Search Results (34)

To achieve the upcycling of annually upsurging lignocellulosic wastes, the artificial humification of furfural residue is investigated under hydrothermal conditions with the objective of producing a high-concentration nitrogen-phosphorus-potassium (NPK) suspension fertilizer. Through orthogonal analysis, process conditions are optimized as a liquid-to-solid (aqueous KOH to furfural residue) ratio of 15, a reaction time of 5 h and a hydrothermal temperature of 160 °C. Subsequently, we screen out a formulation of suspension agents to stabilize the alkaline leachate, in which 0.50% sodium lignosulfonate, 0.20% xanthan gum and 0.05% potassium sorbate are incorporated via wet ball-milling. The Herschel–Bulkley equation well fits the rheological characteristics of the resulting suspension fertilizer with R² value exceeding 0.99. This suspension system is thus determined as one pseudoplastic non-Newtonian fluid. Due to higher static viscosity, it demonstrates superior anti-agglomeration capacity within a temperature range of 15–55 °C, while flowing smoothly through pipes during high-speed spraying onto the soil relied on its shear thinning. These findings provide novel insights for the high-value utilization of bio-waste and the development of new fertilizers with less consumption of energy and water. Full article

The transition toward a circular bioeconomy requires efficient conversion of biogenic wastes and biomass into renewable fuels. This study explores the gasification potential of wastewater sludge (WWS) and food waste (FW), representing high moisture-content biowastes, compared with softwood (SW), a lignocellulosic biomass reference. An Aspen Plus equilibrium model incorporating the drying stage was developed to evaluate the performance of air and steam gasification. The effects of temperature (400–1200 °C), equivalence ratio (ER = 0.1–1), and steam-to-biomass ratio (S/B = 0.1–1) on gas composition and energy efficiency (EE) were examined. Increasing temperature enhanced H₂ and CO generation but reduced CH₄, resulting in a maximum EE at intermediate temperatures, after which it declined due to the lower heating value of the gases. Although EE followed the order SW > FW > WWS, both biowastes maintained robust efficiencies (60–80%) despite high drying energy requirements. Steam gasification increased H₂ content up to 53% (WWS), 54% (FW), and 51% (SW) near S/B = 0.5–0.6, while air gasification achieved 23–27% H₂ and 70–80% EE at ER ≈ 0.1–0.2. The results confirm that wet bio-wastes such as WWS and FW can achieve performance comparable to lignocellulosic biomass, highlighting their suitability as sustainable feedstocks for waste-to-syngas conversion and supporting bioenergy integration into waste management systems. Full article

Corn stover (CS) is an abundant biomaterial, which is regularly rejected during corn harvesting. This biowaste is a typical lignocellulosic source rich in hydroxycinnamates, which are mainly represented by p-coumaric acid and ferulic acid. These polyphenols are largely bound onto the lignocellulosic complex and can be effectively liberated using alkaline catalysis. On this basis, the work described herein targeted at developing a high-performance process for producing hydroxycinnamate-enriched extracts, by deploying alkali-catalyzed hydrothermal and organosolv treatments. For this purpose, sodium carbonate was tested as a benign, natural alkali catalyst, along with the well-studied sodium hydroxide. The kinetic study demonstrated that both the alkali catalyst and the organic solvent (ethanol) may significantly affect polyphenol recovery, a fact further investigated by carrying out response surface optimization. The hydrothermal treatment was shown to be more efficacious than the organosolv one, with regard to total polyphenol recovery, while the sodium carbonate catalysis was less efficient compared to the sodium hydroxide one. Under optimized conditions, the hydrothermal treatment afforded 74.4 ± 3.6 mg gallic acid equivalents per g of dry CS mass. On the other hand, a more thorough investigation of the polyphenolic profile of the extracts obtained clearly demonstrated that the sodium hydroxide-catalyzed organosolv treatment provided almost 76 and 98% higher yields for p-coumaric and ferulic acid, respectively, compared to the hydrothermal treatment. Extract composition impacted the antioxidant activity, and it was revealed that the higher the p-coumaric acid/ferulic acid ratio, the stronger the antioxidant effect. It is proposed that the sodium hydroxide-catalyzed ethanol organosolv treatment of CS may be a particularly promising technique in a lignocellulose biorefinery frame, although improvements might be necessary to further increase treatment performance. Such a process might contribute to fully valorizing agricultural biowastes for the production of high value-added chemicals, in line with the “lignin first’ philosophy. Full article

In the present study, slurry digestate from a centralized anaerobic digestion (AD) plant, designed for dairy manure treatment and biogas-to-power generation, was utilized as a precursor for the preparation of porous biochars at elevated temperatures ranging from 550 to 850 °C. Proximate analysis and thermogravimetric analysis (TGA) were conducted to determine the thermochemical characteristics of the dried digestate and to explain its complex nature in relation to the physicochemical properties of the resulting biochars. Despite the substantial ash content of the precursor biowaste (approximately 30 wt%), primarily composed of inorganic compounds from calcium, the pore properties of the digestate-derived biochars had an overall increasing trend with regard to rising pyrolysis temperature. Nevertheless, some inconsistencies were observed between the samples produced at 550 °C and 850 °C, which highlighted the heterogeneous and complex nature of the precursor digestate. These observations can be attributed to active pyrolysis and the charring of the lignocellulosic components. The maximum Brunauer–Emmett–Teller (BET) surface area exceeded 200 m²/g when pyrolysis was performed at 850 °C. Nitrogen (N₂) adsorption–desorption isotherms and scanning electron microscopy (SEM) confirmed that the porous digestate-based biochars predominantly exhibited both type I (microporous) and type IV (mesoporous) characteristics. Furthermore, the analytical results of energy-dispersive X-ray spectroscopy (EDS) and Fourier transform infrared spectroscopy (FTIR) indicated that oxygen-containing surface functional groups on the resulting biochars were retained after pyrolysis. The surface of the digestate-based biochar was also confirmed to be negatively charged at pH > 3.2. Full article

Corn stover (CS) is a highly abundant type of agricultural biowaste, largely composed of lignocellulosic material. CS may be a particularly rich pool of hydroxycinnamates, represented primarily by p-coumaric acid and ferulic acid; yet, these compounds are bound onto the lignocellulosic matrix, and their release requires an appropriate acid and/or alkaline catalysis. This being the case, this study herein aimed to develop an effective process to boost hydroxycinnamate recovery by employing acid-catalyzed hydrothermal and organosolv treatments. To this end, oxalic acid was tested as a benign, natural acid catalyst, along with the well-examined sulfuric acid. A kinetic assay showed that both the acid catalyst and the use of an organic solvent (ethanol) may greatly impact the rate and level of polyphenol recovery. Under optimized conditions, determined by implementing response surface methodology, it was demonstrated that the organosolv treatment was far more effective than the hydrothermal one, with regard to total polyphenol recovery, while the oxalic acid catalysis was equally efficient as the sulfuric acid one. This treatment afforded 17.8 ± 2.3 mg gallic acid equivalents per g of dry CS mass. However, a thorough insight into the polyphenolic composition of the extracts produced revealed that hydrothermal treatment may enable, apart from p-coumaric and ferulic acid release, the formation of a compound tentatively identified as an ester of p-coumaric acid with a pentose. Furthermore, it was shown that sulfuric acid-catalyzed organosolv treatment provided almost 25 and 34% higher yields for p-coumaric and ferulic acid, respectively, but it strongly inhibited p-coumaric acid-pentose ester formation. These compositional differences appeared to impact the antioxidant activity of the corresponding extracts. It was concluded that the oxalic acid-catalyzed ethanol organosolv treatment of CS may have important potential in a biorefinery context, but improvements are required to further enhance treatment performance. This would lead to replacing corrosive catalysts, such as sulfuric acid, with benign ones, thereby establishing a fully sustainable process for the recovery of bioactive phytochemicals. Full article

Most bioplastics are based on polysaccharides, which are either synthesized from a variously sourced monomer or extracted from some biomass waste. In many cases, some lignocellulosic fibers are then added to the obtained bioplastics to form biocomposites and extend their range of applications beyond packaging films and generically easily biodegradable materials. Plant-extracted tannins, which, as such, might also be building blocks for bioplastics, do nonetheless represent a useful complement in their production when added to polysaccharide-based plastics and biocomposites, since they offer other functions, such as bioadhesion, coloration, and biocidal effect. The variety of species used for tannin extraction and condensation is becoming very wide and is also connected with the local availability of amounts of bio-waste from other productions, such as from the food system. This work tries to summarize the evolution and recent developments in tannin extraction and their increasing centrality in the production of polysaccharide-based plastics, adhesives, and natural fiber composites. Full article

Organic wastes from households, private gardens, the maintenance of urban greenery, and active nature conservation measures are often difficult to manage. This lignocellulosic biomass may be suitable for anaerobic digestion (AD). However, the mono-digestion of plant material, such as waste from active conservation measures for wetlands, results in a low methane (CH₄) yield. The aim of this study was to assess the feasibility of using common reed silage for co-digestion with plant-based biowaste from households. The specific methane yield (SMY) was determined in biochemical methane potential (BMP) tests performed on biowaste, reed silage, and combinations of reed silage with 10%, 30%, 50%, 70%, and 90% of biowaste on a fresh weight basis. The lowest SMY was observed for the mono-digestion of reed silage (160.40 ± 4.09 NL kg_VS⁻¹), while biowaste had the highest CH₄ yield (284.03 ± 7.03 NL kg_VS⁻¹). The subsequent addition of biowaste enhanced CH₄ production from 158.57 ± 7.88 NL kg_VS⁻¹ (10% of biowaste) to 233.28 ± 11.91 NL kg_VS⁻¹ (90% of biowaste). A key advantage of biogas production is its role in reducing CO₂ emissions into the atmosphere, which result from the use of conventional fuels for energy generation. The avoided CO₂ emissions generated in electricity and heat production range between 378.62 kgCO₂ t_TS⁻¹ and 676.36 kgCO₂ t_TS⁻¹ depending on the reed silage-to-biowaste ratio used for biogas production. This study reveals that reed silage is not an optimal feedstock for biogas production, and its share in co-digestion with biowaste should not exceed 10% of the total input to the biogas plant. Full article

Bioresources have been gaining popularity due to their abundance, renewability, and recyclability. Nevertheless, given their diverse composition and complex hierarchical structures, these bio-based sources must be carefully processed to effectively extract valuable raw polymeric materials suitable for producing man-made organic fibres. This review will first highlight the most relevant bio-based sources, with a particular focus on promising unconventional biomass sources (terrestrial vegetables, aquatic vegetables, fungi, and insects), as well as agroforestry and industrial biowaste (food, paper/wood, and textile). For each source, typical applications and the biopolymers usually extracted will also be outlined. Furthermore, acknowledging the challenging lignocellulosic structure and composition of these sources, an overview of conventional and emerging pre-treatments and extraction methods, namely physical, chemical, physicochemical, and biological methodologies, will also be presented. Additionally, this review aims to explore the applications of the compounds obtained in the production of man-made organic fibres (MMOFs). A brief description of their evolution and their distinct properties will be described, as well as the most prominent commercial MMOFs currently available. Ultimately, this review concludes with future perspectives concerning the pursuit of greener and sustainable polymeric sources, as well as effective extraction processes. The potential and main challenges of implementing these sources in the production of alternative man-made organic fibres for diverse applications will also be highlighted. Full article

Nowadays, there is increasing global demand for activated carbon considering its wide usage as an adsorbent of environmental pollutants. Biowaste rich in lignocellulose, like the cone-like flowers of black alder (A_AC), shows promise as a precursor for novel materials. Building upon previous research and this material’s established applicability for removing cyanobacteria cells and cyanotoxins from water, this study investigates the CNOHS composition of A_AC and its potential to inhibit biofilm formation. A comprehensive CNOHS analysis showed the material composition as 64.5%, 1.77%, 28.83%, 2.05%, and 0.12% for C, N, O, H, and S respectively. The material’s efficacy in inhibiting biofilm formation across eight selected bacterial strains was evaluated. The results showed biofilm formation rates of 62.6%, 22.1%, 73.8%, 12.1%, 40.9%, 24.2%, 9.2%, and 7.6% for Escherichia coli, Pseudomonas aeruginosa, Enterobacter cloacae, Salmonella Typhimurium, Proteus mirabilis, Klebsiella pneumoniae, Acinetobacter baumannii, and Enterococcus faecalis, respectively. Biofilm formation is influenced by biotic and abiotic factors, especially the physicochemical properties of the substrate. This study offers insights into the potential of black-alder-derived activated carbon to prevent biofilm formation, highlighting its role in water purification and environmental protection. Full article

The Adrar region (Algeria) has a total of 397,800 date palm trees (Phoenix dactylifera L.). Due to annual palm cleaning, large quantities of lignocellulosic biomass are produced. Depending on the variety, an average of 65 kg of biowaste is obtained per palm tree. Since the value of this biowaste is underrated, most of the palms are burned outdoors, causing air and visual pollution. This work explores the gasification potential of lignocellulosic waste from date palms (Phoenix dactylifera L. Takarbouche variety) into useful energy. The technology investigated is air updraft fixed-bed gasification, thanks to an originally designed and built reactor, with the capability to process 1 kg of feedstock. Four types of palm waste—namely, palms, petioles, bunch, and bunch peduncles—are first characterized (bulk density, proximate analysis, fixed carbon, elemental composition, and calorific value) and then used as feedstock for two gasification tests each. The syngas produced for the four date palm wastes is combustible, with an outlet temperature between 200 and 400 °C. The operating temperature inside the gasifier varies according to the feature of the biomass cuts (from 174 °C for the peduncles to 557 °C for palms). The experimental setup is also equipped with a cyclone, allowing for the recovery of some of the tar produced during the tests. Finally, the results show that the residence time has a positive effect on the conversion rate of date palm waste, which can significantly increase it to values of around 95%. Full article

The growing production of biowaste is causing serious environmental concerns, and composting has emerged as an environmentally friendly solution. This approach contributes to the real circular economy of biowaste, avoiding landfill disposal. This process is flexible as it can be carried out on a domestic or industrial scale. This work focused on the formulation and monitoring of two different composting processes (on a laboratory and domestic scale), to recover biowaste from a university canteen and a rural household, as well as evaluating the quality of the final composts. Three different mixtures of canteen food waste (CFW) and olive wood chips (OWC) were tested at lab scale (CFW:OWC 100:0, 40:60, and 60:40%), with two replicates carried out on the second mixture; a single mixture was tested at the domestic experiment (40:60%). The results showed that both processes reached thermophilic temperatures, with a peak of 65 °C on the lab scale and 75 °C recorded in the domestic composting. Reaching thermophilic temperatures is essential in composting, to maximize the rate of organic matter (OM) decomposition and improve compost quality (e.g., stability and maturation). The moisture content (MC) of biowaste proved to be a critical parameter since the high MC of CFW led to the inhibition of the aerobic process in the mixture without OWC (100% of CFW). On the contrary, a large quantity of OWC (60:40%) showed lower biodegradability due to the presence of lignocellulosic compounds. Analysis of the quality of the final compost revealed that although domestic composting was a process with a low level of control, it allowed obtaining quality compost for agronomic applications, similar to that produced on a laboratory scale. All final composts (after 120 days) were stable and mature, according to the oxygen uptake rate (OUR) and the germination index (GI). Indeed, OUR complied with the regulatory limits (15 and 25 mmolO₂/kgOM.h) to be considered soil correctives or organic fertilizers, evidencing the stability of the materials. All composts are non-phytotoxic (GI above 80%), meaning that they are suitable for plant growth. The composts produced retained a significant amount of carbon (40–70%), with a high value for returning carbon to the soil in stable OM forms. Thus, when applied to the soil, a significant amount of carbon is carried to this compartment, making a valuable contribution to closing the carbon cycle and avoiding the emission of CO₂ into the atmosphere. Overall, it was possible to conclude that biowaste from university canteens and households can be recovered by composting, as long as it is mixed with a bulking agent (such as OWC), which promotes the process and improves the properties of the composts. Full article

This paper focuses on the optimisation of an efficient extraction process for cellulose and lignin from rice straw waste from the Albufera of Valencia using the steam explosion method. This method is particularly pertinent given the environmental and economic challenges posed by the current disposal practices of agricultural waste. The technique comprises a high-temperature cooking stage followed by instantaneous decompression, effectively altering the biomass’s physical and chemical properties to enhance its surface area and porosity. Our adaptation of the steam explosion technique specifically addresses the challenges of rice straw waste, marking a significant departure from previous applications. This innovation is crucial in addressing the urgent need for more sustainable waste management practices, as it effectively deconstructs the lignocellulosic matrix of rice straw. This facilitates the selective extraction of cellulose at a 70% efficiency, with a 20% yield and the subsequent recovery of lignin. The results of this study are significant for sustainable biomaterial production, offering novel insights into optimising these crucial biomass components. By refining the process and focusing on critical parameters, our work advances the application of steam explosion methods for agricultural waste, enhancing efficiency and sustainability. By utilising rice straw biowaste, this research not only proposes a solution to a pressing environmental issue but also demonstrates the potential to create new market opportunities, increase the economic value for rice producers, and significantly reduce the environmental footprint of existing waste disposal methods. The holistic and ecological approach of this study underscores the vital need for innovative strategies in agricultural waste management, positioning the valorisation of rice straw waste as a key component in the pursuit of environmental sustainability. Full article

Pistachio and walnut shells accumulate in large quantities as waste during food processing and represent a promising lignocellulosic biomass for the extraction of valuable components. Subcritical water technology was used as an environmentally friendly technique to study the extraction of active ingredients and other valuable degradation products from walnut and pistachio waste. Subcritical water extraction (SWE) was carried out under different process conditions (temperature (150–300 °C) and short reaction times (15–60 min)) and compared with conventional extraction using different organic solvents (acetone, 50% acetone and ethanol). The extracts obtained from pistachio and walnut shell waste are rich in various bioactive and valuable components. The highest contents of total phenols (127.08 mg GA/g extract at 300 °C for 15 min, from walnut shells), total flavonoids (10.18 mg QU/g extract at 200 °C for 60 min, from pistachio shells), total carbohydrates (602.14 mg TCH/g extract at 200 °C for 60 min, from walnut shells) and antioxidant activity (91% at 300 °C, for 60 min, from pistachio shells) were determined when the extracts were obtained via subcritical water. High contents of total phenols (up to 86.17 mg GA/g extract) were also determined in the conventional extracts obtained with ethanol. Using the HPLC method, sugars and their valuable derivatives were determined in the extracts, with glucose, fructose, furfurals (5-hydroxymethylfurfural (5-HMF) and furfural) and levulinic acid being the most abundant in the extracts obtained by subcritical water. The results show that subcritical water technology enables better exploitation of biowaste materials than conventional extraction methods with organic solvents, as it provides a higher yields of bioactive components such as phenolic compounds and thus extracts with high antioxidant activity, while at the same time producing degradation products that are valuable secondary raw materials. Full article

Recently, the industrial focus has shifted to renewable raw materials due to the exhaustion and rising pressures about environmental and political issues. Lignocellulosic biowaste can be derived from a range of sources, such as animal manure, forestry waste, and agricultural waste, and it can be transformed into lactic acid through a biochemical process. There are 942.63 million cattle in the world and annually generate 3.7 billion tons of manure, which could be used to produce lactic acid. The economic viability of a lactic acid plant from cow manure has not yet been determined and is, thus, considered in this study. Using the modeling program Aspen Plus data and other sources, as well as collecting all economic inputs, the feasibility analysis of a lactic acid plant handling cow manure is assessed in this paper. Three scenarios are calculated to check the feasibility depending on the plant size: scenario I handles 1,579,328 t·year⁻¹, scenario II handles 789,664 t·year⁻¹, and scenario III handles 315,865 t·year⁻¹. The results demonstrate that treating the tested lignocellulosic biomass for the manufacture of lactic acid is economically feasible because the economic analysis shows positive net present values for scenarios I, II, and III. The technoeconomic analysis reveals that the minimum lactic acid selling price for scenario I is 0.945 EUR·kg⁻¹, which is comparable to the cost of commercial lactic acid produced from starch feedstock. Scenario II achieves a minimum selling price of 1.070 EUR·kg⁻¹, and scenario III 1.289 EUR·kg⁻¹. The sensitivity analysis carried out reveals that the factor with the biggest impact on the NPV is the yield. Moreover, this study provides a model of industrial application and technoeconomic evaluation for lactic acid production from cow manure. Full article

Lignocellulosic substrates are considered to be crucial substrates for the production of biofuels. The main objective of the study is to attempt to produce bioethanol using bio-wastes such as mango peels, orange peels, and tapioca shells as renewable sources by employing three bacteria viz., Enterobacter cloacae (ICBP1), Pseudomonas aeruginosa (ICBP7), and Bacillus cereus (ICBP15), which were chosen to produce cellulase enzymes using the submerged fermentation method, which is a novel method for the production of bioethanol. The “zone of clearance” in bacterial growth on CMC agar plates determined the choice. The mixed culture infected units produced a more reduced sugar, i.e., the presence of aldehyde and ketones except sucrose. At 72 h, greater than 41.0 ± 0.48 mL and 0.83 ± 0.07% of ethanol was recovered. This contrasts with the reduced quantities at 24 and 48 h. SDS-PAGE examination showed that the three cellulose-producing bacterial strains (ICPB1, ICPB7, and ICPB15) had enzyme molecular weights of 80–100, 20–30, and 14–20 kDa, respectively, compared to the other 17 isolates. Fourier-transform infrared (FTIR) spectroscopy was used to estimate the bioethanol. The spectrum bands from 1700 to 1800 cm⁻¹ showed bioethanol’s unique absorption characteristics, and GC-MS confirmed 31.38% ethanol. The findings of the research demonstrate that the utilization of fermentation technology, specifically employing microbes, to produce bioethanol from bio-wastes such as fruits and vegetables has the potential to address the worldwide fuel energy requirements. Full article