Biomass, Volume 4, Issue 3 (September 2024) – 25 articles

Black soldier fly larvae (BSFL) treatment offers a promising avenue for manure valorization. However, there is a lack of larval density studies and ton-scale exploration in swine manure bioconversion. This study delves into the efficiency of larval fatty acid (FA) bioconversion, examining the impact of larval density on a kilogram scale and extending the analysis to a ton scale. Across a range of 50 to 600 larvae/kg, the larval FA content decreased from 15.3% to 7.85%. The peak larval FA yield, at 3.04% (based on manure dry matter), occurred at a density of 200 larvae/kg. Both low (50 larvae/kg) and high (600 larvae/kg) densities adversely affected BSFL bioconversion performance. Dominant larval FAs included C12:0 (39.7%), C16:1 (24.2%), C18:1 (17.5%), and C16:0 (8.3%). The scaling-up process maintained a consistent larval FA content and composition but resulted in decreased larvae FA yield due to increased larval mortality. Ultimately, each ton of swine manure yielded 12.4 kg of fresh larvae or 0.71 kg of larval FA components, corresponding to a 1.14% larval FA yield. This study underscores the feasibility of upscaling swine manure treatment using BSFL for FA bioconversion and emphasizes the necessity for large-scale studies to enhance larval survivorship and bioconversion efficiency. Full article

Alternative biomass for energy can reduce fossil fuel use and environmental impacts, providing energy security in semi-arid areas with shallow soils that are not ideal for agro-forestry. The densification of sorghum biomass (SB) brings its energetic characteristics closer those of wood. Higher heating value (HHV) represents the heat produced by a given quantity of fuel. This Brazilian research tested different mixtures of SB, eucalyptus wood (W), and eucalyptus bio-oil (Bo) as briquettes for HHV and least ash. Compressed mixtures of SB+B were compared to W+Bo and SB+W+Bo. The concentrations of bio-oil added to SB/W were 1%, 3%, 4%, and 5%. SB+W+Bo composites’ W content was 0%, 25%, 50%, 75%, and 100%, with Bo as 3% of the weight. Sorghum biomass’ HHV is equivalent to W at 3%Bo. Bo doses of 4% and 5% had the same HHV as 3%. Eucalyptus wood did not have a significantly greater HHV with any amount of Bo. SB+W+3%Bo had the same HHV as W when W was at least 50% of the mixture. At greater than 36%W, the ash content was lower than 3%, meeting the EN-B international standard. The optimal composite mixture was 64%SB+36%W+3%Bo for HHV and ash content. SB briquettes can be more widely adopted given sorghum’s prevalence in semi-arid environments. Full article

This work describes research focused on the recovery of ellagic acid (EA) using solid-state fermentation-assisted extraction (SSF) with Aspergillus niger GH1 and Mexican rambutan peel as support. Several culture conditions (temperature, initial moisture, levels of inoculum, and concentration of salts) were evaluated using a Placket–Burman design (PBD) for screening culture factors followed by a central composite design (CCD) for enhancing the EA. Antioxidant activity and polyphenol content were evaluated in SSF. Temperature (28.2 °C), inoculum (2 × 10⁷ spores/g), and NaNO₃ (3.83 g/L) concentration were identified as a significant parameter for EA in SSF. This enhancing procedure resulted in an increase in EA recovery [201.53 ± 0.58–392.23 ± 17.53 mg/g] and, with two steps of purification, [396.9 ± 65.2 mg/g] of EA compound was recovered per gram of recovered powder. Fermentation extracts reflect inhibition of radicals and the presence of polyphenol content. This work proposes to identify the ideal conditions of fermentation in order to obtain a higher yield high-quality compound from agro-industrial wastes through SSF. Full article

The valorisation of food by-products is an important step towards sustainability in food production. Tomatoes constitute one of the most processed crops in the world (160 million tonnes of tomatoes are processed every year), of which 4% is waste. This translates to 6.4 million tonnes of tomato skins and seeds. Currently, this waste is composted or is used in the production of low-value animal feed; higher value can be achieved if this waste stream is re-appropriated for more advanced purposes. Plant cuticle is a membrane structure found on leaves and fruit, including tomatoes, and is mainly composed of cutin. The main function of plant cuticle is to limit water loss from the internal tissue of the plant. Cutin, which can be recovered from the tomato skins by pH shift extraction, has hydrophobic (water repellent) properties and is therefore an ideal raw material for the development of a novel water-resistant coating. In this study, biomass-based bioplastics were developed. Unfortunately, although these bioplastics have good mechanical properties, their hydrophilic nature results in poor water barrier properties. To mitigate this, a very effective water-resistant coating was formulated using the cutin extracted from tomato peels. The water vapour permeability rates of the bioplastics improved by 74% and the percentage swelling of the bioplastic improved by 84% when treated with the cutin coating. With physicochemical properties that can compete with petroleum-based plastics, these bioplastics have the potential to address the growing market demand for sustainable alternatives for food packaging. Using ingredients generated from by-products of the food processing industries (circular economy), the development of these bioplastics also addresses the UN’s Sustainable Development Goal (SDG) 12, Sustainable Consumption and Production (SCP). Full article

This study focuses on applying ash reduction treatments in order to explore the potential for industrial-scale thermochemical utilization of Spent Mushroom Compost (SMC). SMC is a waste byproduct generated by the mushroom industry. Typically, for every kilogram of produced mushrooms, five kilograms of SMC are discarded, with current disposal methods involving landfills or incineration, causing environmental problems. Utilizing SMC effectively presents challenges due to the inherent properties of this biomass type, characterized by high moisture and ash content, low fixed carbon content, and material heterogeneity. These attributes create difficulties when employing a thermochemical valorization route due to the low carbon content and mineral treatments involved. The results have unveiled the heterogeneous nature of the material and its individual components when physically separated. Among the three identified fractions (agglomerated, woody, and fines), the woody fraction showed the highest potential for thermochemical utilization. Notably, when subjected to washing with distilled water and citric acid treatments, it resulted in up to 66% ash reduction, a significant outcome. Other fractions of the material may find potential applications in agriculture. The effective utilization of such high-volume waste biomasses demands diverse and innovative approaches, underlining the urgency and complexity of the problem and the need to employ the principles of a circular economy. Full article

Lignin, the earth’s second-most abundant biopolymer after cellulose, has long been relegated to low-value byproducts in the pulp and paper industry. However, recent advancements in valorization are transforming lignin into a sustainable and versatile feedstock for producing high-value biofuels, bioplastics, and specialty chemicals. This review explores the conversion of lignin’s complex structure, composed of syringyl (S), guaiacyl (G), and p-hydroxyphenyl (H) units, into value-added products. We critically assess various biochemical and analytical techniques employed for comprehensive lignin characterization. Additionally, we explore strategies for lignin upgrading and functionalization to enhance its suitability for advanced biomaterials. The review emphasizes key areas of lignin valorization, including catalytic depolymerization methods, along with the associated challenges and advancements. We discuss its potential as a feedstock for diverse products such as biofuels, bioplastics, carbon fibers, adhesives, and phenolic compounds. Furthermore, the review briefly explores lignin’s inherent properties as a UV protectant and antioxidant, alongside its potential for incorporation into polymer blends and composites. By presenting recent advancements and case studies from the literature, this review highlights the significant economic and environmental benefits of lignin valorization, including waste reduction, lower greenhouse gas emissions, and decreased reliance on non-renewable resources. Finally, we address future perspectives and challenges associated with achieving large-scale, techno-economically feasible, and environmentally sustainable lignin valorization. Full article

The red seaweed Kappaphycus alvarezii is an economically important gelling agent κappa carrageenan source. Phytochemical analysis has pointed to the presence of various other inorganic and organic compounds, which are expanding the application of biomass as a biostimulant in the agroindustry and as a source of new bioactive molecules in the food, chemical, and pharmaceutical industries. Native to Southeast Asia, K. alvarezii has been introduced as an exotic species in Brazil for commercial large-scale farming. Nowadays, legal farming areas are located in the South and on the South-East coast, but with initiatives to be authorized in the country’s Northeast. The biomass yield in a large-scale farming system can be affected by cultivation techniques and environmental stressors, such as temperature, salinity, water quality, disease, and predators. The use of high-resolution images obtained with unmanned aerial vehicles (UAV or drones) is becoming a popular technology in agriculture, and it has the potential to be employed in seaweed farming to extract a variety of variables and features to predict biomass yield throughout the cultivation period. The present study was conducted to analyze and select multispectral indices obtained from images collected by drone for the detection and quantification of K. alvarezii in a commercial cultivation environment in Brazil. Frequency analysis of pixel values, statistical analyses, and visual interpretations for 24 pre-selected indices was applied according to scores attributed to the efficiency of image segmentation. This analysis resulted in the selection of four indices (ABDI1, ABDI2, CIG, and GNDVI) as the best ones for the segmentation of images in the K. alvarezii commercial farms analyzed. The data obtained are the first step in improving the analysis process of images generated by drones, which will facilitate decision-making and better management, and help scale-up K. alvarezii farming in Brazil. Full article

Lignin, one of Earth’s most abundant biopolymers, is rich in phenolic and aliphatic functional groups, offering significant potential for chemical modification. Technical lignin, a byproduct of the kraft process, is produced in large quantities annually and can be used to enhance the properties of polymer matrices such as polypropylene (PP). PP, a widely used nonpolar polymer, suffers from low surface free energy, leading to poor adhesion properties. Combining PP with polar, renewable-source polymers like lignin can improve these properties. This study investigates the direct acetylation of kraft lignin (KL) to improve its dispersion in the PP matrix and enhance wettability and adhesion. The acetylation of KL was confirmed through FTIR and DSC analyses. PP and acetylated KL (AKL) were combined and processed via continuous extrusion. The blends’ thermal and mechanical properties, lignin dispersion, and wettability were evaluated. Additionally, PP and PP–lignin films were bonded to aluminized biaxially oriented polypropylene (BOPP) for peel tests. Results showed increased surface free energy and improved adhesion, particularly in samples with AKL due to better dispersion. This direct acetylation route significantly enhances PP’s surface free energy and adhesion, presenting a sustainable alternative to fossil-based materials and promoting the use of lignin, a renewable and low-cost polymer. Full article

Côte d’Ivoire has substantially neglected crop residues from farms in rural areas, so this study aimed to provide strategies for the sustainable conversion of these products to hydrogen. The use of existing data showed that, in the Côte d’Ivoire, there were up to 16,801,306 tons of crop residues from 11 crop types in 2019, from which 1,296,424.84 tons of hydrogen could potentially be derived via theoretical gasification and dark fermentation approaches. As 907,497.39 tons of hydrogen is expected annually, the following estimations were derived. The three hydrogen-project implementation scenarios developed indicate that Ivorian industries could be supplied with 9,026,635 gigajoules of heat, alongside 17,910 cars and 4732 buses in the transport sector. It was estimated that 817,293.95 tons of green ammonia could be supplied to farmers. According to the study, 5,727,992 households could be expected to have access to 1718.40 gigawatts of electricity. Due to these changes in the transport, energy, industry, and agricultural sectors, a reduction of 1,644,722.08 tons of carbon dioxide per year could theoretically be achieved. With these scenarios, around 263,276.87 tons of hydrogen could be exported to other countries. The conversion of crop residues to hydrogen is a promising opportunity with environmental and socio-economic impacts. Therefore, this study requires further extensive research. Full article

As the most abundant bioenergy raw material in nature, cellulose can be converted into sugar by hydrolysis, which can be further degraded to produce downstream chemicals, such as polyols. Hydrolysis technology is one of the key steps in the development and utilization of cellulosic biomass resources. In this study, the ionic liquid (IL)-catalyzed hydrolysis of sugarcane cellulose into reducing sugar was studied. Firstly, the hydrolysis of sugarcane cellulose in different ionic liquids (including benzothiazolomethane sulfonate, [HBth][CH₃SO₃] and 1-methyl-3-(3-sulfopropyl)-imidazolium hydrogen sulfate, [C₃SO₃Hmim]HSO₄) in heterogeneous and homogeneous systems to produce reducing sugar was studied. In a homogeneous system, the catalytic effect of an ionic liquid on sugarcane cellulose was explored. The pretreatment, IL dosage (0.1~1.0 g), reaction temperature (100~180 °C), addition of water (0~500 μL), and time (1~6 h) were all discovered as key conditions for hydrolysis. The acidity of an acidic ionic liquid is a key factor affecting the hydrolysis of sugarcane cellulose; meanwhile, effective pretreatment and water are also important. As a comparison, the catalytic effect of [C₃SO₃Hmim]HSO₄ in heterogeneous systems (the maximum yield of 5.98% for total reducing sugars, TRS) was not as good as that of [HBth][CH₃SO₃] in homogeneous systems (33.97%). A higher temperature does not necessarily lead to an increased TRS yield, but it will make the maximum TRS appear earlier. At last, 732 cationic ion exchange resin was used to investigate the separation of reducing sugar and ionic liquid, and the recovery of ionic liquid was investigated by an adsorption–desorption experiment. The ionic liquid can be well separated from TRS in the [HBth][CH₃SO₃] and reused at least five times. Full article

Second- and third-generation biorefineries enable the sustainable management of biomasses within the framework of circular economy principles. This approach aims to minimize waste biomass while generating high-value molecules and bio-energy, such as biogas. Biogas production is achieved via anaerobic digestion, a process where microorganisms metabolize organic compounds in the absence of oxygen to primarily produce CO₂ and CH₄. The efficiency of this process is closely linked to the composition of the biomass and, sometimes, characteristics of the initial matrix can impede the process. To address these challenges, various pretreatments are employed to enhance digestion efficiency and mitigate issues associated with biomass complexity. However, the implementation of pretreatments can be energy-intensive and costly. The extraction of valuable molecules from biomass for various applications can represent a form of pretreatment. This extraction process selectively removes recalcitrant molecules such as lignin and cellulose, which can hinder biodegradation, thereby adding new value to the biomass. These extracted molecules not only contribute to improved anaerobic digestion efficiency but also offer potential economic benefits by serving as valuable inputs across diverse industrial sectors. This article presents a detailed state of the art of the most widespread biomass pretreatments and specifies when biomass is pretreated to improve the biogas yield and, in contrast, when it is treated to extract high-added-value products. Finally, in order to define if the same treatment can be simultaneously applied for both goals, an experimental section was dedicated to the production of biogas from untreated olive mill wastewater and the same biomass after being freeze-dried and after the extraction of polyphenols and flavonoids. The use of pretreated biomass effectively improved the biogas production yield: the untreated olive mill wastewater led to the production of 147 mL of biogas, while after freeze-drying and after polyphenols/flavonoids extraction, the production was, respectively, equal to 169 mL and 268 mL of biogas. Full article

Smallholders play a key role in specialty coffee production. Implementing industrial ecology coffee (IEC) practices is crucial for sustainable coffee production (SCP), aiming to add value, achieve zero waste, and respect the environment. For that purpose, this study used life cycle assessment (LCA) to assess the environmental impact of coffee production, specifically focusing on the global warming potential (GWP) of dry methods (DMs). Data were collected from pilot plant operations in Bondowoso, Indonesia, covering the process from cherry beans (CBs) to coffee powder (CP). A unique aspect of this study is assessing the impact of the DMs: Natural, Anaerobic, Hydro honey, Lactic, and Carbonic Maceration, which were often overlooked in previous research. Observations and experimental results served as primary data for input calculations in LCA. As a result, it was found that for the studied DMs, inputting 150 kg per batch of CBs produced approximately 22.4–22.8 kg of CP. The LCA revealed that for one kg of CP produced by the DMs, GWP ranged from 0.676 kg to 1.168 kg of CO_2-eq, with Natural being the least polluting and Lactic having the highest environmental impact. This study also suggests potential improvements in by-products for novel food and fuel applications. Full article

The objective of this work was to optimize the ultrasound-assisted extraction process of bioactive compounds from byproducts of V. vinifera and C. sinensis using the Taguchi methodology. Moreover, the flavonoid content and the subsequent evaluation of the antioxidant potential through three different assays (ABTS^∙+ radical inhibition, ferric-reducing power (FRAP), and OH^• radical inhibition) were determined. Furthermore, the potential of these metabolites to inhibit the α-amylase enzyme and their protective effect to inhibit the hemolysis due to oxidative processes was assessed. In addition, functional group analysis was performed using Fourier transform infrared spectroscopy. The Taguchi L9 statistical model enabled the increase in bioactive compound yields by evaluating factors such as particle size, temperature, time, and solvent concentration. The samples were found to contain flavonoid-type compounds, which translated into their ability to inhibit free radicals (ABTS^∙+ and OH^•) and act as reducing agents (FRAP). They exhibited inhibitory effects on the α-amylase enzyme involved in the assimilation of starch and its derivatives, along with providing over 50% protection to erythrocytes in the presence of free radicals generated by AAPH. Furthermore, FTIR analysis facilitated the identification of characteristic functional groups of phenolic compounds (O–H, C–H, C=C, C–C, C=O). These findings suggest that the analyzed byproducts can effectively serve as sources of bioactive compounds with potential applications in the formulation of functional foods and medicines. However, it is necessary to conduct compound identification and toxicity analysis to ensure the safety of these bioactive compounds. Full article

The escalating production of biosolids from wastewater treatment plants presents significant environmental and health challenges due to the presence of pathogens, trace organic pollutants, and heavy metals. Transforming biosolids into biochar through pyrolysis offers a sustainable solution, enhancing soil fertility and mitigating greenhouse gas emissions. This review critically evaluates the pyrolysis processes (slow, fast, and flash) for biosolid conversion and examines the impact of biosolid-derived biochar on soil nutrient retention, crop productivity, and greenhouse gas emissions. Findings from various studies demonstrate that BDB can significantly reduce emissions of N₂O, CH₄, and CO₂ while improving soil health. However, challenges such as standardizing production methods, addressing heavy metal content, and ensuring economic feasibility must be overcome. Future research should focus on optimizing pyrolysis conditions, developing regulatory frameworks, and conducting comprehensive economic analyses to support the large-scale implementation of BDB in sustainable agriculture. Full article

Typically, citrus waste is composted on land by producers or used as livestock feed. However, the biorefinery approach offers a sustainable and economically viable solution for managing and valorizing these agricultural residues. This review examines research from the period 2014 to 2024. Citrus waste can be utilized initially by extracting the present phytochemicals and subsequently by producing value-added products using it as a raw material. The phytochemicals reported as extracted include essential oils (primarily limonene), pectin, polyphenolic components, micro- and nano-cellulose, proteins, and enzymes, among others. The components produced from the waste include bioethanol, biogas, volatile acids, biodiesel, microbial enzymes, and levulinic acid, among others. The review indicates that citrus waste has technical, economic, and environmental potential for utilization at the laboratory scale and, in some cases, at the pilot scale. However, research on refining pathways, optimization, and scalability must continue to be an active field of investigation. Full article

Earthworms are a resilient group of species thriving in varied habitats through feeding on decaying organic matter, and are therefore predicted to survive an abrupt sunlight reduction scenario, e.g., a nuclear winter. In this study, the feasibility and cost-effectiveness of foraging earthworms to reduce global famine in such a scenario with or without global catastrophic infrastructure loss was considered. Previously reported earthworm extraction methods (digging and sorting, vermifuge application, worm grunting, and electroshocking) were analysed, along with scalability, climate-related barriers to foraging, and pre-consumption processing requirements. Estimations of the global wild earthworm resource suggest it could provide three years of the protein needs of the current world human population, at a median cost of USD 353·kg⁻¹ dry carbohydrate equivalent or a mean cost of USD 1200 (90% confidence interval: 32–8500)·kg⁻¹ dry carbohydrate equivalent. At this price, foraging would cost a median of USD 185 to meet one person’s daily caloric requirement, or USD 32 if targeted to high-earthworm-biomass and low-labour-cost regions; both are more expensive than most existing resilient food solutions. While short-term targeted foraging could still be beneficial in select areas given its quick ramp-up, earthworms may bioaccumulate heavy metals, radioactive material, and other contaminants, presenting a significant health risk. Overall, earthworm foraging cannot be recommended as a scalable resilient food solution unless further research addresses uncertainties regarding cost-effectiveness and food safety. Full article

Docosahexaenoic acid (DHA, C22:6n-3) is an omega-3 fatty acid with beneficial effects for human health. In view of its increasing demand, DHA traditionally produced by marine fisheries will be insufficient, and an alternative sustainable source is urgently required. Here, we report the isolation and characterization of four novel microalgae strains, PLU-A, B, C and D, with a high DHA content of up to 45% from decayed mangrove samples collected from a coastal area in Singapore. Phylogenetic analysis revealed that these isolates were clustered with Schizochytrium sp. TK6 (OK244290.1) and were identified as Schizochytrium sp. strains. A medium optimization with Schizochytrium sp. PLU-D found a glucose-to-yeast extract ratio of 4:1 to be optimal for high biomass and lipid accumulation of up to 70% in shake flasks. In fed-batch fermentation scale-up with the Schizochytrium sp. PLU-D strain, this translates to 175 g/L dry biomass, 94 g/L lipid and 36.2 g/L DHA. Accordingly, the DHA titer obtained is superior to most of the scale-up production reported thus far, while the DHA content is comparable to two other commercially available DHA algae oils. These results suggest that Schizochytrium sp. PLU-D has high potential to be applied for the sustainable production of DHA. Full article

In this research, the energy potential of switchgrass (SG) was analyzed to find promising directions for producing bioenergy from this biomass. The first direction is determining the thermal energy of bioethanol extracted from SG biomass after its pretreatment, enzymatic hydrolysis (saccharification), and fermentation of the resulting glucose. It was established that after a two-stage pretreatment of 1 ton of SG with dilute solutions of nitric acid and alkali, the largest amount of bioethanol can be extracted with an energy potential of 4.9 GJ. It is also shown that by the utilization of solid and liquid waste, the production cost of bioethanol can be reduced. On the other hand, the direct combustion of 1 ton of the initial SG biomass used as a solid biofuel provides an increased amount of thermal energy of 18.3 GJ, which is 3.7 times higher than the energy potential of the resulting bioethanol extracted from 1 ton of this biomass. Thus, if the ultimate goal is to obtain the maximum energy amount, then another direction for obtaining bioenergy from biomass should be implemented, namely, direct combustion, preferably after pelletizing. Studies have shown that fuel characteristics of SG pellets such as the gross thermal energy and density of thermal energy are lower than those of wood pellets, but they can be improved if the SG biomass is densified into pellets together with binders made from polymer waste. Full article

Biomass is inherently organic and renewable, promoting a circular economy ecosystem. As global consumption patterns change, circular economy strategies have turned into sustainable net-zero strategies for developing countries and developed countries, and its value chain is now included in important biomass energy policies. Many countries are actively transforming their economic growth patterns, developing their own circular economy, targeting ecological sustainable development, and adjusting domestic industrial structures. The concept of a circular society, synergistic with the social economy and developed on the basis of the circular economy, has production and consumption at its core. This research aims to verify the important roles that biomass plays in the circular economy and to initiate a virtuous resource circulation model, promote material recycling and reuse, form a “resources-products-renewable resources” model, and promote better resource use efficiency. It discusses the important roles that the bioeconomy plays when achieving a circular economy and also proposes new economic and policy concepts. The key conclusions cover: (1) the biomass energy–circular economy business model; (2) recognizing the co-benefit of consumers and a prosumer circular economy; and (3) challenges to a renewable cycle under economic applications. Full article

The present work aims to explore Spirulina biomass’ functional and technological marvels and its components, such as C-phycocyanin (C-PC), in modern food systems from a circular economy perspective, evaluating a decade of insights and innovations. This comprehensive review delves into the pivotal studies of the past decade, spotlighting the vital importance of maintaining stability in various food matrices to unleash the full biological impacts. Through the lens of food science intertwined with circular economy principles, this analysis meets health and environmental requisites and explores the harmonious synergy between food systems, economy, and industry. While Spirulina has typically served as a supplement, its untapped potential as a fundamental food ingredient has been unveiled, showcasing its abundant nutritional and functional attributes. Technological hurdles in preserving the vibrant color of C-PC have been triumphantly surmounted through simple temperature control methods or cutting-edge nanotechnology applications. Despite the gap in sensory acceptance studies, the emergence of blue foods introduces groundbreaking functional and innovative avenues for the food industry. Full article

The present study analyzed the effect of temperature, pH, pre-treatment and mixing ratio on the anaerobic digestion process. The parameters during the anaerobic co-digestion of cow manure and food waste were then optimized using the Taguchi experimental design method. ANOVA was carried out to find the significant parameters which influence biogas production. Experimental tests were carried out at laboratory-scale reactors kept at different temperatures (28 °C, 35 °C, and 50 °C). The specific methanogenic performance (SMP) during anaerobic digestion at higher temperatures was characterized with the analysis of acetate, propionate, butyrate, hydrogen, glucose, and formate, and was validated with the literature. The improvement of biogas production with different pre-treatments, i.e., ultrasonic, autoclave, and microwave techniques, was also analyzed. The results showed that the reactor that was maintained at 35 °C showed the highest biogas production, while the reactor that was maintained at a lower temperature (28 °C) produced the lower volume of biogas. As the retention time increases, the amount of biogas production increases. Methanogenic activities of microorganisms were reduced at higher temperature conditions (65 °C). Biogas production increased by 28.1%, 20.23%, and 13.27% when the substrates were treated with ultrasonic, autoclave, and microwave, respectively, compared to the untreated substrate. The optimized condition for the highest biogas production during anaerobic co-digestion of food waste and cow manure is a temperature of 35 °C, a pH of 7 and a mixing ratio (CM:FW = 1.5:0.5). ANOVA showed that temperature is the most important input parameter affecting biogas production, followed by mixing ratio. Full article

Efficient utilization of biomass requires conversion into forms that can be optimally applied in energy generation. Briquetting involves the compaction of biomass into solid blocks that are more efficient than raw biomass, and provides ease of transport and handling. These are improved when the briquettes possess a high density, shatter index, and compressive strength. Due to differences in nature and composition, it is imperative to define optimum conditions for the production of quality and durable briquettes for individual biomasses that are compacted into briquettes. This study investigated the effects of process variables on the strength, durability, and density of biomass briquettes produced using Abura sawdust. The lateral compressive strength and drop shatter index were investigated whilst varying the temperature (100–150 °C), pressure (9–15 MPa), and hold time (15–30 min). The compressive strength ranged between 2.06 and 5.15 MPa, whilst the shatter index was between 50 and 600. Briquette density was between 518.8 and 822.9 kg/m³. The pressure was significant to the determination of the compressive strength (p < 0.1) and the shatter index (p < 0.05). The pressure, temperature, and hold time are significant to the briquette density. Physical and mechanical characteristics of the binderless Abura sawdust briquettes can be improved by optimizing the densification variables during the briquetting process when moderate pressures are used for compaction. Full article

This research investigates the extrusion-based fabrication and characterization of nanocomposites derived from bio-sourced polypropylene (PP) and poly(butylene succinate) (PBS: a biodegradable polymer derived from renewable biomass sources such as corn or sugarcane), incorporating Cloisite 20 (C20) clay nanofillers, with a specific focus on their suitability for electrical insulation applications. The research includes biodegradation tests employing the fungus Phanerochaete chrysosporium to evaluate the impact of composition and extrusion conditions. These tests yield satisfactory results, revealing a progressive disappearance of the PBS phase, as corroborated by scanning electron microscopy (SEM) observations and a reduction in the intensity of Fourier transform infrared spectroscopy (FTIR) peaks associated with C-OH and C-O-C bonds in PBS. Despite positive effects on various properties (i.e., barrier, thermal, electrical, and mechanical properties, etc.), a high clay content (5 wt%) does not seem to enhance biodegradability significantly, highlighting the specific sensitivity of the PBS phase to the addition of clay during this process. This study provides valuable insights into the complex interplay of factors conditioning nanocomposite biodegradation processes and highlights the need for an integrated approach to understanding these processes. This is the first time that research has focused on studying the degradation of nanocomposites for electrical insulation, utilizing partially bio-sourced materials that contain PBS. Full article

Nowadays, the circular economy trend drives researchers in the recovery of various bioactive compounds from agri-food by-products. Enzyme-assisted extraction (EAE) has been shown to be an innovative green technology for the effective extraction of various phytochemicals from agri-food section by-products; therefore, this study aimed to evaluate the application of EAE as green technology to obtain extracts from olive leaves (Olea europaea) for potential industrial production. The used enzymes were Celluclast, Pectinex XXL and Viscozyme L. EAE was conducted under various enzyme dose combinations and an incubation time of 120 min. Obtained extracts were characterized in terms of total polyphenols (TP) and total antioxidant activity (AA). Firstly, the enzyme synergistic effect in the enzymatic extraction of polyphenols was evaluated. TP optimal extraction conditions (468.19 mg GAE (gallic acid equivalent)/L of extract) were achieved after EAE using Pectinex and Viscozyme enzymes (50–50 v/v) and for AA (69.85 AA%). According to the above results, a second experiment investigated the effect of incubation time (min.) and enzyme dose (mL) on the optimal extraction conditions of olive leaves. The final results after optimization were 75% higher than the control sample for the TP content (605.55 mg GAE/L) and 8% higher for the AA (70.14 AA%). These results indicated that EAE is an excellent choice for the green extraction of polyphenols from the olive leaves. Full article

Elephant grass (EG), or Pennisetum purpureum, is gaining attention as a robust renewable biomass source for energy production amidst growing global energy demands and the push for alternatives to fossil fuels. This review paper explores the status of EG as a sustainable bioenergy resource, integrating various studies to present a comprehensive analysis of its potential in renewable energy markets. Methods employed include assessing the efficiency and yield of biomass conversion methods such as pretreatment for bioethanol production, biomethane yields, direct combustion, and pyrolysis. The analysis also encompasses a technoeconomic evaluation of the economic viability and scalability of using EG for energy production, along with an examination of its environmental impacts, focusing on its water and carbon footprint. Results demonstrate that EG has considerable potential for sustainable energy practices due to its high biomass production and ecological benefits such as carbon sequestration. Despite challenges in cost competitiveness with traditional energy sources, specific applications like small-scale combined heat and power (CHP) systems and charcoal production show economic promise. Conclusively, EG presents a viable option for biomass energy, potentially playing a pivotal role in the biomass sector as the energy landscape shifts towards more sustainable solutions; although, technological and economic barriers need further addressing. Full article