The primary objective of this research is to study ways to increase the potential of energy production from food waste by co-production of bioethanol and biomethane. In the first step, the food waste was hydrolysed with an enzyme at different concentrations. By increasing the concentration of enzyme, the amount of reducing sugar produced increased, reaching a maximum amount of 0.49 g/g food waste. After 120 h of fermentation with Saccharomyces cerevisiae, nearly all reducing sugars in the hydrolysate were converted to ethanol, yielding 0.43–0.50 g ethanol/g reducing sugar, or 84.3–99.6% of theoretical yield. The solid residue from fermentation was subsequently subjected to anaerobic digestion, allowing the production of biomethane, which reached a maximum yield of 264.53 ± 2.3 mL/g VS. This results in a gross energy output of 9.57 GJ, which is considered a nearly 58% increase in total energy obtained, compared to ethanol production alone. This study shows that food waste is a raw material with high energy production potential that could be further developed into a promising energy source. Not only does this benefit energy production, but it also lowers the cost of food waste disposal, reduces greenhouse gas emissions, and is a sustainable energy production approach.

This study is the first, to the best of our knowledge, where waste napkin paper was successfully valorized to low-density (27.2 mg cm⁻³) cellulose aerogels for oil sorption material. Two simple methods with different gel coagulators, ethanol and sulfuric acid, were used for preparation of the aerogel. Conditions for the alkaline treatment of the raw material and the pre-freezing temperature in the lyophilization process were optimized. It was found that the water and oil sorption capacities of the aerogels were not significantly affected by alkaline treatment, while they could be adjusted by changing the pre-freezing temperature. Although the produced aerogels were initially amphiphilic, hydrophobic surfaces were obtained by vapor deposition of methyltrimethoxysilane (MTMS) and these materials possessed high sorption capacities, up to 32.24 cm³ g⁻¹ (28.56 g g⁻¹) for pump oil and 26.77 cm³ g⁻¹ (39.59 g g⁻¹) for chloroform. This was comparable to aerogels prepared from fresh cellulosic materials via the sol-gel method, as their sorption capacities varied in the range of 14–45 g g⁻¹.

Co-production is a process based on the biorefinery concept that maximizes the benefit of biomass by reusing residue from the production of one product to produce others. In this regard, biogas is one of the most researched second products for the production of ethanol from cellulosic biomass. However, operating this scheme requires additional investment in biogas processing equipment. This review compiles data from research studies on the co-production of bioethanol and biogas from lignocellulosic biomass to determine which is more worthwhile: leaving the residue or investing more to benefit from the second product. According to previous research, ethanol stillage can be converted to biogas via anaerobic digestion, increasing energy output by 2–3 fold. Techno-economic studies demonstrated that the co-production process reduces the minimum ethanol selling price to a level close to the market price of ethanol, implying the possibility of industrializing cellulosic ethanol production through this scheme.

CO₂ capture is a promising approach to aid in the mitigation of the global environmental crisis caused by greenhouse gas emissions. The efficiency of adsorbents is critical to the success of this approach. Sugarcane bagasse fly ash (SBA) was used in this study as a support to increase the CO₂ adsorption capacity of CaO. The physical and chemical characteristics of SBA treated with various reagents (HCl, H₃PO₄, CH₃COOH, NaOH, NH₃, and H₂O₂) were investigated. The CaO was then loaded at 10–50 wt% on the support surface, and the modified adsorbent was tested for its potential to adsorb CO₂. According to the results of the experiments, the acidic reagent increased the surface area of SBA, whereas the base reagents provided SBA with a higher pore volume and a larger pore size. The different surface characteristics of the modified SBA had a direct impact on its CO₂ adsorption capacity. The adsorbent with NaOH-pretreated SBA and 50% CaO loading had the highest CO₂ adsorption capacity, which was 27% higher than that of unsupported CaO due to the decent distribution of CaO found on the NaOH-treated SBA surface. For a better understanding, a graphical model was finally proposed to describe the aforementioned changes in surface characteristics and adhesion of CaO on the SBA support. These findings show that SBA, a valueless bagasse-incinerating waste material, can be used as a support to increase the CO₂ adsorption capacity of adsorbents, transforming it into a more valuable and environmentally sustainable material. Graphical abstract

In this research, the upgrading of agro-industrial wastes was investigated by using the torrefaction pretreatment technique. Two types of biomass waste, including sugarcane bagasse (SBG) and palm kernel shell (PKS), were used as raw materials. The operating conditions, i.e., torrefaction...

Torrefaction has emerged as a promising thermochemical pretreatment to enhance the fuel properties of agricultural biomass, yet predicting product characteristics remains challenging due to feedstock variability. This study developed and compared four machine learning (ML) models, support vector regression (SVR), artificial neural network (ANN), gradient boosting machine (GBM), and random forest (RF), to predict the higher heating value (HHV), mass yield (MY), and energy yield (EY) of torrefied biomass. A comprehensive dataset comprising 117 experimental samples from 11 biomass types torrefied at 200–280°C for 20–60 min was utilized. Input variables included the contents of proximate composition (ash, fixed carbon, and volatile matter), ultimate composition (C, H, N, O, S), and process conditions (temperature and residence time). SHapley Additive exPlanations (SHAP) analysis revealed that torrefaction temperature was the most influential parameter, followed by volatile matter and ash content. Results demonstrated that GBM consistently outperformed the other models, achieving an acceptably high coefficient of determination, with minimal prediction errors across different input configurations. Notably, simple proximate‐analysis data provided performance comparable to that of more detailed and instrument‐intensive ultimate analysis (UL), highlighting the practical value of GBM for operators handling diverse biomass feedstocks with limited access to specialized analytical instruments.