Investigation of physicochemical characteristics of selected lignocellulose biomass

Insights on comprehensive characterization of distinct growth stages of Sterculia foetida pod as a potential feedstock for bioethanol production

Lignocellulosic biomass explores a sustainable and renewable energy source that could provide a suitable solution to energy demands. However, diversity is the main obstacle that hinders the biorefinery approach to bioethanol production. In this study, the non-edible feedstock, Sterculia foetida pod, green-colored skin (GSFP), and brown-colored skin (BSFP) were used as feedstock for the production of bioethanol. To examine the comprehensive characterization of selected biomass, namely BSFP and GSFP, the various methods, namely physicochemical analysis, proximate analysis, ultimate (CHNS) analysis, bulk density, and calorific value were employed. The functional group analysis, thermal stability, surface morphology, and crystallinity index for biomasses were characterized by FTIR spectroscopy, Thermo-gravimetric (TGA) analysis, scanning electron microscope (SEM), and XRD analysis. The elemental and chemical composition of GSFP and BSFP were extensively evaluated using different methods. The value-added precursors, namely cellulose and lignin isolated from GSFP and BSFP. The cellulose content in GSFP and BSFP pods was found to be 35.28 ± 3.39% and 33.95 ± 4.49% and the lignin content was 17.37 ± 3.54% and 20.79 ± 8.78% respectively. The obtained cellulose from GSFP and BSFP was subjected to two-step acid hydrolysis on different SL ratio (1:10-5:10) to prepare fermentable sugars at different concentration (g/L). Based on the different sugar concentration, the bioethanol concentration (0.91 to 18.78 g/L; 0.23 to 12.23 g/L) and specific bioethanol yield (0.44 to 1.52 g/g; 0.13 to 1.55 g/g) increased for both BSFP and GSFP respectively.

Agro-industrial residue torrefaction to bio-coal: Its physico-chemical characterization and potential applications in energy and environmental protection

Leveraging biofuel derived from biomass stands as a pivotal strategy in reducing CO2 emissions and mitigating the greenhouse effect. Biomass serves as a clean, renewable energy source, offering inherent benefits. However, despite its advantages, biomass encounters obstacles hindering its widespread industrial applications, including its relatively low calorific value, limited grindability, high water content, and susceptibility to corrosion. The torrefaction process has garnered significant attention as an effective method for enhancing the quality of raw biomass for energy production. In this review, we briefly discussed the mechanism of bio-coal preparation using biomass, physico-chemical characterization of different torrefied feedstocks, and the effect of torrefaction parameters, along with the effect of the different types of reactors on biomass torrefaction. Furthermore, bio-coal's emission characteristics and fuel quality throughout the thermal treatment have been covered. Thus, bio-coal finds a wide range of applications in sustainable energy generation, environmental remediation, agri-food development, polymer composites, and others.

Loosening the Solvation Cage in Polysaccharide Polymer Electrolyte for Sustainable Lithium Metal Batteries

Biomass with naturally ion-conducting segments (e.g., hydroxyl) holds promise for sustainable batteries. Several expeditions are proposed to successfully enhance the ion conduction in biomass polymer mainly by intermolecular structure regulation. Presently, the recognition and research of biomass polymer electrolytes are still limited, requiring continuous explorations to promote the application of such promising electrolytes. Herein, a molecularly asymmetric electrolyte is produced, comprising polysaccharides of starch and chitosan. The strong Li+-O (hydroxyl) interactions are replaced by weak Li+-oxygen (O) of ester carbonyl, and the steric hindrance group -NH3 + promotes the immobilization of anion and stabilization of the interface. Such intermolecular chemical modulations of biomass are achieved by a one-pot esterification and protonation of polysaccharides. A loosely-solvating cage structure with the participation of O of ester carbonyl, glycerol, and anion, allowing the rapid conduction (1.82 × 10-4 S cm-1 at 30 °C) and a high migration number (0.49) of Li+. Moreover, Li symmetric cells (2500 h) and Li4TiO5 | Li cells (400 cycles) employing the SCA electrolyte show superior cycling stability. The polysaccharide BPEs and solvation regulation strategy open up a promising avenue for constructing sustainable batteries.

Anaerobic co-digestion of human excreta, food leftovers and kitchen residue: 1 ternary mixture design, synergistic effects and RSM approach

Anaerobic digestion of multiple substrates can generate more biogas while remaining stable, if positive synergistic effects are achieved. The type of co-digested substrates and the mixing ratio used, are the most important variables as each substrate has unique set of characteristics. Optimizing the volume ratios by testing various substrate mixing ratios is a popular method for determining the best-performing ratio of substrate mixture. The ternary mixture design has reportedly been found to quicken the process of testing different mixing ratios with high accuracy without running several experiments. Therefore, a ternary mixture design and a response surface approach are used in this work to ascertain the relationship between substrate mix and responses (biogas yield, methane yield, and synergy). The findings of the experiment revealed that R9 comprising 78.8 % human excreta, 11.8 % food leftovers and 9.4 % kitchen residue, had the highest methane production of 764.79 mLCH4/gVS and a synergistic index of 3.26. Additionally, the 3D response surface plots from the response surface model showed important and shared interactions between Human Excreta, (HE), Food Leftovers (FLO), and Kitchen Residue (KR). HE and KR had a similar positive synergistic effect on biogas yield, methane yield, and synergy, which was not the case for FLO. The response surface plots showed that the predicted responses (methane yield, biogas yield and synergy) increased with increasing HE and KR fractions and decreased with increasing FLO fractions in the substrate mixtures.

Black soldier fly larvae recruit functional microbiota into the intestines and residues to promote lignocellulosic degradation in domestic biodegradable waste

Lignocellulose is an important component of domestic biodegradable waste (DBW), and its complex structure makes it an obstacle in the biological treatment of DBW. Here, we identify black soldier fly larvae (Hermetia illucens L., BSFL) as a bioreactor for lignocellulose degradation in DBW based on their ability to effectively recruit lignocellulose-degrading bacteria. This study mainly examined the lignocellulose degradation, dynamic succession of the microbial community, gene expression of carbohydrate-active enzymes (CAZymes), and co-occurrence network analysis. Investigation of lignocellulose degradation by BSFL within 14 days indicated that the lignocellulose biodegradation rate in the larvae treatment (LT, 26.5%) group was higher than in natural composting (NC, 4.06%). In order to gain a more comprehensive understanding of microbiota, we conducted metagenomic sequencing of larvae intestines (LI), along with the LT and NC. The relative abundance of lignocellulose-degrading bacteria and CAZymes genes in LT and LI were higher than those in NC based on metagenomics sequencing. Importantly, genes coding cellulase and hemicellulase in LI were 3.36- and 2.79-fold higher, respectively, than that in LT, while the ligninase genes in LT were 1.82-fold higher than in LI. A co-occurrence network analysis identified Enterocluster and Luteimonas as keystone taxa in larvae intestines and residues, respectively, with a synergistic relationship to lignocellulose-degrading bacteria. The mechanism of recruiting functional bacteria through the larvae intestines promoted lignocellulose degradation in DBW, improving the efficiency of BSFL biotechnology and resource regeneration.

Anaerobic co-digestion of grass and cow manure: kinetic and GHG calculations

Grass is a highly desirable substrate for anaerobic digestion because of its higher biodegradability and biogas/methane yield. In this study, anaerobic co-digestion of grass, cow manure and sludge was studied under mesophilic conditions for 65 days. Experiments were performed on a feed ratio of grass/manure from 5 to 25%, respectively. The maximum cumulative biogas and methane yield was obtained as 331.75 mLbiogas/gVS and 206.64 mLCH₄/gVS for 25% ratio. Also, the results of the experiments were tested on the three different kinetics model which are the first order kinetic model, modified Gompertz model and Logistics model. As a result of the study, it was found that by using grass nearly 480 × 10⁶ kWh/year electricity may be produced and 0.5 × 10⁶ tons/year CO₂ greenhouse gas emission mitigation may be reached.

A review on sulfur transformation during anaerobic digestion of organic solid waste: Mechanisms, influencing factors and resource recovery

Anaerobic digestion (AD) is an economical and environment-friendly technology for treating organic solid wastes (OSWs). OSWs with high sulfur can lead to the accumulation of toxic and harmful hydrogen sulfide (H₂S) during AD, so a considerable amount of studies have focused on removing H₂S emissions. However, current studies have found that sulfide induces phosphate release from the sludge containing iron‑phosphorus compounds (FePs) and the feasibility of recovering elemental sulfur (S⁰) during AD. To tap the full potential of sulfur in OSWs resource recovery, deciphering the sulfur transformation pathway and its influencing factors is required. Therefore, in this review, the sulfur species and distributions in OSWs and the pathway of sulfur transformation during AD were systematically summarized. Then, the relationship between iron (ferric compounds and zero-valent iron), phosphorus (FePs) and sulfur were analyzed. It was found that the reaction of iron with sulfide during AD drove the conversion of sulfide to S⁰ and iron sulfide compounds (FeS_x), and consequently iron was applied in sulfide abatement. In particular, ferric (hydr)oxide granules offer possibilities to improve the economic viability of hydrogen sulfide control by recovering S⁰. Sulfide is an interesting strategy to release phosphate from the sludge containing FePs for phosphorus recovery. Critical factors affecting sulfur transformation, including the carbon source, free ammonia and pretreatment methods, were summarized and discussed. Carbon source and free ammonia affected sulfur-related microbial diversity and enzyme activity and different sulfur transformation pathways in response to varying pretreatment methods. The study on S⁰ recovery, organic sulfur conversion, and phosphate release mechanism triggered by sulfur deserves further investigation. This review is expected to enrich our knowledge of the role of sulfur during AD and inspire new ideas for recovering phosphorus and sulfur resources from OSWs.

Rapid and Effective Lead Elimination Using Cow Manure Derived Biochar: Balance between Inherent Phosphorus Release and Pollutants Immobilization

Cow manure derived biochar (CMBC) can serve as a promising functional material, and CMBC can be regarded as an ecofriendly approach compared to conventional ones. CM bioadsorbent can be employed for heavy metal immobilization (such as for lead) as well as an amendment to increase soil fertility (e.g., phosphorus). Few studies have examined the surface interactions between pollutants and bioadsorbents when inherent nutrient release is present. In this work, CMBC was prepared and applied for Pb(II) removal, and the vital roles of released phosphorus from CMBC were comprehensively disclosed. Furthermore, CMBC could immobilize part of the Pb(II) in soil and promote plant growth. CM400 was an effective adsorbent whose calculated Q_e reached 691.34 mg·g^-1, and it rapidly adsorbed 98.36 mg·g^-1 of Pb(II) within 1 min. The adsorption mechanisms of Pb(II) by CMBC include ion exchange, physical adsorption, electrostatic attraction, chemical precipitation, surface complexation, and cation-π bond interaction. Based on the residual phosphorus content and adsorption effect, complexation rather than the chemical precipitation had a greater contribution toward adsorption. Besides, as the concentration of Pb(II) increased, the main adsorption mechanisms likely transformed from chemical precipitation to ion exchange and complexation. CMBC not only had a good effect on Pb(II) removal in the solution, but also immobilized the Pb(II) in soil to restrain plant uptake as well as promote plant growth. The main novelty of this work is providing more insights to the cow manure bio adsorbent on Pb immobilization and phosphorus release. This study is expected to serve as a basis and reference for analyzing the release effects of inherent nutrients and the interfacial behaviors with heavy metals when using CMBC and other nutrient-rich carbon-based fertilizers for pollution control.

Safety assessment of charcoal usage and effects of common charcoal ignition aiders on combustion indices

Charcoal is a popular form of biofuel embraced for domestic and industrial purposes. However, the use of Charcoal has some associated challenges, such as the required charcoal pot and setting it into the fire at first by using Charcoal-Ignition-Aiders (CIA) (e.g. discarded paper, nylon, rubber, plastics, petrol, the residue of processed palm oil, maise cob, wood, and kerosene). Coupled with the chemical properties of Charcoal, the resulting gases from CIA are capable of polluting the environment with perceived Adverse-Health-Implications (AHI) on the ecosystem. Therefore, this study conducted a safety assessment of charcoal biofuel usage and the effects of common CIA on combustion indices. This study followed standard methods and the use of peculiar equipment. This study established that Charcoal is commonly used in the studied area because it is cheap, readily available and requires less technical know-how. Considering the combustion indices, using paper as a CIA generated the lowest carbon monoxide (CO) value, 28.1 ppm, with 3,434.54 ppm volatile organic compound, VOC. Compared with the ACGIH standard permissible exposure level of ≤ 30 ppm, the paper gave a lesser CO value of 28.10 ppm among all the CIA. At the same time, all the CIA recorded higher VOC compared with EPA standard permissible exposure level of ≤ 15 ppm. ANOVA analysis conducted on the socio-demographic profile of the respondents, cooking attributes of the respondents, and use of charcoal pot types by the respondents in Zone 1, Zone 2, and Zone 3 gave p-values of 0.032, 0.028, and 0.039, respectively. These imply significant differences within the zones in each of the indices. The average energy content reported for charcoals sourced from oak trees, afara, obeche, mahogany, and iroko woods is 3,2149 kJ/kg compared to the lower ones. Therefore, this study recommended using these charcoals alongside discarded paper as CIA because they are a better combination to reduce AHI.