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.

Background: Light spectra have been demonstrated to result in different levels of comfort or stress, which affect plant growth and the availability of health-promoting compounds in ways that sometimes contradict one another. To determine the optimal light conditions, it is necessary to weigh the vegetable’s mass against the amount of nutrients it contains, as vegetables tend to grow poorly in environments where nutrient synthesis is optimal. This study investigates the effects of varying light conditions on the growth of red lettuce and its occurring nutrients in terms of productivities, which were determined by multiplying the total weight of the harvested vegetables by their nutrient content, particularly phenolics. Three different light-emitting diode (LED) spectral mixes, including blue, green, and red, which were all supplemented by white, denoted as BW, GW, and RW, respectively, as well as the standard white as the control, were equipped in grow tents with soilless cultivation systems for such purposes. Results: Results demonstrated that the biomass and fiber content did not differ substantially across treatments. This could be due to the use of a modest amount of broad-spectrum white LEDs, which could help retain the lettuce’s core qualities. However, the concentrations of total phenolics and antioxidant capacity in lettuce grown with the BW treatment were the highest (1.3 and 1.4-fold higher than those obtained from the control, respectively), with chlorogenic acid accumulation (8.4 ± 1.5 mg g^− 1 DW) being particularly notable. Meanwhile, the study observed a high glutathione reductase (GR) activity in the plant achieved from the RW treatment, which in this study was deemed the poorest treatment in terms of phenolics accumulation. Conclusion: In this study, the BW treatment provided the most efficient mixed light spectrum to stimulate phenolics productivity in red lettuce without a significant detrimental effect on other key properties.

When fossil fuel substitution with biomass is viewed as a potential solution to global warming caused by greenhouse gas emissions, the demand for biomass fuel pellets has increased worldwide. Although agricultural waste is an attractive potential feedstock for fuel pellet production due to its relatively high calorific value and low cost, its excessive ash content is a major drawback. This research investigates the properties of sugarcane bagasse fuel pellets treated by dry and wet torrefaction and evaluates the economic value of selling the fuel pellets, which were priced based on their quality. It was found that the wet torrefaction could significantly reduce the ash content in the product (1% ash content at a torrefaction temperature of above 180°C), resulting in higher quality and more marketable fuel pellets. Consequently, the yield and the net present value of the production of wet torrefied fuel pellets were greater than those of dry torrefied pellets. Nevertheless, the production of fuel pellets from sugarcane bagasse treated by either process is shown to be economically viable.

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