Biomass Conversion and Biorefinery

As global energy demands rise and non-renewable resources decrease, identifying sustainable alternatives is of utmost importance. This study investigates the potential of Carica papaya seeds as a feedstock for bio-oil production. Employing the central composite design of response surface methodology, the extraction process was optimized using heptane as the solvent. The effects of biomass to heptane ratio and extraction time on oil yield were examined. The optimized conditions of 1:11 biomass to heptane ratio (g:mL) and 4-h extraction time yielded an optimal oil yield of 45.77±0.057%. The chemical composition analysis revealed a kinematic viscosity of 12.58 mm2/s at 40°C, indicating favorable flow properties, and a high heating value of 37.52 MJ/kg, suggesting its energy potential. Fourier transform infrared (FTIR) analysis detected carbonyl functional groups and alkanes, indicating the suitability of Carica papaya seed oil for biodiesel production. These findings highlight the promising role of Carica papaya seeds as a renewable feedstock for bio-oil, contributing to sustainable energy development. This research addresses the pressing challenge of depleting non-renewable resources and underscores the significance of Carica papaya seeds as a valuable and eco-friendly source for bio-oil production. Such advancements pave the way for a greener and more sustainable energy future.

This study explores the interplay among environmental quality, economic growth, and bioenergy consumption in the Organization for Economic Cooperation and Development (OECD) countries. Due to profound sustainable implications of energy consumption, understanding this relationship becomes crucial for two reasons: managing the environment sustainably and alleviating energy dependence on fossil fuels. Therefore, we propose a humble contribution by examining the distributional dynamics of carbon emissions, bioenergy consumption, and economic growth considering the nonparametric kernel density and quantile regression approaches. The kernel density estimates depict that concentration is found to be skewed towards the higher distributions in all the variables, except bioenergy consumption. Indicating a similar relative position through a single node across different bands of distribution. The quantile estimates confirm that economic growth, non-renewable energy consumption, and urbanization have a positive impact on carbon emissions, and therefore deteriorate the quality of the environment. However, bioenergy consumption shows a significant and negative effect on carbon emissions hence improves environmental quality efficiently. This paper intends to guide policymakers regarding the carbon emission and bioenergy consumption required to hold back the fossil fuel dependence for a cleaner and greener planet.

In the present study, we evaluated the biogas production from the anaerobic co-digestion of raw glycerol (RG) in combination with swine manure (SM) and the interaction of the microbial community during anaerobic co-digestion. In the same way, different RG and SM concentrations were examined in the range of 6 to 15 g L−1 and 7.5 to 22.5 g L−1, respectively. According to the results, the highest values for biogas yield and methane yield were observed in test 1(6 g RG/7.5 g SM) with 340 mL g−1 COD, test 2 (6 g RG/22.5 g SM) with 330 mL g−1 COD, test 4 (15 g RG/22.5 g SM) with 344 mL g−1 COD, and test 5 (3.75 g RG/15 g SM) with 328 mL g−1 COD. Although the concentration of substrates increases, glycerol remains between 20 and 21% of RG for both tests (2 and 5). An increase in the concentration of RG (> 21% w/w) generated inhibitory effects for the co-digestion process since there was an overload of organic acids, which increase the impurity concentration and lower the biogas yield. Thus, the microbial consortium is a function of the organic load of the RG/SM ratio. The greater the concentration of RG, the higher the population of clostridium and low biogas yield in anaerobic co-digestion.

Present study aims to enhance protease production by employing locally isolated bacterial strains using animal skin (beef) wastes as a substrate. A proximate analysis of the substrate (skin waste) was carried out to know the percentage of protein, fats, and ash. To understand the particle size, shape, and other structural changes, scanning electron microscope (SEM) and Fourier transform infrared spectroscopy (FTIR) of both untreated and treated samples were performed. The substrate showed 83.81% crude protein, 11.23% crude fat, and 4.96% ash contents. SEM and FTIR analysis revealed changes in treated samples as compared to that untreated skin waste (control). In 140 isolated strains, 60 strains showed clear zone on 1% skim milk agar medium. The selected strains were cultured for protease assay on a production medium. The maximum protease (249.65 IU/ml) producing strain was identified as Bacillus cereus AUST-7 morphologically, biochemically, and based on 16S rDNA gene sequencing. The bioprocess parameters like aeration rate, shaking speed, and incubation period were optimized in lab scale bioreactor of 1.5 L capacity. During scale-up in a bioreactor (1.5 L), 2 volumes of aeration rate per volume of liquid medium per minute (VVM) aeration, shaking speed of 500 rpm, and 24 h of incubation period yielded maximum protease (1917.5 IU/mL) under submerged fermentation. The results depicted that defatted skin waste could be utilized as a potential substrate for the cost-effective production of alkaline protease.

The present investigation explored the potential of biochar produced from groundnut shells in the removal of Reactive Orange 16 (RO16) in an aqueous solution. The characteristics of the biochar were evaluated using a thermogravimetric analyzer, scanning electron micrographs (SEM) with energy dispersive system (EDS), and Fourier transform infrared (FT-IR) spectra. The batch adsorption studies were conducted by determining the influencing parameters, namely, solution pH, sorbent dose, solution temperature, and initial RO16 concentration. Furthermore, adsorption isotherm models, namely, Freundlich, Langmuir, and Toth model were used to predict the sorption capacity of the model. Pseudo-first-order and pseudo-second-order kinetic models were developed to understand the sorption of the dye molecules at different time intervals. To evaluate the potential of the sorbent, regeneration studies were performed. A maximum removal efficiency of 73.67% and a sorption capacity of 11.05 mg/g were obtained.

Although feather waste is generated abundantly but rich in natural protein, it is hassled to be digested. To improve the nutritional value of feather waste, compound enzymatic hydrolysis (CEH) was applied to degrade feather waste. Results indicated that the nutritional value of feather meal (FM) produced with CEH was improved in terms of protein solubility increase to 20.75 times and in vitro protein digestibility increase to 10.27 times as compared to fresh FM; this improvement was ascribed to the keratinase breaking up disulfide bond and compound enzymes destroying the smooth surface structure, compact β-sheet structure, and hydrogen bond. In conclusion, CEH is an effective and promising approach to improve the nutrient value of feather waste. The results shed light on the utilization of feather waste for protein resource in feed industry.

Biochar, a carbon-rich pyrolytic product, has demonstrated positive results as a soil improver and carbon sequestration agent. Its production could be an appropriate and innovative practice for agricultural waste management in the context of environmentally smart agriculture. However, considering the relevant effect of the production conditions on the final biochar properties, its characterization is a necessary step, moreover, if an unknown feedstock is being used. Coffee hulls (CH), pineapple stubble (PS), and palm oil fiber (PF) are typical tropical agro-industrial wastes, and biochar from the first two are not reported before. In this work, biochars from them were obtained after 1 h of pyrolysis at 600 °C. Surface area and pH of biochars were close to 60 m2g−1 and 9, respectively (except for PF which was 29 m2g−1), while torrefied biomass (charred material prepared at 300 °C) presented a surface area close to 1 m2g−1 and neutral pH. Fixed C was approximately 80% (PF and CH) and 59% (PS) for biochars and close to 40% in torrefied biomass. It was concluded that key properties of biochars were mostly determined by the feedstock’s origin. Due to its high ash content and surface area, PS biochar was identified as a suitable soil amendment, while PF and CH biochars showed a higher potential for carbon sequestration in soil due to their high fixed carbon content, demonstrating that the production of biochars from widespread tropical wastes tailored for specific environmental uses is possible.