Potential Biorefinery Research Articles

Techno-economic and environmental assessment of dietary fibre extraction from soybean hulls

This research evaluates the economic and environmental feasibility of extracting dietary fibre (DF) from a by-product such as soybean hulls. Techno-economic (TEA) and life cycle assessment (LCA) were carried out to identify the critical factors that may limit the implementation of a potential biorefinery plant. The modelling of the process was carried out on the basis of mass and energy balances, as well as the characteristics of the required equipment. TEA indicators such as minimum selling price (MSP), fixed capital investment, manufacturing costs were evaluated. A cradle-to-gate LCA approach and a functional unit (FU) of 1 kg of product (85% DF content) were considered. Impact categories such as global warming (GW), eutrophication, eco-toxicity, among others, were analysed. The results indicate that the production capacity achieves the plateau at about 56 kt y−1, with an MSP value of 2.6 $·kg−1. Furthermore, the GW profile was 8.76 kg CO2eq per FU, and the main hotspot is the alkaline digestion stage due to the use of potassium hydroxide (KOH). Nevertheless, the management of the hulls from multi-product food plants and switching KOH production to renewable sources may reduce the profile in almost all categories analysed.

Constructing Marine Bacterial Metabolic Chassis for Potential Biorefinery of Red Algal Biomass and Agaropectin Wastes.

Marine red algal biomass is a promising feedstock for sustainable production of value-added chemicals. However, the major constituents of red algal biomass, such as agar and carrageenan, are not easily assimilated by most industrial metabolic chassis developed to date. Synthetic biology offers a solution by utilizing nonmodel organisms as metabolic chassis for consolidated biological processes. In this study, the marine heterotrophic bacterium Pseudoalteromonas atlantica T6c was harnessed as a metabolic chassis to produce value-added chemicals from the affordable red algal galactans or agaropectin, a byproduct of industrial agarose production. To construct a heterologous gene expression device in P. atlantica T6c, promoters related to agar metabolism were screened from the differentially expressed genes using RNA-Seq analysis. The expression device was built and tested with selected promoters fused to a reporter gene and tuned by incorporation of a cognate repressor predicted from the agar-specific polysaccharide utilization locus. The feasibility of the marine bacterial metabolic chassis was examined by introducing the biosynthetic gene clusters of β-carotene and violacein. Our results demonstrate that the metabolic chassis platform enables direct conversion of low-cost red algal galactans or industrial waste agaropectin into valuable bioactive pigments without any pretreatment of biomass. The developed marine bacterial chassis could potentially be used in a biorefinery framework to produce value-added chemicals from marine algal galactans.

Optimizing protein recovery from plant substrate using ultrafiltration: A case study on wheatgrass

Providing the world's population with valuable food and proteins is considered as one of the greatest challenges of the upcoming decade. In this study, a process to recover nitrogen/protein concentrates from wheatgrass using a cascaded ultrafiltration was investigated. First, washing of wheatgrass during a mechanical extraction was examined with a ratio up to 1:2 (press cake/washing fluid, w/w). This was followed by a statistical investigation (full factorial experimental design) on the influences of substrate storage conditions (SSC), pre-shredding (PS) and washing conditions (WC) on the protein content of the resulting fraction, expressed by a nitrogen recovery rate (NRR). Washing of wheatgrass during the mechanical extraction was found to increase NRR by up to 29%–67.8% at a 1:2 ratio (1:0–46.0%, 1:0.5–53.0%, 1:1–58.0%). Significant effects (p-value <0.05) were found in the resulting crude juice for the variation of SSC between fresh and frozen/thawed wheatgrass (NRR 80.5%/62.8%) and for washing/non-washing during the mechanical extraction (NRR 76.1%/67.2%). These significant influences were detected in almost all subsequent fractions, whereas no significant effect was found for the influence of pre-shredding (p-value >0.05). An optimal process consisting of processing freshly harvested wheatgrass and a washing ratio of 1:2 during mechanical extraction led to a protein-rich fraction by ultrafiltration with a NRR of 34.4%. This NRR is comparable to recovery rates achieved with established substrates and processes. The protein-rich fraction can meet the daily requirements of protein quantities and macro minerals such as potassium, magnesium and phosphorous, providing more than 100% of the recommended intake. It was noted that 41.6% of the nitrogen in wheatgrass fell to by-product streams that need to be utilized to increase economic potential (biorefinery).

Bioengineering of biowaste to recover bioproducts and bioenergy: A circular economy approach towards sustainable zero-waste environment

The inevitable need for waste valorisation and management has revolutionized the way in which the waste is visualised as a potential biorefinery for various product development rather than offensive trash. Biowaste has emerged as a potential feedstock to produce several value-added products. Bioenergy generation is one of the potential applications originating from the valorisation of biowaste. Bioenergy production requires analysis and optimization of various parameters such as biowaste composition and conversion potential to develop innovative and sustainable technologies for most effective utilization of biowaste with enhanced bioenergy production. In this context, feedstocks, such as food, agriculture, beverage, and municipal solid waste act as promising resources to produce renewable energy. Similarly, the concept of microbial fuel cells employing biowaste has clearly gained research focus in the past few decades. Despite of these potential benefits, the area of bioenergy generation still is in infancy and requires more interdisciplinary research to be sustainable alternatives. This review is aimed at analysing the bioconversion potential of biowaste to renewable energy. The possibility of valorising underutilized biowaste substrates is elaborately presented. In addition, the application and efficiency of microbial fuel cells in utilizing biowaste are described in detail taking into consideration of its great scope. Furthermore, the review addresses the significance bioreactor development for energy production along with major challenges and future prospects in bioenergy production. Based on this review it can be concluded that bioenergy production utilizing biowaste can clearly open new avenues in the field of waste valorisation and energy research. Systematic and strategic developments considering the techno economic feasibilities of this excellent energy generation process will make them a true sustainable alternative for conventional energy sources.

Ginger waste as a potential feedstock for a zero-waste ginger biorefinery: a review

Ginger waste is an increasingly available renewable feedstock, which is rich in biobased chemicals and materials as well as a source of bioenergy. Ginger waste is explored as a feedstock leading to a potential zero-waste biorefinery.

Enzymatic Conversion of Hydrolysis Lignin—A Potential Biorefinery Approach

Lignin is an abundant and renewable source capable of replacing different raw materials in the chemical industry. It can be obtained from lignocellulosic biomass (LCB) via different pretreatment methods. In the present study, hydrolysis lignin (HL) from the SunburstTM pretreatment technology was utilized to investigate its enzymatic conversion. At first, soluble HL fractions were obtained via alkali solubilization followed by acid precipitation, referred to as acid precipitated lignin (APL). Furthermore, the APL was tested with three different bacterial laccases to identify the optimal conditions for its conversion into small molecular weight fractions. Among the tested laccases, Streptomyces coelicolor A3(2) (ScLac) displayed the highest rate of APL conversion with a high lignin dosage and under extremely alkaline conditions, i.e., 50 g/L in 0.25 M NaOH solution, resulting in higher molecular weight fractions. The increase in the molecular weight and quantitative linkages before and after the enzymatic oxidation of the APL were characterized by size exclusion chromatography (SEC), Fourier-transform infrared spectroscopy (FT-IR), and two-dimensional heteronuclear single quantum correlation nuclear magnetic resonance (2D HSQC NMR) methods.

Exploration of Cucumber Waste as a Potential Biorefinery Feedstock

The exploration of cucumber waste as a potential biorefinery feedstock is reported. Initially, extractives (essential oils) were isolated from cucumber waste via vacuum microwave hydro-distillation (VMHD). The yield and quality of the extractive were compared with respect to traditional hydro-distillation (HD). The essential oils were obtained over a range of microwave power (500, 750, 1000 W) and vacuum pressures (100, 200, 300 mbar). The highest quality (0.49 wt %) was obtained at a microwave irradiation power of 500 W and a vacuum of 300 mbar. VMHD is much quicker and more energy-efficient than HD. Within the context of a zero-waste biorefinery, the extractive-free residues were the solid residues from two different extraction methods were compared and characterized by ATR-IR, 13C solid-state NMR spectroscopy, SEM, TGA, and CHN elemental analysis. The resultant residues are cellulosic-rich, and no significant changes were observed with VMHD and HD treatment. The results indicated that the utilization of these residues can provide an efficient, inexpensive, and environment-friendly platform for the production of cellulosic materials.

Brazilian banana, guava, and orange fruit and waste production as a potential biorefinery feedstock

Brazilian banana, guava, and orange fruit and waste production as a potential biorefinery feedstock

The effect of reactor scale on biochars and pyrolysis liquids from slow pyrolysis of coffee silverskin, grape pomace and olive mill waste, in auger reactors

Several studies have addressed the potential biorefinery, through small-scale pyrolysis, of coffee silverskin (CSS), grape pomace (GP) and olive mill waste (OMW), which are respectively the main solid residues from coffee roasting, wine making and olive oil production processes. However, increasing the scale of reactor to bring these studies to an industrial level may affect the properties, and hence applications, of the resulting products. The aim of this study is therefore to perform pilot scale experiments to compare and verify the results of analytical study (TGA) and bench scale reactor runs, in order to understand the fundamental differences and create correlations between pyrolysis runs at different scales. To this end, pyrolysis liquids and biochars from the slow pyrolysis of CSS, GP and OMW, performed using different scale auger reactors (15 kg/h and 0.3 kg/h), have been analysed (TGA, pH, density, proximate and ultimate analyses, HHV, FTIR, GCMS) and compared. The results showed no major differences in biochars when the temperature and the solid residence time were fixed. However, regarding pyrolysis liquids, compounds from the lab reactor were more degraded than pilot plant ones, due to, in this case, the vapour residence time was longer. Regarding the properties of the pyrolysis products, GP 400 °C biochars showed the best properties for combustion; CSS biochars were especially rich in nitrogen, and 400 °C GP and OMW pyrolysis liquids showed the highest number of phenolics. Hence, this study is considered a first step towards industrial scale CSS, GP and OMW pyrolysis-based biorefinery.

Estimation of Bioethanol, Biohydrogen, and Chemicals Production from Biomass Wastes in Brazil

AbstractThe aim of this study is to evaluate the potential of some selected biomass waste to be used as feedstock in the production of bioethanol and biohydrogen along with chemicals in Brazil. The substrates are rice bran (RB), rice husk (RH), brewer's spent grain (BSG), soybean waste (SW), and wheat waste (WW). These substrates are treated by diluted acid hydrolysis in an autoclave under different conditions of acid concentration, temperature, reaction time, and moisture. The highest concentration of reducing sugars (RS) of RH, RB, BSG, SW, and WW hydrolysates, measured by the 3,5‐dinitrosalicylic acid method (DNS), is 118.16 ± 2.85, 170.39 ± 20.47, 600.97 ± 23.05, 80.38 ± 2.39, and 228.04 ± 3.97 gRS kg−1substrate (dry basis), respectively. Total sugar concentration (cellobiose, glucose, xylose, arabinose) in the RH, RB, BSG, SW, and WW hydrolysates (with highest concentration of RS) is 56.54 ± 3.65, 42.99 ± 0.84, 72.18 ± 2.34, 42.48 ± 0.18, and 78.03 ± 3.06 gsugar kg−1substrate (dry basis). The total potential of bioethanol and biohydrogen production from the biomass assessed is 199.61 million L per year and 96.14 million m3 per year, respectively. Therefore, the assessed biomass is proved to be a potential biorefinery feedstock.

Evaluating the potential of marginal lands available for sustainable cellulosic biofuel production in Italy

The European Union aims to provide as much as one quarter of its transportation fuels via biofuels derived from renewable sources by 2030. To put this into perspective, the Italian government has recently established an ambitious goal to support the wider uptake of advanced second-generation biofuels, including cellulosic biofuels for the transportation sector. A sustainable way forward is to grow perennial biomass crops on marginal lands, however the nationwide availability of those lands for lignocellulosic feedstock production remains uncertain. We identify and evaluate the potential of marginal lands in Italy to produce sizeable amounts of biomass for sustainable cellulosic biofuel production while limiting land use conflicts and negative ecological impacts. We applied spatial multi-criteria decision analysis techniques in geographic information systems to ultimately generate spatially-explicit national land suitability and availability maps at a fine resolution (250-m). We selected a broad range of leading cellulosic biomass crops that includes poplar (Populus × canadensis Moench), willow (Salix alba Linnaeus), black locust (Robinia pseudoacacia Linnaeus), giant reed (Arundo donax Linnaeus), and vetiver grass (Chrysopogon zizanioides Linnaeus). Based on marginality criteria, our results suggest that such biomass plantations of perennial grasses and short rotation trees may produce 3.1–27.4 billion liters of cellulosic ethanol per year from 462,265 to 2,811,064 million hectares of available marginal lands. This estimated production may fulfill 7.8–69.1% of Italy's current liquid transportation fuel consumption, constrained by the requirement that each modelled location be within 70 km of a potential cellulosic biorefinery. Collectively, this study provides the cornerstone of efforts to rationally meet Italy's need for renewable fuels in a sustainable low-carbon economy future.

An enhanced excess sludge fermentation process by anthraquinone-2-sulfonate as electron shuttles for the biorefinery of zero-carbon hydrogen

Excess sludge (ES) largely produced in municipal wastewater treatment plants is known as a waste biomass and the traditional treatment processes such as landfill and incineration are considered as unsustainable due to the negative environmental impact. Fermentation process of ES for the biorefinery of zero-carbon hydrogen has attracted an increasing interesting and was extensively researched in the last decades. However, the technology is far from commercial application due to the insufficient effectivity. In the present study, anthraquinone-2-sulfonate (AQS) as electron shuttles was introduced into the fermentation process of ES for mediating the composition and activity of bacterial community to get an enhanced biohydrogen production. Inoculated with the same anaerobic activated sludge of 1.12 gVSS/L, a series of batch anaerobic fermentation systems with various dosage of AQS were conducted at the same ES load of 2.75 gVSS/L, initial pH 6.5 and 35 °C. The results showed that the fermentation process was remarkably enhanced by the introduction of 100 mg/L AQS, accompanying the lag phase was shortened to 1.35 h from 7.62. The obtained biohydrogen yield and the specific biohydrogen production rate were also remarkably enhanced to 24.9 mL/gVSS and 0.3 mL/(gVSS·h), respectively. Illumina Miseq sequencing showed that Longilinea and Guggenheimella as the dominant genera had been enriched from 9.2% to 0–12.0% and 4.7%, respectively, in the presence of 100 mg/L AQS. Function predicted analysis suggested that the presence of AQS had increased the abundance of genes involved in the transport and metabolism of carbohydrate, amino acid and energy production. Further redundancy analysis (RDA) revealed that the enhanced hydrogen production was highly positively correlated with the enrichment of genera such as Longilinea and Guggenheimella. The research work presents a novel potential biorefinery of ES for the effective production of zero-carbon hydrogen.

Examination and optimization of lignocellulolytic activity of Stereum gausapatum F28 on beechwood sawdust supplemented with molasses stillage

This study provides a detailed analysis of the lignocellulolytic activity of a new isolate Stereum gausapatum F28, a Serbian autochthonous fungi, on beechwood sawdust supplemented with cheap waste, sugar beet molasses stillage. Advanced multiple response optimization techniques were applied to improve ligninolytic and reduce hydrolytic activity as a requirement for potential biorefinery use. The applied techniques were supposed to select cultivation conditions that would give manganese peroxidase and laccase activities above 0.84 and 0.12 U g-1 substrate, respectively, and cellulase and xylanase activities below 1.12 and 1.4 U g-1 substrate. The optimal cultivation conditions that met the set requirements included molasses stillage concentration of 10 %, substrate moisture content of 53 %, incubation temperature of 23.5 ?C, and pH 5.2. The research showed that the addition of molasses stillage had a positive effect on enzyme production and that the optimal stillage concentration differed depending on the enzyme type (for laccase it was &lt;5 %, manganese peroxidase ?12 %, cellulase ?21 % and xylanase ?16 %), which should be taken into consideration when optimizing the desired process.

Techno‐economic assessment of polylactic acid and polybutylene succinate production in an integrated sugarcane biorefinery

AbstractPlastic waste pollution is a growing environmental concern due to the increased use of conventional plastics. This study investigates the techno‐economics of biodegradable, bio‐based plastics, i.e. polylactic acid (PLA) and polybutylene succinate (PBS), as potential substitutes for conventional plastics, to identify the most viable one to be produced in a biorefinery annexed to a typical sugar mill. Six potential biorefinery scenarios were simulated in Aspen Plus®, in which PLA or PBS is derived from sugarcane molasses (1G scenarios), bagasse and harvesting residues (2G scenarios) or a mixture of molasses, bagasse, and harvesting residues (1G2G scenarios). The economic feasibility of the PLA and PBS scenarios was evaluated by means of the minimum selling prices (MSP) for an acceptable return on investment. The PLA scenarios showed lower MSPs than PBS with the 1G2G scenario having the lowest MSP (2965 US$ t–1), comparable to the commonly available PLA from corn grain (5140 US$ t–1). Polylactic acid benefited from lower process energy demands (5.5–5.8 MJ kg–1 of biomass or sugars processed) compared to PBS (5.1–8.2 MJ kg–1), which plays a crucial role in an energy self‐sufficient biorefinery. Furthermore, a 1G‐biorefinery was identified producing a fully biobased PBS at an MSP of 2980 US$ t–1 that is price competitive against fossil‐derived PBS (2380 US$ t–1) and partially bio‐derived PBS (4730 US$ t–1). To date, this was the first study to evaluate the detailed techno‐economics of a fully biobased and biodegradable PBS biorefinery in an energy self‐sufficient context, which was demonstrated to be cost‐competitive against both partial bio‐derived PBS and fully bio‐derived PBS. © 2021 Society of Chemical Industry and John Wiley &amp; Sons, Ltd

Production of ethyl levulinate fuel bioadditive from 5-hydroxymethylfurfural over sulfonic acid functionalized biochar catalysts

In this work, a series of novel -SO3H functionalized biochar materials were prepared and investigated for the first time as catalysts for the production of fuel additive ethyl levulinate (EL) from biomass-derived 5-hydroxymethylfurfural (HMF). The employed biochar was directly produced from vineyard pruning wastes by a simple hydrothermal treatment using water in subcritical conditions followed by 3 different one-step sulfonation processes. The effects of sulfonating agent, reaction temperature, reaction time and alcohol solvent were examined. Full HMF conversion together with outstanding EL yields (over 84%) were achieved at 130 °C and after 6 h over the biochar functionalized with the organosilane 2-(4-chlorosulphonylphenyl)ethyltrimetoxysilane (BioC-S3). Catalyst characterization suggested that the high acid strength (0.983 mmol H+·g−1) derived from the anchoring of arylsulfonic groups were responsible for the promotion of acid-driven etherification and ethanolysis steps. The BioC-S3 catalyst can be recycled without a significant loss of catalytic activity, indicating the stability of – SO3H organosilane group structure in the porous biochar. The obtained results offer a competitive alternative for the production of fuel additives, such as alkyl levulinates, using low-cost and easy-to-prepare biochar-based catalysts, all from lignocellulose resources, as an example to support a future exploitation of a potential biorefinery.

Camellia oleifera shell as a potential agricultural by-product for paper production

The aim of this study was to investigate a potential biorefinery process to realize the high utilization of Camellia oleifera shell (COS), which is an agricultural by-product mainly composed of cellulose, hemicellulose, and lignin. Before treatment by steam explosion, the COS was impregnated with water, 3.0 wt% NaOH solution, or 3.0 wt% H2SO4 solution. The morphological structure and chemical composition of the steam-exploded COS pulp were investigated. The results indicated that the impregnation treatments increased the cellulose content of the steam-exploded COS pulp and decreased the hemicellulose and lignin content. The morphology of steam-exploded COS fiber was short, coarse and stiff. Hydrophobic and colorful handsheets were fabricated by mixing proportional bleached softwood fiber. This study demonstrated that COS was a potential material for the papermaking industry, and the combination of water impregnation and steam explosion treatment for COS was a good pulp process.

Potential ethanol biorefinery sites based on agricultural residues in Alberta, Canada: A GIS approach with feedstock variability

Though numerous studies have investigated optimal locations for biorefineries given the availability of feedstock supplies, few have considered that these supplies could vary over time, thereby potentially failing to meet feedstock requirements. In this paper, we develop a process for identifying a shortlist of five potentially viable biorefinery sites in Alberta, and then consider the stochastic nature of these supplies, and what that variation could mean for supplying a biorefinery. A shortlist of sites was selected based on agricultural residues within a distance of 80 km of the site. Across all sites, a total amount of 16.7 million t [oven dried] y −1 is found to be economically accessible in the province. However, this shortlist is based only on a summation of one-year crop yields surrounding the sites. When crop yield variability (estimated from data over 40 years between 1978 and 2017) is also considered, substantially different results were found. For example, if supply was required to exceed 1.59 million t [oven dried] y −1 , 95% of the time, then two selected sites, which were chosen based on one-year crop yields, must be excluded. Under these circumstances the total amount available across sites falls to 12.4 million t [oven dried] y −1 . Overall, when variability in supply is included as a criterion, site selection and rankings change, suggesting that site selection using only an average or point estimate is not sufficient. Instead, more sophisticated techniques to investigate feedstock supply variability would be useful. • Economic accessibility of agricultural residues can vary substantially over time. • Selecting biorefinery locations based on one year of data is misleading. • Modelling stochastic feedstock supplies can improve biorefinery siting decisions.

Valorization of apple and grape wastes with malic acid-degrading yeasts.

It is estimated that more than 20% of processed apples and grapes are discarded as waste, which is dominated by pomace rich in malic acid that could be converted to high-value organic acids or other chemicals. A total of 98 yeast strains isolated from apple, grape, and plum wastes were evaluated for their ability to degrade malic acid relative to known yeast strains. Most (94%) of the new isolates degraded malic acid efficiently (>50%) in the presence and absence of exogenous glucose, whereas only 14% of the known strains could do so, thus confirming the value of exploring (and exploiting) natural biodiversity. The best candidates were evaluated in synthetic media for their ability to convert malic acid to other valuable products under aerobic and oxygen-limited conditions, with two strains that produced ethanol and acetic acid as potential biorefinery products during aerobic cultivations andoxygen-limited fermentations on sterilized apple and grape pomace. Noteworthy was the identification of a Saccharomyces cerevisiae strain that is more efficient in degrading malic acid than other members of the species. This natural strain could be of value in the wine-making industry that often requires pH corrections due to excess malic acid.

A biorefinery for the valorization of marigold (Calendula officinalis) residues to produce biogas and phenolic compounds

Marigold (Calendula officinalis) market is focused on the extraction of compounds from the flower for homeopathic applications. However, most of the body plant is left as waste for final disposition. This work aims to show an integral valorization of leaves and stem of marigold to produce biogas and phenolic compounds such as vanillin and vanillic acid in a biorefinery scheme. An alkaline pretreatment was carried out to obtain black liquor and to favor the digestibility of the solid residue. The black liquor was oxidized in a high-pressure reactor, reaching experimental yields of 5.09% and 1.16% (based on lignin) for vanillin and vanillic acid, respectively. The remaining solid fraction was fermented through anaerobic digestion, achieving biogas productivity of 1621.3 mL/g of volatile solids. Afterward, these experimental results were used as input parameters to simulate and analyze a potential biorefinery. It was demonstrated that the anaerobic digestion stage affects up to 59% of the capital costs and that the positive economic gains were achieved at flow rates greater than 6.64 ton/h.

Bioenergy in the Canadian Prairies: Assessment of accessible biomass from agricultural crop residues and identification of potential biorefinery sites

Biomass from crop residues as an alternative energy source has generated considerable interest to significantly reduce greenhouse gas emissions, promote energy independence, and promote regional development. Using disaggregate crop production data and a GIS-based service area approach, this study examines the available and accessible biomass from agricultural crop residues and identifies the locations and sizes of potential biorefinery sites in the Canadian Prairies. The economic constraints associated with site selections include the site's road access, economical transport feasibility, economies of scale for residue processing, and workforce availability. In total, we found twelve plants in the Prairie area, six in Alberta, five in Saskatchewan, and one in Manitoba. The amount of total accessible biomass for the identified biorefineries is 35.39 dry million tonnes, which is approximately 40% of the Prairies' available biomass.