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Reed sawdust is a kind of paper mill waste with high cellulose and hemicellulose content. To promote the rational use of resources, it is essential to make full use of waste resources and transform them into new values. In this work, reed sawdust was pretreated with liquid hot water (LHW) at 170 °C for 30 min. A total of 39.00 g/L glucose was obtained after enzymatic saccharification of cellulose at 50 °C, 20 FPU/g-reed sawdust cellulase, 25% (w/v) reed sawdust, in 5 replenishments. When the fermentation was performed 96 h, the medium contained xylo-oligosaccharides (XOS) 11.74 g/L and biomass 15.21 g/L, in which lipid was 4.14 g/L. After spray drying, feed additives containing 29.17% XOS and 10.29% docosahexaenoic acid (DHA) can be prepared. In particular, the hemicellulose and cellulose in reed sawdust are creatively used at the same time without separation, which greatly reduces the cost of purification in traditional processes and provides a new way for the high-value transformation of sawdust resources. [ABSTRACT FROM AUTHOR]

Eucalyptus sawdust is a forest residue that, through a biorefinery approach, can be used to manufacture value-added products in the pulp and paper industries as well as to produce a biofuel. This study examines the suitability of a sequential thermochemical pretreatment that uses processes and reagents commonly utilized in the pulp and paper industry to separate valuable biomass components from eucalyptus sawdust and increase its enzymatic digestibility for ethanol production. The research strategy was based on a forest biorefinery that can be integrated into an existing industrial plant for the production of cellulose pulp. A combination of alkaline solutions was evaluated to obtain an extract rich in tannins and intended to be used in the formulation of wood adhesives. A second alkaline treatment was used to recover lignin and hemicellulose components and improve cellulose digestibility. The cellulose fraction was fermented using three commercial Saccharomyces cerevisiae yeasts (Thermosacc®, PE-2, and CAT). Different process configurations (separate hydrolysis and fermentation (SHF), pre-saccharification followed by simultaneous saccharification and fermentation (PSSF), and simultaneous saccharification and fermentation (SSF)) at 16% (w/v) solid loading by Thermosacc® yeast were also studied. Thermosacc® yeast enabled higher ethanol production than the other strains but resulted in similar productivity. The two-stage alkaline pretreatment of eucalyptus sawdust was successful in recovering 34 g of tannins, 56 g of xylo-saccharides, 16 g of acetic acid, and 90 g of lignin and produced 152 g of ethanol from 1 kg of dry eucalyptus sawdust. [ABSTRACT FROM AUTHOR]

The potential of native as well as acid/alkali pre-treated paddy straw was investigated as inducer substrate for Aspergillus terreus mediated cellulase and xylanase production. The cellulose, hemicellulose and lignin contents of native straw were found to be 25.94%, 17.64% and 15.82%, respectively. However, in the acid/alkali treated straw, cellulose content substantially increased to 48.09%, whereas hemicellulose and lignin contents were reported to be particularly low (11.72%, 5.08%, respectively). The FTIR spectra of native and pre-treated paddy straw further supported the variation in their chemical constituents. A. terreus repertoires were cultivated on native and treated paddy straw under solid state fermentation (SSF) and liquid fermentation (LF) conditions. The LF cultures showed higher cellulase and xylanase activities (Filter Paper cellulase: 45.33 U/L, Carboxymethyl cellulase: 104.75 U/L, β-glucosidase 80.44 U/L, Avicelase: 22.72 U/L and Xylanase: 623.69 U/L) than the respective SSF cultures. Significantly high activities of exoglucanases and endoglucanases were obtained when native straw was used as the growth substrate. The scanning electron micrographs of native and treated straw exhibited disintegration after being subjected to biological treatments, confirming the hyphal adhered growth and production of hydrolysing secretomes by the fungus. Cultivation of A. terreus on native paddy straw in LF culture system resulted in better enzyme production, and holds promise for further optimization. [ABSTRACT FROM AUTHOR]

The pith is the internal part of the sugarcane plant with short and variable fiber length. The presence of pith creates process-related issues in papermaking, so it must be removed from the bagasse. Pith has low calorific value, and burning of pith in boilers also creates boiler operational issues as well as environmental pollution and health hazards. The imposition of stringent emission norms by the environmental regulatory bodies is compelling these industries to search for cleaner alternatives to fuels. Pith is generated in huge quantities so its disposal or management will become a major challenge if industries shift to cleaner fuel. Considering these pressing issues and some recent relevant research reported on pith valorization, this study was planned to explore the potential of pith valorization. Therefore, in the present review, research studies available on alternate routes for the valorization of pith into value-added products have been extensively covered. Since pith is also lignocellulosic biomass, therefore, its valorization after pretreatment and as such direct utilization (without pretreatment) has also been categorically discussed. Furthermore, the promising pathways and prospective research in pith valorization are discussed that will make the sugar and associated pulp and paper mill more economically and environmentally sustainable. [ABSTRACT FROM AUTHOR]

Burning corncob for energy requirements caused a huge waste of biomass resources and serious environment pollution. Herein, this study provided a high-value utilization strategy for corncob. Corncob was first pretreated by hydrothermal process. The collected hydrolysates were converted into furfural by a recyclable solid acid with a yield of 52.35%. The pretreated solid was disintegrated into fibers by disc grinding. When corncob fiber addition is below 15%, the ring crush index, tear index, and tensile strength index of the prepared handsheets increased by 1.43 N·m/g, 0.43 mN·m2/g, and 4.66 N·m/g, respectively, compared with that using pure softwood fibers. Besides, corncob fibers were hydrophilically modified with aminosulfonic acid. Water retention value of paper with the modified fiber addition increased by 48.35%. Therefore, this study provided a method of corncob utilization toward two purposes: furfural production and papermaking. [ABSTRACT FROM AUTHOR]

The rising use of palm oil has increased palm oil waste. Several organisations repurpose the palm oil waste from the extraction process by altering its molecular structure through thermal degradation. This review paper aims to provide an overview of the various degradation methods (pyrolysis, torrefaction, gasification, and hydrothermal) used on palm oil waste, as well as the factors (particle size, pretreatment, and heating rate) that influence degradation and the behaviours (conversion, heating zone, activation energy, pre-exponential factor, and reaction model) that are observed during degradation. The paper also compares and contrasts the thermal degradation latest research in this field from 2018 to 2022, highlighting the advantages and disadvantages of different degradation techniques and identifying research gaps and future recommendations. The review also identified that the activation energy for degradation tends to increase with increasing heating rate and that the conversion of feedstocks to products can be improved through the pretreatment and the waste particle size optimisation. For the reaction model of palm oil waste, the first-order reaction model is often used to describe the degradation of empty fruit bunches (EFB) during pyrolysis, while the 3-dimensional (3D) diffusion (Jander) model is commonly used for oil palm shell (OPS) and the reaction order for mesocarp fibre (MF) varied between studies. [ABSTRACT FROM AUTHOR]

The cultivation of cotton produces about 2–3 tonne of residues per hectare after harvesting. Uprooting and disposal of such a huge amount of cotton residues have become a serious problem. In this review, different technologies developed for clearing standing cotton stalks from the field, performances of available technologies, limitations, and technological gap for future work are discussed. Unlike other crop residues, cotton residue has fiber properties similar to most hardwood species. Hence, it is more suitable for various industrial applications like production of particle board, hardboard, pulp, paper, and corrugated boxes. It is also a cleaner fuel as compared to coal due to lower carbon and ash content based on ultimate analysis. Therefore, it can be used as fuel for power plant and as bio-energy. The potential of the use of cotton stalks for composting, briquetting, biochar, bio-oil, and bioethanol production, etc. is also discussed in the paper. It was observed that, the cotton waste was available in abundance; however, efficient machinery to remove the cotton stalks from field and simultaneously convert it into storable or directly usable form as a raw material for various applications was needed. The use of cotton stalks is techno-economically feasible for various applications but still more work is required in bio-ethanol production from cotton stalks to improve the yield of ethanol and for making the process more economical. [ABSTRACT FROM AUTHOR]

This paper aims to study dark fermentation (DF) in an upflow anaerobic sludge blanket (UASB) reactor during 20 cycles operating at different hydraulic retention times (HRTs) of 3, 9, and 12 h using substrate wastewater from the food industry and granular inoculum sludge from a treatment plant as codigestion to explore the relationship between substrates, metabolites, and microorganisms to increase the biohydrogen (BioH2) yield. Operation conditions were constant pH 5.50 ± 0.50, T = 35 °C and a carbon-to-nitrogen (C/N) ratio of 30. It is noteworthy that DF with HRT = 9 h obtained the highest yields of organic matter degradation, and BioH2 in biogas (~60%) was attributed to the adjustment of pH and the codigestion buffer capacity. During DF with HRT = 9, the reactor was 11 times more productive with regards to HRT = 3 h, resulting in its performance with a better yield mean (6.22 mmol H2 g COD−1) and productivity (0.35 LH2 L−1 d) than other HRTs with lower records of 0.42 mmol H2 g COD−1 and 0.05 LH2 L−1 d, respectively. The high abundance of native populations (Lactobacillus and Lactococcus) and intrinsic inoculum (Citrobacter) led to the highest BioH2 production. Most of the production of acetic acid ~590 mg L−1 and butyric acid ~450 mg L−1 confirmed that BioH2 is mainly produced by acetic and butyric metabolic routes, and a direct relation with the percentage of retention of total suspended solids was also found, supporting the biodegradation capacity of the process. [ABSTRACT FROM AUTHOR]

Pleurotus pulmonarius is an economically important edible mushroom well known for the production of several lignocellulolytic enzymes, including polyphenol oxidase (PPO), EC 1.14.18.1. This enzyme can oxidize and hydrolyze phenolic compounds directly associated with the organoleptic and nutritional properties of foods. Thus, the aim of this paper is to produce and characterize the PPO of P. pulmonarius 21 (CCB21). The fungus was able to produce PPO using peach-palm waste and cocoa bean shell as substrates under solid-state fermentation (SSF) in 5 days of cultivation at 90% humidity (3066 ± 232 U/gds). PPO was partially purified with 60% ammonium sulfate and showed a purification rate of 2.1 times and a yield of 53.92%. The enzyme showed an optimum temperature above 45 °C, an optimum pH in the range of 5.5 to 6.5, and proved quite stable, maintaining 86–88% of its activity for up to 120 min under these conditions. PPO had reduced activity in the presence of β-mercaptoethanol, while EDTA, SDS, Al3+, Cu4+, Li4+, and Mg2+ ions increased their activity. The enzyme presented a Vmax of 4166.65 U/min and a Km of 4.16 mM for pyrocatechol. The results obtained suggest that, due to its thermostability and little influence in the presence of ions and reagents tested, the PPO of P. pulmonarius CCB21 can be an alternative for application in different biotechnological and industrial processes. [ABSTRACT FROM AUTHOR]

The overall purpose of this study is to investigate the potential for producing higher energy biogas at elevated fermentation pressures. Upgrading of biogas is often carried out to increase its methane (energy) content by removing carbon dioxide. Upgrading is used, for example, to give methane of sufficient purity that it can be injected directly into the gas supply grid. In this research, freshwater algae are used as the feedstock for anaerobic digestion (AD) to produce biogas as a source of renewable energy. Although this has been the subject of extensive research over the past few decades, the main reason why AD has not been more widely commercialised is because it can have poor economic viability. In this paper, we used two similar bioreactors of capacity 1.5 L to generate biogas at different pressures. The methane concentration of the biogas increases to at least 70.0% for a headspace pressure greater than 4 bara compared to 57.5% or less when the pressure is less than 1.6 bara. The higher pressure operation therefore reduces the amount of upgrading required leading to a reduction in the cost of this step. Another interesting finding of this study is that the solubility of biogas in the digestate is estimated to be only 3.7% (best fit value) of its solubility in pure water, which is much lower than the values previously reported in the literature. [ABSTRACT FROM AUTHOR]

Energy crops are a new player in the traditional agricultural landscape. The present paper analyses the land uses surrounding and the spatial characteristics of the main energy crops in Sweden (willow, poplar, hybrid aspen and reed canary grass) compared to traditional agricultural crops during the period 2006–2018. Spatial metrics (number of shape characterising points, shape index and rectangularity ratio) are calculated for each field, as well as the nearby land uses at varying distances, at radius: 500 m, 1000 m, 2000 m and 5000 m. A total of 1560 energy crop fields are studied in the 2006 dataset and 3416 fields in the 2018 dataset, which are compared to 58,246 fields with cereal crops in 2006 and 131,354 fields in the 2018 dataset. Results show that, despite being established on previous agricultural land, energy crops present a different spatial profile compared to traditional agricultural crops. Field shapes present less complexity than before, and the overall spatial features become more regular with time in both cases of energy crops and cereals, suggesting an increasing trend in cost-efficient agricultural practices and planning. Important differences concerning land use diversity at different scales are found between plantations versus grasses. In general, willow plantations are located in agriculture-dominated areas (> 70% at 500 m, > 50% at 2000 m), whereas reed canary grass is in forest-dominated landscapes (> 30% at 500 m, > 60% at 2000 m); both contribute to diversifying existing land uses although with varying effects. The results of this study are a basis to assess the impacts of energy crops at landscape level and can translate into applications in energy policy and planning. [ABSTRACT FROM AUTHOR]

Coconut residues have been widely recognized as a promising source of bioproducts and bioenergy, but full access to its potential polymeric matrix, in general, depends upon some pretreatment stage. Organosolv procedure gained recent attention for being eco-friendly combined with an efficient delignification of lignocellulosic biomass. In this regard, this study proposed a literature review on the Scopus database to track the studies focused on the application of organosolv for coconut residues. A total of 17 studies were identified on this subject, then scoping analysis showed that coconut residue, mainly fibers, treated by organosolv under different conditions, have been tested as an adsorbent, source of nanowhiskers, in ethanol production, and in the reinforcement of product properties. Bibliometric analyses, by means of VOSviewer, revealed that Brazil was the country with the highest number of published papers; along with the terms organosolv and coconut, lignin appeared within the most occurred keywords, which highlights the strong association of the organosolv as a route to extract coconut lignin. In addition, the present work also allowed us to enter into a comprehensive discussion of the future challenges and perspectives toward the development of research that aim to enhance coconut residue end uses. [ABSTRACT FROM AUTHOR]

The energy demand in Malaysia has shown a dramatic increase over the last few years: with natural gas and coal being the primary contributors. Nevertheless, due to declining in fossil fuel reserves coupled with negative environmental impacts, shifting to sustainable renewable energy for meeting the future energy demand is recommended. Since Malaysia is rich with natural resources, utilization of biomass energy (bioenergy/biofuel) as the alternative energy is promising to be further explored. Therefore, this review paper intents to discuss the current scenario of different types of biomass energy in Malaysia along with the up-to-date local biomass energy–related environmental policy (from 2016 onwards). In addition, challenges and barriers for large-scale implementation of the biomass energy in Malaysia are to be discussed. Overall, this review paper is interesting as it can assist in promoting the biomass utilization as energy source, and to ensure the future growth of biomass energy market in the country along with its effective implementation while alleviating poor disposal problem and to create job employment opportunities. Furthermore, a collective effort to expand potential biomass feedstocks, apart from oil palm, should be emphasized to encourage the renewable energy production diversification in the nation. [ABSTRACT FROM AUTHOR]

Biomass is a renewable source of bioenergy, making it a promising solution for reducing greenhouse gas (GHG) emissions. Biomass is converted into bioenergy by the thermochemical and biological routes. Among all thermochemical conversion processes, pyrolysis is the most popular due to its ease of operation. Temperature, gas residence time, particle size, and heating rate are important operating parameters in pyrolysis. Bio-oil, biochar, and syngas are the main products from pyrolysis, and by giving suitable upgrading treatment, these products are converted into value-added products. The impact of pyrolysis on the environment is assessed using the life cycle assessment (LCA) tool. This review critically examines the reported literature for the goal and scope of the study, and boundaries are chosen, the process including pretreatment and product upgrading. Most researchers have recommended using biomass for bioenergy production instead of fossil fuel to reduce the impact. The most commonly used software is SimaPro, followed by GaBi, while the commonly chosen boundary is cradle-to-grave, and global warming potential is the most studied impact category. The life cycle impacts due to pyrolysis and pretreatment have been evaluated in this study. Impact variations due to alteration in energy (electricity) sources have also been gauged by undertaking different scenarios. The pyrolysis unit and bio-oil combustion unit are the main contributors (> 30%) of GHG emissions. The topics that were not covered in previous reviews, like environmental impact due to pretreatment and product upgrading, are deliberated in detail in this paper. The potential of biochar as a negative emission technology has also been discussed. Based on the reported work, the gaps are identified, and future research opportunities are presented. Highlights: 1. LCA of pretreatment using data from reference sources and analysis. 2. Impact due to product upgradation is deliberated in this review paper. 3. Scenario analysis for electricity source substitution. 4. New (novel) methods of pyrolysis. 5. Introduction to negative emission technology. [ABSTRACT FROM AUTHOR]

In recent years, there has been a significant deal of interest in the photo-fermentation-based synthesis of biological hydrogen due to its unique advantages, such as high hydrogen yield and the use of renewable raw materials as substrates. This paper assesses biological hydrogen production by photo-fermentation using the purple non-sulfur bacteria Rhodobacter capsulatus and Rhodospirillum rubrum cultivated in Rhodobacter capsulatus V minimal (RCV) medium. Lactose was used as a carbon source at a starting concentration of 10 g/L. An investigation of the use Rhodobacter capsulatus and Rhodospirillum rubrum strains in mixed culture confirmed the viability of the use of a co-culture system in detriment of mono-culture systems. On average, co-cultured hydrogen responses resulted in 1.43- and 1.50-fold increases in hydrogen productivity and yield, respectively, between the two species. The experiments were also conducted in a 1.5-L stirred tank reactor using repeated batch cycles, with or without medium renewal. The medium renewal allowed for the removal of organic acids produced by cellular metabolism and ensured stable and long-term hydrogen production, reaching peak productivity 278.05 mmol H2/L/day and maximum yield 19.67 mol H2/mol lactose (82% of the theoretical yield). For comparative purposes, a subsequent assay was carried out in the same initial conditions without medium renewal. An accumulation of organic acids resulted in lower peak productivity of 104.47 mmol H2/L/day and lower peak hydrogen yield of 11.71 mol H2/mol lactose confirming viability of medium renewal strategy to improve hydrogen production in photo-fermentation. [ABSTRACT FROM AUTHOR]

The suitability of globe artichoke crop residues to be transformed into bioethanol was assessed in this paper from the field to the fermenter. A 2-year field trial on "Opera F1" (OF1), a hybrid variety of globe artichoke, resulted in an average annual production of residues of 14 t/ha. The residual biomass of OF1 is made up of 24% glucan and 17% hemicelluloses and is rich in soluble sugars. Water extraction (WE) (100 °C, 15 min) was initially applied to remove simple sugars that can be transformed into saccharification and fermentation inhibitors during the pretreatments. Subsequent dilute acid hydrolysis (DAH) (H2SO4 2%, 121 °C, 1 h) produced a slurry with 17.7, 4.2, and 0.5% (dry matter: DM) of soluble sugars, acetic acid, and total furanic compounds, respectively, and a solid fraction with 52% glucan and 14% xylan, with practically 100% digestibility. Slurry enzymatic hydrolysis (45 FPU/g DM, 7 CBU/g DM, 24 h) had a 69% glucan yield, showing an inhibition of the saccharification process due to the presence of simple sugars and inhibitors. Co-fermentation of the enzymatic slurry with Escherichia coli MS04 produced 12.5 g/L ethanol with a volumetric productivity of 0.52 g/L/h and 76.0% fermentation efficiency after 24 h of fermentation. Considering all sugars generated during DAH, the applied strategy allowed a production of 283 kg/t DM and 2399 kg/ha of bioethanol, against the theoretical value of 2806 kg/ha. [ABSTRACT FROM AUTHOR]

Reshmy et al. [[4]] reviewed cellulase immobilization strategies for biofuel production, discussing different cellulase immobilization strategies, factors, and its kinetics for enhanced biofuel production. A paper by Yadva et al. [[1]] on multidisciplinary pretreatment approaches to improve the bio-methane production from lignocellulosic biomass presents an overview of physical, chemical, biological, and combinatorial pretreatment methods of lignocellulosic substrates and their effect on AD process. There has been an increasing role and significance of industrial bioprocessing and sustainable developments in different walks of life - be it human life or animal life, plant life, or overall on the environment, which has attained global relevance related to sustainable development goals. [Extracted from the article]

Biofuel covers major parts of the transportation sector in the global economic scenarios. Therefore, the impact assessment parameters like environmental, economic, and social are necessary to evaluate for better understanding. Keeping in mind, a life cycle assessment of biodiesel has been done using Jatropha curcas as feedstock. All the steps from cradle (cultivations, pre-treatment, and transesterification) to gate (biodiesel production) have been evaluated. The functional unit of one ton of biodiesel has been taken as reference, and environmental impacts are assessed accordingly using SimaPro. In the current paper, the conventional and room temperature process for biodiesel production is compared in terms of mid-point categories like greenhouse gas (GHG) emission and other endpoint categories like human health, ecosystems, and resources. The results from the life cycle assessment (LCA) indicates that the room temperature process is more energy-saving than the conventional process. Room temperature biodiesel produced around 1195 kg CO2 eq of emission contributing to global warming, whereas the conventional biodiesel contributed around 1228 kg CO2 eq to GHG emission. Further, the Monte Carlo analysis was carried out to quantify the uncertainty in the process in terms of normalized global warming potential. The biodiesel production from the room temperature process can be explored at the industrial level in future. [ABSTRACT FROM AUTHOR]

With the rise in global population, industrialization, and economic expansion, the persistent overconsumption of conventional fossil fuels has resulted in the depletion of fossil fuel reserves. This has fuelled the need to investigate and boost scientific research efforts on sustainable and renewable bioenergy feedstock. A substitute that can minimize reliance on nonrenewable energy resources while also lowering greenhouse gas emissions. In this context, biofuels have received a great deal of interest in recent years as a prospective substitute for conventional fossil fuels. The prime reason behind this is the feedstock utilized in their synthesis. The feedstocks employed here are environmentally safe, nontoxic, and emit little to no pollution. These feedstocks are classified into four generations: first, second, third, and fourth. Food crops and lignocellulosic biomass and waste constitute first- and second-generation feedstocks. The third- and fourth-generation feedstock is microalgae. This paper provides a comprehensive overview of feedstocks utilized to produce biofuels, including the various pre-treatment methods, strategies, and techno-economic analysis in order to pave the way for next-generation biofuels. It also covers the advantages, drawbacks, challenges, and current developments. [ABSTRACT FROM AUTHOR]

Cow dung is generally used as the feedstock material for the anaerobic digestion to produce biogas. A selection of alternate biomass material is needed to reduce the consumption or to eliminate the use of cow dung. Recently, cottonseed hull has been considered as the primary substrate to produce biogas. In this paper, the effect of biogas production on anaerobic co-digestion of CD with pre-treated CSH using sulfuric acid, hydrochloric acid, hydrogen per oxide, and acetic acid is investigated. The concentration of each acid has been varied as 1%, 2%, and 3%. In addition, the two alkaline, namely, sodium hydroxide and calcium hydroxide, are used at different concentrations of 4%, 6%, and 8%. The biogas yield obtained from the mono-digestion of pre-treated CSH and the co-digestion of CD with chemically treated CSH at the ratio of 75:25 (CD: CSH) using the experimental results are compared. The enhancement of biogas production from the batch reactors at mesophilic temperature where the cow dung is mono- and co-digested with acid-treated and alkaline-treated cotton seed hull are observed and compared. The maximum biogas yield is achieved for the treated CSH at the concentration of 6% NaOH that offers 13-fold improvement over untreated CSH during mono-digestion. Whereas in co-digestion, it achieved a 6-fold improvement over untreated CSH with the ratio of 75:25 at the concentration of 6% Ca(OH)2. [ABSTRACT FROM AUTHOR]

Hydrothermal liquefaction (HTL) is an evolving technology that can convert waste with high moisture and low energy content to electricity, heat, hydrogen and other synthetic fuels more efficiently. The lee side is that the HTL process produces enormous amounts of wastewaters (HTWW), having high organic and nutrient load. The discharge of the HTWW would contaminate the environment and result in the loss of valuable bioenergy sources. The valorisation of HTWW has drawn considerable interest. Therefore, this review highlights the valorisation of wastewater during the HTL of biomass. The review paper begins with the discussion of the role of microalgae in valorizing the HTWW. The survey illustrates that the selection of appropriate technology is dependent on biomass characteristics of the microalgae. Finally, potential research opportunities are recommended to improve the viability of the HTL wastewater valorisation for bioenergy production. Overall, this review concludes that combining various processes, such as microalgae-anaerobic digestion, and bio-electrochemical system - microalgae-anaerobic digestion would be beneficial in maximizing HTWW valorisation. [ABSTRACT FROM AUTHOR]

In this paper, pulsed light (red light, 625 nm) with different parameters were set to study the response of cyanobacterial photosynthetic rate to pulse frequency, intensity, and duty ratio by using the oxygen electrode, in order to achieve optimized light mode for high-efficiency cultivation of microalgae. The results showed that pulsed light with high frequency and small-duty ratio could alleviate photoinhibition under high light stress and achieve similar even higher photosynthetic rate compared to continuous light with the same peak intensity. Photosynthetic rate of cyanobacteria under the same intensity and duty ratio rose with the increase of frequency and reached a relatively stable high level when the frequency went above 100 Hz. Interestingly, under the condition of 2100-µmol photon m−2 s−1 peak intensity, 33% duty ratio, and 200 Hz, the photosynthetic rate was 1.13 times that under continuous light (2100 µmol photon m−2 s−1), saving nearly 67% of the input light energy and improving the conversion rate of light energy by 3.4 times. Mechanisms of pulsed light effect are also analyzed, based on the consumption and accumulation of intermediate substance. The conclusion of this study plays a positive role in reducing the operating cost of algal cultivation by the photobioreactor and even provides a new idea in the microalgal growth under outdoor stress conditions. [ABSTRACT FROM AUTHOR]

Lignin is an aromatic compound found as a major component of plant cell wall and therefore, present abundantly in nature as a renewable resource. Due to its organic nature, it has the potential to serve as feedstock for value addition to sustainable bioproducts. Under biorefinery concept, each of the plant biomass components viz. cellulose, hemicellulose, and lignin must be converted to some or the other products. Thus, development of different strategies to valorize lignin for chemicals other value-added products can remove the economic constraint on bioethanol-based biorefineries. However, lignin is highly heterogenous than its counterparts and therefore, very recalcitrant to bioconversion making its biovalorization very difficult. To fully utilize the potential of lignin, it is necessary to understand its degradation process and develop efficient biochemical/microbial strategies to achieve cost-effective lignin bioconversion. In recent times, many innovations have taken place in sustainable microbial utilization and bioconversion of lignin. Therefore, this paper focuses on the progress made in lignin biotransformation's for production of bio-based products, chemicals, and bioenergy in the context of biorefinery concept, with a critical perspective on biotechnological advancements, challenges, and future needs. [ABSTRACT FROM AUTHOR]

Bioethanol is expected to have a major contribution to transportation fuel consumption; hence, environmental analyses are crucial tools to evaluate its environmental performances. In this paper, a life cycle assessment is carried out to study the environmental performance of a bioethanol production system from Tunisian waste dates. The life cycle foreground data were derived from process simulation, while the background data were provided by the Ecoinvent 3.3 database. The impact assessment method applied is the ReCiPe midpoint (H). Seven environmental impact categories are discussed in detail in the interpretation section: global warming, acidification, eutrophication, agricultural land occupation, water depletion, cumulative energy, and cumulative exergy demands. The results indicate that 1 MJ of bioethanol produced from waste dates generates approximately 0.07 kg CO2-eq, which appears comparable with second-generation bioethanol production. One MJ of bioethanol requires approximately 1.087 MJ-eq of primary energy consumption of which 1.065 MJ is nonrenewable. The electric power generation process is the main contributor to most of the environmental impact categories (process hot spot). Therefore, it is strongly recommended to rely on renewable electricity generation to ensure relevant environmental improvements. [ABSTRACT FROM AUTHOR]

Biomass represents 10% of the total energy use and 55% of all renewable energy in Mexico. It is a key energy source to help Mexico achieve a low-carbon development path to comply with the strict climate mitigation targets needed to avoid catastrophic consequences. However, a major limitation in the construction of reliable future mitigation scenarios is the lack of information regarding in-country greenhouse emission factors associated to both traditional and modern bioenergy devices. This paper aims to close this gap, providing detailed estimates of energy and emission factors from bioenergy devices in the Mexican residential and industrial sectors. In particular, four energy tasks, comprising 67% of current bioenergy use in the country, were selected (charcoal production, biomass drying, space heating, and cooking) with a total of nine bioenergy devices: traditional earth mound charcoal kiln, flash dryer, heater, five types of cookstoves, and an open fire. The thermal efficiency ranged from 10 ± 1 to 26 ± 5% for the cooking devices, 95 ± 1 to 96 ± 1% for the space heater, 34 ± 8% for the charcoal kiln, and 10 ± 2% for the biomass dryer. The modified combustion efficiency was calculated to be 88 ± 1% for the earth mound charcoal kiln, 96–98% for the cookstove, and 93–98% for the space heater. The products of incomplete combustion ranged from 21 ± 6 to 48 ± 12 g for the cooking devices and 58 ± 18 to 340 ± 107 g for the space heaters. CO2 emission factors ranged from 102 ± 2 to 119 ± 2 g/MJ for the local biomass stoves. Relative to other pollutants, the CO emissions per energy unit were the highest, ranging from 1193 ± 184 mg/MJ for the space heater to 18,121 ± 1232 mg/MJ for the earth mound charcoal kiln. The total global warming potential was estimated to be 35 ± 2 gCO2e/MJ for the ONIL stove (modified) and 158 ± 4 gCO2e/MJ for the earth mound charcoal kiln. The estimates presented in this study represent an important contribution to Mexico's inventories in terms of energy performance and emissions parameters of four energy tasks in the industrial and residential sectors. This information will be a baseline to estimate carbon footprint, life cycle assessments, GHG emissions scenarios, and mitigation strategies for local and regional Mexican conditions. [ABSTRACT FROM AUTHOR]

CaO and phosphates showed synergistic effects in the regulation of pyrolysis products in the pyrolysis of when they were directly mixed with camphor wood. The alkyl phenol yield increased during the pyrolysis process of corn straw fermentation residue directly mixed with KH2PO4 supported by γ-Al2O3. Rice stalks from agricultural crops are often disposed as waste. However, the potassium phosphate impregnated raw straw pyrolysis with CaO and Al2O3 has not been reported. This paper studied the synergistic effects of CaO or Al2O3 and three potassium phosphates (i.e., KH2PO4, K2HPO4·3H2O, and K3PO4·3H2O) in the rice straw pyrolysis through pyrolysis–gas chromatography-mass spectrometer (Py-GC/MS) experiments. The results showed that CaO/Al2O3 and potassium phosphates showed synergistic effects in the regulation of the types or contents of phenols, ketones, aldehydes, etc. and increased the contents of phenols, aldehydes, acids, and levoglucosan (LG) from most samples and increased those of ketones compared with those catalyzed by potassium phosphates alone. They were suitable for the production of ketone-rich and acid-low bio-oil, which is an important precursor for the preparation of power or jet fuel. The highest contents of ketones (HCK) reached 56.65% and 56.02% in the pyrolysis of K3PO4·3H2O impregnated rice straw with CaO or Al2O3, respectively. The lowest contents of acids and acetic acid (LCA) were nearly or equal to 0, respectively. HCK and LCA were respectively significantly higher and lower than the values reported in the literatures for biomass catalytic pyrolysis using CaO/Al2O3 and potassium phosphates alone or in combination. Dehydration reactions, etc. were further promoted under the co-catalysis of the two catalysts, and some phenols could be converted to benzene products, etc. For 50% K3PO4·3H2O impregnated sample, the yields of furans reduced sharply after CaO addition. For most impregnated samples except 50% K2HPO4·3H2O and 30% and 50% K3PO4·3H2O samples, the contents of total furans and furfural increased after Al2O3 addition. Highlights: CaO/Al2O3 and potassium phosphates showed synergistic effects in the regulation of the types or contents of phenols, ketones, aldehydes, etc. They were suitable for the production of ketone-rich and acid-low bio-oil, which was an important precursor for the preparation of power or jet fuel. Dehydration reactions, etc. were further promoted under the co-catalysis of the two catalysts, and some phenols could be converted to benzene products, etc. The lowest contents of acids and acetic acid were nearly or equal to 0, respectively. [ABSTRACT FROM AUTHOR]

In this paper, the regions where Cynara cardunculus L. is cultivated in Turkey are revealed, with data obtained from several locations in Turkey. Furthermore, the installation of active biogas plants in these regions has been identified, and the utilization of Cynara cardunculus L. residues as a biomass source, particularly in Izmir biogas plants, has been investigated. To begin, the amount of Cynara cardunculus L. cultivated in the world and Turkey has been determined. According to the Food and Agriculture Organization of the United Nations (FAO)'s recent data for 2019, approximately 1.6 million tons of Cynara cardunculus L. were produced globally, with Turkey accounting for nearly 2.5% of this quantity. The data from the Biomass Energy Potential Map for Turkey (BEPA) was reviewed, and it was calculated that approximately 40 thousand tons of Cynara cardunculus L. are produced in Turkey each year. Furthermore, the agricultural production of this crop in Turkey generates roughly 225 thousand tons of residues. In comparison to other regions, the Izmir region generates 32.5% of Turkey's Cynara cardunculus L. residues. However, no research on the evaluation of this residue potential and the utilization of Cynara cardunculus L. residues in biogas production has been conducted to date. As a result, it was aimed at the residual potential of Cynara cardunculus L. in various regions of Turkey, as well as its potential utilization as a biomass resource for biogas plants in these areas. It has been calculated that 1.65% of the Izmir population could supply its energy demands by utilizing the energy equivalent of the Izmir region's wastes. [ABSTRACT FROM AUTHOR]

This paper introduces a methodological framework for assessing the sustainability of solid biofuels in Mexico. The designed framework comprises 13 normalized indicators and two diagnostic studies, covering the economic, social, environmental, and institutional sustainability dimensions, and their intersections. Indicators are normalized using the concept of load capacity of a system, similarly to the planetary boundaries. Thus, the graphical representation of results facilitates their multidimensional analysis. The framework was applied to three case studies: traditional fuelwood in rural households, charcoal for restaurant grilling, and electricity cogeneration from sugarcane bagasse. This was part of an iterative process of testing and refining the framework and simultaneously demonstrating its application in the Mexican bioenergy context. This led to the conclusion that the resulting framework (a) provides a useful, quantitative, and comprehensive overview of both broad and specific sustainability aspects of the assessed system; (b) requires a balance of accessible but also scattered or sensitive data, similarly to most existing frameworks; (c) is highly flexible and applicable to both modern and traditional solid biofuels; and (d) is simple to communicate and interpret for a wide audience. Key directions for improvement of the framework are also discussed. [ABSTRACT FROM AUTHOR]

Biomass is considered an important source of energy, in particular wood and forestry waste are one of the major sources of biomass energy in some places for residential use. However, little information is given for industrial use. This paper evaluates the environmental life cycle of the combustion of forestry waste for the generation of heat that is used in a sawmill. The sawmill produces plywood and timber in the state of Durango, Mexico, and produces forestry waste that needs to be valorized into energy. Hence, its environmental impact assessment was compared when fuel oil is used for energy generation. The results of the life cycle assessment suggest that the heat generated by the combustion of biomass is environmentally more attractive, obtaining a negative mitigation of − 107.8% in the category of eutrophication potential, when is compared with fuel oil. Thus, considering the indexes of each of the categories, the potential environmental index (PEI) was 0.064 when forestry waste is used in contrast with 0.156 PEI/MJ for fuel oil. It is concluded that the waste obtained in the forestry industry can be used for heat generation and thus contributes to the energy required for the forestry industry, with less environmental impacts than fuel oil. [ABSTRACT FROM AUTHOR]

Life cycle assessments conducted in the last decade on forest-derived solid biofuels contain key insights to assess the environmental impact of such fuels under different contexts. This paper reports on the results of a systematic review of 87 studies that applied life cycles assessment on five types of solid biofuels: firewood, charcoal, wood chips, briquettes, and pellets. By considering the particularities of the countries in which the studies were conducted, biomass sources, end-uses and life cycle methodological choices, and key insights were derived about the global distribution of studies and what existing works can contribute to general understanding of the sustainability of wood-based fuels. First, most life cycles assessment focus on modern solid biofuels in developed countries, only 13% were on traditional solid biofuels such as firewood and charcoal in developing countries. Secondly, there are remarkable inconsistencies across studies in how they report and define their system boundaries. Thirdly, global warming potential is the most widely applied impact category. A meta-analysis of a subset of the studies (N = 26) revealed that, in general, forest-derived solid biofuels have lower global warming potential than fossil-based alternatives. Given the global imbalance of life cycle assessment efforts on forest-derived solid biofuels, there is need to mobilize capacities in order to increase applications in developing nations. However, persistent low uptake of standardized application and reporting in life cycle assessment studies perpetuates oft-mentioned limitations for cross-study comparisons. An approach to standardize system boundaries is proposed to partially address these limitations. [ABSTRACT FROM AUTHOR]

In Mexico, the possibility to exploit orange peels or sugarcane straw to generate heat has not been fully explored, even though they are major agronomic wastes generated in Mexico. Therefore, this paper aims to assess the heat generation's environmental and economic performance from these feedstocks in a fruit-processing facility located in Veracruz, Mexico. The environmental performance was assessed through the life-cycle assessment methodology, while the economic performance was estimated through the total levelized cost of energy (TLCE) considering two scenarios: (1) a base scenario where orange peels are burnt to produce process steam, and (2) a second scenario where sugarcane straw is co-fired with it. Both scenarios assume to partially displace heavy-fuel–oil (HFO) for steam generation. Results indicate that the impacts of the use of residual biomass-based heat on the potential global warming, ozone layer depletion, marine aquatic ecotoxicity, and cumulative energy demand are 34–63% lower than when using HFO and decrease the TLCE by 18–21%. However, there is also an increase in other environmental impact categories such as human toxicity, photochemical oxidation, or eutrophication. The use of orange from organic farms improves the environmental results in some of these categories. The drying and combustion of the biomass, as well as the waste treatment, are the major contributors to the environmental impacts. On the other hand, capital and fuel costs are the major contributors to TLCE. Overall, the use of orange peels and sugarcane straw to generate heat is attractive from the environmental and economic point of views. [ABSTRACT FROM AUTHOR]

Combination of chemical treatment by cosolvent with hydrodynamic cavitation is a novel technique of intensification of alkali-catalyzed transesterification of sunflower oil with methanol. The paper investigated the effect of operating parameters such as reaction mixture inlet pressure (p1), methanol to oil molar ratio (M1), the concentration of catalyst (Cc), methanol to tetrahydrofuran (THF) molar ratio (M2), temperature (T), and a number of passes through the hydrodynamic cavitation reactor (n) of transesterification of sunflower oil in the presence of the cosolvent assisted by hydrodynamic cavitation (ACTC) on the triglyceride conversion (TC). ACTC was performed by a venturi-type cavitation reactor (VCR) of a given design. The effect of the operational parameters on the TC was investigated by the method of independent variation of the value of one operating parameter. The obtained results indicated that (a) at p1 ≥ 304.0 kPa TC increased from TC = 0 to TC = 98% following the rise in p1; (b) maximum TC = 95% was achieved at M1 = 3; (c) rise in M1 within range 3 ≤ M1 ≤ 9 led to a linear increase from TC = 95 to TC = 100%; (d) maximum TC = 95% was achieved at 1.0%wt ≤ Cc ≥ 1.1%wt; (e) maximum TC = 99% was achieved at M2 = 1.5; (f) TC linearly decreased from TC = 95 to TC = 88% with T rise from T = 20 to T = 55 °C; (g) the rise in n resulted in a linear increase of TC from TC = 94 (n = 1) to TC = 99% (n = 10); and (h) cavitation yield (CY) declines from CY = 0.528 (n = 1) to CY = 0.056 g/J (n = 10). [ABSTRACT FROM AUTHOR]