Search Results (575)

This study deals with the successful exploitation of easily available and renewable potato peel waste (PPW) as an excellent feedstock in the production of PHA using Ralstonia eutropha. The process entailed the extraction of bioactive components from PPW by use of solvent-based procedures and screening of their antioxidant and antidiabetic activity. The extracted PPW biomass was subject to acid hydrolysis using different concentrations of sulfuric acid for hydrolysis and solubilization of sugar components. The obtained liquid (acid) hydrolysates were initially assessed to biosynthesize PHA. Activated charcoal-based detoxification of acid hydrolysates was observed to be more efficient in promoting bacterial growth and accumulation of PHA. Acid-pretreated PPW biomass was further enzymatically hydrolysed to accomplish full saccharification and used to produce PHA. The effects of provision of nutrients and employing stress state conditions were assessed to improve bacterial growth and PHA accumulation. In both hydrolysates under optimal conditions, R. eutropha demonstrated the highest biomass productivity of 7.41 g/L and 7.75 g/L, PHA accumulation of 66% and 67% and PHA yield of 4.85 g/L and 5.19 g/L, respectively. XRD, FT-IR, TGA and DSC analysis of produced PHA were studied. The results showed that the produced PHA displayed similar physicochemical and thermal properties to commercially available PHB. Overall, this work illustrates the possibilities of abundantly available PPW, which can be transformed into bioactive compounds and high-value bioplastics via a coupled bioprocess. This approach can develop process economics and sustainability within a cyclic biorefinery system and serve further industry applications. Full article

The aviation industry faces increasing pressure to reduce its environmental impact and achieve net-zero emissions by 2050. In this context, sustainable aviation fuels (SAF) have emerged as a critical alternative to conventional jet fuels. This study provides a comprehensive analysis of SAF technologies from a chemical engineering perspective, highlighting key production routes, technological maturity levels, and implementation challenges. A bibliometric analysis using the Scopus database and VOSviewer software was conducted to identify research trends and thematic clusters in SAF literature. The analysis reveals a growing interest in advanced biofuels and physicochemical conversion technologies, particularly those supported by catalytic and thermochemical processes. Certified and emerging SAF pathways were examined with respect to their process efficiency, feedstock availability, and scalability. Additionally, the study explores the potential of Latin America as a strategic region for SAF development, considering its abundant biomass resources and ongoing pilot projects. This critical and holistic analysis aims to support researchers, engineers, and policymakers in understanding the current state and future directions of SAF technologies within the framework of chemical process design and optimization. Overall, Hydroprocessed Esters and Fatty Acids Synthetic Paraffinic Kerosene (HEFA-SPK) and Fischer–Tropsch Synthetic Paraffinic Kerosene (FT-SPK) are identified as the most mature and widely deployed SAF production routes, whereas Alcohol to Jet (ATJ), Synthesized Iso-Paraffins (SIP), and Direct Sugar to Hydrocarbons (DSHC) remain at earlier technological stages despite their long-term potential for feedstock diversification and reduced environmental impacts. The analysis also underscores Latin America, where abundant biomass resources, consolidated agro-industrial systems, and emerging SAF research initiatives create favorable conditions for future development and deployment. Full article

Rice husk (RH) is a widely available lignocellulosic residue for biohydrogen production but requires effective pretreatment to overcome lignin-related recalcitrance. This study investigates the kinetics of lignin removal from RH using 3% sodium hydroxide (NaOH) and water pretreatments at high temperatures between 100 and 129 °C (25 °C control) with short reaction times (15–60 min) in an autoclave system. Biomass composition, solid yield, delignification efficiency, and enzymatic hydrolysis for glucose production were evaluated. NaOH pretreatment achieved up to 72.72% lignin removal at 129 °C after 60 min, significantly outperforming water pretreatment, which reached a maximum delignification of 20.24% under the same conditions. Kinetic analysis revealed first-order reaction behavior, with the kinetic rate constants varying between 5.14 × 10⁻⁵ and 4.31 × 10⁻³ with water pretreatment and from 3.73 × 10⁻⁴ to 2.46 × 10⁻² with NaOH and activation energies of 42.61 kJ mol⁻¹ K⁻¹ and 39.31 kJ mol⁻¹ K⁻¹ for water and NaOH pretreatment, respectively. Enhanced lignin removal improved cellulose accessibility, resulting in glucose yields from enzymatic hydrolysis of up to 52.13 mg/g for NaOH-treated samples, double those obtained with water pretreatment (26.97 mg/g). While NaOH pretreatment achieved higher lignin removal efficiency and glucose yield, it exhibited significantly higher environmental impacts across multiple categories, including global warming potential and terrestrial ecotoxicity, based on the life cycle assessment (LCA). Even water-based pretreatment showed considerable burdens; thus, both pretreatment methods impose high life cycle impacts when applied to RH, which makes it an unsustainable feedstock for glucose production under the evaluated conditions. Alternative feedstocks or improved process integration strategies are required for environmentally viable biohydrogen production. Full article

Recent advances in agricultural biotechnology and sustainable farming have drawn attention to biochar as a multifunctional material for environmental remediation. Among its emerging applications, biochar has demonstrated remarkable potential in wastewater treatment, particularly as an efficient and sustainable adsorbent for pollutant removal. Numerous studies over the past decades have highlighted its effectiveness in eliminating a wide range of contaminants. This efficiency is mainly due to its abundant feedstock availability, simple production processes, and favorable surface and structural properties. This review summarizes current developments in biochar use for wastewater treatment, emphasizing its adsorption capabilities and the underlying mechanisms responsible for pollutant removal. Key modification strategies, physical, chemical, and biological, are discussed in detail to illustrate how biochar performance can be optimized for specific treatment goals. Furthermore, the prospects of biochar-based technologies are explored, with a focus on their role in addressing both inorganic and organic pollutants. This review also describes the use of biochar in adsorbing metals, organic contaminants, and industrial waste. The integration of biochar into sustainable water management systems presents a promising pathway toward achieving long-term environmental and agricultural resilience. Full article

Agricultural residues, such as vineyard prunings, are abundant yet underutilized resources with potential for conversion into value-added products. In this study, vineyard prunings were investigated for the first time as feedstock for nutrient-enriched biochars intended for use as enhanced efficiency fertilizers (EEFs). Four biochars were produced using distinct physical (industrial-scale pyrolysis, CO₂-assisted pyrolysis) and chemical (MgCl₂, AlCl₃ pretreatment) procedures. Their adsorption capacities for nitrogen (N), phosphorus (P), and potassium (K) were evaluated across a wide pH range (2–13). Optimization studies, including dosage, kinetics, and isotherms, revealed maximum Langmuir adsorption capacities of 10.4 mg N g⁻¹ and 12.7 mg P g⁻¹, which were comparable to or higher than other low-cost agricultural biochars, confirming the competitive performance of vineyard pruning-derived biochars. Beyond adsorption efficiency, these biochars provide additional benefits by valorizing a widely available viticulture residue, reducing open-field disposal and burning, and generating low-cost fertilizers that may reduce nutrient leaching and improve soil health. This work introduces a novel circular pathway linking vineyard waste management to sustainable nutrient delivery, integrating agricultural byproduct utilization with environmental remediation strategies. Full article

Lignocellulosic biomass wastes are renewable carbon resources that can be available for conversion into biofuels. There is a growing interest in utilizing a broader range of alternative biomass feedstocks such as agri-crop residues aside from the traditional forest-origin wood residues for fuel pellet production. However, crop residues typically have low and inconsistent fuel quality. This paper investigated the effectiveness of the combined steam explosion and water leaching pretreatment techniques to upgrade the fuel properties of wheat straw. The experimental treatments involved auto-catalyzed steam explosion and acid-catalyzed steam with and without subsequent water leaching. Using steam explosion catalyzed by dilute H₂SO₄ at a low concentration of 0.5 wt%, results showed the highest ash, Si, and Ca removal efficiencies of 82.2%, 91.1%, and 74.3%, respectively. Moreover, there was significant improvement in fuel quality in terms of fuel ratio (0.34) and calorific value HHV (21.9 MJ/kg), as well as a pronounced increase in the comprehensive combustibility index at the devolatization stage, indicating better combustion characteristics. Overall, the results demonstrate that with adequate pretreatment, the quality of agri-pellets derived from wheat straw could potentially be on par with wood pellets that are utilized for heat and power generation and residential heating. To mitigate the dry matter loss due to steam explosion, future studies shall consider using the process effluent to produce biofuel. Full article

This paper investigates how the existing pellet plant of the Energy Community of Karditsa (ESEK) can be leveraged to strengthen RESCoop operations by integrating a variety of biomass feedstocks as (i) urban residual biomass, (ii) forest residues, and (iii) alternative sources such as spent coffee grounds (SCGs). The RESCoop envisions an extended role as an Energy Service Company (ESCO) by installing and operating biomass boilers in local public buildings. The paper provides an overview of the technical and business support that was provided to the RESCoop for the development of such new business activities and aggregates the lessons learned from engaging the rural society towards sustainable bioenergy production. More specifically, the study covers the logistical aspects of the new RESCoop value chains, including availability, collection, transportation, and processing of the feedstocks along with their costs. A base case scenario investigates the feasibility of installing biomass boilers in municipal buildings through a detailed financial viability study examining capital and operational expenses, revenues, and key financial indicators. Further, the environmental and socio-economic impacts of the new RESCoop activities are evaluated in terms of CO₂ equivalent savings compared to fossil fuel solutions and new job creation, respectively. This detailed analysis highlights the potential for sustainable bioenergy integration and provides valuable insights for similar initiatives aiming to diversify and enhance sustainable energy practices in local communities. Full article

Despite the positive dynamics of biogas and biomethane production in Poland, the country still lags behind Western European leaders per capita. With the ongoing phaseout of coal and the growing demand for power system flexibility, the importance of alternative solutions, with particular emphasis on renewable gases, is growing. Furthermore, capturing methane from manure and food waste offers a significant opportunity to significantly reduce the release of harmful gases into the atmosphere, as well as to recycle nutrients, which in turn translates into enhanced environmental performance (ESG). This places biogas production in Poland among the current and important issues of the energy transition. The available research relates to a limited extent to the conditions of biogas production and processes, particularly in the Polish market. With this in mind, the challenge was taken up to provide up-to-date knowledge on the management challenges of the biogas sector in Poland—today’s situation, conditions and development potential until 2030 and beyond. The analysis draws on regulatory reports, official records, EU policy documents, and industry data, offering practical insights for policymakers, investors, and researchers. The review’s methodology is based on economic analysis and evaluation techniques. The analysis revealed that management challenges in Poland’s biogas sector differ in severity and systemic impact. The priority ranking of barriers is as follows: policy and regulatory barriers, economic barriers, technological barriers, and social barriers. Moreover, the analysis confirms that feedstock price volatility and revenue instability are core components of the economic barrier category, directly affecting managerial decision-making, risk perception, and the overall investment climate in the Polish biogas industry. Full article

The 2000 series aluminium alloys are an attractive option for lightweight structures, but solidification cracking in fusion welding remains an issue in additive manufacturing technologies. Al-Cu-Li alloys, in particular, have gained considerable attention due to their excellent strength-to-weight ratio and corrosion and fatigue resistance, making them highly suitable for aerospace components. Nevertheless, their narrow solidification range makes them highly susceptible to cracking, porosity formation, and elemental evaporation during fusion-based AM processes. These challenges underscore the necessity for advanced processing technologies and the development of suitable feedstock materials to ensure weld integrity and optimal performance. Although Al–Cu–Li alloys are highly valued in the aerospace sector, the application of wire arc additive manufacturing (WAAM) is currently limited by the lack of commercially available wire compositions. This study focuses on the use of powder metallurgy Al-Cu-Li wires in wire arc additive manufacturing, specifically using plasma metal deposition technology, to explore welding characteristics. This research demonstrates the development of an alternative wire using powder metallurgy for WAAM. Powder metallurgy wires were deposited on 5053 and 7075 aluminium substrates, and their microstructure, chemical composition, and mechanical properties were analysed. Key findings include significant elemental losses of Li and Cu during deposition—approximately 55% and 25%, respectively—as well as noticeable variations in microstructure, porosity, and grain morphology, depending on the substrate. Deposits on the 5083 aluminium exhibited more equiaxed grains and a higher chemical homogeneity compared to those on the 7075 substrate. This work establishes a link between material design and additive manufacturing by demonstrating that powder metallurgy Al–Cu–Li wires can be effectively processed by WAAM, achieving controlled elemental losses and a uniform microstructure that enhances weld integrity in aerospace components. Full article

In 2017, Brazil launched its National Biofuel Policy (RenovaBio) to reduce greenhouse gas emissions from the transportation matrix, aligned with the National Determined Contribution commitments under the Paris Agreement. The authors of this Technical Note formed a working group that structured the methodological framework for RenovaCalc, the computational tool used by producers to quantify the carbon intensity of biofuels certified under RenovaBio. The framework is based on the Life Cycle Assessment approach, in accordance with internationally recognized standards and bioenergy policy guidelines. For the 2025 cycle, 331 production units (75% of Brazil’s total) had their biofuels under certification obtained using RenovaCalc, which is currently available for biodiesel, ethanol, biomethane, and sustainable aviation fuel produced from numerous feedstocks. The calculator is widely adopted and possibly the most important life cycle tool in Brazil. Full article

Hygienization by hydrothermal carbonization (HTC) of chicken manure (CM) at 250 °C allows its valorization as soil amendment or even organic fertilizer. To test if this hypothesis is also valid for feedstocks from free-range breeding, respective material of a small farm in southern Spain was comprehensively chemically characterized. The hydrochar of the manure collected from the ground of the farm was rich in mineral matter. After HTC, 68% of the organic carbon (C) was recovered, whereas 82% of the nitrogen (N) was lost most likely by volatilization and with the discarded process water. Despite this, 2.8% of the total N in the hydrochar was identified as inorganic N (N_i). Solid-state ¹³C and ¹⁵N NMR spectroscopy revealed aromatization of organic C and N, although alkyl C and amide N still contributed with 23% and 35% to the total organic C and N, respectively. The obtained distribution of N-forms indicated that enough N_i is plant-available for early plant growth, while the remaining N occurs in structures that can be slowly mobilized during advanced plant development. Low heavy metal concentrations suggest low phytotoxicity. Pot experiments with lettuce, sunflower, and tomato plants confirmed species- and dosage-dependent effects. A dosage of 3.25 t ha⁻¹ improved lettuce and sunflower yields, whereas a dosage of 6.5 t ha⁻¹ provided no additional growth benefits but caused phytotoxic reactions of the tomato plants. Our results support HTC as a strategy to valorize CM from free-range farms, although, due to the high variability of such materials, we recommend a thorough chemical characterization and phytotoxic tests before its application. Full article

Olive tree pruning (OTP), a widely available agricultural residue in Mediterranean countries, represents a promising lignocellulosic feedstock for anaerobic digestion. However, its recalcitrant structure limits its biodegradability and methane yields, necessitating effective pretreatment approaches. In this context, hydrogen peroxide in combination with ultraviolet (UV) radiation (UV/H₂O₂) at ambient temperature was used as a pretreatment method for enhancing methane production from OTP. Three concentrations of H₂O₂ (0, 1, and 3% w/w) alone or in combination with UV radiation, at different retention times (8, 14, and 20 h), were evaluated to enhance OTP depolymerization and methane generation. In addition, the combination of UV/H₂O₂ with alkali (UV/H₂O₂/NaOH) was compared with the typical alkaline pretreatment (NaOH) in terms of lignocellulosic biomass fractionation and biochemical methane potential (BMP). Results showed that increasing H₂O₂ concentration during UV/H₂O₂ pretreatment enhanced hemicellulose solubilization. Both NaOH and UV/H₂O₂/NaOH pretreatment promoted lignin reduction (37.3% and 37.8%), resulting in enhanced BMP values of 330.5 and 337.9 L CH₄/kg TS, respectively. Considering operational energy requirements (heating at 80 °C and irradiance for 20 h) and methane energy recovery, net energy balances of 45.52 kJ and 66.65 kJ were obtained for NaOH and UV/H₂O₂/NaOH, respectively. Full article

Biochar is increasingly recognized as a multifunctional soil amendment that improves soil fertility, nutrient cycling, and crop productivity. Studies across field, greenhouse, and incubation settings show that biochar enhances nutrient retention, reduces leaching, and regulates carbon, nitrogen, and phosphorus cycling. Its effects are shaped by intrinsic physicochemical properties and interactions with soil minerals, microbial communities, and enzymatic processes. Short-term benefits of biochar applications often include improved nutrient adsorption and water regulation, while long-term applications support stable soil organic matter formation, root development, and fertilizer use efficiency. Biochar also reshapes soil microbial diversity and activity. Beneficial bacterial groups such as Proteobacteria and Actinobacteria, along with fungi such as Mortierella, respond positively, enhancing nitrogen fixation, phosphorus solubilization, and organic matter decomposition. Meanwhile, biochar applications could suppress pathogens. Enzyme activities, including urease and phosphatase, are typically stimulated, driving nutrient mobilization. Yet outcomes remain context-dependent, with biochar feedstock, application rate, soil conditions, and crop type influencing results; excessive use may suppress enzymatic activity, reduce nutrient availability, or shift microbial communities unfavorably. Practically, biochar can improve fertilizer efficiency, restore degraded soils, and reduce greenhouse gas emissions, contributing to climate-smart agriculture. Future work should prioritize long-term, multi-site trials and advanced analytical tools to refine sustainable application strategies. Full article

Hydrogen is being increasingly recognized as a promising clean, renewable energy carrier. Among the available production pathways, biological processes, particularly dark fermentation of residual biomasses and agricultural by-products, represent an appealing approach aligned with circular economy principles. These feedstocks are abundant and low cost; however, their relatively low energy density constrains process efficiency. To mitigate this limitation, research efforts have concentrated on optimizing substrate composition and implementing pre-treatment strategies to enhance hydrogen yields. Numerous studies have explored the potential of agricultural and livestock residue, yet reported outcomes are often heterogeneous in terms of units, systems, and experimental conditions, complicating direct comparison. This review consolidates current knowledge and identifies effective strategies to optimize biohydrogen generation. Among the investigated substrates, corn stover emerges as the most promising, with hydrogen yields up to 200 [mL H₂/gVS (Volatile Solids)]. Evidence further suggests that inoculum processing, including enrichment or pre-treatment, can substantially improve performance, often more effectively than substrate processing alone. When both inoculum and substrate are treated, hydrogen yields may increase up to fourfold relative to untreated systems. Overall, integrating suitable feedstocks with targeted processing strategies is crucial to advancing sustainable biohydrogen production. Full article

Lignocellulosic biomass—the non-edible fraction of plants composed of cellulose, hemicellulose, and lignin—is the most abundant renewable carbon resource and a key lever for shifting from fossil to bio-based production. Agro-industrial residues (straws, cobs, shells, bagasse, brewery spent grains, etc.) offer low-cost, widely available feedstocks but are difficult to process because their polymers form a tightly integrated, three-dimensional matrix. Within this matrix, lignin provides rigidity, hydrophobicity, and defense, yet its heterogeneity and recalcitrance impede saccharification and upgrading. Today, most technical lignin from pulping and emerging biorefineries is burned for energy, despite growing opportunities to valorize it directly as a macromolecule (e.g., adhesives, foams, carbon precursors, UV/antioxidant additives) or via depolymerization to low-molecular-weight aromatics for fuels and chemicals. Extraction route and severity strongly condition lignin structure linkages (coumaryl-, coniferyl-, and sinapyl-alcohol ratios), determining reactivity, solubility, and product selectivity. Advances in selective fractionation, reductive/oxidative catalysis, and hybrid chemo-biological routes are improving yields while limiting condensation. Remaining barriers include feedstock variability, solvent and catalyst recovery, hydrogen and energy intensity, and market adoption (e.g., low-emission adhesives). Elevating lignin from fuel to product within integrated biorefineries can unlock significant environmental and economic benefits. Full article