Biomass

The aim of this study is the quantitative and qualitative characterization of food waste from the restaurant sector in Riobamba, Ecuador as part of circular economy efforts. A weekly analysis of waste generation data collected from 13 participating restaurants showed that the average daily food waste generated was 18.48 kg/restaurant/day. The highest percentage (55%) was produced by organic waste, which was primarily composed of waste from vegetables. Plastics represented most of the recyclable waste (21%), and 24% of the waste was disposable. With a low dry matter content of 24.33 ± 5.12% and an average moisture level of 75.68 ± 5.12%, the high organic content indicates its potential for value-adding through biological recycling processes like anaerobic digestion and composting. Fruit and vegetable waste had high moisture levels (80.3 ± 2.54% and 81.2 ± 2.75%, respectively), which made them perfect for composting and biogas production. However, the moisture and dry matter contents differed greatly amongst the waste categories. The increased dry matter concentration of animal protein waste (54.5 ± 4.30%) indicated that it may be converted into products with added value, such as animal meal and oils. Plant protein waste needs to be processed quickly to avoid spoiling because of its extraordinarily high moisture content (95.7 ± 3.20%) and low dry matter (4.3 ± 3.20%). The findings underscore the necessity for focused measures, such as composting, anaerobic digestion, and enhanced recycling, to optimize resource recovery and mitigate environmental consequences. Full article

Pineapple (Ananas comosus) is one of the most economically important fruit cultivars in South Africa. The fruit is locally consumed, processed into various industrial products or exported to foreign markets. Approximately 115,106 metric tons of pineapple fruit are harvested in South Africa. The pineapple value chain generates significant amounts of waste, in the form of pomace, peel, crown, stem, core and base. If not properly treated, pineapple waste (PAW) could have a profound detrimental impact on the environment. This calls for advanced technological platforms to transform PAW into useful bio-based products. A biorefinery is a potent strategy to convert PAW into multiple food and non-food products while effectively disposing of the waste. The objective of this review is to explore possible pathways for the valorization of PAW into energy and material products in a biorefinery. The paper looks at 10 products including biogas, biohythane, bioethanol, biobutanol, biohydrogen, pyrolytic products, single-cell proteins, animal feed, vermicompost and bioactive compounds. Several platforms (i.e., biochemical, chemical, physical and thermochemical) are available to convert PAW into valuable goods. Amongst them, the biochemical route appears to be the most favorable option for the valorization of PAW. Anaerobic digestion and fermentation are well-established biochemical technologies for PAW valorization. These methods are simple, low-cost, eco-friendly and sustainable. The focal point of emerging research is the enhanced efficacy of biorefinery platforms. The commercialization of PAW biorefining is a potential gamechanger that could revitalize the entire South African economy. Full article

India’s rapidly growing automobile industry has intensified the need for sustainable fuel alternatives to reduce dependency on imported fossil fuels and mitigate greenhouse gas (GHG) emissions. This study examines the potential of second-generation biorefineries as a comprehensive solution for efficient biomass valorization in India. With a projected bioethanol demand of 10,160 million liters by 2025 for India’s 20% ethanol blending target, there is an urgent need to develop sustainable production pathways. The biorefinery approach enables simultaneous production of multiple valuable products, including bioethanol, biochemicals, and bioproducts, from the same feedstock, thereby enhancing economic viability through additional revenue streams while minimizing waste. This paper systematically analyzes available biomass resources across India, evaluates integrated conversion technologies (biochemical, thermochemical, and synergistic approaches), and examines current policy frameworks supporting biorefinery implementation. Our findings reveal that second-generation biorefineries can significantly contribute to reducing GHG emissions by up to 2.7% of gross domestic product (GDP) by 2030 while creating rural employment opportunities and strengthening energy security. However, challenges in supply chain logistics, technological optimization, and policy harmonization continue to hinder large-scale commercialization. The paper concludes by proposing strategic interventions to overcome these barriers and accelerate the transition toward a sustainable circular bioeconomy in India. Full article

This study explores the extraction and utilization of tannins from Acacia sp. bark residues for water treatment applications. As a by-product of forest management, Acacia sp. bark is valorized through tannin-based coagulant production, contributing to the circular (bio)economy. A systematic review with bibliometric analysis was first conducted to assess the technical–scientific landscape, identifying methodologies and technologies applied to extract and produce natural tannin-based coagulants from Acacia sp. bark residues for water treatment. From the portfolio of analyzed publications, and which followed the thematic axis addressed and the inclusion criteria, only a single study focuses on performing a life cycle assessment (LCA). Due to the relevance of the topic and the clear lack of existing literature, an environmental assessment of the extraction and production of condensed tannins was performed using the LCA methodology from a gate-to-gate perspective. Among the six process stages, spray drying and adsorption (purification) were the primary sources of environmental impact due to their high energy consumption and makeup ethanol use, respectively. The most effective strategy to enhance environmental performance would be reducing water consumption in extraction, thereby lowering energy demand in spray drying. Since both extraction and spray drying require significant energy, decreasing water use and allowing higher moisture content in the condensed tannin extract would mitigate energy consumption. The LCA study thus proved essential in guiding process development toward a reduced environmental footprint. Full article

The energy crisis has highlighted the need for a significant change in Kosovo’s lignite-based electrical energy system, particularly greater investments in renewable energy sources. These sources would provide greater price stability, centralized accessibility, and relatively affordable investment costs. This research tries to analyze the basic attitudes behind the behavior of the students from the agricultural faculty in Kosovo in order to acquire a better understanding of their preferences for renewable energy source purchases, using the Best–Worst Scaling (BWS) method and cluster analysis. Students’ perspectives on renewable energy show strong environmental and price conscientiousness in BWS methods (first and second rank), while the rate of eco-skeptic students reaches only 23% in the cluster analysis, which is a very promising sign of the younger generation’s growing dedication to sustainability. Students, as future decision-makers, can play a critical role in making the transition to a more sustainable and resilient agricultural system. Green transition in Kosovo can be reached by combining the importance of dissemination and marketing tools with the pressing demand for renewable energy solutions, which might be interesting not only for Kosovo, but (considering the expectable enlargement) also for the EU. Full article

China has abundant biomass and renewable energy resources suitable for producing green methanol via biomass thermochemical conversion. Given China’s increasing demand for sustainable fuel alternatives and the urgency to reduce carbon emissions, optimizing biomass utilization through gasification is critical. Research has highlighted the potential of integrating biomass gasification with water electrolysis to enhance efficiency in green methanol production, leveraging China’s vast biomass reserves to establish a cleaner energy pathway. Four main biomass gasification technologies—fixed-bed, fluidized-bed, pressurized fluidized-bed, and entrained-flow—have been investigated. Fixed-bed and bubbling fluidized-bed gasification face low gas yield and scaling issues; whereas, circulating fluidized-bed gasification (CFB) offers better gas yield, carbon efficiency, and scalability, though it exhibits high tar and methane in syngas. Pressurized fluidized-bed gasification improves gasification intensity, reaction rate, and equipment footprint, yet stable feedstock delivery under pressure remains challenging. Entrained-flow gasification achieves high carbon conversion and low tar but requires finely crushed biomass, restricted by biomass’ low combustion temperature and fibrous nature. Current industrially promising routes include oxygen-enriched and steam-based CFB gasification with tar cracking, which reduces tar but requires significant energy and investment; oxygen-enriched combustion to produce CO₂ for methanol synthesis, though oxygen in flue gas can poison catalysts; and a new high oxygen equivalence ratio CFB gasification technology proposed here, which lowers tar formation and effectively removes oxygen from syngas, thereby enabling efficient green methanol production. Overcoming feedstock challenges, optimizing operating conditions, and controlling tar and catalyst poisoning remain key hurdles for large-scale commercialization. Full article

Cotton biomass residues consist of an important portion of the agricultural byproducts. In this work, we systematically analyzed and compared the morphology and thermal properties of nine cotton biomass byproducts. The unique tubular and/or porous morphology of some samples (e.g., main stems, branch stems, and petioles) implied their structural advantage in the development of electric supercapacitors and pollutant absorbents. The higher heating values of the nine samples ranged between 17 and 20 MJ kg⁻¹, higher than some of the other common agricultural byproducts (e.g., rice husk and sugarcane bagasse). The moisture content showed a positive correlation (p > 0.05) to the dehydration temperature of the differential scanning calorimetric plots. The residual char after thermogravimetric analysis could be separated into a high-yield cluster (34.4–26.6%) of leaf blades, bracts/peduncles, burrs, defatted meal, and petioles, and a low-yield cluster (20.5–13.6%) of main stems, branch stems, cotton gin waste, and cottonseed hull. These observations and data are useful for a better understanding of the fundamental chemistry of cotton biomass byproducts. Growing knowledge is useful for improving their recycling strategies and may shed light on the exploration of new value-added products or applications from these cotton biomass byproducts for a circular economy with sustainable agriculture. Full article

Microalgae have emerged as a valuable source of essential nutrients and bioactive compounds, such as proteins, polyphenols, and polysaccharides, which are critical for overall health. Recent research has demonstrated the therapeutic potential of microalgae in addressing a variety of health conditions, including inflammation, oxidative stress, Type 2 diabetes mellitus (T2DM), and neurological disorders. The aim of this paper is to investigate the chemical composition, nutritional value, and biological properties of microalgae. Relevant information was gathered through a comprehensive search of scientific databases, including PubMed, Science Direct, Google Scholar, and the Cochrane Library. Key microalgal strains such as Spirulina platensis, Chlorella vulgaris, Haematococcus pluvialis, and Dunaliella salina have shown notable health-promoting properties. For instance, Spirulina platensis is rich in proteins, vitamins, and polyunsaturated fatty acids, while Chlorella vulgaris offers significant levels of chlorophyll and carotenoids. Haematococcus pluvialis is recognized for its high astaxanthin content and Dunaliella salina for its beta-carotene content. These microalgae strains have demonstrated beneficial effects in managing type 2 diabetes mellitus, alleviating oxidative stress, and offering neuroprotective potential. This paper provides an overview of microalgae’s nutritional composition, their medicinal properties, and their promising role in treating chronic diseases, with a particular focus on their applications in antidiabetic and neuroprotective therapies. Full article

Decentralized energy generation by renewable fuels is an alternative to energy dependency and reduction in greenhouse gas emissions, with biogas emerging as a promising option. Brazil, as the second largest ethanol producer, generates several by-products in the production of this biofuel that could be used for biogas production. In this study, the potential for biogas production and electricity generation from biogas was evaluated. Furthermore, an economic analysis was conducted with calculations of discounted net present value (NPV), internal rate of return (IRR), return on investment (ROI), Levelized Cost of Electricity (LCOE), and sensitivity analysis related to the implementation of vinasse anaerobic digestion, and vinasse and filter cake co-digestion in seven sugarcane mills in Paraná state, Brazil. The results demonstrated that co-digestion and higher sugarcane milling capacities benefit biogas generation and economic aspects. Additionally, implementing anaerobic digestion for electricity production was viable in all scenarios, indicating that biogas from the sugarcane sector could be a viable alternative for decentralized energy generation. Full article

Hydrothermal liquefaction (HTL) technology has garnered immense research interest due to its potential to convert wet biomass into petroleum-like biocrude. Understanding the reaction mechanism and kinetics of HTL is crucial for understanding the process better, estimating the yields, and scaling up. On the other hand, reaction mechanisms and kinetics largely depend upon the feedstock composition and reaction parameters of HTL. However, the literature lacks an in-depth analysis of the reaction mechanism and kinetics concerning biocrude yield and product distribution for a single to multi-feedstock scenario. This review focuses on the reaction mechanisms of various biomolecular components of lignocellulosic biomass, proteins, and lipids in the HTL process under sub- and supercritical conditions. Furthermore, the HTL reaction kinetics, effect of reaction conditions on reaction mechanisms, and product distribution are explored. The findings agree that reaction temperature and retention time follow inverse relations for high biocrude yield. A high heating rate is recommended for higher biocrude yield to avoid cracking and recombination processes. A high solvent/feedstock ratio, depending on feedstock composition, was favored for optimum biocrude yield. In addition, catalysts and reaction solvents, especially organic solvents, effectively contribute towards high biocrude yield, even up to 70%. Heterogeneous catalysts are favored due to reusability and improved biocrude quality. Also, hydrothermal co-liquefaction (multi-feedstock) use for improving biocrude yield was debated. A detailed discussion on the reaction kinetics of various biomolecular components in the HTL process revealed that reactions in HTL normally follow the first-order rate law. Finally, the authors outline the pointers for future research in HTL for industrial upscaling. Full article

As the raw material transition from fossil to renewable feedstock progresses, the demand for biogenic raw materials for industrial purposes will increase. This applies above all to the energy and chemical sectors. However, the capacities for biogenic energy and carbon sources to be provided by agriculture and forestry are limited. This review examines the contribution that biogenic raw materials and CO₂ from biogenic sources can make to sustainable chemical production in the EU. It analyses statistical data from the EU and studies from the chemical industry. First priority needs to be given to edible biomass for the sector of nutrition. When it comes to the industrial use of biomass, sectors should be prioritised that cannot do without carbon-supplying raw materials. This is particularly the case in the field of organic chemistry. This review focuses on bio-based organic chemical products and gives an outlook on the future of chemical production in Europe based on primary, secondary, and tertiary biomass and CO₂ from biogenic sources. Finally, two new indicators for economically and ecologically sustainable industrial use of biomass are proposed. Both indicators can support the determination of the sustainability status of the sustainable integration of agriculture, forestry, residual, and biowaste management in bioeconomic value networks. Full article

Brown seaweed could be a viable option for biogas production, with the added advantage of not competing with land-based crops, which negates the food vs. fuel argument. To optimise the process, this research investigates using mechanical and chemical pre-treatment to increase the biomethane yield of seaweed. The biomethane potential, biodegradability index, and biomethane yields were determined as well as the kinetics based on the hydrolysis of the anaerobic digestion process. Mechanical pre-treatment showed the highest increase in methane yield for the smaller size (<1.7 mm), recording yields of 126.16 mL/g VS after 28 days when compared to 31.54 mL/g VS for the control (2–3 mm). Chemical pre-treatment yielded higher methane rates (34.59–60.33 mL/g VS) than the control, but not as high as the mechanical pre-treatment processes. First-order kinetics described the anaerobic digestion process, with k-values between 0.050 and 0.106. The biodegradability index was between 0.145 and 0.580. The research increased the knowledge base of the potential of the Ecklonia Maxima seaweed to produce biogas. Careful consideration of the impact on the overall process must be completed to determine the advantages or disadvantages of including a pre-treatment step in the process under consideration. Full article

Oil and biodiesel produced from lipidic microorganisms are gaining attention in the scientific area. However, intracellular oil needs additional steps for its recovery for transesterification, which generally uses catalysts. In this context, thermal processes that do not use catalysts demand to be investigated. Therefore, the objective was to produce oil and biodiesel from Mortierella isabellina biomass by direct transformation of dry microbial biomass without using a catalyst. Near-critical fluid extraction (nCFE) of lipids followed by direct transesterification was carried out with the same equipment, as an intensification process. A central composite design was used to evaluate the influence of temperature, pressure, and solvent mass-to-feed mass ratio on the extraction yield. Microbial lipids produced by submerged fermentation and extracted by nCFE with ethanol were used for biodiesel production. The highest total extraction yield (55.4 wt%) and biodiesel conversion (22.2%) were obtained at 300 °C and 20 MPa with 30 g of ethanol/g of fungal biomass. The other conditions yielded extraction yields and biodiesel conversions ranging from 9.7 to 46.0% and from 1.5 to 22.0%, respectively. The interaction between temperature and pressure was significant (p < 0.05), with a positive correlation, indicating that higher temperatures and pressures yielded higher biodiesel conversion rates. The process intensification is advantageous because it is developed sequentially in one step and uses only ethanol as a solvent/reagent, without catalysts. Therefore, the direct extraction and transesterification of Mortierella isabellina lipids demonstrated to be technically feasible and an environmentally friendly technology for the production of fungal oil and biodiesel. The oil can be used in the food and cosmetic industries because it has nutrients that regulate physiological mechanisms promoting human health, while biodiesel can be used in the transport sector and in stationary engines. Full article

Soil fertilization with fertilizers derived from renewable sources is a topic of great interest in terms of the sustainable management of organic waste. To optimize the management of nitrogen supplied to the soil with digestates, it is necessary to deepen knowledge on the process of mineralization of organic nitrogen over time. In this research, a laboratory incubation system was utilized to study the impact of various digestate sources on nitrogen mineralization processes in soils and nitrogen mineralization kinetics. Six types of digestates of different origins and composition were administered to soil and the soil samples were placed under controlled conditions. The release of N was determined by measuring ammonium-N and nitrate-N concentrations in leachates during a 12-week period of incubation. The nonlinear regression technique was used to fit the cumulative leaching of total N to the Stanford and Smith first-order kinetic model during the incubation period. The results showed that the differences between digestates, nitrogen and organic carbon concentration, and C/N ratio influenced both ammonification and nitrification processes in the soil and the nitrogen mineralization kinetics. The processing of the statistical data highlighted that the potentially mineralizable nitrogen (MPN) followed first-order kinetics. Full article

Achieving “Zero Hunger” (SDG 2) requires overcoming complex challenges, especially in vulnerable communities in developing countries. Livestock plays a key role in food security, but limited resources threaten productivity, prompting interest in innovative solutions like microalgae supplementation in ruminant diets. Microalgae offer potential benefits by enhancing productivity and nutrition while addressing local protein deficiencies. However, barriers such as economic costs, processing requirements, and resistance to changing traditional feeding practices present challenges. This review examines the feasibility of microalgae-based livestock feed as a sustainable strategy to improve food security, particularly in arid, climate-affected regions. Biomass yield estimates suggest that small-scale cultivation can meet livestock nutritional needs; for example, a 22-goat herd would require approximately 88 g of microalgae per day to enrich meat with polyunsaturated fatty acids. Semi-continuous production systems could enable smallholders to cultivate adequate biomass, using local agricultural resources efficiently. This approach supports food security, improves meat quality, and strengthens community resilience. Collaboration among researchers, extension services, and local farmers is essential to ensure the effective adoption of microalgae feed systems, contributing to a sustainable future for livestock production in vulnerable regions. Full article

Carrots, scientifically known as Daucus carota L., are among the most popular and widely consumed vegetables. They are used for cooking and juice production, both industrially and in households, resulting in large amounts of waste each year, mainly from the peel. The peels are rich in antioxidant compounds that can be used either as cosmetics or as food and feed additives. Therefore, in this work, the extraction of these compounds was optimized using green techniques (pulsed electric field and/or ultrasonication) and solvents. Response surface methodology was applied to achieve the optimization. Under optimum conditions, the total polyphenol yield was 8.26 mg gallic acid equivalents per g dry weight (dw) and the total carotenoid content was 137.44 μg β-carotene equivalents per g dw. The optimum extract reportedly showed an antioxidant capacity of 76.57 μmol ascorbic acid equivalents (AAE) per g dw by FRAP assay and 63.48 μmol AAE per g dw by DPPH assay, while the total ascorbic acid content was 2.55 mg per g dw. Furthermore, chromatographic quantification of individual bioactive compounds through a diode array detector was performed, wherein catechin yielded the highest proportion (18.6%) of the total 6.88 mg/g dw. This study addressed inquiries regarding the valorization of bioactive compounds from carrot peels, as well as several strategies for recovering their diverse bioactive components using green procedures and solvents. Full article

Natural resources are currently overexploited to provide food supply for the ever-increasing world population, and because of the intensification of agricultural and food production, there is a growing rate of waste generation. This waste biomass is usually dumped into landfills, causing unprecedented damage to ecosystems. Nowadays, circular economy strategies are channeled towards waste harnessing, aiming at reducing the irrational use of resources and minimizing waste generation. Potatoes are the second largest food crop after cereals, and there is an overwhelming amount of waste derived from potato tuber processing, composed almost exclusively of peels. Potato peels (PPs) are considered a source of polyphenolic compounds, largely represented by chlorogenic acid and other structurally related hydroxycinnamates, which possess a spectrum of bioactivities; however, there is a lack of analytical data compilations that could be of assistance in pertinent studies. With this as the conceptual basis, the scope of this review focused on a particular class of polyphenols, the so-called hydroxycinnamates, to deliver compiled data associated with the occurrence, retrieval, and application of this group of compounds derived from potato waste with major emphasis being given to PPs. It is believed that the collection of data of this nature, due to their undisputed significance in studies pertaining to bioeconomy, biorefinery, and food waste valorization, would provide a highly useful contribution to the field. Full article

This study examines the influence of biomass burning on the organic content of urban aerosols in Zagreb, Croatia, by analyzing anhydrosugars, elemental carbon (EC), organic carbon (OC), and water-soluble organic carbon (WSOC) in PM_2.5 and PM₁ fractions collected during different seasons of 2022. Seasonal trends showed that the highest average concentrations of PM_2.5 (27 µg m⁻³) and PM₁ (17 µg m⁻³) were measured during the winter and decreased in the spring, summer, and autumn, which is in accordance with the specific activities and environmental conditions typical for each season. Different sources of OC and WSOC were noticed across different seasons; levoglucosan (LG) was measured during the winter (1314 ng m⁻³ in PM_2.5 and 931 ng m⁻³ in PM₁), indicating that biomass that was mostly used for residential heating was the main source rather than the agricultural activities that are usually common during warmer seasons. The contribution of LG to PM was 5.3%, while LG contributed to OC by up to 13.4% and LG contributed to WSOC by up to 36.5%. Deviations in typical seasonal variability of LG/WSOC revealed more intense biomass burning episodes during the autumn and several times during the winter season. A back trajectories HYSPLIT model revealed a long-range transport biomass emission source. The levoglucosan-to-mannosan (LG/MNS) ratios indicated the burning of mixed softwood and hardwood during colder seasons and the burning of softwood during warmer seasons. Spearman’s correlation tests and principal component analysis showed a strong and statistically significant (p < 0.05) correlation between LG, PM, OC, EC, and WSOC only during the winter season, demonstrating that they had the same origin in the winter, while their sources in other seasons were diverse. Full article

Basic inventory is required for proper understanding and utilization of Earth’s natural resources, especially with increasing soil degradation and species loss. Soil carbon is newly refined at >30,000 Gt C (gigatonnes C), ten times above prior totals. Soil organic carbon (SOC) is up to 24,000 Gt C, plus plant stocks at ~2400 Gt C, both above- and below-ground, hold >99% of Earth’s biomass. On a topographic surface area of 25 Gha with mean 21 m depth, Soil has more organic carbon than all trees, seas, fossil fuels, or the Atmosphere combined. Soils are both the greatest biotic carbon store and the most active CO₂ source. Values are raised considerably. Disparity is due to lack of full soil depth survey, neglect of terrain, and other omissions. Herein, totals for mineral soils, Permafrost, and Peat (of all forms and ages), are determined to full depth (easily doubling shallow values), then raised for terrain that is ignored in all terrestrial models (doubling most values again), plus SOC in recalcitrant glomalin (+25%) and friable saprock (+26%). Additional factors include soil inorganic carbon (SIC some of biotic origin), aquatic sediments (SeOC), and dissolved fractions (DIC/DOC). Soil biota (e.g., forests, fungi, bacteria, and earthworms) are similarly upgraded. Primary productivity is confirmed at >220 Gt C/yr on land supported by Barrow’s “bounce” flux, C/O isotopes, glomalin, and Rubisco. Priority issues of species extinction, humic topsoil loss, and atmospheric CO₂ are remedied by SOC restoration and biomass recycling via (vermi-)compost for 100% organic husbandry under Permaculture principals, based upon the Scientific observation of Nature. Full article