Biofuel Production Process Research Articles

Integration of biosorption operation with biorefinery and biofuel production processes in context of bioeconomy and zero-waste approaches: a pre-feasibility study on Nigella sativa L

Integration of biosorption operation with biorefinery and biofuel production processes in context of bioeconomy and zero-waste approaches: a pre-feasibility study on Nigella sativa L

Graphene oxide mediated enhanced cellulase production using pomegranate waste following co-cultured condition with improved pH and thermal stability

High production cost of cellulase enzyme is one of the major hurdles in economic biomass to biofuel production process at industrial scale. In this context, development of advanced approaches to produce low-cost commercial cellulase is highly demanding. Therefore, in the present study, simultaneous effect of pomegranate waste (PW) and graphene oxide (GO) has been studied to improve the cellulase production along with improved stability towards the incubation temperature and different pH environment. Crude cellulase production has been achieved at high substrate concentration of PW using co-culturing of strains Cladosporium cladosporioides NS2 and Rhizopus oryzae NS5 under the solid-state fermentation (SSF) while using GO as the nanocatalyst. At a substrate concentration of 7.0 g of PW, highest enzymatic activity of 42 IU/gds FP, 271 IU/gds EG and 422 IU/gds BGL have been achieved by mean of 1.5% GO after 72 h. In addition, crude enzyme exhibits 45–55 °C and 3.5–6.5 as the most favorable incubation temperature and pH range, respectively in presence of 1.5% GO. This study reports a potential strategy to improve the production of crude enzyme along with enhanced thermal and pH stability with the implementation of GO as a nanocatalyst. Thus, the present approach offers a sustainable way to produce crude enzyme that can have numerous industrial applications along with economic biomass to biofuels production technology by providing easy, as well as high yield of sugar production via enzymatic hydrolysis of cellulosic biomass. Nevertheless, recycling of GO when employed as catalyst during the entire process remains to be challenging, and therefore efforts should made to overcome this issue.

Sustainability evaluation of microalgae biodiesel production process integrated with nutrient close-loop pathway based on emergy analysis method

To make comprehensive assessment on sustainability of microalgae biofuel production process integrated with nutrient close-loop pathways, Emergy Analysis methodology was adopted based on case studies: microalgae biodiesel production integrated with Nutrient Recycling Pathway in Case A and microalgae biodiesel production integrated with Protein Production as By-Product Pathway in Case B. Emergy results show that microalgae biodiesel system integrated with Nutrient Recycling Pathway is more sustainable, and factor analysis shows that water source with higher unit emergy value and electricity with lower one are more favorable to improve sustainability performance of the integrated process. Besides, different generations of biofuel are also assessed by Emergy Analysis method, and the third-generation biodiesel shows the most sustainable potentials than the previous.

Stimulating effects of glycerol on the growth, phycoremediation and biofuel potential of Chlorella pyrenoidosa cultivated in wastewater

Chlorella pyrenoidosa is one of the potential microalgae to build sustainable processes for biofuel production alongside the phycoremediation of wastewater. However, low lipid content and impaired lipid quality are major reasons that make the produced microalgal-biofuel uneconomic. Here, we show supplementation of glycerol, a byproduct of biodiesel industry, at a concentration of 3 gL −1 in synthetic wastewater (SWW) can enhance up to 133.74% lipid accumulation (30.76 ± 0.93% dry wt. basis) in C. pyrenoidosa, as compared to control, without glycerol (13.16 ± 0.25% dry wt. basis). Further, the glycerol supplementation improved the biodiesel quality, as evident from the fatty acid profiling. The glycerol supplementation stimulated the microalgal growth also, both under shake flasks and reactor scale studies. Besides, the glycerol supplementation improved the phycoremediation potential with up to 96.35, 47.22 and 79.88% removal in phosphate, nitrate and chemical oxygen demand (COD) within 15 days of microalgal growth period. Synergistically, up to 457.80 ± 1.11 mgL −1 exopolysaccharides production was attained in the microalgal culture. Such an attempt forwards a stepping-stone for developing sustainable future energy and wastewater treatment infrastructure. • Glycerol improves the growth and biofuel potential of Chlorella pyrenoidosa . • Augmented phycoremediation of SWW using Chlorella pyrenoidosa with glycerol. • Improved fatty acid profile for providing biodiesel as per International standards. • First report on microalgal EPS production through glycerol supplementation.

Life cycle and techno-economic assessment of source-separated wastewater-integrated microalgae biofuel production plant: A nutrient organization approach

Microalgae cultivating in wastewater enabling nutrient uptake for biomass and biofuel generation is regarded as a promising pathway to increase sustainability of microalgae biofuel production process. A source-separated nutrient organization approach for the process of wastewater-based microalgae biofuel is proposed in this study. Comparative life cycle assessment (LCA) method and Techno-economic analysis (TEA) approach are employed to assess sustainability and economic performance of the proposed nutrient approach. Two scenarios are used to validate our study. Scenario 1 is based on the source-separated nutrient delivery approach with microalgae integrated wastewater in tertiary treatment. Scenario 2 is based on non-separated-point nutrient delivery policy and microalgae integrated with secondary wastewater treatment. The results show that the source-separated nutrient approach is effective for reducing the environmental impacts and increasing commercial potential of microalgae biofuel.

Crystal Structure and Molecular Mechanism of Phosphotransbutyrylase from Clostridium acetobutylicum.

Acetone-butanol-ethanol (ABE) fermentation by the anaerobic bacterium Clostridium acetobutylicum has been considered a promising process of industrial biofuel production. Phosphotransbutyrylase (phosphate butyryltransferase, PTB) plays a crucial role in butyrate metabolism by catalyzing the reversible conversion of butyryl-CoA into butyryl phosphate. Here, we report the crystal structure of PTB from the Clostridial host for ABE fermentation, C. acetobutylicum, (CaPTB) at a 2.9 Å resolution. The overall structure of the CaPTB monomer is quite similar to those of other acyltransferases, with some regional structural differences. The monomeric structure of CaPTB consists of two distinct domains, the N- and C-terminal domains. The active site cleft was formed at the interface between the two domains. Interestingly, the crystal structure of CaPTB contained eight molecules per asymmetric unit, forming an octamer, and the size-exclusion chromatography experiment also suggested that the enzyme exists as an octamer in solution. The structural analysis of CaPTB identifies the substrate binding mode of the enzyme and comparisons with other acyltransferase structures lead us to speculate that the enzyme undergoes a conformational change upon binding of its substrate.

Desulphurization of drop-in fuel produced through lipid pyrolysis using brown grease and biosolids feedstocks

Biosolids can be incorporated as a water replacement into a two-stage thermal process for biofuel production from brown greases, significantly reducing the overall environmental impact of the process. Unfortunately, the use of biosolids resulted in an appreciable amount of sulphur in the pyrolytic oils produced in the final stage of the process. Here, we first evaluated the relationship between the sulphur content of fatty acids pyrolysis liquid products and pyrolytic conditions. Afterwards, we evaluated the sulphur removal efficiency of several approaches such as distillation, extraction and adsorption. Through a combination of distillation and liquid-liquid extraction, we achieved a desulphurization of up to 95% reaching a final sulphur concentration of 15 ± 4 ppm.

Functional characterization of a highly specific l-arabinose transporter from Trichoderma reesei

BackgroundLignocellulose biomass has been investigated as a feedstock for second generation biofuels and other value-added products. Some of the processes for biofuel production utilize cellulases and hemicellulases to convert the lignocellulosic biomass into a range of soluble sugars before fermentation with microorganisms such as yeast Saccharomyces cerevisiae. One of these sugars is l-arabinose, which cannot be utilized naturally by yeast. The first step in l-arabinose catabolism is its transport into the cells, and yeast lacks a specific transporter, which could perform this task.ResultsWe identified Trire2_104072 of Trichoderma reesei as a potential l-arabinose transporter based on its expression profile. This transporter was described already in 2007 as d-xylose transporter XLT1. Electrophysiology experiments with Xenopus laevis oocytes and heterologous expression in yeast revealed that Trire2_104072 is a high-affinity l-arabinose symporter with a Km value in the range of sim 0.1–0.2 mM. It can also transport d-xylose but with low affinity (Kmsim 9 mM). In yeast, l-arabinose transport was inhibited slightly by d-xylose but not by d-glucose in an assay with fivefold excess of the inhibiting sugar. Comparison with known l-arabinose transporters revealed that the expression of Trire2_104072 enabled yeast to uptake l-arabinose at the highest rate in conditions with low extracellular l-arabinose concentration. Despite the high specificity of Trire2_104072 for l-arabinose, the growth of its T. reesei deletion mutant was only affected at low l-arabinose concentrations.ConclusionsDue to its high affinity for l-arabinose and low inhibition by d-glucose or d-xylose, Trire2_104072 could serve as a good candidate for improving the existing pentose-utilizing yeast strains. The discovery of a highly specific l-arabinose transporter also adds to our knowledge of the primary metabolism of T. reesei. The phenotype of the deletion strain suggests the involvement of other transporters in l-arabinose transport in this species.

A Review of Energy Consumption in the Acquisition of Bio-Feedstock for Microalgae Biofuel Production

Microalgae biofuel is expected to be an ideal alternative to fossil fuels to mitigate the effects of climate change and the energy crisis. However, the production process of microalgae biofuel is sometimes considered to be energy intensive and uneconomical, which limits its large-scale production. Several cultivation systems are used to acquire feedstock for microalgal biofuels production. The energy consumption of different cultivation systems is different, and the concentration of culture medium (microalgae cells contained in the unit volume of medium) and other properties of microalgae vary with the culture methods, which affects the energy consumption of subsequent processes. This review compared the energy consumption of different cultivation systems, including the open pond system, four types of closed photobioreactor (PBR) systems, and the hybrid cultivation system, and the energy consumption of the subsequent harvesting process. The biomass concentration and areal biomass production of every cultivation system were also analyzed. The results show that the flat-panel PBRs and the column PBRs are both preferred for large-scale biofuel production for high biomass productivity.

Analysis on improving the conversion rate and waste reduction on bioconversion of Citrullus lanatus seed oil and its characterization

The works focus on maximizing the efficiency and reducing the wastage of reactant to make the possibility of upscaling in the bio-fuel production process for maximum yield conditions. Bio-oil derived from the Citrullus lanatus (Watermelon) for synthesizing methyl ester was used as a feedstock. The value of 1.13 mg KOH/g FFA content is recorded in the oil by employing the titration technique. Henceforth, transesterification using base catalyst reaction was allowed to transform watermelon seed oil into methyl ester. The experimental variables like methanol to oil molar ratio, KOH, and time remained for optimization based on the Taguchi technique. The outcome of the work was a 6:1 M ratio, 1 wt% KOH, 150 min and 55 °C are optimal experimental conditions for maximum conversion efficiency of 93.2%. Amid the four entities, the molar ratio was identified as the substantial influencing variable. The EN14214 standards were compared with characteristics of watermelon methyl ester, and the values obtained have fulfilled the requirements.

A critical perspective on the scope of interdisciplinary approaches used in fourth-generation biofuel production

The use of algae in biofuel production is more sustainable as compared to crop-based resources as it doesn't compromise food security, rainforests, or arable land. Furthermore, the utilization of molecular biology methods such as CRISPR/Cas9 with guided RNA for genetic modification in algae has opened up new avenues to meet the future energy demand. Recently, a progressive shift in the paradigm of algal growth from an open system (raceways) to a closed system (e.g.; PBRs) has been observed because the latter is more efficient in biofuel production as it provides optimized growth conditions. Several algal species have been genetically engineered and characterized for different parameters, especially their ability to grow in a closed system. Since the advent of the closed system viz. fermenters for industrial applications, several advancements have been made in its design and functions to optimize the growth of industrially used microbial strains and the yield of their bio-products. Genetically engineered algae have diverse growth condition requirements varying even at strain levels, consequently, an enormous amount of significant information or data is available on the optimization of algal growth conditions in PBRs. In conjunction with different computational biological approaches, the high throughput analysis of data becomes fast, enabling to predict the scale-up production process and capital cost and investment requirements. Systematic and planned, altogether applications of genetic engineering, PBRs, and computational approaches should not only help to make the production of fourth-generation biofuels more convenient but also pave the way of different interdisciplinary approaches to be used in algal biofuel production processes in near future.

Mitigation of CO2 emissions by transforming to biofuels: Optimization of biofuels production processes

Biodiesel is typically produced from a wide variety of edible vegetable oils. The cost of biofuels is projected to rise in the future as an alternative and ecologically suitable replacement to traditional fuel. Reliable and inexpensive raw materials, including meat processing by-products or waste animal fats, have rapidly attracted interest in biodiesel production. The operational and reaction parameters play an important role in the conversion of processes and biodiesel yield. Kinetic models explain the reaction rate and process optimization to improve the biodiesel conversion process. The process intensification approaches applied by different researchers are illustrated in the current study. This paper proposes a groundbreaking solution to stepping up biodiesel development by utilizing a coalescer reactor and a preliminary review to justify the solution's potential for further analysis. Optimization techniques and kinetics studies used to enhance biodiesel production from renewable sources are explored in the current review paper.

Cellulosic biofuel production using emulsified simultaneous saccharification and fermentation (eSSF) with conventional and thermotolerant yeasts

BackgroundFuture expansion of corn-derived ethanol raises concerns of sustainability and competition with the food industry. Therefore, cellulosic biofuels derived from agricultural waste and dedicated energy crops are necessary. To date, slow and incomplete saccharification as well as high enzyme costs have hindered the economic viability of cellulosic biofuels, and while approaches like simultaneous saccharification and fermentation (SSF) and the use of thermotolerant microorganisms can enhance production, further improvements are needed. Cellulosic emulsions have been shown to enhance saccharification by increasing enzyme contact with cellulose fibers. In this study, we use these emulsions to develop an emulsified SSF (eSSF) process for rapid and efficient cellulosic biofuel production and make a direct three-way comparison of ethanol production between S. cerevisiae, O. polymorpha, and K. marxianus in glucose and cellulosic media at different temperatures.ResultsIn this work, we show that cellulosic emulsions hydrolyze rapidly at temperatures tolerable to yeast, reaching up to 40-fold higher conversion in the first hour compared to microcrystalline cellulose (MCC). To evaluate suitable conditions for the eSSF process, we explored the upper temperature limits for the thermotolerant yeasts Kluyveromyces marxianus and Ogataea polymorpha, as well as Saccharomyces cerevisiae, and observed robust fermentation at up to 46, 50, and 42 °C for each yeast, respectively. We show that the eSSF process reaches high ethanol titers in short processing times, and produces close to theoretical yields at temperatures as low as 30 °C. Finally, we demonstrate the transferability of the eSSF technology to other products by producing the advanced biofuel isobutanol in a light-controlled eSSF using optogenetic regulators, resulting in up to fourfold higher titers relative to MCC SSF.ConclusionsThe eSSF process addresses the main challenges of cellulosic biofuel production by increasing saccharification rate at temperatures tolerable to yeast. The rapid hydrolysis of these emulsions at low temperatures permits fermentation using non-thermotolerant yeasts, short processing times, low enzyme loads, and makes it possible to extend the process to chemicals other than ethanol, such as isobutanol. This transferability establishes the eSSF process as a platform for the sustainable production of biofuels and chemicals as a whole.

Integrated strategy for coproducing bioethanol and adipic acid from lignocellulosic biomass

Numerous processes that produce only fuel from lignocellulosic biomass have the drawback that they are not economic. To overcome this, a biorefinery process is developed to coproduce ethanol as a renewable fuel and adipic acid as a value-added product. This strategy incorporates biomass fractionation, enzymatic hydrolysis of cellulose to ethanol, and catalytic conversion of hemicellulose to adipic acid. The developed experimental-based process model is used to evaluate the economic feasibility and environmental impact of the integrated coproduction strategy. The results show that the coproduction biorefinery has a lower minimum selling price for ethanol ($2.84/gallon of gasoline equivalent) and less environmental impact (2.44 kg CO2 eq. for climate change and 0.32 kg oil eq. for fossil depletion) than current biofuel production processes. This suggests that biorefinery can be improved economically and environmentally with the coproduction of value-added commodities.

Insight into the recent advances of microwave pretreatment technologies for the conversion of lignocellulosic biomass into sustainable biofuel

The utilization of renewable lignocellulosic biomasses for bioenergy synthesis is believed to facilitate competitive commercialization and realize affordable clean energy sources in the future. Among the pathways for biomass pretreatment methods that enhance the efficiency of the whole biofuel production process, the combined microwave irradiation and physicochemical approach is found to provide many economic and environmental benefits. Several studies on microwave-based pretreatment technologies for biomass conversion have been conducted in recent years. Although some reviews are available, most did not comprehensively analyze microwave–physicochemical pretreatment techniques for biomass conversion. The study of these techniques is crucial for sustainable biofuel generation. Therefore, the biomass pretreatment process that combines the physicochemical method with microwave-assisted irradiation is reviewed in this paper. The effects of this pretreatment process on lignocellulosic structure and the ratio of achieved components were also discussed in detail. Pretreatment processes for biomass conversion were substantially affected by temperature, irradiation time, initial feedstock components, catalyst loading, and microwave power. Consequently, neoteric technologies utilizing high efficiency-based green and sustainable solutions should receive further focus. In addition, methodologies for quantifying and evaluating effects and relevant trade-offs should be develop to facilitate the take-off of the biofuel industry with clean and sustainable goals.

Technological advances for improving fungal cellulase production from fruit wastes for bioenergy application: A review

Fruit wastes can be imperative to elevate economical biomass to biofuels production process at pilot scale. Because of the renewable features, huge availability, having low lignin content organic nature and low cost; these wastes can be of much interest for cellulase enzyme production. This review provides recent advances on the fungal cellulase production using fruit wastes as a potential substrate. Also, the availability of fruit wastes, generation and processing data and their potential applications for cellulase enzyme production have been discussed. Several aspects, including cellulase and its function, solid-state fermentation, process parameters, microbial source, and the application of enzyme in biofuels industries have also been discussed. Further, emphasis has been made on various bottlenecks and feasible approaches such as use of nanomaterials, co-culture, molecular techniques, genetic engineering, and cost economy analysis to develop a low-cost based comprehensive technology for viable production of cellulase and its application in biofuels production technology.

Role of Catalysis in Biofuels Production Process – A Review

AbstractIn the past few years, biofuels have emerged as renewable alternative to encounter global energy requirements in a greener way. Biomass is a sustainable cost‐effective natural resource with wide diversity for conversion to biofuel such as biodiesel, biogas, bio‐oil, biohydrogen, etc. via various chemical, thermal, or biochemical routes. Catalysis plays a pivotal role to convert biomass to biofuels, but conventional catalysts show a lot of short comings. To address these problems, a novel nanocatalysts approach is considered to be the most promising option. Nanocatalysts offer extremely high surface area, enhanced selectivity, better stability and catalytic activity at an atomic and molecular level in comparison to bulk catalysis. Here an insight about the limitation of traditional catalysts, the importance of nanocatalysts, various types of nanocatalysts, and their application in conversion of biomass to biofuel is given. It emphasizes the state‐of‐the‐art developments in terms of catalysis and catalytic processes that are anticipated to play a crucial role in biomass conversion to fuel are emphasized and the chemistry behind nanocatalyst design for biofuel production and reduction of inhibitory effect is highlighted.

Bio-refinery approaches based concomitant microalgal biofuel production and wastewater treatment

Adopting the biorefinery approaches on the coupled process of phycoremediation and biofuel production using freshwater microalgae. A green microalga, Scenedesmus sp., cultivated in various concentrations of domestic wastewater (0, 20, 40, 60, 80, 100%v/v). Maximum biomass productivity was obtained 62 mg/L/day cultivated in 100%v/v wastewater. During the stationary phase, the biomass was harvested adopting the flocculation technique. Interestingly, Scenedesmus sp., preferentially utilized 71.2% nitrate, 89.6% phosphorus, 23.5% calcium, 2% magnesium, 97.7% sulphate, 30% ammonia, 10.9% chloride, and 15.2% alkalinity in the wastewater which contribute to the wastewater treatment. Lipid productivity was found to be 19 mg/L/day. The fatty acid profile of transesterified lipids was characterized by adopting FT-IR, GC–MS, and 1H NMR. The extracted biomass was utilized for the feedstock for bioethanol production. The amount of reducing sugar was found to be 11.2% (w/v). Acid hydrolyzed reducing sugars subjected to fermentation using Saccharomyces cerevisiae NCIM3288. Bioethanol was found to be 10.4 g/L after distillation.

Porous Biochars Derived from Microalgae Pyrolysis for CO2 Adsorption

In order to slow down the greenhouse warming caused by excessive CO₂ emissions and effectively exploit the byproducts produced during the biofuel production process, N-doped porous biochars derived from the byproducts of microalgae (chlorella and spirulina) pyrolysis by combining urea and KOH modification were synthesized in this article to remove CO₂ in simulated flue gas. The physicochemical properties of the microalgae porous biochars were investigated via characterization tools, involving pH, Brunauer–Emmett–Teller (BET), scanning electron microscopy (SEM), X-ray photoelectron spectroscopy (XPS), and Fourier-transform infrared spectroscopy (FTIR). CO₂ adsorption kinetics, thermodynamics, and CO₂ adsorption performance were also studied. Results reveal that the functional groups and specific surface areas of microalgae biochars are substantially increased via urea and KOH modification, and nitrogen-containing functional groups (mainly involving N–H, C–N, etc.) are major adsorption sites for CO₂ adsorption. The key control step for CO₂ adsorption is external mass transfer, and the CO₂ adsorption process over the microalgae porous biochars is mainly physical adsorption. Moreover, the chlorella-based porous biochars CNK-2 and spirulina-based porous biochars SNK-2 have optimal CO₂ removal performances, and their maximum adsorption capacities, respectively, reach 3.44 and 3.09 mmol/g at 25 °C. The results of regeneration studies demonstrate that, after 10 regeneration experiments, CNK-2 and SNK-2 still possess high CO₂ sorption performances (reaching 3.09 and 2.78 mmol/g, respectively), exhibiting good regeneration potential.

Perspectives for Greening European Fossil-Fuel Infrastructures Through Use of Biomass: The Case of Liquid Biofuels Based on Lignocellulosic Resources

Given the importance of climate change it is vital to find a transition away from fossil fuels. The transition will include electrification of several sectors, for example road transport, but considering the strong dependency on carbon-based fuels and associated infrastructures, it is reasonable to assume that biomass-based hydrocarbon will play a key role to smoothen the transition away from fossil fuels. This study provides an analysis of direct and indirect technological options for liquid biofuels based on lignocellulosic resources in the context of greening European fossil-fuel infrastructures. Direct options are those which result in integration of biogenic feedstock in a fossil-based process and then co-processing in a downstream conventional unit or substituting a conventional part of the production chain of a liquid fuel by a bio-based one. Indirect options are those which pave the way for ramping-up biomass supply chain in the form of infrastructure and market. Examples of direct options in the focus of this study are biomass gasification for production of intermediates and biomass pyrolysis substituting fossil feedstock. Examples of indirect options are co-firing biomass in coal-fired power plants and integrating biomass gasification plants with district heating (DH) networks. Such options are important for establishing biomass supply chains and markets. This study also assesses the potential of biomass use in other industrial sectors not directly related with fossil-based fuel or energy production, such as the pulp and paper industry and the iron and steel industry. In this context, opportunities and barriers for both direct and indirect greening options are discussed, focusing mainly on technological and logistic aspects. It is highlighted that fossil-fuel infrastructures can act as drivers for the development of advanced biofuels production as they can reduce the initial risks, in terms of cost and technological maturity, offering the opportunity to increase gradually the demand for biomass, and develop the logistic infrastructure. It is, however, important to make sure that such biofuel production processes are part of a long-term strategy, which needs incentives to overcome current barriers and eventually phase out fossil infrastructures.