•Deep eutectic solvent studies on biomass pretreatment have been reviewed.•Basics of DES fractionation of lignocellulosic biomass have been summarized.•Mechanisms of using DES for biomass ...fractionation have been discussed.•Prospects and challenges for future works have been outlined.
Biomass recalcitrance hinders efficient utilization of lignocellulosic biomass, making pretreatment process a crucial step for successful biorefinery process. Pretreatment processes have been developed for processing biomass, while technical obstacles including intensive energy requirement, high operational cost, equipment corrosions resulted from currently applied techniques promote the development of new pretreatment process for biomass. The deep eutectic solvent (DES) has been recognized as a promising solvent for biomass pretreatment, although the DES application toward biomass is still in its nascent stage. This review summarized the current researches using DES for biomass pretreatment, focusing particularly on lignin extraction and saccharification enhancement of lignocellulosic biomass. The mechanisms for biomass fractionation using DES as agents are introduced. Prospect and challenge were outlined.
•Digestate valorization studies were reviewed.•Potential of recovering digestate as renewable resource was estimated and discussed.•Prospects of digestate valorization based on process and product ...aspects were outlined.
Anaerobic digestion is recognized as promising technology for bioenergy production from biowaste, with huge quantity of digestate being produced as the residual waste. The digestate contains substantial amounts of organic and inorganic matters that be considered highly risky contaminants to the receiving environments if not properly treated, but also potential renewable resources if are adequately recovered. This prospect review summarized the current research efforts on digestate valorization, including aspects of resource recovery and the proposed applications, particularly on the conversion techniques and economic feasibility. The prospects for digestate valorization were highlighted at the end of this review.
•Research on syngas upgrades and novel gasification processes of MSW were reviewed.•Ways to make MSW gasification a sustainable and affordable route were outlined.•A graphical assessment protocol was ...proposed to comprehend reactions was proposed.•Research prospects to provide a reference for future work were discussed.
The production of hydrogen-rich syngas from municipal solid waste (MSW) by pyrolysis/gasification is one of the most promising waste-to-energy pathways for realizing a circular bioeconomy. This mini-review provides an overview of current research and development efforts in the field, focusing on the development of syngas upgrades and novel gasification processes, with the ultimate goal of making MSW gasification a sustainable and affordable route for the final disposal of MSW. A graphical assessment protocol is proposed to support comprehension of the main reactions that are involved in the MSW gasification. MSW gasification studies are reviewed with the prospects considered to provide a reference for future work.
•Formation and structures of lignin and principles of pulping are listed.•Obstacles to realize lignin biorefinery are discussed.•A biorefinery proposal based on Kraft lignin is addressed.
Lignin is a ...huge energy and carbon reserve but owing to its highly biologically recalcitrant nature it is commonly regarded as a waste in lignocellulosic biomass biorefinery. To realize the lignin biorefinery, it is proposed to use Kraft lignin, isolated from black liquor from Kraft pulping mills, as starting material to be fragmented by fast pyrolysis or selective catalysis to aromatic sub-units and to be post-refining with additional cleavage reaction and separation/purification as commodity aromatics pool in chemical industries. This Note calls for research efforts on detailed investigation of the feasibility of this proposed scenario.
Anaerobic digestion (AD) is a biological process that can convert organic substrates to biogas in the absence of oxygen. The AD process has been practiced for centuries; however, it is still a ...research focus in contemporary literature. This mini-review selected papers published in 2015 and summarized the improvement and technological advancement and revealing current research and development trends for the biogas from AD process. A discussion on the challenges and prospects for developing improved AD technologies is provided.
•Recent R&D works for biogas and anaerobic digestion process were reviewed.•Substrates, reactors, treatments, operation and system analysis were covered.•Research focuses and ways forward for AD process were discussed.
•Studies on role of DIET on enhanced methanogenesis was reviewed.•Effective strategies to enhance anaerobic digestion performance were highlighted.•Experimental supports to DIET for methanogenesis ...were listed.•Prospects and challenges for further studies were outlined.
The role of direct interspecies electron transfer (DIET) on enhancement of methanogenesis has been studied. This mini-review updated the current researches on the potential role of DIET on enhanced performance for anaerobic digestion of organic substrates with effective strategies implemented. Since most experimental observations correlated with the DIET mechanism are yet to be consolidated, this article categorized and discussed the current experimental observations supporting DIET mechanism for methanogenesis, mainly based on those with supplement of carbon materials, from which the prospects and challenges for further studies to confirm the role of DIET in anaerobic digestion processes were highlighted.
•Reviews the current research focuses on enzymatic saccharification.•Improvement on pretreatment processes is discussed.•Enhanced enzyme production, recycling and novel strains are ...discussed.•Combined saccharification and fermentation processes are discussed.•Economy of the enzymatic saccharification is discussed.
To realize lignocellulosic biorefinery is of global interest, with enzymatic saccharification presenting an essential stage to convert polymeric sugars to mono-sugars for fermentation use. This mini-review summarizes qualitatively the research focuses discussed the review articles presented in the past 22 months and other relevant papers. The research focuses on pretreatment with improved efficiency, enhanced enzyme production with high yields and high extreme tolerance, feasible combined saccharification and fermentation processes, detailed mechanisms corresponding to the enzymatic saccharification in lignocellulosic biorefinery, and the costs are discussed.
Room-temperature ionic liquids (ILs) are molten salts at around room temperatures. The current researches of using ILs for efficient pretreatment for lignocellulosic biomass are updated in this ...article. The aspects of synthesis of high-performance ILs, recycling of used ILs with minimum use of utility, development of IL-tolerant enzymes, and optimization of the entire process economy were discussed. The mechanisms of IL solvation and the potential for IL-based biomass refinery are also highlighted.
Microalgae are being promoted as a superior alternative feedstock for sustainable biofuel production and recently they are also being increasingly recognized as phytoremediation agents in ...bioremediation. Other than these, microalgae have been utilized as a sustainable feed in aquaculture for many years. The success of microalgae as a feed is based on the nutritional quality of microalgae, which are rich in protein, carbohydrates, fats, vitamins, minerals, and other beneficial biologically active components such as carotenoids and polyunsaturated fatty acids. Standards for the evaluation of microalgae include the assessment of various qualities such as digestibility, bioavailability, and toxicity analysis. This review provides comprehensive information regarding the current status and desirable characteristics of microalgae as a feed ingredient. Feed quality assessments such as protein quality, toxicological and microbiological analysis for microalgae are discussed. The techno-functional components of microalgae are presented in the feed perspective. The utilization of microalgae in various animal husbandry sectors and aquaculture are summarized. The advantages – disadvantages of microalgae as a feed is also presented, along with future research prospects. In short, this review will provide an overall view of the nutritional quality of microalgae and its beneficial application as a sustainable feed ingredient.
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•Microalgal components in feed provide nutritional and functional value.•Techno-functional properties of microalgal biomolecules are reviewed.•Antioxidants and anti-inflammatory compounds improve stress tolerance in animals.•Immune modulators boost immune response and disease resistance in farm animals.•Prebiotic activity has the potential to reduce GHG emissions of the livestock industry.
•Biochar modification protocols were discussed based on literature reports.•Studies on applications of pristine and modified biochars were reviewed.•Advances in biochar modification research were ...delineated.•Research trends on applications of modified biochars were outlined.
Biochars are the solid product of biomass under pyrolysis or gasification treatment, whose wholesale prices are lower than commercial activated carbons and other fine materials now in use. The employment of biochars as a renewable resource for field applications, if feasible, would gain apparent economic niche. Modification using physical or chemical protocol to revise the surface properties of biochar for reaching enhanced performances of target application has attracted great research interests. This article provided an overview of biochar application, particularly with the respect to the use of modified biochar as preferred soil amendment, adsorbent, electrochemical material, anaerobic digestion promotor, and catalyst. Based on literature works the current research trends and the prospects and research needs were outlined.
