs. The effects of temperature and time on the wet torrefaction process of almond-tree pruning were simultaneously evaluated through the severity factor. Higher temperatures and longer holding times brought the fuel properties of wet-torrefied solid products closer to those of sub-bituminous coal. The most severe operating conditions (i.e., 300 °C held for 60 min, or a severity factor equal to 7.68) allowed achieving an energy densification ratio of 1.67. However, the optimal processing conditions in terms of energy yield, which were found at a severity factor of 5.78, led to 57.1 wt% solid yields, with a higher heating value of 24.0 MJ/kg and an energy densification ratio of 1.36. • Wet torrefaction of almond-tree pruning was performed for the first time. • The combined effect of temperature and time was analyzed using the severity factor. • Higher heating values progressively increased from 17.61 MJ/kg to 29.32 MJ/kg. • Severely wet-torrefied products became similar to lignite and sub-bituminous coal. • The optimal processing conditions were determined by the Gain and Loss Method. [ABSTRACT FROM AUTHOR]

Background: Hokkaido was the first Japanese prefecture to be affected by COVID-19. Since the beginning of the pandemic, the Japanese government has been publishing the information of each individual who was tested positive for the virus. Method: The current study analyzed the 1269 SARS-CoV-2 cases confirmed in Hokkaido in order to examine sex-based differences in symptomology and infectiveness, as well as the status of reinfections and the viral transmission networks. Results: The majority of asymptomatic patients were females and older. Females were 1.3-fold more likely to be asymptomatic (p < 0.001) while a decade of difference in age increased the likelihood of being asymptomatic by 1% (p < 0.001). The data contained information up to quaternary viral transmission. The transmission network revealed that, although asymptomatic patients are more likely to transmit the virus, the individuals infected by asymptomatic cases are likely to be asymptomatic (p < 0.001). Four distinct co-occurrences of symptoms were observed, including (i) fever/fatigue, (ii) pharyngitis/rhinitis, (iii) ageusia/anosmia, and (iv) nausea/vomiting/diarrhea. The presences of diarrhea (p = 0.05) as well as nausea/vomiting (p < 0.001) were predictive of developing dyspnea, i.e., severe disease. About 1% of the patients experienced reinfection. Conclusions: Sex and symptomatology appear to play important roles in determining the levels of viral transmission as well as disease severity.