Microwave heating processing as alternative of pretreatment in second-generation biorefinery: An overview

The development of a feasible biorefinery is in need of alternative technologies to improve lignocellulosic biomass conversion by the suitable use of energy. Microwave heating processing (MHP) is emerging as promising unconventional pretreatment of lignocellulosic materials (LCMs). MHP applied as pretreatment induces LCMs breakdown through the molecular collision caused by the dielectric polarization. Polar particles movement generates a quick heating consequently the temperatures and times of process are lower. In this way, MHP has positioned as green technology in comparison with other types of heating. Microwave technology represents an excellent option to obtain susceptible substrates to enzymatic saccharification and subsequently in the production of bioethanol and high-added compounds. However, it is still necessary to study the dielectric properties of materials, and conduct economic studies to achieve development in pilot and industrial scale. This work aims to provide an overview of recent progress and alternative configurations for combining the application of microwave technology on the pretreatment of LCMs in terms of biorefinery.Financial support is gratefully acknowledged from the Energy Sustainability Fund 2014-05 (CONACYT-SENER), Mexican Centre for Innovation in Bioenergy (Cemie-Bio), Cluster of Bioalcohols (Ref. 249564). This study was supported by the Secretary of Public Education of Mexico PROMEP project/103.5/13/6595 – UACOAH-PTC-292 and PROMEP project/DSA/103.5/14/10442 – UACOAH-PTC-312. We gratefully acknowledge support for this research by the Mexican Science and Technology Council (CONACYT, Mexico) for the infrastructure project - INFR201601 (Ref. 269461) and CB-2015-01 (Ref. 254808). The author A. Aguilar-Reynosa thanks to Mexican Science and Technology Council (CONACY, Mexico) for master fellowship support

Hydrothermal processing, as an alternative for upgrading agriculture residues and marine biomass according to the biorefinery concept : a review

The concept of a biorefinery that integrates processes and technologies for biomass conversion demands efficient utilization of all components. Hydrothermal processing is a potential clean technology to convert raw materials such as lignocellulosic materials and aquatic biomass into bioenergy and high added-value chemicals. In this technology, water at high temperatures and pressures is applied for hydrolysis, extraction and structural modification of materials. This review is focused on providing an updated overview on the fundamentals, modelling, separation and applications of the main components of lignocellulosic materials and conversion of aquatic biomass (macro- and micro- algae) into value-added products.The authors Hector A. Ruiz and Bruno D. Fernandes thank to the Portuguese Foundation for Science and Technology (FCT, Portugal) for their fellowships (grant number: SFRH/BPD/77361/2011 and SFRH/BD/44724/2008, respectively) and Rosa M. Rodriguez-Jasso thanks to MexicanScience and Technology Council (CONACYT, Mexico) for PhD fellowship support (grant number: 206607/230415)

Biomass for Bioenergy

Lignocellulosic wastes has been widely discussed as a promising natural chemical source and alternative feedstock for second-generation biofuels. However, there are still many technical and economic challenges facing its utilization. Lignin is one of the components of lignocellulosic biomass, and is the most rigid constituent and can be considered as a glue providing the cell wall with stiffness and the plant tissue with compressive strength. In addition, it provides resistance to chemical and physical damage. Resistance of lignocelluloses to hydrolysis is mainly from the protection of cellulose by lignin and cellulose binding to hemicellulose. The present book provides basic knowledge and recent research on different applications of biomass, focusing on the bioenergy and different pretreatment methods that overcome the aforementioned hurdles

Towards practical application of gasification: a critical review from syngas and biochar perspectives

Syngas and biochar production are mainly influenced by temperature, feedstock properties, gasifying agent, pressure, and the mass ratio between gasifying agent and feedstock with temperature being the most significant factor. Increasing temperature generally promotes syngas production while suppressing biochar production. The selection of gasifiers (fixed bed, fluidized bed, and entrained flow) is highly dependent on scale requirement (e.g., volume of feedstock and energy demand), feedstock characteristics (e.g., moisture and ash content), and the quality of syngas and biochar. Updraft fixed bed gasifiers are suitable for the feedstocks with a moisture content up to 50 wt.%. High ash feedstocks such as Indian coal, dried sewage sludge, and municipal solid waste that are not suitable for fixed bed gasifiers, have been successfully gasified in bubbling fluidized bed reactors. Woody biomass is not suitable for entrained flow gasifiers unless specialized feeding methods are employed such as wood torrefaction and grinding followed by the existing feeding methods for pulverized coals, biomass-oil biochar slurry preparation followed by pumping, wood or torrefied wood slurry preparation followed by pumping, etc. Syngas and biochar can potentially be contaminated by NH3, H2S, and tar, which can be removed using catalysts (e.g., Ni-based), metal oxides-based sorbents, and thermal and catalytic cracking methods. Existing syngas and biochar upgrading methods suffered from various problems such as economic infeasibility, limited productivity, and fouling, and future syngas and biochar upgrading methods should be aimed to have the features of reliability, security, affordability, and sustainability, towards the practical, large-scale production of syngas- and biochar-based products. One potential solution is to develop integrated systems by combining biochar upgrading and application with syngas upgrading, which warrants an integrated perspective based on both life cycle assessment and economic analysis

Biomass Processing for Biofuels, Bioenergy and Chemicals

Biomass can be used to produce renewable electricity, thermal energy, transportation fuels (biofuels), and high-value functional chemicals. As an energy source, biomass can be used either directly via combustion to produce heat or indirectly after it is converted to one of many forms of bioenergy and biofuel via thermochemical or biochemical pathways. The conversion of biomass can be achieved using various advanced methods, which are broadly classified into thermochemical conversion, biochemical conversion, electrochemical conversion, and so on. Advanced development technologies and processes are able to convert biomass into alternative energy sources in solid (e.g., charcoal, biochar, and RDF), liquid (biodiesel, algae biofuel, bioethanol, and pyrolysis and liquefaction bio-oils), and gaseous (e.g., biogas, syngas, and biohydrogen) forms. Because of the merits of biomass energy for environmental sustainability, biofuel and bioenergy technologies play a crucial role in renewable energy development and the replacement of chemicals by highly functional biomass. This book provides a comprehensive overview and in-depth technical research addressing recent progress in biomass conversion processes. It also covers studies on advanced techniques and methods for bioenergy and biofuel production

scaling up of simultaneous saccharification and fermentation of microwave alkali pretreated emptyfruit bunch for lactic acid production

Oil palm empty fruit bunches (EFB), a major solid waste in the palm oil industries is a source of lignocellulosic biomass. Cellulose, which is the major component of EFB can be converted to lactic acid. Production of lactic acid is desirable because it can be utilized in industries including bioplastics, chemicals, and cosmetics. The aim of this study is to produce lactic acid on a larger scale from microwave-alkali (Mw-A) pretreated oil palm EFB using simultaneous saccharification and fermentation (SSF) process with Rhizopus oryzae fungus. The present work is divided into four different stages; pretreatment of EFB, development of practical and effective procedure for inoculum build up for lactic acid production on a pilot scale, optimization of process to improve the yield by using fed batch mode operation and scale up of lactic acid production in 150 L fermentor. The Mw-A pre-teatment proved to be an effective method for removing lignin, preserving cellulose fraction and enhancing the enzymatic hydrolysis of EFB. The composition changes on the lignin, hemicelluloses and cellulose after pretreatment was used as indicators to represent the effectiveness of the pretreatment. In order to fulfill the requirement of massive inoculum production for large scale fermentation, a study was performed to develop a protocol in preparing inoculum for lactic acid production from EFB. Multi-stage inocula were developed and their fermentation ability was assessed. The procedure performed eliminated the requirement of huge quantity of spore suspension and improved the fermentation consistency. In order to obtain the desired morphological form of Rhizopus pellets, several parameters such as concentration of spore suspension, storage time and doses of inoculum were varied. Longer storage time of spore suspension of more than three days led to the formation of free mycelia. Low inoculum concentrations of 107 spores/ml are beneficial for formation of pellet. In addition, xylose has a positive effect on pellet formation compared to glucose. To achieve a high lactic acid concentration in the broth, high solids loading was required to allow a higher rate of glucose conversion. However, a decrease in the final lactic acid concentration was observed when running SSF at a massive insoluble solids level. High osmotic pressure in the medium led to poor cellular performance and caused the Rhizopus oryzae pellets to break down, affecting the lactic acid production. The process performance was further improved using a fed-batch operation mode. The fed-batch operation was observed to facilitate higher lactic acid concentration of 12 g/L, compared with the SSF batch mode with final lactic acid concentration of 6.8 g/L. For scale-up of the lactic acid fermentation, the strategy was adopted to provide almost equivalent oxygen mass transfer coefficient (kLa) to the different-sized fermentor systems (16 L and 150 L), thus ensuring the same amount of dissolved oxygen supply in each fermentation broth. At kLa value of 0.06 s-1, final lactic acid concentration in both scales were found identical

Bio-hydrogen and Methane Production from Lignocellulosic Materials

This chapter covers the information on bio-hydrogen and methane production from lignocellulosic materials. Pretreatment methods of lignocellulosic materials and the factors affecting bio-hydrogen production, both dark- and photo-fermentation, and methane production are addressed. Last but not least, the processes for bio-hydrogen and methane production from lignocellulosic materials are discussed

Biomass Wastes for Energy Production

Environmental problems are forcing a rethinking of the world’s energy supply system. In parallel, there is an increasing amount of global solid waste production. A fundamental shift toward greater reliance on biomass wastes in the world’s energy system is plausible because of ongoing major technological advances that hold the promise of making the conversion of biomass into high-quality energy carriers, like electricity and gaseous or liquid fuels, economically competitive with fossil fuels. Therefore, waste-to-energy systems have become a paramount topic for both industry and researchers due to interest in energy production from waste and improved chemical and thermal efficiencies with more cost-effective designs. This biomass shift is also important for industries to become more efficient by using their own wastes to produce their own energy in the light of the circular economy concept. This book on “Biomass Wastes for Energy Production” brings novel advances on waste-to-energy technologies, life cycle assessment, and computational models, and contributes to promoting rethinking of the world’s energy supply systems