Search Results (968)

Excessive acidity restricts the utilization of citrus pulp, a major by-product of the dried tangerine peel industry. To overcome this bottleneck, a functional microbial consortium (BsHpMrF) comprising Bacillus subtilis L4, Hanseniaspora pseudoguilliermondii B4, and Monascus ruber CGMCC 10910 was constructed for efficient biological deacidification. The consortium exhibited a synergistic effect, achieving an 88.23% reduction in total acidity and converting the acidic pulp into a neutral, bio-stabilized substrate. Untargeted metabolomics analysis revealed that this efficiency was driven by the concurrent activation of the TCA cycle and glyoxylate shunt for organic acid mineralization, coupled with membrane lipid remodeling (increased unsaturation) to enhance acid tolerance. Notably, the fermentation process functioned as a “metabolic factory”, significantly enriching the matrix with bioactive lipids (e.g., 10-HDA, nervonic acid) and indole-3-acetic acid (IAA, 414.28 mg/L). Application assays demonstrated that the fermentation products acted as a potent biostimulant for soybean sprouts, significantly promoting lateral roots and eliciting the accumulation of antioxidant phenolics and flavonoids. This study provides a sustainable “waste-to-treasure” strategy, valorizing acidic citrus pulp into a functional biostimulant for high-quality edible sprout production, thereby achieving a sustainable “waste-to-food” circular loop. Full article

Within a waste biorefinery framework, integrating agro-industrial by-products into the circular economy requires a detailed understanding of the thermochemical conversion behaviour of low-grade carbonaceous materials. This study evaluates the co-pyrolysis characteristics of Soma lignite (SL) and pectin-rich sugar beet pulp (SBP) as a sustainable route for upgrading these resources into clean energy carriers. Interactions between the two feedstocks were analysed by thermogravimetric measurements, triple-region kinetic modelling, and quantitative synergy indices at six mixing ratios, including the pure samples (100:0, 80:20, 60:40, 40:60, 20:80, and 0:100 wt% SL:SBP). The Reactivity Index ($R_{\mathrm{m}}$) increased from 0.97 × 10⁻⁴ s⁻¹K⁻¹ for pure SL to 8.65 × 10⁻⁴ s⁻¹K⁻¹ for the 20:80 blend, showing that SBP acts as a highly reactive biomass component that accelerates devolatilisation in the main pyrolysis region. Synergy analysis indicated a shift from inhibitory behaviour in coal-rich blends to slightly positive synergy in SBP-rich mixtures, with the onset of positive $\Delta TC$ around 60 wt% SBP under the present single-heating-rate, non-replicated TGA conditions. This tentative threshold-like behaviour suggests that a critical level of literature-supported, hypothesised hydrogen-donating biomass radicals may be required to overcome the structural resistance of the coal matrix. Within these experimental limitations, the apparent macro-kinetic deviations and first-order Arrhenius parameters suggest that SL/SBP co-pyrolysis follows a complex, non-additive pathway that should be further validated by multi-heating-rate and product characterisation studies in future work. The primary contribution of this work lies in proposing this distinct threshold-like biomass fraction at the macro-kinetic level that governs the transition from heat-transfer-limited antagonism to radical-influenced synergy in low-rank coal and pectin-rich biomass blends. Overall, the combined $\Delta TC$, $\Delta E$ and $R_{\mathrm{m}}$ descriptors provide useful macro-kinetic benchmarks for guiding the optimisation of thermochemical processes for low-grade carbonaceous resources. Full article

The growing production of lithium-ion batteries is leading to an increase in waste, which contains elements considered critical in industry, like cobalt, manganese and nickel. Urban mining offers an opportunity to recover these elements and reintroduce them into the value chain. This study aimed to detect and recover metals of interest present in discarded lithium-ion batteries and determine the influence of flotation operating parameters on the recovery of the detected elements through an experimental design. The batteries subjected to the flotation experiments were obtained from various types of common disused mobile devices. They were dismantled by separating the copper sheets from the anode and the aluminum sheets from the cathode, to be subjected to a comminution process and elemental composition analysis using X-ray fluorescence. Only the cathode components were subjected to flotation. The flotation process was carried out by controlling the level of agitation and aeration and the flotation time using an automated flotation cell. The experiments were configured in a 2³ experimental design. Average recoveries of approximately 67% for cobalt, 64% for manganese, and 63% for nickel were achieved at a pH of 12.5 and a pulp density of 3.33 g/L using MIBC as the sole reagent. Statistical analysis at a 95% confidence level identified agitation, aeration, and flotation time both individually and in combination as significant factors. Linear models were developed to predict metal recovery, showing good agreement with experimental data (errors < 10%; standard deviation < 3%). Full article

The orange juice industry generates large amounts of waste, leading to significant environmental impacts. Within the framework of a citrus biorefinery, this study evaluates an integrated pilot-scale scheme combining essential oil extraction with hydrolysis of orange waste. A self-designed modular system was used, characterized by ease of operation and maintenance, consisting of a 20 L sealed reactor and a condenser with water recirculation. Essential oil extraction was carried out by hydrodistillation, producing 35 mL of essential oil per run and a yield of 2.57 mL per 100 g of orange peel. Hydrolysis was investigated using a 2³ factorial design considering time (30 and 60 min), waste type (with and without pulp), and H₂SO₄ concentration (0 and 0.25% v/v). ANOVA results showed that the waste type was the dominant factor, while the acid concentration had no significant effect. The optimal hydrolysis condition was waste with pulp, 0% acid, and 30 min, achieving 108.5 g/L of glucose and 30.4 g/L of xylose. Under these conditions, the kinetics of glucose and xylose release were determined. The energy consumption was 45.96 MJ, equivalent to 70.61 kJ/g of glucose and 236.59 kJ/g of xylose, with corresponding costs of 0.0017 and 0.0057 USD/g, respectively. Orange waste containing pulp, obtained directly from juice-processing facilities, exhibits greater valorization potential than orange waste without pulp to produce essential oil, glucose, and xylose within a biorefinery scheme. Full article

This research focuses on developing bioplastic films using agrifood industrial waste, which included starch from avocado seed, cellulose from cornstalk, carrot and beet peel, and pulp from a food company in México. The films were produced with a matrix of gelatin and glycerol, and different formulations of starch and cellulose. The films were characterized and tested as wrappers of Manchego cheese. The films containing starch are transparent; films with cellulose showed opacity and paper-like structure. Films containing starch–cornstalk cellulose showed the highest hydrophobic properties. In turn, films with carrot cellulose had the highest plastic properties with high elongation capacity and the lowest Young modules; films with starch and other celluloses showed the opposite data. The highest thermal capacity was observed in films containing cellulose from cornstalks and beet waste. In turn, the highest temperatures of transition, crystallization, and melting were registered in films containing starch. Films with starch and cellulose served well as wrappers of Manchego cheese, conserving 92% of the weight of cheese after 21 days of storage at 4 °C. All films were biodegradable in compost after 10 days, and they were degradable by physicochemical factors after 40 days. Full article

The valorization of industrial waste in agriculture represents a key strategy within the circular economy framework. In this context, the present study aimed to assess the feasibility and potential of fertilizers derived from black mass, a by-product of alkaline battery recycling, as alternative sources of Zn and Mn in citrus cultivation, evaluating their effects on fruit quality and food safety. The experiment was conducted in Pedreguer (Alicante, Spain) in ‘Navelina’ cultivar using Carrizo and C-35 rootstocks, comparing conventional fertilization with black mass-based formulations applied as sulfates (BMSs) and lignosulfonates (BMLSs). The results showed that the evaluated micronutrient sources significantly increased foliar Zn concentrations up to 17.9 mg·kg⁻¹ and Mn concentrations up to 28.1 mg·kg⁻¹, values markedly higher than those observed in the Control treatment (15.20 mg·kg⁻¹ Zn and 11.5 mg·kg⁻¹ Mn). No adverse effects on yield or fruit quality were detected: Average fruit weight remained close to 200 g per fruit, and the proportion of non-marketable fruit did not exceed 2% in any treatment. Regarding food safety, Pb, Cr, and Ni concentrations in pulp and peel were below the maximum levels established by European Union regulations, with maximum values of 0.02 mg·kg⁻¹ for Ni and 0.04 mg·kg⁻¹ for Pb on a dry matter basis, while Cd, Co, and Hg were not detected. Overall, black mass-derived fertilizers enhanced Zn and Mn availability in plants without compromising plant physiology or fruit quality and maintained safe levels of heavy metals. These results support their use as a sustainable alternative for mineral fertilization in citrus orchards and reinforce their contribution to reducing the consumption of virgin raw materials and advancing toward more circular agricultural systems. Full article

The discharge of untreated paper mill effluent poses significant ecological risks due to its high organic and nutrient loads. This study aimed to assess the phytoremediation potential of Azolla pinnata for treating paper mill effluent. Response Surface Methodology (RSM) and Artificial Neural Network (ANN) modeling approaches were applied and optimization was used for pollutant removal and plant biomass production. Experiments were designed using a Central Composite Design with two independent variables: effluent concentration (0, 50, and 100%) and plant density (10, 20, and 30 g per container). The responses measured were biochemical oxygen demand (BOD), chemical oxygen demand (COD) removal efficiencies, and final biomass yield after 16 days of exposure. RSM produced statistically significant (p < 0.05) second-order regression models for all three responses (coefficient of determination; R² > 0.98), while ANN showed slightly lower prediction errors within the experimental range studied. Maximum observed removal efficiencies were 91.74% for BOD, 80.91% for COD, and 92.66 g biomass yield under 50% effluent concentration and 30 g plant density. Optimization via both models suggested closely comparable operating conditions (79% effluent concentration and 29 g biomass) for optimal performance. The results indicate that A. pinnata demonstrates potential as a low-cost, nature-based treatment system for industrial effluent remediation under controlled conditions. The integration of data-driven optimization with biological treatment contributes to sustainable effluent management strategies by reducing chemical inputs, minimizing energy demand, and enabling biomass generation with potential downstream valorization. Full article

With the increasing emphasis and protection on forest resources worldwide, the development of non-wood plant fiber raw materials has become a key path to promote the green and sustainable development of China’s pulp and paper industry. In this study, Super-Arundo donax, a new non-wood fiber raw material, was systematically investigated for its applicability in the bleaching process. Firstly, by adjusting key bleaching technical variables such as alkali dosage, time, oxygen pressure and temperature, the oxygen delignification process of the Super-Arundo donax kraft pulp was optimized. The data revealed that under the experimental conditions of 3.0% alkali dosage, 60 min bleaching time, 100 °C bleaching temperature, 0.6 MPa oxygen pressure and 0.6% MgSO₄ dosage, the bleached pulp yield reached 91.58%, the brightness was 42.04% ISO, and its tensile index was 60.92 N·m/g, bursting index was 4.16 kPa·m²/g, and tear index was 5.45 mN·m²/g, respectively. To further enhance the bleaching effect, the study introduced the H₂O₂ enhanced oxygen delignification process. The alkali dosage, bleaching temperature and H₂O₂ dosage were selected as the process parameters, with the pulp yield and brightness as the response indicators. A central composite design was adopted to construct a response surface model, and the interaction effects among various factors were analyzed. The optimized optimal process conditions are as follows: pulp concentration 10%, alkali dosage 2.84%, bleaching temperature 105 °C, H₂O₂ dosage 4.85%, bleaching time 60 min, MgSO₄ dosage 0.6%. Under these conditions, the pulp yield was 89.76% and the brightness reached 53.85% ISO. Therefore, Super-Arundo donax possesses excellent pulp-making and papermaking properties, and is expected to serve as a high-quality non-wood fiber raw material to alleviate the pressure on traditional papermaking raw materials and contribute to the green, sustainable and low-carbon transformation of the pulp and paper industry. Full article

This study explores the potential of using paper pulp mill sludge (PPMS) as an economical substrate for producing high-value protease enzymes with an indigenous bacterial strain, Bacillus tropicus P4. Isolated directly from PPMS, B. tropicus P4 showed high protease-producing ability, approximately 134 U/mL after 48 h—more than three times the yield of the benchmark strain (B. megaterium). Among various additives tested to boost enzyme production, Tween 80 emerged as the most effective, increasing enzyme activity by more than threefold compared to the control. Scale-up experiments in bioreactors of 5 L and 150 L confirmed that B. tropicus P4 maintains high protease yields under typical cultivation conditions with minimal modifications, specifically the addition of Tween 80 (1%) and increased total solids concentration (25 g/L). In the 5 L bioreactor, enzyme production peaked at approximately 755 U/mL within 24 h, while the 150 L bioreactor consistently achieved high enzyme activity (~848 U/mL). These results support the feasibility of a simple and scalable approach for converting industrial sludge into high-value protease enzymes, contributing to resource recovery and circular bioeconomy strategies. Full article

The aim of this study was to investigate the potential for co-bioleaching of ground printed circuit boards (PCBs) and flotation tailings using a single-stage biohydrometallurgical process. The ground PCB sample was a finely divided waste product from industrial shredding, which was collected using an air filtration system. The flotation tailings sample was mainly composed of pyrite (49%), quartz (29%), gypsum (8%), feldspar (8%), and chlorite (6%). The experiment was carried out in laboratory-scale reactors at 35 °C with constant aeration and a flotation tailings pulp density of 5% (solid-to-liquid ratio). In a control reactor, only flotation tailings were leached. In an experimental reactor, both flotation tailings and ground PCBs were leached simultaneously. The experiment was conducted in two stages. In the first stage, the experiment was carried out in a batch mode. The second stage involved two reactors operating continuously in cascade. During the experiment, we monitored the dynamics of several key parameters as a function of PCB concentration, including pH, redox potential, the concentrations of Fe³⁺ and Fe²⁺ ions, and the number of microbial cells. The 16S rRNA gene analysis revealed that the presence of PCBs had a significant effect on the composition of the microbial community. The concentration of PCB was gradually increased in order to examine the limits of the process and optimize potential economic benefits. The increase was done in 3 stages: 5 g/L in the first stage, from 5 to 12 g/L in the second stage, and up to 35.5 g/L in the third stage. However, this increase had a negative effect on the pyrite oxidation rate and the effectiveness of PCB bioleaching in continuous mode. The bioleaching efficiency of copper from printed circuit boards (PCBs) was above 70% in batch mode and above 80% in continuous mode at PCB concentrations up to 12 g per liter. Copper recovery decreased to around 53.1–61.6% as the PCB concentration continued to increase. The nickel leaching efficiency in batch mode was 46.3 ± 4.8%. In continuous mode, the nickel recovery decreased as the PCB concentration increased, reaching 48.53% in the first stage, then declining to 37.62% in the second stage and finally dropping to 27.06% in the third stage, depending on the higher concentration of PCB. Full article

The rising cost of conventional protein sources such as soybean meal has prompted the search for sustainable and economical alternatives in aquafeeds. Sugar beet pulp (SBP), an abundant by-product of the sugar industry, possesses nutritional potential but is limited by its high fiber and anti-nutritional factors. Solid-state fermentation (SSF) offers a promising approach to enhance its nutritive value and functional properties. This study evaluated the effects of dietary inclusion of mixed microbial solid-state fermented beet pulp (FBP) on the growth, systemic health and intestinal function of juvenile yellow catfish (Pelteobagrus fulvidraco). First, orthogonal optimization determined Lactiplantibacillus plantarum:Saccharomycopsis fibuligera:Bacillus subtilis = 1:3:3 as the optimal ratio, significantly improving the nutritional profile of FBP. Based on this optimized FBP, an 8-week feeding trial, five isonitrogenous and isolipidic diets were formulated by replacing 0–12% soybean meal with FBP. The results demonstrated that 9% FBP inclusion yielded optimal growth performance and significantly improved muscle texture. At the systemic level, FBP supplementation reduced serum lipid markers and liver enzyme activities while enhancing antioxidant capacity. At the intestinal level, FBP promoted intestinal health by increasing key digestive enzyme (lipase, trypsin, amylase) activities, stimulating villus development, and improving intestinal antioxidant status. Furthermore, gut microbiota analysis revealed that dietary FBP supplementation significantly modulated intestinal microbial composition, with notable enrichment of genera such as Leucobacter. In conclusion, FBP is a multi-functional ingredient that enhances growth, product quality, systemic physiology, and intestinal health in yellow catfish aquaculture. These findings provide a viable strategy for the sustainable utilization of agricultural by-products in aquafeeds. Full article

This study investigated the application of biochar obtained from black liquor, a residue generated during the Kraft pulping process in the paper industry, as a sustainable soil amendment in barley (Hordeum vulgare L.) cultivation. The biochar was produced through controlled pyrolysis at 450 °C and subsequently characterized with respect to elemental composition, porosity, specific surface area, and chemical stability, confirming its suitability for agricultural use. The experiment comprised three treatments: unamended soil (control), soil supplemented with 3% biochar, and soil fertilized with NPK, all conducted under controlled growth conditions. The results showed that biochar significantly improved key soil fertility indicators, increasing cation exchange capacity from 11 to 19 cmol(+)/kg and soil organic matter from 2.1% to 2.6%. Mineral nitrogen availability increased from 7.0 mg/kg to 10.5 mg/kg in the biochar treatment compared with the control. At the plant level, biochar enhanced early barley growth, with plant height increasing from 25 cm to 27 cm and chlorophyll content rising from 32.35 SPAD units to 39 SPAD units. Although NPK fertilization produced slightly higher immediate growth responses, biochar contributed to improved soil chemical properties and nutrient retention. Overall, the results suggest that black liquor-derived biochar shows potential as a complementary soil amendment under controlled conditions. Full article

To establish a biorefinery within kraft-pulp mills, the extraction of fermentable sugars must be balanced with the preservation of fiber quality for papermaking. This study investigates this trade-off by applying partial enzymatic hydrolysis to unbleached high-kappa eucalyptus kraft pulp to co-produce bioethanol and packaging-grade materials. Although the mass-transfer limitations inherent to the high-consistency strategy (15% solids or 150 g L⁻¹) restrict extensive saccharification (keeping glucose conversion below 5% at 1.5 h), it naturally directs the process toward a low-severity regime essential for fiber conservation. Structural analysis (X-ray diffraction and microscopy) revealed that enzymes preferentially targeted amorphous regions, increasing crystallinity (from ≈74% to ≈82%) but reducing intrinsic fiber strength (tear) over time (dropping from ~5.6 to ~2.3 mN·m²·g⁻¹ within 30 min). However, a strategic window for valorization has been identified. Instead of direct papermaking, hydrolyzed residue is highly effective as a strength-enhancing additive. When blended (20% w w⁻¹) with commercial pulp, the modified fibers improved interfiber bonding, restored the tensile strength, and significantly increased the Burst Index (up to ~1.7 kPa·m²·g⁻¹). These results demonstrate a viable industrial approach using partial hydrolysis to recover hemicellulose-based sugars for biofuels, while transforming the solid fraction into a high-performance reinforcement agent for paper packaging. This approach effectively converts a potential trade-off into a synergistic dual-product stream. Full article

Residual lignin generated by pulp, paper, and biorefining industries is commonly burned for energy, despite its potential as a renewable source of aromatic compounds. Studies focusing on microbial lignin degradation contribute to lignin valorization and represent a sustainable strategy to enhance biomass circularity. Here, we report the isolation of Klebsiella sp. IL2_9 from a ruminal consortium and demonstrate its ability to degrade and metabolize organosolv lignin. After 24 h of cultivation, the strain removed 22% of the initial lignin content. FTIR analysis revealed alterations in functional groups associated with guaiacyl and syringyl units, indicating structural modification of the polymer. GC–MS analyses further showed the consumption of lignin-derived aromatics, including vanillin, 2-aminobenzoic acid, and 4-hydroxybenzoic acid, along with the formation of vanillyl alcohol and phenyllactic acid derivatives. Overall, these findings highlight the potential of Klebsiella sp. IL2_9 as a promising biotechnological candidate for lignin valorization under anaerobic conditions. Full article

Bio-CO₂ is part of the natural carbon cycle and represents a sustainable carbon source for the production of Renewable Fuels of Non-Biological Origin (RFNBOs), such as synthetic methanol. This study addresses the critical knowledge gap in aligning diverse biogenic CO₂ sources with e-methanol requirements in the EU by providing harmonized mapping, based on datasets, literature sources, and reported industrial statistics at the sectoral and country level. Bio-CO₂ streams from biogas and biogas upgrading, biomass combustion, pulp and paper, bioethanol production, and the food and beverage sector are evaluated for total emissions, CO₂ concentrations and purity, the geographical distribution, seasonality, and impurity profiles. Results show that approximately 350 Mtpa of bio-CO₂ are emitted across the EU, with highly heterogeneous characteristics. Biogas upgrading and fermentation-based processes generate highly pure CO₂ streams (>98–99%), yet their small and dispersed nature complicates logistics. In contrast, biomass-combustion and pulp and paper sectors provide large volumes (around 214.6–298.2 Mtpa and 73.9 Mtpa CO₂, respectively), but in diluted streams (typically 3–15% and 10–20%). Replacing just 10% of the EU maritime fuel demand with e-methanol would require 53.6 Mtpa of bio-CO₂ and 58 GW of electrolyzer capacity, a stark contrast to the current operational 385 MW. The findings highlight the need for infrastructure planning and aggregation hubs to enable the large-scale deployment of RFNBO methanol in the maritime sector. Full article