Biorefinery Route Research Articles

Exploring different processes for starch extraction from microalgae and synthesis of starch-chitosan plastic films

Microalgae could become a more sustainable starch source than conventional crops. However, available refinery processes are lacking. In this study, we develop different innovative processes to refine microalgal starch and obtaining starch-based bioplastics. After lipid extraction, defatted microalgae were treated by different routes: enzymatic treatment with Alcalase; sonication in hot water or dimethyl sulfoxide (DMSO) followed by precipitation with ethanol.Enzymes allows to extract 70 % of proteins while recovering 75 % of the initial starch in the residual pellet, with a purity of 58 %. The most effective configuration based on sonication and water/DMSO extraction allowed to recover up to 80 % starch with 80–91 % purity.Chitosan improved the mechanical properties of the obtained starch-based films. The use of defatted algae or purified starch gave different properties to the films (as rigidity and water stability) showing the possibility to tailor the material characteristics depending on the biorefinery route applied.

Holistic lignocellulosic biorefinery approach for dual production of bioethanol and xylonic acid coupled with efficient dye removal

The complete valorization of lignocellulosic biomass (LCB) to valuable bio-products with one-step fractionation is still challenging. This study represents sustainable waste-free biorefinery routes for efficient fractionation of LCB, employing a novel pretreatment method using hydrotropic p–toluenesulfonic acid (TsOH) mixed with pentanol. The potential of LCB pretreatment using TsOH/pentanol reagent as lignin absorbent with co-production of bioethanol and xylonic acid was investigated. Biomass pretreatment at 120 °C for 40 min with 20% TsOH dosage was the optimal condition that significantly dissolved more than 88.2% of lignin and 95.1% of hemicellulose in the biphasic phase, while 95.6% of cellulose was retained in the solid phase. Further fermentation of cellulose-rich fraction using Saccharomyces cerevisiae resulted in 225 g kg−1 bioethanol yield. In addition, xylose-rich phase was converted into xylonic acid by Gluconobacter oxydans fermentation with a yield of 202 g kg−1. Importantly, the isolated lignin was altered by acid groups during sulphonation through TsOH/pentanol pretreatment, which makes lignin a potential adsorbent for cationic contaminants in wastewater. In particular, the isolated lignin achieved high adsorption capacity (300 mg/g) of methylene blue. The proposed biorefinery routes showed a high net positive energy of 3.65 MJ kg−1 dry biomass with an energy ratio of 1.70. Therefore, this study provides an innovative synergistic pretreatment using TsOH/pentanol as a promising fractionation process for efficient cascade valorization of LCB into valuable bio-products.

The Sustainable Approach of Process Intensification in Biorefinery Through Reactive Extraction Coupled with Regeneration for Recovery of Protocatechuic Acid.

In the current scenario, where environmental degradation, global climate change, and the depletion of petroleum feedstock pose significant challenges, the chemical industry seeks sustainable alternatives for manufacturing chemicals, fuels, and bioplastics. Biorefining processes that integrate biomass conversion and microbial fermentation have emerged as preferred approaches to create value-added compounds. However, commercializing biorefinery products is hindered by dilute concentrations of final products and the demand for high purity goods. To address these challenges, effective separation and recovery procedures are essential to minimize costs and equipment size. This article proposes a biorefinery route for the production of protocatechuic acid (PCA) by focusing on in situ PCA separation and purification from fermentation broth. PCA is a significant phenolic molecule with numerous applications in the pharmaceutical sector for its anti-inflammatory, antiapoptotic, and antioxidant properties, as well as in the food, polymer, and other chemical industries. The chemical approach is predominantly used to produce PCA due to the cost-prohibitive nature of natural extraction techniques. Reactive extraction, a promising technique known for its enhanced extraction efficiency, is identified as a viable strategy for recovering carboxylic acids compared to conventional methods. The extraction of PCA has been explored using various solvents, including natural and conventional solvents, such as aminic and organophosphorous extractants, as well as the potential utilization of ionic liquids as green solvents. Additionally, back extraction techniques like temperature swing and diluent composition swing can be employed for reactive extraction product recovery, facilitating the regeneration of the extractant from the organic phase. By addressing the challenges associated with PCA production and usage, particularly through reactive extraction, this proposed biorefinery route aims to contribute to a more sustainable and environmentally friendly chemical industry. The incorporation of PCA in the biorefinery process allows for the utilization of this valuable compound with diverse industrial applications, thus providing an additional incentive for the development and optimization of efficient separation techniques.

Biphasic lignocellulose fractionation for staged production of cellulose nanofibers and reactive lignin nanospheres: A comparative study on their microstructures and effects as chitosan film reinforcing

The effective fractionation of lignocellulose and the enhancement of its components require formidable efforts. This study explored synergistic biorefinery routes for the holistic conversion of lignocellulose biomass to green nanomaterials through one-pot fractionation using recyclable p-toluenesulfonic acid (p-TsOH)/pentanol reagents. The potential of p-TsOH/pentanol pretreatment of aspen biomass under various temperatures (80–180 °C) for co-production of cellulose nanofibers (CNFs) and lignin nanospheres (LNSs) was investigated. The optimal pretreatment temperature, which minimizes cellulosic degradation and promotes the holistic conversion of biomass, was 120 °C. In addition to its highly digestible nature, the cellulose-rich residue produced high-quality CNFs with a diameter <100 nm, good crystallization, and thermostability, making it suitable for various applications. Lignin characterization, molecular dynamics simulation, and density functional theory analyses of the recovered lignin revealed well-protected β-O-4 bonds (47.3/100 Ar), uniform molecular weights (Mw, 2815 g/mol; Mn, 1704 g/mol; PDI, 1.65), < 1% sugar content, fewer condensed structures, and nanosize shapes (100–300 nm) due to the molecular interactions of p-TsOH and pentanol with lignin units. Moreover, 0.4% LNSs additions reduced the chitosan film thickness by 53% and enhanced its tensile strain and strength by 33 and 59%, respectively, as compared to the pure chitosan film. This study provides a sustainable platform for the co-production of biobased CNFs and LNSs using cutting-edge fractionation of LCB, which is a breakthrough toward industrial biorefineries.

Towards an integrated decision‐making support framework for the sustainable production and use of biomass

The decision-making landscape to maximize the use of sustainable biomass resources, and achieve long-term environmental and socioeconomic benefits, is complex with a high level of uncertainty in biomass supply and logistics, technical and economic performance of the biorefinery routes, lifecycle performance of the finished products, and other sustainability criteria. Numerous decision-making support models have been developed but these models usually assess only a few specific aspects of technology, regulations, economic, environment, and society. Decision-making support models with a limited capability to capture environmental and socioeconomic performance of the biorefining pathways are not able to identify the best available biorefining routes. This study reviews and discusses recent progress on the harmonization, standardization, and integration of the existing decision-making support models that aim to improve the comparability of the results of these models when different pathways are being assessed and align the decisions made at the strategic, tactical and operational levels. With the growing number of climate-change policies and greenhouse gas (GHG) emission reduction targets, national and international efforts to harmonize the input databases, the model assumptions and system boundaries, and the integration of the existing models have been increasing. However, the deployment of the integrated frameworks among the bioeconomy stakeholders that are capable of evaluating and identifying the promising biorefining routes with significant economic, social and environmental benefits is still not a common practice. This study proposes an integrated decision-making support framework to identify cost-competitive, low-carbon fuel production pathways that are technically viable and can potentially provide maximum GHG emission reduction.

Emerging technologies for conversion of sustainable macroalgal carrageenan biomass into L-lactic acid: A state-of-the-art review

The environmental awareness and concerns (plastic pollution) worldwide have driven the development of sustainable and environmentally friendly biopolymer derived from renewable materials. Biopolymers, especially L-lactic acid (L-LA) have played a crucial role in manufacturing polylactic acid, a biodegradable thermoplastic. Recently, L-LA production from non-edible macroalgal biomass has gained immense attraction due to it offers the simplest saccharification process for the biorefinery route. However, the commercialization of macroalgal-based L-LA is still limited due to high production costs. This paper has comprehensively reviewed the potential and development of third-generation feedstock for L-LA production, including significant technological barriers to be overcome for potential commercialization purposes. Then, an insight into the state-of-the-art hydrolysis and fermentation technologies using macroalgae as feedstock are also deliberated in detail. Furthermore, this review provides a conceivable picture of macroalgae-based L-LA biorefinery and future research directions that can be served as an important guideline for scientists, policymakers, and industrial players.

Biocrude oil production from a self-settling marine cyanobacterium, Chroococcidiopsis sp., using a biorefinery approach

Although the whole microalgal biomass is typically used as a feedstock for hydrothermal liquefaction (HTL), the conversion of a primary metabolite (i.e., carbohydrate) to biocrude is very low. In this study, a self-settling cyanobacterium (i.e., Chroococcidiopsis sp.) was used to understand the effect of carbohydrate removal, as a pretreatment, on the net energy recovery from the residual biomass. The optimum biocrude yields from pretreated and control biomass were 50.2% (350 °C) and 41.3% (300 °C), respectively. For the temperature range studied, the biocrude yield from the pretreated biomass was higher compared to that obtained from the control feedstock. Further, maximum alkane formation of 42.7 and 23.3% occurred for pretreated and control biomass, respectively, at 325 °C. Total organic carbon and total nitrogen values in the aqueous phase liquid obtained from pretreated biomass were at least 1.31 and 1.23 times lower when compared to the corresponding values obtained from control biomass. When APL was recycled as a source of nutrients, it reduced the biomass yield (24.1%) and pigment content (68.4%) in Chroococcidiopsis sp. Further, a model was developed to understand how the cellular carbohydrate content would affect the net energy recovery for the proposed biorefinery route.

Evaluation of bio-oil/biodiesel production from co-pyrolysis of corn straw and natural hair: A new insight towards energy recovery and waste biorefinery

The present study evaluated the total energy output and economic feasibility of biodiesel production coupled with value-added nitrogen-containing compounds (NCCs) through co-pyrolysis of low- and high-protein biowaste. Corn straw (CS) and human hair waste (HW) were used at different blend ratios of 0%, 25%, 50%, 75%, and 100%, w/w. Individual pyrolysis of HW showed 20.7% higher bio-oil yield than CS due to higher volatiles in HW, while co-pyrolysis resulted in synergistic action which enhanced both bio-oil yield with higher fatty acids/esters proportion. The highest recorded bio-oil yield was 46.3% using 75% HW blend ratio, which showed insignificant difference with that of HW. In addition, co-pyrolysis resulted in reduction of NCCs by 13.7% comparing to HW, with simultaneous enhancement of fatty acids and esters contents by 67.8% and 13.2%, respectively. Therefore, transesterification of co-pyrolyzed bio-oil showed the highest biodiesel proportion of 20.7%, representing 4.7-times and 61.7% higher than CS and HW, respectively. In addition, transesterified co-pyrolyzed bio-oil showed 27.0% NCCs, which was 8.2-times higher than that of CS. Due to the higher calorific value of biodiesel compared to bio-oil, biodiesel of the co-pyrolyzed bio-oil showed the highest total energy output in the biorefinery route (3753 MJ/ton biomass), which was higher than the total energy output from the conventional route of bio-oil production from CS (3738 MJ/ton biomass). However, additional revenue of 39,860 US$/ton biomass was estimated in the biorefinery route due to NCCs fraction, which provides a new insight towards future industrial applications.

A novel wastewater-derived cascading algal biorefinery route for complete valorization of the biomass to biodiesel and value-added bioproducts

Integration of multiproduct algal biorefineries with wastewater treatment systems could offer a sustainable approach to produce green products in a circular bioeconomy paradigm while keeping the water-energy-environment nexus sustainable. The present study demonstrated a novel biorefinery route employing a newly isolated self-flocculating microalga Chlamydomonas sp. BERC07. Here, the urban wastewater served as a low-cost growth media and improved biomass production (1.24 g/L) by 2-fold with concomitant removal of 100% total nitrogen, 94% total phosphorus, 56% COD, and 41% BOD. To lower the harvesting cost, an inducible sedimentation-based harvesting system was developed by employing the lowest dose of a commercial-grade flocculant, potash alum (0.27 kg/1000L culture) which improved the sedimentation rate of algal flocs by 240-fold with a biomass recovery efficiency of 96–98%. Later, the wastewater-derived biomass was subjected to downstream processing in a cascading fashion for its complete valorization. The biomass yielded 1.83 mg/g of carotenoids and 480 mg/g of lipids. The lipids were transesterified to produce biodiesel which completely met the preset European and American biodiesel quality standards. After carotenoids and lipids extraction, the residual biomass was fermented using Aspergillus niger and Aspergillus oryzae for the very first time. Interestingly, the A. oryzae outcompeted the A. niger and produced 131.6 U/mL of α-amylase along with 375–384 mg/g of mycoproteins utilizing 75–100 g/L of the residual algal biomass as a sole feedstock. All solvents involved in the product recovery were recycled to the primary wastewater, leaving no waste at the end of the processing pipeline. Overall, the data demonstrated a novel and sustainable biorefinery route with the most efficient harvesting and the complete valorization of the biomass, in a zero-waste approach. However, further upscaling, life cycle assessment, and technoeconomic analyses will be required to assess the economic and environmental sustainability of the proposed biorefinery route.

Innovative approach for rapeseed straw recycling using black solider fly larvae: Towards enhanced energy recovery

The present study evaluated bio-recycling of rapeseed straw (RS) mixed in different ratios with chicken manure using black soldier fly larvae (BSFL) followed by biodiesel and protein production as an innovative waste management and biorefinery route. Among different treatments, 20% RS ratio showed high fiber biodegradation with enhanced larval biomass yield and lipid accumulation. The average larval development time on the chicken manure was 18.3 days, which significantly reduced to 14.0 days using 20% RS. In addition, application of 20% RS significantly enhanced the survival rate, with higher conversion efficiency comparing to the control. Interestingly, saturated fatty acids content of the produced biodiesel at 20% RS was much higher than that reported for the biodiesel produced currently from rapeseed oil, which resulted in higher cetane number. Based on the current biodiesel industry from rapeseed oil, 1 ha of rapeseed produces 4.2 tons of dry RS annually, that can be converted to 689.4 kg ha−1 of biodiesel using BSFL. In addition, the potential application of BSFL technology could reduce CO2 emissions by 10.42 tons ha−1. In conclusion, this study suggests BSFL as a promising mini-livestock for innovative RS management through indirect conversion of lignocelluloses into biodiesel.

An Overview of Recent Advancements in Microbial Polyhydroxyalkanoates (PHA) Production from Dark Fermentation Acidogenic Effluents: A Path to an Integrated Bio-Refinery.

Global energy consumption has been increasing in tandem with economic growth motivating researchers to focus on renewable energy sources. Dark fermentative hydrogen synthesis utilizing various biomass resources is a promising, less costly, and less energy-intensive bioprocess relative to other biohydrogen production routes. The generated acidogenic dark fermentative effluent [e.g., volatile fatty acids (VFAs)] has potential as a reliable and sustainable carbon substrate for polyhydroxyalkanoate (PHA) synthesis. PHA, an important alternative to petrochemical based polymers has attracted interest recently, owing to its biodegradability and biocompatibility. This review illustrates methods for the conversion of acidogenic effluents (VFAs), such as acetate, butyrate, propionate, lactate, valerate, and mixtures of VFAs, into the value-added compound PHA. In addition, the review provides a comprehensive update on research progress of VFAs to PHA conversion and related enhancement techniques including optimization of operational parameters, fermentation strategies, and genetic engineering approaches. Finally, potential bottlenecks and future directions for the conversion of VFAs to PHA are outlined. This review offers insights to researchers on an integrated biorefinery route for sustainable and cost-effective bioplastics production.

Spent coffee grounds based circular bioeconomy: Technoeconomic and commercialization aspects

Coffee consumption produces enormous amount of spent coffee grounds (SCG), a material that contain plenty of lipids, polyphenols, carbohydrates, proteins, and various other components. Valorisation of SCG is a contour for sustainable value added product recovery with greater attention in determining economic and ecological tasks. The integrated biorefinery approach in valorisation brings more valuable products meanwhile reduces the residue waste formation which enhance the environment and economy. The primary techno-economic and life cycle assessment of SCG biorefinery were discussed as compared to the single phase biorefinery under its operating condition for small scale collection of SCG. This review explains the various SCG biorefinery routes and its effective bioconversion, different value added products recovery and profitable integration approaches. For instance, extraction of fatty acids and carbohydrates with subsequent conversion of by products into bioenergy, biofuel and biochemicals in circular economy loop has profitable potencies. Besides, the various biorefinery strategies to expose the possibilities of SCG for deriving multiple products and its impact on economics were highlighted. The sustainable biorefinery for SCG valorisation were developed by applying the principles of circular bioeconomy. The future SCG biorefinery perspective shows that the higher valued bioactive compounds production and bioenergy production to industrial scale to achieve higher economic viability. The outcome of this review reveals that SCG is an excellent raw material for a variety of industrial integrated biotechnological approaches, reduces the cost associated with of raw materials, saves the landfill and promotes the bioeconomy.

Upcycling the anaerobic digestion streams in a bioeconomy approach: A review

Gaseous and liquid anaerobic digestion (AD) streams, currently are at best used for electricity and heat production or simply spreading at the fields, respectively. However, electricity and heat are economically produced from other renewables and advanced fertilizers are needed to avoid leaching and boost nutrients capture. Hence, AD seeks new opportunities to support circular bioeconomy. The overall objective of this review is to present state-of-the-art resource recovery routes for upcycling the AD streams to reduce carbon footprint and formulate alternative products to increase sustainability. Technical barriers and integrated systems to upcycle AD streams through biological means are presented. New technologies and methods to capture CH4, CO2 and nutrients from the digested residual resources are presented, as a) methanotrophs cultivation to be used as feed ingredients; b) CO2 conversion and micro-nutrients capturing from microalgae to be valorized for a wide range of applications (e.g. biofuels, food and feed, fertilizers, bioactive compounds); c) CO2 transformation to biodegradable plastics precursors (e.g. Polybutylene succinate, Polyhydroxyalkanoate); d) digestate valorization for biochar production to support efficient agricultural usage. Moreover, the environmental factors and life cycle assessment perspectives of the novel biorefinery routes are revised highlighting the need for regionalized models or assessments that can reveal the most sustainable routes based on local conditions and requirements. Despite AD poses some positive characteristics related to environmental benefit and emissions reduction, the present work reveals that the novel routes can further enhance sustainability metrics supporting circular bioeconomy.

Adaptability of a Caproate-Producing Bacterium Contributes to Its Dominance in an Anaerobic Fermentation System.

The transformation of diverse feedstocks into medium-chain fatty acids (MCFAs) by mixed cultures is a promising biorefinery route because of the high value of MCFAs. A particular concern is how to maintain the microbial consortia in mixed cultures to achieve stable MCFA production. The Chinese strong aroma-type liquor (Baijiu) fermentation system continually produces caproic acid for decades through a spontaneous inoculation of anaerobes from pit mud into fermented grains. Therefore, illuminating the dominant caproate-producing bacterium (CPB) in pit mud and how the CPB is sustained in the spontaneous fermentation system will help to reveal the microbiological mechanisms of stable caproate production. Here, we examined pit mud samples across four Chinese strong aroma-type Baijiu-producing areas and found that a caproate-producing Caproicibacterium sp. was widely distributed in these distilleries, with relative abundance ranging from 1.4 to 35.5% and an average abundance of 11.4%. Through controlling carbon source availability, we obtained different simplified caproate-producing consortia and found that the growth advantage of Caproicibacterium sp. was highly dependent on glucose. Then, two strains, named Caproicibacterium sp. strain LBM19010 and Caproicibacterium sp. strain JNU-WLY1368, were isolated from pit mud of two regions. The metabolic versatility of this species utilizing starch, maltose, glucose, and lactate reflected its adaptability to the fermentation environment where these carbon sources coexist. The simultaneous utilization of glucose and lactate contributed to the balance between cell growth and pH homeostasis. This study reveals that multiple adaptation strategies employed by the predominant CPB promotes its stability and dominance in a saccharide- and lactate-rich anaerobic habitat. IMPORTANCE The Chinese strong aroma-type liquor (Baijiu) fermentation environment is a typical medium-chain fatty acid-producing system with complex nutrients. Although several studies have revealed the correlation between microbial community composition and abiotic factors, the adaptation mechanisms of dominant species to abiotic environment are still unknown in this special anaerobic habitat. This study identified the predominant CPB in Chinese strong aroma-type Baijiu fermentation system. Metabolic versatility and flexibility of the dominant CPB with a small-size genome indicated that this bacterium can effectively exploit available carbon and nitrogen sources, which could be a key factor to promote its ecological success in a multispecies environment. The understanding of growth and metabolic features of the CPB responsible for its dominance in microbial community will not only contribute to the improvement of Chinese strong aroma-type Baijiu production but also expand its potential industrial applications in caproate production.

Experimental exploration of processes for deriving multiple products from spent coffee grounds

Valorizing spent coffee grounds (SCG) through hydrothermal liquefaction (HTL) has great potential for biocrude production. To improve its economic viability, an integrated biorefinery route for SCG valorization was proposed in this study. High-value polyphenols and polysaccharides were extracted using water under ultrasound assistance. A central composite design was applied to jointly maximize the yields of both polyphenols and polysaccharides. Under the optimal conditions: a solid:water ratio of 1:23, an ultrasound power of 213 W, and an extraction time of 30 min at the temperature of 68 °C, the polyphenols yield was 1.0 wt.% (10 mg gallic acid equivalent/g SCG) and polysaccharides’ yield was 1.1 wt.% (11 mg glucose equivalent/g SCG). The biochemical compositions of raw and post-extraction SCG were characterized and exhibited appreciable difference, implying the impact of ultrasound-assisted extraction on feedstock composition. HTL of both raw and post-extraction SCG were conducted under three different temperatures (270 °C, 295 °C & 320 °C). It was found that 295 °C was the most desirable temperature, resulting in a biocrude yield of 31.1 wt.% and 27.7 wt.% for raw and post-extraction SCG, respectively. As for the biocrudes’ chemical composition, ester is the main component and increasing HTL temperature favored the fatty acid formation over ester, consequently led to more formation of amides.

Microalgae for high-value products: A way towards green nutraceutical and pharmaceutical compounds

Microalgae is a renewable bioresource with the potential to replace the conventional fossil-based industrial production of organic chemicals and pharmaceuticals. Moreover, the microalgal biomass contains carotenoids, vitamins, and other biomolecules that are widely used as food supplements. However, the microalgal biomass production, their composition variations, energy-intensive harvesting methods, optimized bio-refinery routes, and lack of techno-economic analysis are the major bottleneck for the life-sized commercialization of this nascent bio-industry. This review discusses the microalgae-derived key bioactive compounds and their applications in different sectors for human health. Furthermore, this review proposes advanced strategies to enhance the productivity of bioactive compounds and highlight the key challenges associated with a safety issue for use of microalgae biomass. It also provides a detailed global scenario and market demand of microalgal bioproducts. In conclusion, this review will provide the concept of microalgal biorefinery to produce bioactive compounds at industrial scale platform for their application in the nutraceutical and pharmaceutical sector considering their current and future market trends.

Valorization of agricultural residues: Different biorefinery routes

Agricultural residues are naturally available lignocellulosic biomass having high content of carbon. These residues should imminently be discarded to prevent pollution or can be harnessed for the production of bioenergy and bio-based products. This paper reviews the various types of agricultural residues such as rice straw, wheat straw, maize straw etc and their utilization for the generation of high valuable products. Basic components of agricultural residues which act as a feedstock for bioenergy production and also different biorefineries of agricultural residues based on cellulose, hemicellulose, and lignin for the transformation of lignocellulosic biomass into valuable products are discussed. Economic analysis performs a major role in technical advancement to ensure economic viability for the valorization of agricultural residues. This paper casts insight into the techno-economic analysis and the life-cycle assessment, the most pertinent approach to assess the environmental consequences of the developed products. To conclude, a discussion and suggestion for future studies is presented.

Technical, economic and environmental assessement of bioethanol biorefinery from waste biomass

This study presents a sequential three-steps methodology for the technical, economic and environmental assessment (TEEA) of bioethanol production from waste biomass. In EU the most abundant waste biomasses produced in 2018 could be ascribed to three main categories: lignocellulosic (329.41 Mt), starch (160 Mt) and sugar-based (58.56 Mt). The technical assessment compiled an inventory of the waste biomasses and subsequently designed their biological conversion into ethanol through integrated biorefinery processes by means of material flow analysis (MFA); the economic assessment was aimed at the definition of the cut-off size of the biorefinery plant necessary to achieve profitability; the environmental assessment was based on Life Cycle Analysis (LCA) and energy balance (i.e. energy input consumption). For each of the three waste biomass categories, at least one that was significant as available amount and representative in terms of physico-chemical characteristics, was evaluated: sugarcane for sugar-based, potatoes for starch-based and rice straw, cattle manure and organic fraction of municipal solid waste (OFMSW) for lignocellulosic biomasses. The technical assessment of the biorefinery routes lead to the following yields (kg of bioethanol per kg of biomass): 0.16, 0.17, 0.22, 0.19 and 0.14 respectively. The economic profitability was reached by all biorefineries and Net Present Value (M€) were: 0.85 for sugarcane, 0.11 for potatoes, 0.09 for rice straw, 0.11 for cattle manure and 0.39 for OFMSW. From the environmental perspective, cattle manure reached the highest reduction of climate change and acidification impacts compared to other biomasses, while sugarcane achieved the lowest energy input consumption (around 64%).

A close-loop integrated approach for microalgae cultivation and efficient utilization of agar-free seaweed residues for enhanced biofuel recovery

The aim of this work was to evaluate a novel integrated biorefinery route for enhanced energy recovery from seaweeds and microalgae. Agar extraction prior to anaerobic digestion recorded the highest biogas productivity of 32.57 L kg−1 VS d−1. Supplementation of the microalgal growth medium with anaerobic digestate from agar-extracted biomass enhanced the microalgal growth, recording the highest dry weight of 4.57 g L−1 at 20% digestate ratio. In addition, lipid content showed the highest value of 25.8 %dw. Due to enhancement of growth and lipid content, 20% digestate ratio showed the highest lipid productivity and FAMEs recovery (65.2 mg L−1 d−1 and 123.3 mg g−1dw, respectively), with enhanced biodiesel characteristics. The present study estimated annual revenue of 1252.7 US$ ton−1 from the whole Gracilaria multipartita biomass conversion into biogas, while that through agar extraction deserved 36087.0 US$ ton−1, with enhanced annual biodiesel yield by 69.7% over the control medium.

A Novel 2,5-Furandicarboxylic Acid Biosynthesis Route from Biomass-Derived 5-Hydroxymethylfurfural Based on the Consecutive Enzyme Reactions

2,5-Furandicarboxylic acid (FDCA) is a promising bio-based building block as a green alternative to petroleum-based terephthalate in polymer production. Most of FDCA is produced by the oxidation of 5-hydroxymethylfurfural (HMF), which is derived from hexose. Although the chemical conversion is widely applied, the biocatalytic conversion is expected due to the relatively mild condition and fewer toxic chemicals consumption. However, it's difficult to catalyze the conversion of HMF to FDCA by a single enzyme. Here, a newly enzymatic cascade reaction process was introduced with a yield of 94.0% by the combination of 5-hydroxymethylfurfural oxidase (HMFO) and lipase. Briefly, a flavine adenosine dinucleotide independent (FAD-independent) HMFO of Methylovorus sp. MP688 was used to convert HMF to 2,5-diformylfuran (DFF) and 5-formylfuroic acid (FFA), which consecutively transformed to FDCA by a lipase Novozym 435. To facilitate the purification, a coupled alkali precipitation was developed to recover FDCA from organic solvent with an improved purity from 84.4 to 99.0% and recovery of 78.1%. This work will help to construct the green biorefinery route for the bulk FDCA from biomass by enzymes.