Microalgae dewatering is a major obstruction to industrial-scale processing of microalgae for biofuel prodn. The dil. nature of harvested microalgal cultures creates a huge operational cost during dewatering, thereby, rendering algae-based fuels less economically attractive. Currently there is no superior method of dewatering microalgae. A technique that may result in a greater algal biomass may have drawbacks such as a high capital cost or high energy consumption. The choice of which harvesting technique to apply will depend on the species of microalgae and the final product desired. Algal properties such as a large cell size and the capability of the microalgae to autoflocculate can simplify the dewatering process. This article reviews and addresses the various technologies currently used for dewatering microalgal cultures along with a comparative study of the performances of the different technologies.

Dewatering of microalgal cultures : a major bottleneck to algae-based fuels

A critical review of analytical methods in pretreatment of lignocelluloses: Composition, imaging, and crystallinity.

Lignocellulosic biomass is the most abundant and renewable material in the world for the production of biofuels. Using lignocellulosic biomass derived biofuels could reduce reliance on fossil fuels and contribute to climate change mitigation. A profound understanding of the physicochemical properties of lignocellulosic biomass and the analytical characterization methods for those properties is essential for the design and operation of associated biomass conversion processing facilities. The present article aims to present a comprehensive review of physicochemical properties of lignocellulosic biomass, including particle size, grindability, density, flowability, moisture sorption, thermal properties, proximate analysis properties, elemental composition, energy content and chemical composition. The corresponding characterization techniques for these properties and their recent development are also presented. This review is intended to provide the readers systematic knowledge in the physicochemical properties of lignocellulosic biomass and characterization techniques for the conversion of biomass and the application of biofuels.

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Review of physicochemical properties and analytical characterization of lignocellulosic biomass

Photo-curing 3D printing technique and its challenges

https://cyberleninka.org/article/n/735321.pdf

Recent developments and innovations in solid state fermentation

Production of biofuels from renewable feedstocks has captured considerable scientific attention since they could be used to supply energy and alternative fuels. Bioethanol is one of the most interesting biofuels due to its positive impact on the environment. Currently, it is mostly produced from sugar- and starch-containing raw materials. However, various available types of lignocellulosic biomass such as agricultural and forestry residues, and herbaceous energy crops could serve as feedstocks for the production of bioethanol, energy, heat and value-added chemicals. Lignocellulose is a complex mixture of carbohydrates that needs an efficient pretreatment to make accessible pathways to enzymes for the production of fermentable sugars, which after hydrolysis are fermented into ethanol. Despite technical and economic difficulties, renewable lignocellulosic raw materials represent low-cost feedstocks that do not compete with the food and feed chain, thereby stimulating the sustainability. Different bioprocess operational modes were developed for bioethanol production from renewable raw materials. Furthermore, alternative bioethanol separation and purification processes have also been intensively developed. This paper deals with recent trends in the bioethanol production as a fuel from different renewable raw materials as well as with its separation and purification processes.

/pdf/bioethanol-production-from-renewable-raw-materials-and-its-kfqxqyeweh.pdf

Bioethanol Production from Renewable Raw Materials and Its Separation and Purification: A Review.

This review aims to present current knowledge of the fungi involved in lignocellulose degradation with an overview of the various classes of lignocellulose-acting enzymes engaged in the pretreatment and saccharification step. Fungi have numerous applications and biotechnological potential for various industries including chemicals, fuel, pulp, and paper. The capability of fungi to degrade lignocellulose containing raw materials is due to their highly effective enzymatic system. Along with the hydrolytic enzymes consisting of cellulases and hemicellulases, responsible for polysaccharide degradation, they have a unique nonenzymatic oxidative system which together with ligninolytic enzymes is responsible for lignin modification and degradation. An overview of the enzymes classification is given by the Carbohydrate-Active enZymes (CAZy) database as the major database for the identification of the lignocellulolytic enzymes by their amino acid sequence similarity. Finally, the recently discovered novel class of recalcitrant polysaccharide degraders-lytic polysaccharide monooxygenases (LPMOs) are presented, because of these enzymes importance in the cellulose degradation process.

/pdf/lignocellulose-degradation-an-overview-of-fungi-and-fungal-537d1hx0g1.pdf

Lignocellulose degradation: An overview of fungi and fungal enzymes involved in lignocellulose degradation.

Compositional analysis of lignocellulosic feedstocks

This work investigates the methodology of producing a 3D-printed microreactor from the acrylic resin by PolyJet Matrix process. The PolyJet Matrix technology employs different materials or their combinations to generate 3D-printed structures, from small ones to complex geometries, with different material properties. Experimental and numerical methods served for the evaluation of the geometry and production of the microreactor and its hydrodynamic characterization. The operational limits of the single-phase flow in the microchannels, further improvements and possible applications of the microreactor were assessed based on the hydrodynamic characterization.

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Microreactor Production by PolyJet Matrix 3D-Printing Technology: Hydrodynamic Characterization§.

Lytic polysaccharide monooxygenases (LPMO) release a spectrum of cleavage products from their polymeric substrates cellulose, hemicellulose, or chitin. The correct identification and quantitation of these released products is the basis of MS/HPLC-based detection methods for LPMO activity. The duration, effort, and intricate analysis allow only specialized laboratories to measure LPMO activity in day-to-day work. A spectrophotometric assay will simplify the screening for LPMO in culture supernatants, help monitor recombinant LPMO expression and purification, and support enzyme characterization. Based on a newly discovered peroxidase activity of LPMO, we propose a fast, robust, and sensitive spectrophotometric activity assay using 2,6-dimethoxyphenol (2,6-DMP) and H2O2. The fast enzymatic assay (300 s) consists of 1 mM 2,6-DMP as chromogenic substrate, 100 µM H2O2 as cosubstrate, and an adequate activity of LPMO in a suitable buffer. The high molar absorption coefficient of the formed product coerulignone (e469 = 53,200 M−1 cm−1) makes the assay sensitive and allows reliable activity measurements of LPMO in concentrations of approx. 0.5–50 mg L−1. The activity assay based on 2,6-DMP detects a novel peroxidase activity of LPMO. This activity can be accurately measured and used for enzyme screening, production, and purification, and can also be applied to study binding constants or thermal stability. However, the assay has to be used with care in crude extracts, because other enzymes such as laccase or peroxidase will interfere with the assay. We also want to stress that the peroxidase activity is a homogeneous reaction with soluble substrates and should not be correlated to heterogeneous LPMO activity on polymeric substrates.

/pdf/a-fast-and-sensitive-activity-assay-for-lytic-polysaccharide-2hp1jdjln4.pdf

Božidar Šantek

Papers

Bioethanol Production from Renewable Raw Materials and Its Separation and Purification: A Review.

Lignocellulose degradation: An overview of fungi and fungal enzymes involved in lignocellulose degradation.

Compositional analysis of lignocellulosic feedstocks

Microreactor Production by PolyJet Matrix 3D-Printing Technology: Hydrodynamic Characterization§.

A fast and sensitive activity assay for lytic polysaccharide monooxygenase.