Waste Biomass Research Articles

Microwave Assisted Biodiesel Production from Waste Cooking Oil Using Steel Slags as Catalyst

AbstractAn innovative catalytic system for biodiesel synthesis starting from waste biomass (waste cooking oil, WCO) in the presence of waste material (steel slags) as the catalyst under microwave irradiation is described. The reaction conditions were optimized by using response surface methodology (RSM) based on Box‐Behnken Design (BBD) taking time, temperature, and catalyst weight as factors. The optimum conditions, leading to 97 % conversion of WCO into FAMEs (fatty acid methyl esters) were found to be: 18 min reaction time, 134 °C and 380 mg of catalyst for 1.0 mL of WCO. The recyclability of the catalyst was tested at different experimental conditions, and by increasing the reaction times for subsequent cycles, the catalytic efficiency remained steady. The alkalinity of both as‐received steel slags and steel slags recovered after three reaction cycles was tested with the Hammett indicator method. The steel slags were also characterized by Scanning Electron Microscopy (SEM), Energy Dispersive X‐ray Fluorescence (ED‐XRF), X‐Ray Diffraction (XRD), Thermogravimetric Analysis (TGA), X‐ray Photoelectron Spectroscopy (XPS).

Sustainable Combination of Waste with Waste: Utilization of Biomass to Recover Critical Metals from Spent Lithium ion Batteries

The generation of e‐waste from lithium ion batteries (LIBs) is rapidly increasing due to the rising utilization of LIBs in portable electronics, and electric vehicles, with an average life span of 3‐5 years. The disposal of spent LIBs is a major environmental concern due to the presence of high percentages of toxic heavy metals and corrosive electrolytes. Efficient and sustainable recycling of spent LIBs has become immensely important, both environmentally and from a circular economy perspective, as LIBs serve as secondary sources of critical metals needed for renewable energy conversion and storage systems. We provide a concise review of metal recovery from spent LIBs using waste biomass in a green and sustainable approach for resource generation, in addition to the valorization of waste biomass. Biomass is used to recover metals from spent LIBs, acting as lixivient, reductant, and as absorbent. We have also discussed a reverse strategy utilizing ‘black mass’ from spent LIBs as catalyst for biomass conversion to value‐added products. The concept of “circular economy” is highlighted in a “killing two birds with one stone” approach through the utilization of biomass for the recovery of metals from spent LIBs and vice versa.

Improved nutritional value of surplus bread and perennial ryegrass via solid-state fermentation with Rhizopus oligosporus.

Solid-state fermentation (SSF) is a sustainable method to convert food waste and plant biomass into novel foods for human consumption. Surplus bread crusts (BC) have the structural capacity to serve as an SSF scaffold, and their nutritional value could be increased in combination with perennial ryegrass (PRG), a biorefining feedstock with high-quality protein but an unpleasant sensory profile. SSF with Rhizopus oligosporus was investigated with these substrates to determine if the overall nutritional value could be increased. The BC-PRG SSFs were conducted for up to 72 h, over which time the starch content had decreased by up to 89.6%, the total amino acid (AA) content increased by up to 141.9%, and the essential amino acid (EAA) content increased by up to 54.5%. The BC-PRG SSF demonstrated that this process could potentially valorise BC and PRG, both widely available but underexplored substrates, for the production of alternative proteins.

Optimization of erosion performance of biomass and pet waste based composites using artificial neural network

Optimization of erosion performance of biomass and pet waste based composites using artificial neural network

Environmental Impact of Poultry Manure Gasification Technology for Energy and Ash Valorization

Thermochemical technologies offer potential solutions for energy recovery and mitigating the environmental impacts of biomass waste. Poultry manure (PM), a nutrient-rich biomass but also a potentially problematic biomass waste, presents an opportunity for recovery and recycling. This study compares the environmental performance of a real-scale novel gasification technology called Chimera (designed and developed through an EU LIFE program) in locally treating PM with anaerobic digestion (AD) and incineration. Using life cycle assessment (LCA), the potential environmental impacts of the technologies were assessed using the Environmental Footprint (EF) 3.0 midpoint life cycle impact assessment method. We performed an attributional LCA with substitution. The selected functional unit (FU) is the treatment of one tonne (1000 kg) PM at 40% dry matter in the Netherlands in 2021 for 20 years. The LCA results of the three technologies compared showed that no single technology outperformed the other across all the impact categories. Climate change scores for the various technologies were −383 (incineration), −206 (Chimera), and −161 (anaerobic digestion) kg CO2 eq./FU. The results were influenced mainly by the potential utilization of the substituted heat and electricity. This study expands the existing literature on environmental sustainability assessments of PM treatment technologies. It underscores the prospects for these technologies to promote circularity while also indicating the bottlenecks for the potential environmental impacts and highlighting the most sensitive aspects that can influence the environmental performance of these technologies.

Exploring Recent Advances in Lignocellulosic Biomass Waste Delignification Through the Combined Use of Eutectic Solvents and Intensification Techniques

Growing awareness of resource sustainability and waste management has driven the search for circular-economy solutions. Lignocellulosic biomass waste, the most abundant renewable carbon resource, offers green potential as an alternative to declining non-renewable fuels. However, due to its recalcitrant nature, it requires pre-processing to convert it into valuable products like energy and chemicals. Biorefineries play a key role in this process by promoting the integral use of biomass, by finding ways to utilize lignin, previously treated as waste. Common pretreatment methods are unsustainable, prompting research into eco-friendly solvents and advanced techniques like ultrasound- and microwave-assisted methods. Recent approaches have also explored the use of eutectic solvents, which, when combined with these intensification techniques, offer promising results. These green technologies improve delignification efficiency, which in turn improves the saccharification process, reduces solvent use, and minimizes environmental impact. Despite progress, challenges remain in making these methods economically viable and adaptable to diverse biomass types. This review article highlights recent advances in sustainable treatment technologies, including the combined use of eutectic solvents and process-intensification techniques, and the potential of the obtained lignin in various industrial applications. It also discusses future prospects for more environmentally friendly processes in biomass utilization.

A review on the role of various machine learning algorithms in microwave-assisted pyrolysis of lignocellulosic biomass waste

The fourth industrial revolution will heavily rely on machine learning (ML). The rationale is that these strategies make various business operations in many sectors easier. ML modeling is the discovery of hidden patterns between multiple process parameters and accurately predicting the test values. ML has provided a wide range of applications in Chemical Engineering. One major application of ML can be found in the microwave-assisted pyrolysis (MAP) of lignocellulose bio-waste. MAP is an energy-efficient technology to obtain high-saturated hydrogen-rich liquid fuels. The main focus of this review study is understanding the utilization of various types of ML algorithms, including supervised and unsupervised techniques in microwave-assisted heating techniques for diverse biomass feedstocks, including waste materials like used tea powder, wood blocks, kraft lignin, and others. In addition to developing effective ML-based models, alternative traditional modeling approaches are also explored. In addition to various thermochemical conversion processes for biomass, MAP is also briefly reviewed with several case studies from the literature. The conventional modeling methodology for biomass pyrolysis with microwave heating is also discussed for comparison with ML-based modeling methodologies.

Realization of quasi-steady-state piled smouldering using sequential operation chambers for industrial treatment of biomass wastes.

Piled smouldering has great potential for treatment and utilization of biomass wastes. However, its unsteady-state nature limits its industrial utilization, as well as treatment of smoke. This article addresses this issue by proposing the sequential operation of numerous smouldering chambers to realize steady- or quasi-steady-state piled smouldering. The superposition characteristics of sequential unsteady-state curves were analysed theoretically, and a code was developed to determine an appropriate number of piled chambers at an allowance oscillation percentage. Smouldering experiments were performed on a single mini chamber (length × width × height: 340 × 140 × 140 mm3) containing piled wood pellets mixed with wood powder. The superposition of sequential burning rate curves was demonstrated using the code based on the mass loss data of experiments. Analysis shows that the perfect-steady state is possible given the superposition value of the burning rate curve is a constant in this proposed system. Experiments show that the molar ratio of CO/CO2 in smoke is almost a constant around 0.5 during densely piled smouldering, showing the great potential for self-sustained burning out the smoke. Based on the experimental results, the calculation results show that the relative oscillation range of burning rate (OSC) decreases from 75% to 3% while increasing the number of chambers from 2 to 7. This work provides a novel technology to enable quasi-steady-state smouldering for industrial utilization.

Optimization of Briquetting Process Parameters for Rice Straw Biofuels

The optimization of briquetting process parameters for producing biofuels from rice straw, a widely available agricultural waste. By systematically varying key parameters such as pressure, temperature, and moisture content, we aimed to enhance the physical and thermal properties of the briquettes. Through experimental design and statistical analysis, we identified optimal conditions to maximize briquette density and calorific value while minimizing ash content. The findings show that optimized briquetting greatly enhances the efficiency and potential of rice straw as a renewable energy source, providing a sustainable alternative to traditional fuels. This research contributes to advancing biofuel production technologies and promoting the utilization of agricultural waste for energy generation. Briquetting technology has great potential to transform waste biomass in affordable, effective and environmentally safe, high-quality solid fuel for households and industry use. This study focuses on optimizing the briquetting process for rice straw to enhance its quality as a biofuel. Key parameters, including compaction pressure, moisture content, binding agent type, and particle size, were systematically varied to improve density, durability, hardness, calorific value, and reduce ash content. Results indicate significant improvements in briquette performance, with calorific values increasing to 17.5 MJ/kg and ash content reducing to 4%. Optimized briquettes offer enhanced mechanical strength and combustion efficiency, positioning rice straw briquettes as a viable, eco-friendly alternative to traditional fossil fuels, contributing to sustainable energy and agricultural residue management.

RSM-based co-gasification of palm oil decanter cake and sugarcane bagasse: Syngas production and biochar characteristics

The production of syngas (CO + H2) and biochar from biomass waste co-gasification promotes sustainable energy while addressing environmental remediation challenges. This study investigates the co-gasification of palm oil decanter cake (PODC) and sugarcane bagasse (SB) to optimize syngas production and obtain biochar in a fixed bed horizontal tube furnace reactor. Operating variables, including temperature (700–900 °C), biomass ratio (30–70 wt%), and particle size (0.25–2 mm), were optimized using Response Surface Methodology with the Box-Behnken design. Characterization analyses including Brunauer-Emmett-Teller (BET), Fourier Transformed Infrared (FTIR), and Field Emission Scanning Electron Microscopic (FESEM) analyses were conducted on the biochar. The optimal conditions yielded a syngas volume of 41.5 vol% and a biochar of 0.3 wt%, achieved at 900 °C temperature, 42 wt% PODC biomass ratio, and 2 mm particle size. BET analysis revealed a mesoporous structure biochar with surface area of 398.55 m2/g, pore volume of 0.13 cm3/g, and pore diameter of 6.49 nm. FTIR analysis indicated the presence of hydroxyl groups, carbonyl groups, aromatic compounds, and hydrocarbon structures. FESEM analysis showed well-defined pore structures on the biochar surface, with EDX analysis confirming a dominant carbon content of 83.32 wt%. These findings substantially enhance sustainable approaches in energy production, agriculture, and wastewater treatment, while effectively tackling environmental issues associated with biomass waste.

Construction of an Anode Material for Sodium-Ion Batteries with an Ultrastable Structure.

The reserves of sodium resources are much larger than those of lithium resources, and they are widely distributed and easy to produce and can be widely used in photovoltaic energy storage and other industries on the premise of this advantage. However, how to produce hard carbon anodes at a low cost for the preparation of energy storage materials requires continuous exploration and experimentation to find the optimal solution. Here, we used waste sour date shell biomass as a precursor for a hard carbon anode obtained by simple acid treatment and two pyrolyses. It is shown that acid washing after prepyrolysis has a significant effect on the electrochemical performance of the sour date shell-derived hard carbon (ZJ), constructing a stable structure that makes it easier for sodium ions to be embedded and dislodged, and the carbon particles are homogeneous and free of bonding and electrode cracking. The ZJ-1500-HCl pyrolyzed at 1500 °C has a high reversible capacity of 329.1 mAh g-1, 94.1% initial Coulombic efficiency (ICE), 90.54% capacity retention efficiency cycling 300 cycles at a current density of 300 mA g-1, and a resistivity below 10 Ω. It has good cycle stability and a good multiplier performance. It is expected to be used in practical production and photovoltaic energy storage in the future.

Optimization of waste biomass demineralization through response surface methodology and enhancement of thermochemical and fusion properties

This study examines the impact of leaching with dilute hydrochloric acid solution on the reduction of ash content and the thermal degradation behavior of sugarcane bagasse. Response surface methodology (RSM) was used to statistically design the experiments and investigate the effect of three independent variables: treatment time, solid-to-liquid ratio, and reagent concentration. The leaching conditions were further optimized and experimentally validated for maximum ash reduction for suitability of treated biomass as feedstock for thermochemical conversion technologies. Reagent concentration and treatment time directly affected ash reduction, while the solid-to-liquid ratio inversely influenced it. Concentration had the highest impact, and treatment duration had the least. The maximum 78.2% ash reduction was achieved by treating the biomass with 1 M HCl for 80 min at a solid-to-liquid ratio of 50:1 (wt/vol). This ash reduction also resulted in a 9.82% increase in higher heating value (HHV). Hemicellulose hydrolysis during leaching was observed through chemical composition and Fourier-transform infrared spectroscopy (FTIR). Ash fusion temperatures increased, indicating more thermally stable biomass. Thermogravimetric analysis (TGA) showed elevated maximum degradation temperature and activation energy.

Utilizing Waste Biomass from Agricultural and Forestry Sustainable Resources: Biomass Conversion to Functional Adsorbent Material for Efficient Removal of Total Phosphate in Practical Water.

The promotion of the utilization of waste agricultural and forestry resources (AFRs) as a means of combating environmental pollution represents an advanced and necessary development approach with the potential to achieve sustainable development. In this work, an advanced adsorbent with a functional Mg-Al bimetallic layer was prepared using waste sawdust biomass (WSD) as a raw material. The layer serves as the primary active component for adsorbing total phosphate from both simulated and real wastewater. The hierarchical structure of the Mg-Al bimetallic hydroxide-modified waste sawdust biomass (MA@WSD) has an abundance of nanosheets on its surface, providing ample binding sites and an enhanced specific surface area of 175.99 m2/g. Under the optimal conditions, the maximum removal efficiency toward phosphate can reach 99.99%. The adsorption of phosphate by MA@WSD follows the pseudo-second order kinetic (PSOK) model, indicating that chemisorption is the rate-determining step. Moreover, the thermodynamic data demonstrate the spontaneous nature of the adsorption process, indicating the favorable characteristics of the developed material. The adsorption mechanism can be summarized as the collaboration of physical adsorption, electrostatic interaction, and chemical adsorption. The results of the regeneration process indicate that MA@WSD exhibits a retention of 50.3% of its initial adsorption performance following the fifth testing cycle, thereby suggesting its potential for comparable reusability. The MA@WSD performs well in adsorbing total phosphate in real river water, and the removal efficiency of MA@WSD is evidently superior to commercial activated carbon, which is at least 70% higher than that of the commercial activated carbon. Besides, the 5-time average removal efficiency toward total phosphate by MA@WSD is 62.9%, evidently higher than the 29.1% of commercially available activated carbon, indicating its potential as an alternative for treating phosphorus-containing wastewater. The research provides theoretical support for harmless treatment, resource utilization, carbon sequestration, and emission reduction of waste biomass.

Seasonal occurrence and ecological risk assessment of polycyclic aromatic hydrocarbons in the sediments and water in the left-bank canals of Indus River, Pakistan.

This study investigated a pressing environmental concern: the presence, distribution, sources, and ecological implications of sixteen polycyclic aromatic hydrocarbons (PAHs) in the left-bank canals of Kotri barrage-Akram, Pinyari, and Phuleli of the Indus River in Pakistan. These vital waterways, crucial for industrial, domestic, and agricultural activities, are experiencing contamination threats from anthropogenic sources, particularly PAHs. The study collected three water and two sediment samples from each canal in pre-monsoon and post-monsoon seasons. Then the EPA's liquid-liquid extraction method and gas chromatography determined the concentrations of PAHs. The findings of this study reveal alarming contamination levels, with pre-monsoon concentrations ranging from 22.256 to 836.455ng/L in water and 1,459.941 to 43,179.243ng/g in sediments. The post-monsoon concentrations ranged from 60.352 to 5663.058ng/L in water and 2976.770 to 15,238.335ng/g in sediments. The diagnostic ratios and principal component analysis (PCA) identified multiple sources of contamination, including industrial and domestic wastewater discharge, solid waste burning, vehicular emissions, biomass combustion, and petroleum residues. Furthermore, the assessment of the toxic equivalency factor (TEF) underscored the heightened carcinogenic potential of certain PAHs, notably benzo(a)pyrene and benzo(a)anthracene. Thus, the high levels of PAH contamination pose severe health risks to both human populations and aquatic ecosystems, emphasizing the urgency of addressing this issue. Stricter regulations governing industrial and domestic waste discharge, advocacy for cleaner fuel technologies, and the implementation of effective waste management practices must be initiated as crucial strategies in safeguarding the environmental integrity of the left-bank canals and the health of the surrounding communities.

Theoretical Assessment of Agro-Waste for Biogas Production Based on Novel Methodology Related to Biochemical Potential

Agricultural and waste biomasses present viable solutions for utilization in the energy sector, achieving sustainable and long-term transformation into energy and fuel. However, it is important to carefully evaluate the competing applications for these feedstocks, considering both short- and long-term stability. Biomass for biogas production in agriculture and waste management is used due to its availability and ease of handling. Considering everything mentioned, evaluating the most suitable raw materials for biogas production is crucial for meeting sustainability criteria and promoting biomass as an energy source. In this paper, an examination of different biomass sources as possible feedstock to produce biogas by applying a theoretical approach to the proximate and final analysis results of those materials is presented. Based on data from the raw material analysis, the theoretical biochemical methane potential (TBMP) for the considered samples was calculated. Furthermore, the mass and energy balance for the case study biogas plant was also performed. According to the obtained results, the considered feedstocks show the validity of their use for biogas production considering the fulfillment of the raw material minimum quantity, mandatory residue arrangement, and achieving higher efficiency of the energy conversion process.

Sustainable adsorption of methylene blue by biocompatible agro waste biomass: optimization, kinetic isotherms, and ecotoxicity evaluation

Sustainable adsorption of methylene blue by biocompatible agro waste biomass: optimization, kinetic isotherms, and ecotoxicity evaluation

Physical–Chemical–Biological Pretreatment for Biomass Degradation and Industrial Applications: A Review

Lignocellulosic biomass, including agricultural, forestry, and energy crop waste, is one of Earth’s most abundant renewable resources, accounting for approximately 50% of global renewable resources. It contains cellulose, hemicellulose, and lignin, making it crucial for biofuels and bio-based chemicals. Due to its complex structure, single-pretreatment methods are inefficient, leading to the development of combined pretreatment technologies. These methods enhance cellulose accessibility and conversion efficiency. This paper analyzes the principles, advantages, and disadvantages of various combined pretreatment methods and their practical benefits. It highlights recent research achievements and applications in biofuel, biochemical production, and feed. By integrating multiple pretreatment methods, biomass degradation efficiency can be significantly improved, energy consumption reduced, and chemical reagent use minimized. Future advancements in combined physical, chemical, and biological pretreatment technologies will further enhance biomass utilization efficiency, reduce energy consumption, and protect the environment, providing robust support for sustainable renewable energy development and ecological protection.

Modern-Day Green Strategies for the Removal of Chromium from Wastewater

Chromium is an essential element in various industrial processes, including stainless steel production, electroplating, metal finishing, leather tanning, photography, and textile manufacturing. However, it is also a well-documented contaminant of aquatic systems and agricultural land, posing significant economic and health challenges. The hexavalent form of chromium [Cr(VI)] is particularly toxic and carcinogenic, linked to severe health issues such as cancer, kidney disorders, liver failure, and environmental biomagnification. Due to the high risks associated with chromium contamination in potable water, researchers have focused on developing effective removal strategies. Among these strategies, biosorption has emerged as a promising, cost-effective, and energy-efficient method for eliminating toxic metals, especially chromium. This process utilizes agricultural waste, plants, algae, bacteria, fungi, and other biomass as adsorbents, demonstrating substantial potential for the remediation of heavy metals from contaminated environments at minimal cost. This review paper provides a comprehensive analysis of various strategies, materials, and mechanisms involved in the bioremediation of chromium, along with their commercial viability. It also highlights the advantages of biosorption over traditional chemical and physical methods, offering a thorough understanding of its applications and effectiveness.

Optimizing catalytic performance: Reduction of organic dyes using synthesized Fe3O4@AC magnetic nano-catalyst

This article presents a sustainable method for the catalytic reduction of both simple and binary dye systems using magnetic activated carbon (Fe3O4@AC) synthesized from almond shells, an agricultural waste biomass. The reduction of methylene blue (MB) and Congo red (CR) was investigated in the presence of NaBH4, and a series of physical-chemical experiments were conducted to elucidate the mechanism of dye conversion and its performance. The results confirmed the successful synthesis of Fe3O4 nanoparticles on the activated carbon surface. The calculated rate constants in a simple system were 0.34 min⁻1 for MB and 0.25 min⁻1 for CR, in the binary system, the Fe3O4@AC catalyst demonstrated enhanced selectivity for the cationic MB dye, attributable to the robust, attractive surface charge. The study aimed to enhance catalytic performance by employing optimization curves generated from a three-level Box-Behnken Design (BBD) simulation. Experimental results indicated that the optimal catalyst dose, dye concentration, and reaction duration were 4–7 mg, 80–120 mg/L, and 5–20 min, respectively. Response surface methodology (RSM) was developed by processing the findings from 17 replicated experiments using a two-quadratic polynomial model, establishing a functional link between the experimental parameters and MB conversion. Optimal conditions for MB conversion were determined to be 7 mg of catalyst, 80 mg/L of MB concentration, and a reaction time of 12.5 minutes, resulting in an estimated conversion rate of 99.99 %. This prediction was validated by experimental findings, with regression analysis confirming a high correlation (R2 > 0.99) between the predicted and observed values. Additionally, the Fe3O4@AC catalyst demonstrated good recyclability and stable performance over three consecutive cycles, maintaining high conversion efficiency without loss of performance. These findings demonstrate that Fe3O4@AC is a viable approach for the rapid and efficient remediation of dyes in water.

An analysis of the textural properties of activated carbons obtained from biomass via the LBET, NLDFT and QSDFT methods

This article presents the unique research results of the comprehensive analysis of the porous structure of activated carbons obtained from biomass waste materials from the wood industry during activation in an air atmosphere. The porous structure was analysed on the basis of nitrogen and argon adsorption isotherms via complementary multi-method analysis, i.e. the new numerical clustering-based adsorption analysis, the non-local density functional theory and the quenched solid density functional theory methods. The analytical results for the prepared activated carbons were compared with analogous results obtained for commercial activated carbon. On the basis of the conducted studies it has been determined that the new numerical clustering-based adsorption analysis method gives credible and valuable information on the textural properties of activated carbons which are in strict correlation and mutually complement with the results of the analysis with the use of the quenched solid density functional theory method. The research results obtained in this paper, it has also been shown that from waste materials of the wood industry, in a relatively cheap and cleaner production process, it is possible not only to obtain carbonaceous materials almost comparable to commercial activated carbon, but also to manage the waste in accordance with the principles of a closed-loop economy and sustainable development. The paper pays also attention to the often overlooked economic and ecological aspects, which should nevertheless be taken into account when comparing different adsorbents, rather than their textural properties alone.