Raw Biomass Research Articles

Atlas of Microscopic Images of Raw Biomass Used in Fuel Production

As nations strive toward achieving sustainability and reducing reliance on fossil fuels, biomass has emerged as an indispensable component of worldwide energy portfolios. Biomass, derived from organic materials such as plants, agricultural residues, forestry byproducts, and organic waste, is a renewable energy source and abundant resource with significant potential across various sectors. Responsible biomass energy production can aid in waste management, reduce greenhouse gas emissions, and mitigate environmental pollution by utilizing organic materials that would otherwise be discarded. With the anticipated growth in biomass use for energy, it is essential to establish analytical techniques for assessing the quality of the fuel feedstock materials. This will enable to better comprehend the implications of using biomass fuels on public health and our ecosystem. One such technique is reflected light microscopy, which has the potential to significantly enhance the conventional (physical and chemical) quality assessment of biomass-derived fuels. This technique enables rapid observations of material constituents and identification of impurities, and it can be applied not only to fuels but also to biomass-based pellets used in animal feed and bedding. Given the scarcity of publicly accessible microscopic images of biomass materials, the “Atlas of Microscopic Images of Raw Biomass” fills this gap by offering a comprehensive collection of 553 images. These photomicrographs capture the optical characteristics of a diverse array of biomass feedstock, demonstrating unique morphological and structural features. This visual documentation can serve as a valuable resource for researchers, industry professionals, educators, and enthusiasts interested in investigating the complexities of biomass forms.

Cultivation of Aurantiochytrium sp. Using Pickle Seasoning Liquid Waste and Application of the Raw Biomass for Fish Aquaculture

AbstractAurantiochytrium sp. strain L3W is a heterotrophic microorganism that produces docosahexaenoic acid (DHA) and eicosapentaenoic acid (EPA), which are essential for the growth of marine fish. In this study, pickle seasoning liquid waste was used for culturing strain L3W and the raw biomass of strain L3W was then fed to red sea bream fingerlings (Pagus major) to confirm its usability as a source of DHA and EPA. The strain L3W was cultured on the three pickle seasoning liquid waste samples, Akimurasaki, Hiroshimana, Shisohijiki, diluted with sand-filtered seawater at initial pH values of 4 and 7 under unsterile conditions. The growth of strain L3W was highest at 3.71 g/L on Hiroshimana at an initial pH of 7 with DHA and EPA production at 71.4 and 6.8 mg/g-biomass, respectively. Preparing the raw biomass of strain L3W by the 200 L-scale cultivation using the American Type Culture Collection 790By+ medium because of the DHA and EPA contents close to that produced in the Hiroshimana medium with an initial pH of 7, the raw biomass was spiked to the diet at 3%, 5%, and 10%. The final DHA and EPA contents in the whole body were increased by 4.26 and 3.03 times, respectively, by adding the strain L3W biomass at 10%. These results confirmed the feasibility of a carbon cycling scenario in which the strain L3W is cultivated using liquid food waste with the resultant biomass is utilized as a source of DHA and EPA for fish aquaculture. Graphical Abstract

Metal-modified biochars prepared from blue algae and their ability of adsorbing phosphates from water and utilization as soil amendment

The problem of blue algae accumulation can be alleviated by utilizing blue algae as biomass for resource utilization, which can remove excess phosphates from water to alleviate eutrophication. Herein, Magnesium (Mg) and/or lanthanum (La) were used to modify biochar via high-temperature slow pyrolysis with blue algae as the raw biomass. These modified biochars exhibited abundant carbon (18.0%-50.3%), oxygen content (17.4%-49.1%), along with a high specific surface area (82.26-233.80 m2/g). The surface of metal-modified biochar was enriched with hydroxyl and carboxyl groups and metal elements were efficiently incorporated into biochars. Adsorption kinetic and isotherm experiments were conducted under the optimal pyrolysis temperature of 600 °C, pH of 6.0, and adsorbent dosage of 2.0g/L. The adsorption kinetics studies by metal-modified biochars for phosphate fitted well pseudo-second-order model Redlich-Peterson isotherm model. Biochar modified by Mg and La exhibited the highest removal efficiency (97.8%) for phosphate at adsorption equilibrium. The adsorption mechanism involved the electrostatic interaction between hydroxylated metal oxides and negatively charged phosphate ions and the precipitation of phosphate ions through chemical reactions with metal oxides in the solution. After phosphate adsorption, the pristine and metal-modified biochars derived from blue algae were applied as the soil amendment. Biochar adsorbed phosphate apparently improved the germination rate of seeds facilitated the height, width, weight, and chlorophyll content of vegetable seedlings, and induced oxidative stress, which proved that the biochar recovered after adsorption was a high-quality soil amendment. This study provides a new approach for the treatment of phosphate wastewater and the algae application.

Storage stability of phycobiliproteins in a hydroalcoholic solution evaluated by an optical method

The aim was to evaluate the stability of pigments of the phycobiliprotein group extracted from the biomass of the Spirulina (Arthrospira) platensis cyanobacterium and the Porphyridium purpureum red microalgae. Water extracts of phycobiliproteins were obtained following a double freezing of the raw biomass of Arthrospira platensis and Porphyridium purpureum. An extraction was carried out with a phosphate buffer (0.05 M, pH = 7) in the cold (5 °C) for 24 hours. To the extracts obtained, 96% ethanol was added until its concentration in the solution was 20%. The hydroalcoholic extracts of phycobiliproteins were stored for three months. Pigment concentrations were monitored by an optical method. The allophycocyanin pigment demonstrated the highest storage stability. The highest degradation rate of phycobiliproteins was observed during their storage in the light at room temperature. The degradation rate of pigments under these conditions was 9and 80-fold higher (for B-phycoerythrin and C-phycocyanin, respectively) than similar indices during their storage in the dark and in the cold. C-phycocyanin was the least stable, compared to other studied phycobiliproteins. Its degradation rate under all storage options was 5to 10-fold higher than that of B-phycoerythrin under similar conditions. An essential conservation requirement for C-phycocyanin and β-phycoerythrin in hydroalcoholic solutions was the absence of light. For C-phycocyanin, a low temperature was necessary as well. Storage of B-phycoerythrin in the dark at room temperature is acceptable. These conditions can ensure the conservation of up to 86% of pigments in hydroalcoholic solutions for 25–30 days.

Predicting the higher heating value of products through solid yield in torrefaction process

Torrefaction is a widely employed method to upgrade biomass for energy purpose. The higher heating value (HHV) serves as a vital indicator for assessing the energy potential of biomass. Nevertheless, HHV measurement is a time-consuming and costly process. HHV of raw biomass, torrefied biomass, and biochar has been extensively estimated using the results of elemental analysis and/or proximate analysis. However, these data must be repeatedly measured for each target object. To reduce the efforts required for the measurement of each object, this study proposes, for the first time, the use of solid yield (the most easily obtainable data) to predict the HHV of torrefied biomass.A total of 215 sets of data were retrieved from different biomass types undergoing various torrefaction technologies. Artificial neural network (ANN) and hierarchical linear regression (HLR) were employed to develop prediction models. Solid yield demonstrated a clear correlation to HHV for each individual biomass; however, diverse biomass types exhibited significant variation. Therefore, the results of elemental analysis of raw feedstocks were incorporated to account for variations in feedstock types and to iterate the models. Generally, ANN is superior to HLR in predicting the HHV of torrefied biomass with the optimized model achieving an R2 of 0.9133. Additionally, two biomasses subjected to two torrefaction technologies were used to validate the model, and an R2 of 0.9676 was achieved.As a result, in a torrefaction process, once the raw biomass is analyzed, the HHV of any torrefied biomass can be predicted simply by measuring the weight of the product.

Biopolyurethane coatings with silica-titania microspheres (MICROSCAFS®) as functional filler for corrosion protection

In this work, we studied a biopolyurethane (BioPU) coating derived from a bio-based polyol and isocyanate for the protection of carbon steel against corrosion. The direct utilization of polyols obtained from raw biomass represents a novelty in polyurethane coatings production. The protective properties of these coatings were enhanced by incorporating unique silica-titania (ST) MICROSCAFS®, which are microspheres exhibiting interconnected macro- and mesoporosity. They were loaded with tannic acid (TA), an eco-friendly corrosion inhibitor. Confirmation of TA loading into the ST carriers (therefore called ST\\TA) was achieved through Attenuated total reflectance - Fourier-transform infrared spectroscopy (ATR-FTIR) and Thermogravimetric (TG) analyses. TG analysis revealed that ST\\TA particles contain approximately 34 wt% TA, and their average particle diameter is approximately 25 ± 5 μm, observed by SEM. The TGA shows slightly improved thermal resistance of the coatings modified with the filler MICROSCAFS®. Furthermore, it was observed that the fillers strengthened the coating hardness without negatively affecting the adhesion strength. Electrochemical Impedance Spectroscopy (EIS) results demonstrated that all modified coatings exhibited very good to excellent resistance in mild corrosive environments. The coatings maintained a high impedance modulus (|Z|) at low frequencies and phase angle values close to −90° across a wide frequency range, over an immersion period of 80 days in a 0.05 M NaCl solution. After 80 days of immersion, the best coating, BPU-ST\\TA, displayed |Z| of 3 × 1010 Ω cm2. Scanning Vibrating Electrode Technique (SVET) analysis revealed the inhibitory behaviour of TA. For the BPU-ST\\TA sample, inhibition of both anodic and cathodic activities was clearly visible, with a significant reduction of the current densities starting at 1 h and up to at least 24 h of immersion. In summary, the BioPU coatings modified with tannic acid-loaded MICROSCAFS® exhibit improved barrier properties and notable corrosion inhibition capacity in mild corrosive environments.

Antioxidants and biomethane production from Opuntia varieties

In this study, Opuntia varieties were investigated for their potential to fit a biore-finery approach. This work proposed the extraction of antioxidants and the production of biomethane from their solid effluents. Three Opuntia varieties –O. ficus-indica var. Milpa Alta (OfiM), O. ficus-indica var. Copena (OfiC) and O. engelmannii (Oe)– were subjected to solvent extraction. Our results revealed that 80% methanol yielded the highest amount of phenolic compounds (8.99 mg/g) and flavonoids (1.67 mg/g) in OfiM. Subsequently, biomethane potential experiments compared raw and residual biomasses, as well as inoculum-to-substrate ratio (ISR, 0.5, 1.5 and 2.5). Biomethane yields were lower with residual biomass compared to raw Opuntia. The highest biomethane yield of 552 mL CH4/g VS was achieved with raw OfiM at ISR 2.5. For the second assay of OfiM, biomethane yields were 412 and 458 mL CH4/g VS, respectively for residual and raw biomasses. Despite a decrease of approximately 10% in biomethane yield due to extraction operation, the coupling of both processes becomes highly desirable to obtain high-value extractable compounds and substantial biomethane production, which is a step towards the Opuntia biorefinery.

Cavitation-assisted synthesis and chracterization of a novel catalyst from waste coconut trunk biomass for biodiesel production

In the current study, a novel heterogeneous catalyst has been prepared from waste coconut trunk biomass using an ultrasound-assisted batch reactor. It is observed from the characterization studies that the raw coconut trunk biomass consists of the maximum amount of silicon dioxide (SiO2) present in it which is further converted to mullite (composition of 3Al2O3.2SiO2) with a composition of 94.18 % (analyzed through Energy Dispersive Spectroscopy (EDAX) studies) is formed through the reaction in an ultrasound reactor processed at a very mild reaction temperature and reaction time 80℃ and 90mins. Synthesis of catalyst at mild process conditions will help to enhance the formation of energy-intensive products at a low cost. It is also observed from the XRD studies of raw feedstock and synthesized catalyst a change in the crystalline structure from hexagonal silicon dioxide to orthorhombic mullite shape. In comparison with the surface area of the raw biomass and mullite, a large amount of surface area ∼ 32 m2/g is observed which is due to the process of reaction in a highly intense ultrasound reactor. A change in the morphological structure of raw feedstock and synthesized catalyst is also observed through scanning electron microscope (SEM) analysis. The activity of the synthesized catalyst has been analyzed through its application in the production of biodiesel from waste cooking oil is also studied., and a yield of 75 % with a conversion of 74 % is observed at process conditions of 1:3 (oil: ethanol) (volumetric ratio), 3 (wt%) of catalyst concentration and 3hrs of reaction time. A prospective aspect of the implication of the entire work to analyze the life cycle analysis (LCA) is also reported in terms of environmental friendliness and sustainability.

Cold plasma/alkaline pretreatment facilitates corn stalk fractionation and valorization towards zero-waste approach

The present study employed alkaline hydrogen peroxide pretreatment coupled with cold plasma for corn stalk’s complex biopolymers fractionation and valorization through enzymatic hydrolysis. This hurdle approach enables the prolonged generation of reactive oxidative species, initiating chemical reactions otherwise hardly possible under ambient conditions. A delignification rate between 76±1 and 86±2 % was obtained under different process parameters in a significantly shorter time compared to conventional alkaline pretreatment. Up to 94±4 % of cellulose in treated biomass was converted to glucose after enzymatic hydrolysis, achieving around 3.5 times higher glucose yield than the raw biomass. Different spectroscopic analyses confirmed specific alterations in the structure of the lignin-rich fraction caused by cold plasma. Micro- and nanoscale lignin particles obtained were rich in total phenolic content, reaching up to 140±20 and 107±12 µg gallic acid equivalents (GAE) per mg of lignin, respectively. The proposed concept of corn stalk fractionation through biorefinery can open new opportunities for valorizing different agricultural waste types.

Investigation of mechanisms of sulfamethoxazole adsorption on novel adsorbents developed from reed canary grass

In this work, reed canary grass and activated carbons developed from this biomass were used as novel adsorbents to remove sulfamethoxazole (SMX) from water. Raw biomass adsorbent with the lowest surface area demonstrated the lowest SMX adoption capacity of 20.2 ± 1.6 mg/g and the activated carbon adsorbent with the highest surface area showed the highest adsorption capacity of 160.5 ± 4.2 mg/g. π-π, hydrogen bonding, Lewis acid base, and hydrophobic interactions are the possible mechanisms that could be responsible for adsorption of SMX on the adsorbents. Methanol, hydrochloric acid solution, sodium hydroxide solution, and deionized water were used to desorb SMX from the adsorbent. The results of using 20 mL of solvent at 35 °C showed that methanol could desorb loaded SMX with a higher desorption efficiency (80.1 ± 2%) than the aqueous solvents (9.5-46.5%). Decreasing the temperature to 25 °C decreased the desorption efficiency of methanol to 58.5 ± 1%. By decreasing the methanol volume to 5 mL, SMX desorption efficiency could remain comparable (59.1 ± 1.2%). Reusing the adsorbent in 4 adsorption desorption cycles showed that SMX adsorption capacity reduced from 124.9 ± 3.8 mg/g in the first adsorption cycle to 82.1 ± 2.2 mg/g in the second adsorption cycle and was stable in the third and fourth cycles.

Alkaline hydrogen peroxide pretreatment of bamboo residues and its influence on physiochemical properties and enzymatic digestibility for bioethanol production

Bamboo is a perennial rapid-growing plant that is given preference for renewable biosources for biofuels and bio-based chemical conversion. Bamboos are rich in cellulose and have highly recalcitrant biomass due to high lignin. Bamboo is abundantly available in Northeastern India and can be utilized as a feedstock biofuels. Here, we evaluated the pretreatment of bamboo residues Dendrocalamus strictus with different concentrations of alkali, hydrogen peroxide, and alkaline hydrogen peroxide and its influence on biomass digestibility for enhancement of sugar recovery with Celic C cellulase enzyme blend. Enzymatic hydrolysis data indicated untreated raw biomass showed a digestibility of 40% after 48 h of incubation. The biomass pretreated with alkali showed a maximum digestibility of 61% obtained from 10% loaded with 0.5% w/v NaOH. Pretreatment of the bamboo with H2O2 shows a maximum digestibility of 75% from biomass loaded with 1% w/v of H2O2. Combinational pretreatment of alkaline hydrogen peroxide showed a maximum efficiency of biomass digestibility of 83% attained from biomass loaded with 1% w/v NaOH-H2O2. Crystallinity index (CrI) analysis showed that CrI increased from 64% to 70.75% in pretreated biomass. FTIR and SEM analysis show changes in functional groups, morphology, and surface of biomass in pretreated biomass. Compositional analysis shows that 68% of lignin removal is obtained from alkaline hydrogen peroxide pretreatment. Cellulose content increased from 52% to 65%, and hemicellulose decreased from 18.6% to 8.6%. Results indicated that the potential possibility of bamboo waste biomass as feedstock for biorefinery products and alkaline hydrogen peroxide pretreatment methods is an efficient strategy for sugar recovery for bioethanol production.

Combustion and co-combustion of biochar: Combustion performance and pollutant emissions

Biomass is a renewable and clean energy source, offering the potential to reduce fossil fuel consumption and greenhouse gas emissions when it is used as a biofuel. However, the disadvantages of raw biomass such as poor grindability, high moisture content, and low calorific value hinder its widespread industrial combustion. Thermochemical conversion techniques are widely used to convert biomass to biochar, which serves not only as an adsorbent and soil amendment but also as solid fuels alternative to fossil energy. The upgraded biochar exhibits better physicochemical properties and improved combustion performance. This paper focuses on the properties and combustion behavior of biochar as a solid fuel, reviewing common production techniques of biochar and their effects on yields and properties of biochar. It also examines the combustion characteristics and kinetics of biochar in single- and co-combustion scenarios with other fuels, such as coal, sludge, and petroleum coke, analyzing the influencing factors of combustion behavior and kinetic parameters. This study further investigates the emission characteristics during the combustion of biochar, including gaseous pollutants (such as CO, NOx, SOx, and HCl), ash-related issues, and particulate matter (PM) emissions. Additionally, a new fuel type named “bioslurry”, which is developed with biochar as a main material, is introduced. Furthermore, this paper discusses the techno-economic and environmental aspects of biochar application, exploring the feasibility of its industrial production and utilization.

Adsorption dynamics of Eriochrome Black dye removal using raw and ultrasonicated Pithecellobium seed biomass: ANN modeling and mechanisms

Utilization of Ultrasonic modified Pithecellobium dulce seed biomass, proved the efficacy in Eriochrome black dye remediation. The study investigates the sorption dynamics of Eriochrome Black (EB) dye removal using raw and ultrasonicated Pithecellobium seed biomass combined with Artificial Neural Network (ANN) modeling for the elucidation of underlying mechanisms. To improve the adsorption performance, Pithecellobium dulce biomass has been subjected to ultrasonication. The characterization of modified seed adsorbent revealed the adsorptive properties of biomass for the removal process. Varying impacts of dye adsorption were studied revealing the optimal parameters to be pH of 5, temperature of 303 K, contact time of 40 min-Ultrasonicated Pithecellobium dulce (UPDB) biomass; 80 min – Raw Pithecellobium dulce biomass (RPDB), and dose of 5 g/L and 2.5 g/L for RPDB and UPDB respectively. Isotherm and Kinetic analysis revealed the Freundlich and pseudo-first order models to be best fitting for the current system. Ultrasonicated seed biomass exhibited enhanced adsorption capacity of 126.9 mg/g compared to 83.8 mg/g for raw seed biomass. Thermodynamic investigation infers the spontaneity and exothermic nature of adsorption process. The ANN model for the prediction of eriochrome black dye adsorption onto ultrasonic modified Pithecellobium dulce seed biomass exhibited better correlation coefficient of 0.9559 indicating the better prediction of trained model for dye removal process. Thus, ANN model provides a better prediction of the relation between operational factors and dye removal.

Assessing thermal hazards and toxicity of raw biomass particles from prevalent agricultural crops in China

Fire and explosion hazards pose significant safety concerns in the processing and storage of biomass particles, warranting the safe utilization of these particles. This study employed scanning electron microscopy, thermogravimetric analysis, and cone calorimetry to investigate the thermal hazards and toxicity of raw biomass particles from four prevalent agricultural crops in China: rice, sorghum, corn, and reed. Among the samples, corn exhibited the highest heat output of 8006.82 J/g throughout the thermal decomposition process. The quantitative evaluation of critical heat flux, heat release rate intensity, fire growth rate index (FIGRA), post-ignition fire acceleration (PIFA) and flashover potential (X) revealed a substantial fire risk inherent to all the examined straw samples. Notably, corn displayed the lowest FIGRA value of 8.30 kW/m2 s, while rice demonstrated the minimum PIFA value of 16.11 kW/m2 s. Moreover, the X values for all four biomass particle types exceeded 10 under varying external heat flux levels, indicating their high propensity for fire hazards. Analysis of CO and CO2 emissions during combustion showed all four biomass samples exhibited high concentrations throughout, from the initial stages to the end. The present study offers crucial insights for formulating comprehensive fire safety guidelines tailored to the storage and processing of biomass particles.

Recycling of wasted wool fibers from sheep shearing for green building components: A review

It is nowadays recognized that the building sector causes the greatest environmental impact in terms of both waste production and carbon emissions. Within the context of ecologically sustainable development (ESD), the construction sector is looking for more eco-friendly materials, such as natural fibres. Natural fibers are worldwide recognized as ideal replacement for traditional construction materials, providing excellent thermal and acoustic insulation for building but also for adoption as reinforcement fibers in cement mortars, composite materials, solid boards/panels, raw biomasses, multi-layers, filled loosen/foaming types, particles, slurry types, coils, bricks, etc. The aim of this work is to provide a clear overview on the natural fibers currently employed in the green production of building components, with the main focus on wool fibers deriving from the livestock sector, where wool waste disposal is a crucial problem. This article is a review conducted using the Systematic Literature Review (SLR) approach, a globally recognized method that is not inherently innovative. The innovation of this article lies in the addressed topic, which is relatively new and has only recently gained significant attention, resulting in a limited number of highly relevant articles in the literature.A systematic literature review of the use of wool fibers for green building components is conducted herein to highlight the characteristics that make such material a usable resource in the construction sector and the limits of its use. Given the findings from the reviewed papers, the authors could document that most of the reviewed articles aimed at analyzing the mechanical, thermal, and acoustic properties of building components containing wool fibres. The review highlights that the strength of the wool fiber relies on its thermal properties which can be exploited for building thermal insulation. The wool fiber is also featured to provide good resistance to flexural loads; conversely, all the studies highlighted a negative effect of wool fibers on the compressive behavior of the investigated building components. The analysis of the acoustic properties showed that given the strong capacity of the wool fiber to absorb sound, wool is a great alternative to the conventional materials derived from non-renewable resources.Nevertheless, despite the eligibility of such fiber to be employed soon in the building sector, the analysis about the economic viability of the manufacturing process suggests that the high costs for the raw material, labor, electricity, and above all the high volume of water have to be drastically reduced by prompting the development of sheep wool fiber waterless processing. The achieved results could represent a first step in planning the sustainable re-use of wool waste as natural, renewable, and biodegradable fiber in the construction sector, providing the possibility of creating a new supply chain and solving the problem of its disposal.

Direct transformation of rice straw to electricity and hydrogen by a single yeast strain: Performance and mechanism

Lignocellulosic waste is one of the most abundant renewable energy sources. However, pretreatment or complex microbial consortia are usually required for the biological transformation into energy products. This study demonstrates the direct transformation of raw rice straw biomass into electricity and hydrogen without any pretreatment by employing a single yeast strain, Cystobasidium slooffiae JSUX1, in microbial fuel cells (MFCs). The yeast-MFCs exhibit a maximum power density of 28.56 ± 2.54 mW/m2 with simultaneous production of hydrogen gas (4.9 ± 0.52 L/m3) from raw straw. Further analysis reveals that enzymes secreted by the yeast strain degraded rice straw into sugars or organic acids, serving as fuel for electricity and hydrogen production. In addition, humic acid (HA) and Fe-HA derived from biomass consumption serve as electron mediators for extracellular electron transfer (EET) in MFCs. This study demonstrates the power of the yeast strain for renewable energy recovery from straw, diversifying the toolbox for the lignocellulose industry.

Pollutant Emissions and Oxidative Potentials of Particles from the Indoor Burning of Biomass Pellets.

Residential solid fuel combustion significantly impacts air quality and human health. Pelletized biomass fuels are promoted as a cleaner alternative, particularly for those who cannot afford the high costs of gas/electricity, but their emission characteristics and potential effects remain poorly understood. The present laboratory-based study evaluated pollution emissions from pelletized biomass burning, including CH4 (methane), NMHC (nonmethane hydrocarbon compounds), CO, SO2, NOx, PM2.5 (particulate matter with an aerodynamic diameter ≤2.5 μm), OC (organic carbon), EC (element carbon), PAHs (polycyclic aromatic hydrocarbons), EPFRs (environmentally persistent free radicals), and OP (oxidative potential) of PM2.5, and compared with those from raw biomass burning. For most targets, except for SO2 and NOx, the mass-based emission factors for pelletized biomass were 62-96% lower than those for raw biomass. SO2 and NOx levels were negatively correlated with other air pollutants (p < 0.05). Based on real-world daily consumption data, this study estimated that households using pelletized biomass could achieve significant reductions (51-95%) in emissions of CH4, NMHC, CO, PM2.5, OC, EC, PAHs, and EPFRs compared to those using raw biomass, while the differences in emissions of NOx and SO2 were statistically insignificant. The reduction rate of benzo(a)pyrene-equivalent emissions was only 16%, much lower than the reduction in the total PAH mass (78%). This is primarily attributed to the more PAHs with high toxic potentials, such as dibenz(a,h)anthracene, in the pelletized biomass emissions. Consequently, impacts on human health associated with PAHs might be overestimated if only the mass of total PAHs was counted. The OP of particles from the pellet burning was also significantly lower than that from raw biomass by 96%. The results suggested that pelletized biomass could be a transitional substitution option that can significantly improve air quality and mitigate human exposure.

Resource recovery and contaminants of emerging concern mitigation by microalgae treating wastewater

This study aimed to investigate the recovery of agricultural biostimulants and biogas from microalgae treating wastewater, in the framework of a circular bioeconomy. To this end, municipal wastewater was treated in demonstrative raceway ponds, and microalgal biomass (Scenedesmus sp.) was then harvested and downstream processed to recover biostimulants and biogas in a biorefinery approach. The effect of microalgal biostimulants on plants was evaluated by means of bioassays, while the biogas produced was quantified in biochemical methane potential (BMP) tests. Furthermore, the fate of contaminants of emerging concern (CECs) over the process was also assessed. Bioassays confirmed the biostimulant effect of microalgae, which showed gibberellin-, auxin- and cytokinin-like activity in watercress seed germination, mung bean rooting, and wheat leaf chlorophyll retention. In addition, the downstream process applied to raw biomass acted as a pre-treatment to enhance anaerobic digestion performance. After biostimulant extraction, the residual biomass represented 91% of the methane yield from the raw biomass (276 mLCH4·g−1VS). The kinetic profile of the residual biomass was 43% higher than that of the unprocessed biomass. Co-digestion with primary sludge further increased biogas production by 24%. Finally, the concentration of CECs in wastewater was reduced by more than 80%, and only 6 out of 22 CECs analyzed were present in the biostimulant obtained. Most importantly, the concentration of those contaminants was lower than in biosolids that are commonly used in agriculture, ensuring environmental safety.

Efficient Enzymatic Hydrolysis and Polyhydroxybutyrate Production from Non-Recyclable Fiber Rejects from Paper Mills by Recombinant Escherichia coli

Non-recyclable fiber rejects from paper mills, particularly those from recycled linerboard mills, contain high levels of structural carbohydrates but are currently landfilled, causing financial and environmental burdens. The aim of this study was to develop efficient and sustainable bioprocess to upcycle these rejects into polyhydroxybutyrate (PHB), a biodegradable alternative to degradation-resistant petroleum-based plastics. To achieve high yields of PHB per unit biomass, the specific objective of the study was to investigate various approaches to enhance the hydrolysis yields of fiber rejects to maximize sugar recovery and evaluate the fermentation performance of these sugars using Escherichia coli LSBJ. The investigated approaches included size reduction, surfactant addition, and a chemical-free hydrothermal pretreatment process. A two-step hydrothermal pretreatment, involving a hot water pretreatment (150 °C and 15% solid loading for 10 min) followed by three cycles of disk refining, was found to be highly effective and resulted in an 83% cellulose conversion during hydrolysis. The hydrolysate obtained from pretreated biomass normally requires a detoxification step to enhance fermentation efficiency. However, the hydrolysate obtained from the pretreated biomass contained minimal to no inhibitory compounds, as indicated by the efficient sugar fermentation and high PHB yields, which were comparable to those from fermenting raw biomass hydrolysate. The structural and thermal properties of the extracted PHB were analyzed using various techniques and consistent with standard PHB.

Upgrading lignocellulosic biomass to high-value products through the pretreatment driven by bio-based ethylene glycol solvent

Sustainable processing of lignocellulosic biomass is meaningful for comprehensive biomass conversion. Here, a ball milling (BM) assisted biomass-derived ethylene glycol (BEG) pretreatment is proposed to removes nearly 90 % of the lignin and increases cellulose accessibility by 3 times than raw biomass, facilitating subsequent enzymatic saccharification or catalytic conversion for 5-hydroxymethylfurfural (HMF), achieving yields of 92.9 % and 32.6 %. The synergistic effect of BM/BEG positively impacted delignification, followed by saccharification and HMF conversion. Introduction of biomass-derived solvent recovers the lignin with a well-preserved chemical structure, uniform molecular weight, short side chains, and high purity, making it highly suitable for downstream utilization. Density functional theory revealed hydrogen bonding and good miscibility between BEG and lignin units, suggesting reaction mechanisms and pathways. Molecular dynamics simulations showed that the solubilizing effect of BEG on lignin promoted cellulase-cellulose binding, thereby enhancing saccharification efficiency. The successful use of BEG solvents to maximize the biomass value is conducive to achieve closed-loop biorefinery approaches.