Life cycle and economic assessment of sugarcane bagasse valorization to lactic acid

Life cycle environmental benefits of recycling waste liquor and chemicals in production of lignocellulosic bioethanol

In recent decades, numerous bioconversion processes and techniques have been developed to utilize lignocellulosic biomass as feedstock in the production of bio-based fuels and materials. However, waste treatment, an important sub-system, is seldom considered in the life cycle assessment of lignocellulose derived products. This study comprehensively investigated the environmental impacts of bioethanol and electricity cogeneration from sugarcane bagasse, with a focus on recycling techniques adopted in waste treatment. A life cycle assessment indicated that high recycle rate of black liquor, acid and waste washing water can substantially reduce the consumption of fresh water, related chemicals and energy by 70-80%. Environmental impacts relating to global warming, acidification potential and primary energy demand can be decreased by 5-10 times or even entirely eliminated. These study outcomes demonstrate significant environmental benefits of integrating waste recycling techniques into lignocellulose biorefinery process, providing a solid foundation for future industrial development.

Techno-economic assessment of sugarcane bagasse pith-based briquette production and performance analysis of briquette feed gasifier-engine system

Utilizing agriculture co-products and agricultural residues directly leads to Energy, Economic, and Environmental sustainability. Sugar production industries produce a considerable amount of sugarcane bagasse (SB) as a co-product, whereas SB is used in paper-mill sectors, which have a large amount of waste as sugarcane bagasse pith (SBP). In this view, the novelty of the present study aims to ensure the economic viability of the SBP briquette production plant, after that, briquette-based producer gas (PG) generation and application to compression ignition (CI) engine for diesel substitution. The economic analysis includes the Net Present Value (NPV) and Profitability Index (PI) for the feasibility check. And gasifier-engine analysis includes the effect of gasification equivalence ratio (GER), engine compression ratio (CR), and load on engine brake thermal efficiency (BTE), diesel saving, Sound, Exhaust gas temperature (EGT), and emissions (CO, HC, CO2, NOx). Further, operating variables were optimized with the desirability approach of Response surface methodology (RSM). In the result, NPV and PI values were found to be Rs 49,64,379.5 (≈0.06 million USD) and 1.98, respectively. However, the economic feasibility of the plant is sensitive to capital cost, briquette market price, and discount percentages. Regarding gasifier-engine performance, the maximum diesel substitution was found to be 66.15% at dual fuel (DF) mode engine run. RSM-based optimization result showed the optimum operating setting of 0.10 GER, 16 CR, and 9.93 kg load at 1500 rpm with a composite desirability of 0.798. Accordingly, at optimal input parameters, the magnitudes of engine performance as BTE, Sound, CO, HC, CO2, and NOx were found to be 27.18%, 91.21 db, 0.10%vol., 53.19 ppm, 2.33%vol., and 8.43 ppm respectively. Thus, the higher value of the economic index and substantial amount of diesel fuel saving through the gasifier-engine system ensures the economic feasibility of briquetting and power generation technology.

High titer (>200 g/L) lactic acid production from undetoxified pretreated corn stover

Lignocellulosic biomass is a reliable feedstock for lactic acid fermentation, low product titers hamper the scale production of cellulosic lactic acid. In this study, a Densifying Lignocellulosic biomass with Chemicals (sulfuric acid) pretreatment based cellulosic lactic acid biorefinery system was developed and demonstrated from multi-dimensions of producing bacteria, fermentation modes, corn stover solid loadings, fermentation vessels, and product purification. Results suggested that several lactic acid bacteria exhibited high fermentation activity in high solid loading corn stover hydrolysates. Remarkably, simultaneous saccharification co-fermentation performed in 100-mL flasks enabled 210.1 g/L lactic acid from 40% solid loading corn stover hydrolysate. When simultaneous saccharification co-fermentation was performed in 3-L bioreactors, 157.4 g/L lactic acid was obtained from 35% solid loading corn stover hydrolysate. These obtained lactic acid titers are the highest reports until now when lignocellulosic biomasses are used as substrates, making it efficient for scale production of cellulosic lactic acid.

Saccharina latissima, candy-factory waste, and digestate from full-scale biogas plant as alternative carbohydrate and nutrient sources for lactic acid production

To substitute petroleum-based materials with bio-based alternatives, microbial fermentation combined with inexpensive biomass is suggested. In this study Saccharina latissima hydrolysate, candy-factory waste, and digestate from full-scale biogas plant were explored as substrates for lactic acid production. The lactic acid bacteria Enterococcus faecium, Lactobacillus plantarum, and Pediococcus pentosaceus were tested as starter cultures. Sugars released from seaweed hydrolysate and candy-waste were successfully utilized by the studied bacterial strains. Additionally, seaweed hydrolysate and digestate served as nutrient supplements supporting microbial fermentation. According to the highest achieved relative lactic acid production, a scaled-up co-fermentation of candy-waste and digestate was performed. Lactic acid reached a concentration of 65.65 g/L, with 61.69% relative lactic acid production, and 1.37 g/L/hour productivity. The findings indicate that lactic acid can be successfully produced from low-cost industrial residues.

Techno-Economic Analysis of 2,3-Butanediol Production from Sugarcane Bagasse

Sugarcane bagasse (SCB) is a significant agricultural residue generated by sugar mills based on sugarcane crop. Valorizing carbohydrate-rich SCB provides an opportunity to improve the profitability of sugar mills with simultaneous production of value-added chemicals, such as 2,3-butanediol (BDO). BDO is a prospective platform chemical with multitude of applications and huge derivative potential. This work presents the techno-economic and profitability analysis for fermentative production of BDO utilizing 96 MT of SCB per day. The study considers plant operation in five scenarios representing the biorefinery annexed to a sugar mill, centralized and decentralized units, and conversion of only xylose or total carbohydrates of SCB. Based on the analysis, the net unit production cost of BDO in the different scenarios ranged from 1.13 to 2.28 US$/kg, while the minimum selling price varied from 1.86 to 3.99 US$/kg. Use of the hemicellulose fraction alone was shown to result in an economically viable plant; however, this was dependent on the condition that the plant would be annexed to a sugar mill which could supply utilities and the feedstock free of cost. A standalone facility where the feedstock and utilities were procured was predicted to be economically feasible with a net present value of about 72 million US$, when both hemicellulose and cellulose fractions of SCB were utilized for BDO production. Sensitivity analysis was also conducted to highlight some key parameters affecting plant economics.

Advances and opportunities in integrating economic and environmental performance of renewable products

There is a growing global need to transition from a fossil-based to a bio-based economy to produce fuels, chemicals, food, and materials. In the specific context of industrial biotechnology, a successful transition toward a sustainable development requires not only steering investment toward a bioeconomy, but also responsibly introducing bio-based products with lower footprints and competitive market prices. A comprehensive sustainability assessment framework applied along various research stages to guide bio-based product development is urgently needed but currently missing. To support holistic approaches to strengthen the global bioeconomy, the present study discusses methodologies and provides perspectives on the successful integration of economic and environmental performance aspects to guide product innovation in biotechnology. Efforts on quantifying the economic and environmental performance of bio-based products are analyzed to highlight recent trends, challenges, and opportunities. We critically analyze methods to integrate Techno-Economic Assessment (TEA) and Life Cycle Assessment (LCA) as example tools that can be used to broaden the scope of assessing biotechnology systems performance. We highlight the lack of social assessment aspects in existing frameworks. Data need for jointly applying TEA and LCA of succinic acid as example commodity chemical are assessed at various Technology readiness levels (TRLs) to illustrate the relevance of the level of integration and show the benefits of the use of combined assessments. The analysis confirms that the implementation of integrated TEA and LCA at lower TRLs will provide more freedom to improve bio-based product's sustainability performance. Consequently, optimizing the system across TRLs will guide sustainability-driven innovation in new biotechnologies transforming renewable feedstock into valuable bio-based products.

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.

A negative-carbon footprint process with mixed biomass feedstock maximizes conversion efficiency, product value and CO2 mitigation

The great variety of biomass species offers unique features for synergistic optimization of process outcomes. In this work, spent mushroom substrate and bagasse with optimize ratio were processed to produce value-added products of activated carbon and biofuel yet achieve negative CO₂ emission. By integrating experimental characterization, this work uses process simulation, techno-economic analysis and life-cycle assessment to evaluate the techno-economic viability and CO₂ footprint of processes with single or dual-/mixed-biomass feedstocks. The combination of biomass species provides unique match of the production of flue gas and primary carbon that is critical for the optimization of mass and energy flow. Such combination has been demonstrated effective to improve product yield and energy efficiency. Results show that mixed biomass feedstock offers favourable figures such as high carbon efficiency of 66.74%, short payback period of 3.16 years, considerable net present value of 80.48 million dollars, and low GWP of -2.37 kg CO₂-eq.

Advancement of biorefinery-derived platform chemicals from macroalgae: a perspective for bioethanol and lactic acid

The extensive growth of energy and plastic demand has raised concerns over the depletion of fossil fuels. Moreover, the environmental conundrums worldwide integrated with global warming and improper plastic waste management have led to the development of sustainable and environmentally friendly biofuel (bioethanol) and biopolymer (lactic acid, LA) derived from biomass for fossil fuels replacement and biodegradable plastic production, respectively. However, the high production cost of bioethanol and LA had limited its industrial-scale production. This paper has comprehensively reviewed the potential and development of third-generation feedstock for bioethanol and LA production, including significant technological barriers to be overcome for potential commercialization purposes. Then, an insight into the state-of-the-art hydrolysis and fermentation technologies using macroalgae as feedstock is also deliberated in detail. Lastly, the sustainability aspect and perspective of macroalgae biomass are evaluated economically and environmentally using a developed cascading system associated with techno-economic analysis and life cycle assessment, which represent the highlights of this review paper. Furthermore, this review provides a conceivable picture of macroalgae-based bioethanol and lactic acid biorefinery and future research directions that can be served as an important guideline for scientists, policymakers, and industrial players.

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E-waste derived silica-alumina for eco-friendly and inexpensive Mg-Al-Ti photocatalyst towards glycerol carbonate (electrolyte) synthesis: Process optimization and LCA

Valorization ofe-waste, i.e. waste printed circuit board (WPCB) through mechano-chemical activation to obtain silica as the catalyst support and alumina as the catalyst precursor for eco-friendly synthesis of inexpensive highly proficient photocatalyst has been explored. The WPCB derived silica-supported layered double oxide photocatalyst (MATLS_W) and its counterpart (MATLS_C) involving commercial silica and alumina precursors were synthesized through the wet-impregnation method under energy-efficient solar simulated quartz halogen lamp (SSQHL) irradiations to improve its photocatalytic properties compared to conventional methods. The prepared MATLS_Wpossessed a significantly low band-gap-energy (1.58 eV) that rendered efficient photocatalysis in the green-synthesis of glycerol carbonate (GC) (an effective electrolyte). The catalytic performance of the optimal MATLS_Wresulted in a superior yield of GC (98.68%) compared to that rendered by MATLS_Ccatalyst (GC yield: 96.56%) at optimal process conditions. Detailed life cycle assessment (LCA) of the entire process (deploying Ecoinvent 3.5 database) dictated conducive environmental impacts concerning 1 kg GC synthesis alongside a scale-up study for 1 MT GC synthesis encompassing silica-alumina extraction from WPCB, MATLS_W preparation, and employment of SSQHL-radiated batch reactor (SSQHLBR) (56.64% less energy consumption than conventional). The overall process deploying the novel MATLS_Win conjunction with the effectual reactor demonstrated superiority over the conventional GC synthesis process through appreciable reductions of environmental impact parameters, namely GWP, FDP, and HTP by 5.78%, 3.60%, and 5.72% respectively. The developed green process for e-waste utilization can procreate an effective waste management protocol towards a cleaner world.

Sugarcane valorization: selection of process routes based on sustainability index

Increasing awareness about sustainability has compelled the recent researchers to explore different methods for evaluation. Conventionally the sustainability of a process was majorly dependent on the economics feasibility. Recently need of incorporation of environmental and social concerns in overall sustainability assessment has been realized. Authors in their prior work has published a framework for performing sustainability assessment of biomass processing enterprises. The present work is on selection of sugarcane valorization pathways based on the sustainability index using the same framework. Six alternative routes are compared based on their economic, environment and social criteria. Life cycle assessment of each process is performed as per ISO 14040/44 to evaluate the environmental criteria. Integrated method of value function (MIVES) is used for consolidation of different indicators and criteria. Amongst the process alternatives considered for assessment, 1G2G ethanol route is observed to have highest sustainability index (0.864) owing to relatively lower environmental impact whereas first generation butanol production route (1GRS) had the least sustainability index of 0.090 on account of decreased yield and less products. Sensitivity analysis performed on the model showed no significant change in the ranking of the alternatives.

Resource recovery of lignocellulosic biomass waste into lactic acid - Trends to sustain cleaner production

Biomass waste generation concerns regulatory authorities to develop novel methods to sustain biotransformation processes. Particularly, lactic acid (LA) is a bulk commodity chemical used in diverse industries and holds a growing global market demand. Recently, lignocellulosic waste biomass is preferred for LA bio-production because of its non-edible and inexpensive nature. However, the information about new pretreatment methods for lignocellulosic feedstock, and novel strains capable to produce LA through fermentation is limited. Therefore, this review highlights the advancement of pretreatments methods of lignocellulosic biomass and biotransformation. Herein, we first briefly explored the main sources of lignocellulosic waste biomass, then we explored their latest advances in pretreatment processes particularly supercritical fluid extraction, and microwave-assisted extraction. Approaches for bioconversion were also analyzed, such as consolidated bioprocessing (CBP), simultaneous saccharification and fermentation (SSF), separate hydrolysis fermentation (SHF), among other alternatives. Also, new trends and approaches were documented, such as metagenomics to find novel strains of microorganisms and the use of recombinant strategies for the creation of new strains. Finally, we developed a holistic and sustainable perspective based on novel microbial ecology tools such as next-gen sequencing, bioinformatics, and metagenomics. All these shed light on the needs to culture powerful microbial isolates, co-cultures, and mixed consortia to improve fermentation processes with the aim of optimizing cultures and feedstock pretreatments.