State-of-the-art and future directions of machine learning for biomass characterization and for sustainable biorefinery

Machine learning(ML)has emerged as a significant tool in the field of biorefinery,offering the capability to analyze and predict complex processes with efficiency.This article reviews the current state of biorefinery and its classification,highlighting various commercially successful biorefineries.Further,we delve into different categories of ML models,including their algorithms and applications in various stages of biorefinery lifecycle,such as biomass characterization,pretreatment,lignin valorization,chemical,thermochemical and biochemical conversion processes,supply chain analysis,and life cycle assessment.The benefits and limitations of each of these algorithms are discussed in detail.Finally,the article concludes with a discussion of the limitations and future prospects of ML in the field of biorefineries.

Electrochemical Biorefinery toward Chemicals Synthesis and Bio-Oil Upgrading from Lignin

Recalcitrance and the inherent heterogeneity of lignin structure are the major bottlenecks to impede the popularization of lignin-based chemicals production processes.Recent works suggested a promising pathway for lignin depolymerization and lignin-derived bio-oil upgrading via an electrochemical biorefinery(a process in which lignin valorization is performed via electrochemical oxidation or reduction).This review presents the progress on chemicals synthesis and bio-oil upgrading from lignin by an electrochemical biorefinery,relating to the lignin biosynthesis pathway,reaction pathway of lignin electrochemical conversion,inner-sphere and outer-sphere electron transfer mechanism,basic kinetics and thermodynamics in electrochemistry,and the recent embodiments analysis with the emphasis on the respective feature and limitation for lignin electrochemical oxidative and reductive conversion.Lastly,the challenge and perspective associated with lignin electrochemical biorefinery are discussed.Present-day results indicate that more work should be performed to promote efficiency,selectivity,and stability in pursuing a lignin electrochemical biorefinery.One of the most promising developing directions appears to be integrating various types of lignin electrochemical conversion strategies and other existing or evolving lignin valorization technologies.This review aims to provide more references and discussion on the development for lignin electrochemical biorefinery.

Shell biorefinery: A comprehensive introduction

Biomass refinery is considered to be a key technology in the 21 st century due to the importance of the sustainable production of various bioderived fuels and fine chemicals. Besides the synthesis of oxygen-containing chemicals mainly from lignocellulosic biomass, nitrogencontaining chemicals belong to some of the most important commodity and fine chemicals. In this introductory short review, the main similarities and difficulties between petroleum oil-and biorefinery will be discussed and future challenges will be highlighted. As a particular example, recent developments in the shell biorefinery – the utilization of shell waste – will be reviewed. Particular emphasis will be placed on the structure of shell biomass, the current and emerging fractionation methods and the conversion of chitin and chitosan to various heteroatomcontaining chemicals. This review is meant to provide an introduction to beginners in the field of biorefinery as well as a comprehensive discussion of recent proceedings in the field of shell biorefinery. An outlook on the future potential and challenges will be given.

Integrated Forest Biorefinery:Value-added Utilization of Dissolved Organics in the Prehydrolysis Liquor of Prehydrolysis Kraft (PHK) Dissolving Pulp Production Process

The concept of integrated forest biorefineries(IFBRs) has gained significant interest.The prehydrolysis kraft(PHK) dissolving pulp production process is a suitable example of IFBR concept for the production of dissolving pulp and utilization of dissolved hemicelluloses,acetic acid,and lignin in the prehydrolysis liquor(PHL).This review paper highlights recent progress related to the recovery and utilization of dissolved organics(e.g.,hemicelluloses,acetic acid,and lignin) in the PHL of the PHK dissolving pulp production process.Integrated multi-step recovery and separation processes have been developed for this purpose to accommodate the complex nature of the PHL.Potential products,including xylan-based compounds,acetic acid,and lignin,are also discussed in detail.

Biorefinery of Rice Husk to Obtain Functionalized Bioactive Compounds

The biomass industrialization valorisation of grains and cereals is considered an opportunity for the countries where agro-industrial activity is one of its main economic activities,rendering new higher-value products with a concomitant solution to waste accumulation issues.To that end,in this work we describe and characterise bioactive compounds generation from rice husk by semisolid fermentation,obtained from 500 g of the material at room temperature and 60%humidity with mixed cultures of Phanerochaete chrysosporium and Gloeophyllum trabeum.The extract was evaluated in different situations:murine mammary tumour cells(4T1),normal cells(NIH 3T3)and in Lactobacillus acidophilus,and Trichoderma harzianum.The results exhibited that the extract inhibited 4T1 cells at concentrations higher than 20μg/mL,but did not inhibit normal cells,and displayed germicide activity after 3 days incubations.We propose that these functionalized compounds have a potential application in industry/agriculture/medicine obtained from rice husk waste.

Succinic Acid Production across Candidate Lignocellulosic Biorefinery Feedstocks

Non-food lignocellulosic crops with both high biomass yields and superior adaptation to marginal lands have significant potential as biofuel feedstocks that can replace fossil fuels. Deployment of dedicated crops into single biofuels, however, has been reduced by conversion technology costs and low petroleum prices. Integrated biorefinery strategies, in which value-added coproducts are generated in conjunction with biofuels, by comparison offer opportunities to overcome this economic disadvantage. The objective of this research was to evaluate succinic acid accumulation across candidate lignocellulosic feedstocks. Feedstock entries included pearl millet x napiergrass hybrids (“PMN”;Pennisetum glaucum [L.] R. Br. × P. purpureum Schumach.), napiergrass (P. purpureum Schumach.), annual sorghum (Sorghum bicolor [L.] Moench), pearl millet (P. glaucum [L.] R. Br.), perennial sorghum (Sorghum spp.), switchgrass (Panicum virgatum L.), sunn hemp (Crotalaria juncea L.), giant miscanthus (Miscanthus × giganteus J. M. Greef & Deuter) and energy cane (Saccharum spp. L.). Replicated field plots, as well as an independent greenhouse trial, were characterized for succinic acid content. The PMN, napiergrass, sunn hemp and energy cane entries had greater (P ≤ 0.05) succinic acid yields, up to 556 kg·ha-1, in field trials. Napiergrass and PMN entries similarly had higher succinic acid yields under greenhouse conditions;however, irrigation treatments did not alter succinic acid accumulation in this study. Napiergrass, PMN, and energy cane thus are promising biorefinery feedstocks.

Towards Biorefinery Production of Microalgal Biofuels and Bioproducts: Production of Acetic Acid from the Fermentation of <i>Chlorella</i>sp. and <i>Tetraselmis suecica</i>Hydrolysates

Successful commercialization of microalgal bio-industry requires the design of an integrated microalgal biorefinery system that facilitates the co-production of biofuels, high-value products and industrial chemicals from the biomass. In this study, we investigated the use of sugar hydrolysate obtained from enzymatic saccharification of microalgal biomass (Chlorella sp. and T. suecica) as fermentation feedstock to produce industrially important chemicals, in particular acetic acid and butyric acid. By using hydrolysate with low sugar content as substrate for the anaerobic fermentation (1.5 - 2.4 g/L), we were able to prevent the bacterium C. saccharoperbutylacetonicum from activating its solventogenesis pathway. As a result, the fermentation process generated a product stream that was dominated by organic acids (acetic acid and butyric acid) rather than solvents (butanol, ethanol and acetone). Acetic acid constituted up to 92 wt% of Chlorella’s fermentation products and 80 wt% of T. suecica’s fermentation products. For T. suecica, the fermentation consumed almost all of the sugar available in the hydrolysate (up to 92% of initial sugar) and produced a reasonable yield of fermentation products (0.08 g fermentation products/g sugar). The Gompertz equation was successfully used to predict the formation kinetics of acetic acid and other fermentation products across both species. The results in the study demonstrate the production of industrially important chemicals, such as acetic acid and butyric acid, from the fermentation of microalgal sugar. The process described in the study can potentially be used as a value-adding step to generate biochemicals from cell debris in an integrated microalgal biorefinery system.

Biodiesel Production Based in Microalgae: A Biorefinery Approach

It is of great knowledge nowadays that the use of fossil fuels is responsible for the emission of gases that intensify the greenhouse effect, which threatens the survival of the humankind. The gravity of this fact could be mitigated through the indirect use of solar energy for fuels derived from vegetable that can be planted and cultivated by the world of renewable and non-polisher. Microalgae play an important role in this regard, as they have promising characteristics as potential raw material for the production of biofuels, able to absorb large amounts of CO2. Chlorophyll organisms convert these simple substances in the atmosphere, absorbing sunlight into chemical energy stored, that is, compounds with high energy, biomass can also be used to obtain biocompounds human nutritional supplement and food animal, however, have been found an important number of difficulties to economically viable production like high cost of production of dry biomass and oil extraction. Here, we review the main approaches of biorefinery concept appearing as an alternative to achieve economic viability of the production of bio-diesel based on microalgae. The major points are the following: 1) use of re-residual water, 2) marketing of Carbon Credits, and 3) development of co-products resulting from high value added.

Determination of the Place of Implementation of a Biorefinery Based on Logistics Parameters

Airlines and the aviation industry are committed to emission reduction targets. Biokerosene was pointed out as one of the key elements to achieving this goal. The use of oilseeds in the production of biokerosene is interesting due to the great Brazilian experience in the production of biofuels from this raw material. In view of this scenario, this dissertation has as its main objective the definition of the place of implantation of a biorefinery in Brazilian territory that has aviation biokerosene as its main product. For this, data on supply and demand for fossil aviation kerosene in Brazilian regions were collected, an extensive review was carried out in scientific articles on the oleaginous raw materials used for the production of this biofuel, and logistical parameters were selected and used as criteria for that selection. The oilseeds selected for the production of biofuel were macaúba and soybean and the state was chosen for the implementation of the biorefinery was Goiás. Based on logistical parameters, the city of Formosa (GO) was selected to host the biorefinery. The soybean crushers located in Luziania, Anápolis, Ipameri, and Itumbiara were chosen as suppliers of soybean oil and the city of Formosa (GO) as the headquarters for the commercial planting of macaúba. The destination of this fuel will be Petrobrás Distribuidora S.A., an aviation fuel distributor authorized by the ANP based in the city of Brasília (DF).

A Biorefinery Concept for Energy Intensive Industries Focusing on Microalgae and Anaerobic Digestion

The biorefinery concept will be important to the energy industry as it allows a multi-process, multi-product biomass based industry. Continued increases in the prices of fossil fuels, the uncertainty of their availability and the environmental impacts of their extraction are favouring the implementation of sustainable energy production. This article provides a literature review of algal biomass utilisation, process utilisation, technological and economic factors when applying the biorefinery concept to energy intensive industries （whether retro-fitting or new buildings）. This report focuses on opportunities in Finland for innovation, process integration and the development of supply chains whilst using flue gases as a feedstock for the microalgae. Currently, most research is on thermal combustion technologies. Microalgae provide an excellent opportunity to reduce carbon dioxide emissions by mitigation in such industries as pulp and paper. However, a beneficial driver would be feed-in tariffs or green trade certificates but are not necessary for the potential success within the industry. Reducing the overall economic costs with process integration and efficient technologies is beneficial for commercialisation of microalgae biorefineries. Microalgae biorefinery with a high efficiency could help improve the cost effectiveness of microalgae derived biofuels. The remaining algae after harvesting could be used for biogas production, which could be upgraded for vehicle fuel or the production of heat and power. An economically viable microalgae biorefinery with appropriate technologies and integrated for optimum efficiency is therefore possible.

Literature Review on Biorefinery Processes Integrated to the Pulp Industry

Biorefinery is a new term to designate two main subjects, bioproducts and bioenergy, which play important roles towards a more bio-based society. This paper reviews the current biorefineries model as well as its future importance focusing on pulp mill opportunities. There are currently several different levels of integration in biorefineries which add to their sustainability, both economically and environmentally. Enzymatic pretreatment for biomass deconstruction aiming to release the polysaccharides is a key technology in the future biorefineries and it is currently the subject of intensive research.

Exploring hemp seed hull biomass for an integrated C-5 biorefinery:Xylose and activated carbon

Large quantities of hemp hulls can be completely utilized for creation of value-added products (cost effective biofuels and biochemicals) through a biorefinery approach. A sustainable approach in making xylose, a low calorie sweetener and high surface area activated carbons (AC) for super capacitors, attracts interest. The AC when leveraged as a co-product from biorefinery process makes it more cost effective and, in this paper, we discuss the production of xylose and AC from hemp seed hull with methane sulphonic acid (MSA) hydrolysis. Xylose recovery with MSA hydrolysis was 25.15 g/L when compared to the traditional sulphuric acid (SA) hydrolysis of 19.96 g/L at the same acid loading of 1.8 %. The scanning electron microscope (SEM) images and Fourier transform infrared (FT-IR) spectra indicate partial delignification along with hemicellulose hydrolysis responsible for high xylose recovery. Post hydrolysis fibers were KOH activated and carbonized to make AC. The MSA hydrolyzed and KOH activated fiber produced pure, fluffier and finer particle AC with a drastic increase in surface area 1 452 m2/g when compared to SA hydrolyzed of 977 m2/g. These results indicate the potential of MSA in dilute acid hydrolysis of biomass for xylose recovery and production of high surface area activated carbon. From a production standpoint this can lead to increased use of sustainable low-cost agricultural biomass for making high surface area AC as components in supercapacitors.

Advances in microbial engineering for the production of value‑added products in a biorefinery

Microbial biorefineries to produce chemicals from renewable feedstock provides attractive advantages,including mild reaction conditions and sustainable manufacturing.However,low-efficiency biorefineries always result in an uncompetitive biological process compared to the current petrochemical process.Thus,improving microbial capacity to maximize product yield,productivity,and titer has been recognized as a central goal for bioengineers and biochemists.The knowledge of cellular biochemistry has enabled the regulation of microbial physiology to couple with chemical production.The rapid development in metabolic engineering provides diverse strategies to enhance the efficiency of chemical biosynthesis pathways.New synthetic biology tools as well as novel regulatory targets also offer the opportunity to improve biorefinery environmental adaptivity.In this review,the recent advances in building efficient biorefineries were showcased.In addition,the challenges and future perspectives of microbial host engineering for increased microbial capacity of a biorefinery were discussed.

Integrated lignocellulosic biorefinery:Gateway for production of second generation ethanol and value added products

An increasing demand for energy and depleting petroleum sources has elevated the need for producing alternative renewable resources.Owing to the prominence of lignocellulosic biomass as bio-renewable and the most abundant resource on Earth,this critical review provides perceptions into the potential of lignocellulosic biomass for production of second generation(2G)ethanol and value added products in a biorefinery manner.The efficient utilization of all three components of lignocellulosic biomass(i.e.,cellulose,hemicellulose and lignin)would play a significant role in the economic viability of cellulosic ethanol.The pretreatment method is the key to the success of bioconversion processes and greatly influences the economics of biorefinery process.Biotechnology tools and process engineering play pivotal roles in development of integrated processes for production of biofuels,biochemicals and biomaterials from lignocellulosic biomass.Although,lignocellulosic biorefinery has ample scopes,commercial production of biofuels and chemicals is still challenging.In this context,this review entails concept of lignocellulose biorefinery,latest developments in 2G ethanol production process,importance and market potential of 2G ethanol as renewable fuel and value added chemicals,integration of processes,challenges for integrated production of fuel together with value added chemicals and future directions.

Resistance mechanisms and reprogramming of microorganisms for efficient biorefinery under multiple environmental stresses

In the fermentation process of biorefinery,industrial strains are normally subjected to adverse environmental stresses,which leads to their slow growth,yield decline,a substantial increase in energy consumption,and other negative consequences,which ultimately seriously hamper the development of biorefinery.How to minimize the impact of stress on microorganisms is of great significance.This review not only reveals the damaging effects of different environmental stresses on microbial strains but also introduces commonly used strategies to improve microbial tolerance,including adaptive evolution,reprogramming of the industrial host based on genetic circuits,global transcription machinery engineering(gTME)and bioprocess integration.Furthermore,by integrating the advantages of these strategies and reducing the cost of system operation,the tolerance of industrial strains,combined with production efficiency and process stability,will be greatly improved,and the development prospects of biorefinery will be more widespread.

Biorefinery process for production of bioactive compounds and bio-oil from Camellia oleifera shell

A biorefinery process was developed in this study to obtain bioactive compounds and bio-oil from Camellia oleifera shells.Four different extraction techniques(water,ethanol,ultrasound-assisted deionized water,and ultrasound-assisted ethanol)were utilized to extract tea saponin and tannin from C.oleifera shells.Results showed that ethanol had better extraction capacity than did deionized water,and ultrasound could promote the dissolution of tannin and tea saponin in solution.The thermogravimetric curves of the samples treated under the four conditions moved toward high temperatures.This phenomenon indicated the thermal stability of the residue was significantly improved.The pretreatment showed a slight effect on the chemical compositions of bio-oil.Specifically,the samples treated with ethanol and ultrasound-assisted deionized water contained higher phenol contents(81.07%and 81.52%,respectively)than the other samples.The content of organic acid decreased with an increase in the phenol content.

Catalyst design and structure control for photocatalytic refineries of cellulosic biomass to fuels and chemicals

Lignocellulosic biomass is the largest renewable hydrocarbon resource on earth.Converting cellulose,one of the major components of lignocellulose,powered by solar energy is a promising way of providing lowcarbon-footprint energy chemicals such as H_(2),HCOOH,CO,and transportation fuels.State-of-the-art biorefineries target the full use of biomass feedstocks as they have a maximum collection radius of 75-100 km,requesting efficient and selective photocatalysts that significantly influence the outcome of photocatalytic biorefineries.Well-performed photocatalysts can harvest a broad solar spectrum and are active in breaking the chemical bonds of cellulose,decreasing the capital investments of biorefineries.Besides,photocatalysts should control the selectivity of cellulose conversion,originating target products to level down separation costs.Charge separation in photocatalysts and interfacial charge transfer between photocatalysts and cellulose affect the activity and selectivity of cellulose refineries to H2 and carbonaceous chemicals.To account for the challenges above,this review summarizes photocatalysts for the refineries of cellulose and downstream platform molecules based on the types of products,with the structure features of different types of photocatalysts discussed in relation to the targets of either improving the activity or product selectivity.In addition,this review also sheds light on the methods for designing and regulating photocatalyst structures to facilitate photocatalytic refineries of cellulose and platform molecules,meanwhile summarizing proposed future research challenges and opportunities for designing efficient photocatalysts.

Crop residues: applications of lignocellulosic biomass in the context of a biorefinery

Interest in lignocellulosic biomass conversion technologies has increased recently because of their potential to reduce the dependency on non-renewable feedstocks. Residues from a variety of crops are the major source of lignocellulose, which is being produced in increasingly large quantities worldwide. The commercial exploitation of crop residues as feedstocks for biorefineries which could be used to produce a variety of goods such as biofuels, biochemicals, bioplastics, and enzymes is an attractive approach not only for adding value to residues but also for providing renewable products required by the expanding bioeconomy market. Moreover, the implementation of biorefineries in different regions has the potential to add value to the specific crop residues produced in the region. In this review, several aspects of crop residue application in biorefineries are discussed, including the role of crop residues in the bioeconomy and circular economy concepts, the main technical aspects of crop residue conversion in biorefineries, the main crop residues generated in different regions of the world and their availability, the potential value-added bioproducts that can be extracted or produced from each crop residue, and the major advantages and challenges associated with crop residue utilization in biorefineries. Despite their potential, most biomass refining technologies are not sufficiently advanced or financially viable. Several technical obstacles, especially with regard to crop residue collection, handling, and pre-treatment, prevent the implementation of biorefineries on a commercial scale. Further research is needed to resolve these scale-up-related challenges. Increased governmental incentives and bioeconomic strategies are expected to boost the biorefinery market and the cost competitiveness of biorefinery products.

Potassium hydroxide based biorefinery concepts for non-wood bioresources

The paper and paperboard production in 2016 in the world was 110.07 million tones.1 Bangladesh consumes only about 3.5~4 kg paper and board products per capita,while the developed countries consume about 300 kg/capita.Bangladesh’s consumption is also much lower than the world’s average(@50 kg/capita)and the Asia’s average(@50 kg/capita).2 To reach the world’s or Asia’s level,Bangladesh’s consumption of paper and board products needs to increase 10 folds.As forest resources are very limited in Bangladesh,alternative fibrous raw materials are required to achieve this goal.Therefore many studies have been carried out on alternative raw materials available in Bangladesh.

Highlights of the 2017 Atlantic Biorefinery Conference

The 2017 Atlantic Biorefinery Conference was held over three days from June 7th to 9th,at the Hugh john Flemming Forestry Centre in Fredericton,NB.The goals of the conference mirror the goals of BioNB:to promote and foster the biotech sector in New Brunswick and the Maritimes in general.The format has been consistent for at least the last three years(years attended by the author of this report).The first day,conference attendees were divided into self-selected groups(indicated when registering)for technology demonstration tours.The following two days featured talks on technology,research,project proponents,and policy development,all in support of the bio-economy.The speaker sessions were all in one-stream.These were complimented by tradeshow booths,networking events,and facilitated business-to-business meetings,as well as a poster session for which a prize was awarded for the best student poster.