Augmented hydrolysis of acid pretreated sugarcane bagasse by PEG 6000 addition: a case study of Cellic CTec2 with recycling and reuse

Two-stage biohydrogen and methane production from sugarcane-based sugar and ethanol industrial wastes: A comprehensive review

The transition to renewable energy sources is crucial to ensure a sustainable future. Although the sugar and ethanol industries benefit from this transition, there are untapped opportunities to utilize the waste generated from the sugar and ethanol process chains through two-stage anaerobic digestion (TSAD). This review comprehensively discusses the utilization of various sugarcane-based industrial wastes by TSAD for sequential biohydrogen and methane production. Factors influencing TSAD process performance, including pH, temperature, hydraulic retention time, volatile fatty acids and alkalinity, nutrient imbalance, microbial population, and inhibitors, were discussed in detail. The potential of TSAD to reduce emissions of greenhouse gases is demonstrated. Recent findings, implications, and promising future research related to TSAD, including the integration of meta-omics approaches, gene manipulation and bioaugmentation, and application of artificial intelligence, are highlighted. The review can serve as important literature for the implementation, improvement, and advancements in TSAD research.

Sugarcane wastes as microbial feedstocks: A review of the biorefinery framework from resource recovery to production of value-added products

Sugarcane industry is a major agricultural sector capable of producing sugars with byproducts including straw, bagasse, and molasses. Sugarcane byproducts are no longer wastes since they can be converted into carbon-rich resources for biorefinery if pretreatment of these is well established. Considerable efforts have been devoted to effective pretreatment techniques for each sugarcane byproduct to supply feedstocks in microbial fermentation to produce value-added fuels, chemicals, and polymers. These value-added chains, which start with low-value industrial wastes and end with high-value products, can make sugarcane-based biorefinery a more viable option for the modern chemical industry. In this review, recent advances in sugarcane valorization techniques are presented, ranging from sugarcane processing, pretreatment, and microbial production of value-added products. Three lucrative products, ethanol, 2,3-butanediol, and polyhydroxyalkanoates, whose production from sugarcane wastes has been widely researched, are being explored. Future studies and development in sugarcane waste biorefinery are discussed to overcome the challenges remaining.

Sustainable valorization of sugarcane residues: Efficient deconstruction strategies for fuels and chemicals production

The global climate crisis and the ongoing increase in fossil-based fuels have led to an alternative solution of using biomass for fuel production. Sugarcane bagasse (SCB) is an agricultural residue with a global production of more than 100 million metric tons and it has various applications in a biorefinery concept. This review brings forth the composition, life cycle assessment, and various pretreatments for the deconstruction techniques of SCB for the production of valuable products. The ongoing research in the production of biofuels, biogas, and electricity utilizing the bagasse was elucidated. SCB is used in the production of carboxymethyl cellulose, pigment, lactic acid, levulinic acid, and xylooligosaccharides and it has prospective in meeting the demand for global energy and environmental sustainability.

Emerging trends in high-solids enzymatic saccharification of lignocellulosic feedstocks for developing an efficient and industrially deployable sugar platform

For the techno-commercial success of any lignocellulosic biorefinery, the cost-effective production of fermentable sugars for the manufacturing of bio-based products is indispensable. High-solids enzymatic saccharification (HSES) is a straightforward approach to develop an industrially deployable sugar platform. Economic incentives such as reduced capital and operational expenditure along with environmental benefits in the form of reduced effluent discharge makes this strategy more lucrative for exploitation. However, HSES suffers from the drawback of non-linear and disproportionate sugar yields with increased substrate loadings. To overcome this bottleneck, researchers tend to perform HSES at high enzyme loadings. Nonetheless, the production costs of cellulases are one of the key contributors that impair the entire process economics. This review highlights the relentless efforts made globally to attain a high-titer of sugars and their fermentation products by performing efficient HSES at low cellulase loadings. In this context, technical innovations such as advancements in new pretreatment strategies, next-generation cellulase cocktails, additives, accessory enzymes, novel reactor concepts and enzyme recycling studies are especially showcased. This review further covers new insights, learnings and prospects in the area of lignocellulosic bioprocessing.

Advanced Bioethanol Production: From Novel Raw Materials to Integrated Biorefineries

The production of so-called advanced bioethanol offers several advantages compared to traditional bioethanol production processes in terms of sustainability criteria. This includes, for instance, the use of nonfood crops or residual biomass as raw material and a higher potential for reducing greenhouse gas emissions. The present review focuses on the recent progress related to the production of advanced bioethanol, (i) highlighting current results from using novel biomass sources such as the organic fraction of municipal solid waste and certain industrial residues (e.g., residues from the paper, food, and beverage industries); (ii) describing new developments in pretreatment technologies for the fractionation and conversion of lignocellulosic biomass, such as the bioextrusion process or the use of novel ionic liquids; (iii) listing the use of new enzyme catalysts and microbial strains during saccharification and fermentation processes. Furthermore, the most promising biorefinery approaches that will contribute to the cost-competitiveness of advanced bioethanol production processes are also discussed, focusing on innovative technologies and applications that can contribute to achieve a more sustainable and effective utilization of all biomass fractions. Special attention is given to integrated strategies such as lignocellulose-based biorefineries for the simultaneous production of bioethanol and other high added value bioproducts.

Chestnut Shells as Waste Material for Succinic Acid Production from Actinobacillus succinogenes 130Z

Currently, the full exploitation of waste materials for the production of value-added compounds is one of the potential solutions to lower costs and increase the sustainability of industrial processes. In this respect, the aim of this work was to evaluate the potential of chestnut shells (CSH) as substrate for the growth of Actinobacillus succinogenes 130Z, a natural producer of succinic acid that is a precursor of several bulk chemicals with diverse applications, such as bioplastics production. Hydrolysis of ammonia pretreated CSH in citrate buffer with the Cellic CTec2 enzyme mix was optimized and strain performance was studied in bottle experiments. Data showed co-consumption of citrate, glucose and xylose, which resulted in a change of the relative ratio of produced acids, providing an insight into the metabolism of A. succinogenes that was never described to date. Furthermore, high C:N ratios seems to have a favorable impact on succinic acid production by decreasing byproduct formation. Finally, yield and volumetric production rate of succinic acid were studied in controlled 2 L bioreactors demonstrating the potential use of CSH as renewable raw material.

Chestnut Shells as Waste Material for Succinic Acid Production from Actinobacillus succinogenes 130Z

Currently, the full exploitation of waste materials for the production of value-added compounds is one of the potential solutions to lower costs and increase the sustainability of industrial processes. In this respect, the aim of this work was to evaluate the potential of chestnut shells (CSH) as substrate for the growth of Actinobacillus succinogenes 130Z, a natural producer of succinic acid that is a precursor of several bulk chemicals with diverse applications, such as bioplastics production. Hydrolysis of ammonia pretreated CSH in citrate buffer with the Cellic CTec2 enzyme mix was optimized and strain performance was studied in bottle experiments. Data showed co-consumption of citrate, glucose and xylose, which resulted in a change of the relative ratio of produced acids, providing an insight into the metabolism of A. succinogenes that was never described to date. Furthermore, high C:N ratios seems to have a favorable impact on succinic acid production by decreasing byproduct formation. Finally, yield and volumetric production rate of succinic acid were studied in controlled 2 L bioreactors demonstrating the potential use of CSH as renewable raw material.