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The sustainable management of residual waste streams generated from the pulp and paper industry (PPI) has garnered increasing concerns due to the energy crisis and the pressing environmental threats posed by substantial effluent discharges. Using renewable lignocellulosic waste for resource generation presents a revolutionary approach to achieve environmental sustainability. Integrating the PPI with biorefinery processes allows for diversification beyond paper production and facilitates resource recovery. This review critically evaluates the valorization of waste streams from the PPI, with a pronounced emphasis on expanding into bioenergy and biofuels production, while also fostering the development of innovative biomaterials, such as biochar and activated carbon for applications with high added-value, such as environmental remediation and supercapacitors development, thus ensuring long-term sustainability. The review also emphasizes the significance of adopting a circular economy and its role in achieving environmental sustainability, with a particular emphasis on thermochemical technologies, which hold promise for resource recovery from wastewater. Furthermore, the review identifies critical bottlenecks in the path of waste stream valorization and engages in a forward-looking discussion on future prospects within the PPI. [Display omitted] • Black liquor contains major inhibitors e.g., furfural, 5-hydroxymethylfurfural. • Black liquor is used as a low-cost sugar, to produce e.g., bioethanol, biobutanol. • Paper mill wastewater used e.g., graphene sheet development, biochar, carbon fuel cell. • Porous carbon by black liquor showed capacitances for supercapacitor electrode. • Integrated biorefineries can achieve sustainability by Kraft pulp conversion. [ABSTRACT FROM AUTHOR]

The pulp and paper industry is recognized as a well-established sector, which throughout its process, generates a vast amount of waste streams with the capacity to be valorized. Typically, these residues are burned for energy purposes, but their use as substrates for biological processes could be a more efficient and sustainable alternative. With this aim, it is essential to identify and characterize each type of waste to determine its biotechnological potential. In this context, this research highlights possible alternatives with lower environmental impact and higher revenues. The bio-based pathway should be a promising alternative for the valorization of pulp and paper industry wastes, in particular for bioproduct production such as bioethanol, polyhydroxyalkanoates (PHA), and biogas. This article focuses on state of the art regarding the identification and characterization of these wastes, their main applied deconstruction technologies and the valorization pathways reported for the production of the abovementioned bioproducts. [ABSTRACT FROM AUTHOR]

[Display omitted] • Office paper waste is processed using physiochemical and enzymatic hydrolysis. • The yeast is isolated from rotten banana for the fermentation process. • Box-Behnken analysis was used to determine optimal conditions for key variables. • A blended membrane was applied for the purification process. • Amicon cell and polymeric membrane dehydrate ethanol–water combinations. One potential replacement for fossil fuels is the generation of biofuel from biomass feedstock. To reach the global sustainability goals, it is also necessary to address a number of issues, such as reducing environmental pollution, climate change, and carbon emissions. This work was aimed to convert the office paper waste as biomass feedstock into bioethanol through a sustainable pathway. The office paper waste was hydrolyzed via physiochemical and enzymatic hydrolysis, the liberated glucose was estimated at 15.72 g/L using the optimum conditions of 15 % HCl and 6 % office paper waste followed by enzymatic hydrolysis. The yeast isolate B2 that was applied for the fermentation process was isolated from rotten banana, identified as Hanseniaspora uvarum (STDF-B2) and submitted to GenBank with accession number (OP800106). The Box-Behnken design was applied to estimate the optimal conditions for the three most significant variables depending on the one variable at a time results. A blended membrane of sulphonated polyvinyl chloride with poly(2-acrylamido-2-methyl-1-propanesulfonic acid) (SPVC-PAMPS) was applied for the purification of both standard ethanol and produced bioethanol via pervaporation technique (PV). The morphology, chemical composition, mechanical properties and permeability of the membrane were all analyzed in various ways. Following purification using a membrane-integrated amicon cell, the total permeate flows of the laboratory-prepared ethanol and generated bioethanol were 289.54 and 253.06 (g/m2 h), respectively. [ABSTRACT FROM AUTHOR]

Summary: A novel bioprocess design to convert paper mill sludge (PMS) to biofuels is proposed in this work. The design utilizes cellulosic fiber recovered from the PMS via optimized de‐ashing (HCl washing) step. This work specifically provided a technical and economic analysis of paper mill sludge conversion into biofuel production using a novel protocol. The protocol is based on scanning electron microscopy (SEM) analysis to assess the quality of the contained cellulose prior to further processing. The results are crucially important to determine the suitability of the PMS feedstock to produce biofuels. SEM analysis was employed as a preliminary screening tool to evaluate sludge digestibility and conversion. The SEM characterization technique established a direct relationship between the fiber morphology, presence of crystals salts and sugar yield after enzymatic hydrolysis. Substantial structural changes were observed before and after de‐ashing the sludge samples, leading to a correlation between the surface morphology and the washing step. The results suggested that de‐ashing changes the surface morphology and upon analysis, increased the sugar yield up to about 86% as opposed to 2.2% in sludge sample A as an example. The PMS conversion into biofuel was simulated using Aspen PLUS and compared to a similar process using corn stover as feedstock. The simulation results showed it is 20% cheaper to produce bioethanol from PMS compared to corn stover. The simulation revealed less energy demand by around 13 320 MJ/h compared to that when corn stover was used. [ABSTRACT FROM AUTHOR]

Bioethanol production using paper wastes seems a promising approach towards sustainable energy, but mainly hindered by hazardous ink. Therefore, in our experimental plan various methods were applied for the deinking of waste newspapers, laser printed papers and examination papers. A newly designed paper pulper reduced the pulping time from 6 h to 2 h. Cellulase (15 FPU/g) from Aspergillus oryzae MDU-4 was found effective for the deinking of newspapers, whereas laccase isozymes (150 U/g) from Ganoderma lucidum MDU-7 along with 2 mM HOBt was preferred for the ink removal and degradation from the examination papers. Ozonation in the presence of Tween-80 was found to be efficient in the removal of toxic toners used in laser printing papers. The biologically and physically deinked papers, studied with the help of SEM, TEM, FTIR, and XRD analysis revealed significant changes in the chemical and surface structure. Moreover, the saccharification of deinked papers with the help of an enzymatic consortium of Trichoderma citrinoviride MDU-1 resulted in 305 mg/g, 377 mg/g, and 409 mg/g release of sugars from the newspaper, examination paper, and laser printed paper, respectively. Finally, the enzymatic hydrolysates fermented with Saccharomyces cerevisiae NCIM-3640 produced 3.35 g/L ethanol, with 40.85% ethanol yield. Image 1 • Pulping time was reduced from 6 h to 2 h by designing a new pulp maker. • Cellulase and laccase were effective for the deinking of NP and EP, respectively. • Ozonation was found appropriate for the removal of toners from PP. • Optimized deinking methods were comparatively better than chemical process. • Ink free paper hydrolysates resulted in 40.85% ethanol yield using S. cerevisiae. [ABSTRACT FROM AUTHOR]

Bioethanol is considered to be a possible substitute for non‐renewable fossil fuels. Biofuels, including bioethanol, are gradually replacing coal and oil for energy production. It is expected that, by 2040, fossil fuels' contribution to the world's energy demands will only be 25% with the remaining contribution made up by biofuels. One of the major factors affecting ethanol production is the cost of raw materials, which can be substantially reduced by utilizing industrial or agricultural lignocellulosic wastes. Using waste paper as a feedstock for bioethanol production would reduce the production cost and may eliminate problems in managing this waste material in the environment. The cellulose, hemicellulose, and lignin in waste paper are less complicated and so only mild pretreatment is needed before enzymatic hydrolysis and fermentation. This review covers topics such as bioethanol as a promising alternative to petroleum fuels, feedstocks for bioethanol production, lignocellulosic technology and challenges for ethanol production, advantages and disadvantages of pretreatments methods, waste paper as feedstock for ethanol production, processing of waste paper to ethanol, and the different integration methods of hydrolysis and fermentation. © 2019 Society of Chemical Industry and John Wiley & Sons, Ltd. [ABSTRACT FROM AUTHOR]

Paper sludge samples collected from recycling mills exhibited high ash content in the range of 54.59%–65.50% and glucose concentrations between 21.97% and 31.11%. Washing the sludge reduced the total ash content to between 10.7% and 19.31% and increased the concentration of glucose, xylose and lignin. Samples were screened for ethanol production and fed-batch simultaneous saccharification and fermentation (SSF) was optimised for the washed samples that resulted in highest and lowest ethanol concentrations. Maximum ethanol concentrations of 57.31 g/L and 47.72 g/L (94.07% and 85.34% of the maximum theoretical yield, respectively) was predicted for high and low fermentative potential samples, respectively, and was experimentally achieved with 1% deviation. A generic set of process conditions were established for the conversion of high ash-containing paper sludge to ethanol. Techno-economic analysis based on three different revenue scenarios, together with Monte Carlo analysis revealed 95% probability of achieving IRR values in excess of 25% at a paper sludge feed rate of 15 t/d. Feed rates of 30 t/d and 50 t/d exhibited a cumulative probability of 100%. This study presents the technical feasibility and economic viability of paper mills expansion towards bioethanol production from paper sludge. [ABSTRACT FROM AUTHOR]

In this study we investigated the technical feasibility of convert paper mill sludge into fuel ethanol. This involved the removal of mineral fillers by using either chemical pretreatment or mechanical fractionation to determine their effects on cellulose hydrolysis and fermentation to ethanol. In addition, we studied the effect of cationic polyelectrolyte (as accelerant) addition and hydrogen peroxide pretreatment on enzymatic hydrolysis and fermentation. We present results showing that removing the fillers content (ash and calcium carbonate) from the paper mill sludge increases the enzymatic hydrolysis performance dramatically with higher cellulose conversion at faster rates. The addition of accelerant and hydrogen peroxide pretreatment further improved the hydrolysis yields by 16% and 25% (g glucose / g cellulose), respectively with the de-ashed sludge. The fermentation process of produced sugars achieved up to 95% of the maximum theoretical ethanol yield and higher ethanol productivities within 9 h of fermentation. [ABSTRACT FROM AUTHOR]

The economics of Recycled Paper Sludge conversion into ethanol was here assessed with emphasis on integrating a cellulase recycling system. Without cellulases recycling this process presented positive economic outputs (payback period of 7.85 years; 10.90 Million US$ of accumulated NPV) despite the modest ethanol titers. Recycling both free and solid-bound enzymes allowed considerable savings of enzyme but also an increase on annual costs (0.88%), resulting on a superior economic output: payback period decreased to 7.25 years; accumulated NPV increased to 14.44 Million US$. Recycling exclusively the liquid fraction enabled a clear costs reduction, however, also total ethanol decreased, attenuating the abovementioned benefits. Targeting higher ethanol concentrations, superior solids consistencies were also evaluated. Despite a costs reduction, total ethanol decreased due to a higher ethanol retention on the solid. A sensitivity analysis further revealed that the cost of enzymes and ultrafiltration membrane may be critical on enzyme recycling economic feasibility. [ABSTRACT FROM AUTHOR]

The feasibility of cellulase recycling in the scope of bioethanol production from recycled paper sludge (RPS), an inexpensive byproduct with around 39% of carbohydrates, is analyzed. RPS was easily converted and fermented by enzymes and cells, respectively. Final enzyme partition between solid and liquid phases was investigated, the solid-bound enzymes being efficiently recovered by alkaline washing. RPS hydrolysis and fermentation was conducted over four rounds, recycling the cellulases present in both fractions. A great overall enzyme stability was observed: 71, 64 and 100% of the initial Cel7A, Cel7B and β-glucosidase activities, respectively, were recovered. Even with only 30% of fresh enzymes added on the subsequent rounds, solid conversions of 92, 83 and 71% were achieved for the round 2, 3 and 4, respectively. This strategy enabled an enzyme saving around 53–60%, while can equally contribute to a 40% reduction in RPS disposal costs. [ABSTRACT FROM AUTHOR]

Primary sludge, from different pulp and paper mills, was used as feedstock in simultaneous saccharification and fermentation (SSF) processes to produce ethanol. SSF was carried out with Saccharomyces cerevisiae ATCC 26602 yeast and NS 22192 enzymatic extract using 150 g L −1 of carbohydrates (CH) from primary sludge. The effect of sterilization, reduction of enzyme dosage and fed-batch vs. batch conditions were studied. The removal of sterilization can be considered since no contamination or atypical by-products were observed, although SSF efficiency slightly decreased. The reduction of the enzyme dosage from 35 to 15 FPU g CH −1 was successful. Despite of initial mixing difficulties, batch SSF enabled higher ethanol concentration (41.7 g L −1 ), conversion yield (48.9%) and productivity (0.78 g L −1 h −1 ), compared to the fed-batch process at the same conditions of low enzyme dosage of 5 FPU g CH −1 and high solids content of 21.7%, rarely found in literature. [ABSTRACT FROM AUTHOR]

Abstract: As a significant fraction of municipal solid waste, waste paper is a potential source for producing bioethanol. In the present paper, bioethanol production from various waste papers (newspaper, office paper, cardboard and magazine) using an enzyme complex (Cellic Ctec 1) was evaluated from an economic standpoint. Four bases cases without pre-treatment and two state-of-the-art cases (including dilute acid pre-treatment for office paper and oxidative lime pre-treatment for newspaper) were constructed using laboratory experimental data, literature values, expert consultations and simulation using AspenPlus™. Several scenarios were also carried out to assess the sensitivity of various technology parameters (i.e. solids loading in saccharification, anaerobic digestion and fermentation efficiency, and sugar yields in pre-treatment). The sensitivity analysis suggested that the economic performance of bioethanol produced from waste paper could be improved significantly with an up to 25% reduction in minimum ethanol selling price (MESP) by increasing solids loading in saccharification and with a 6% reduction in MESP by enhancing fermentation efficiency. The comparison of the bioethanol selling price at pump (reference year 2009) and the petrol price showed bioethanol produced from newspaper, office paper and cardboard were economically competitive with petrol. [Copyright &y& Elsevier]

Pulp and paper industry primary sludge being largely composed of lignocellulosic fibres, it could be used as carbon source by bacteria having cellulolytic capability. The aim of this study was to evaluate the use of cellulose contained in this type of sludge for Clostridium thermocellum to produce ethanol, hydrogen and cellulases. In an ATCC 1191 medium containing 5 kg m −3 dry primary sludge from recycled paper mill, batch culture reached stationary phase after 2 days. All of the available cellulose was hydrolysed after 60 h of incubation, with a final pH of 5.83. Metabolites produced after 60 h of fermentation were acetate (8.50 mol m −3 ), ethanol (11.30 mol m −3 ), lactate (8.75 mol m −3 ), formate (0.27 mol m −3 ), hydrogen (11.20 mol m −3 ) and carbon dioxide (18.41 mol m −3 ). Cellulase activity was detected in the supernatant after 36 h, with a maximal activity of 0.25 U cm −3 at 72 h. Pulp and paper primary sludge appeared to be a readily usable substrate for C. thermocellum at this concentration, yielding both potential biofuels (hydrogen and ethanol) as well as active cellulases. [ABSTRACT FROM AUTHOR]

Titanium dioxide is emerging as new class of catalyst support for fuel cell reactions. Via pulsed laser deposition, we prepare hierarchically organized and vertically aligned TiO 2 /Pt nanostructured films on microfibrous carbon paper (CP) substrate at room temperature. Microstructural analyses reveal a metal-support interaction between TiO 2 and Pt. Namely; (i) the particles size of Pt on TiO 2 is smaller than those of Pt grown onto carbon paper substrate under similar condition of synthesis and (ii) Pt metallic state is transformed to ionized Pt 2+ and Pt 4+ . Compared to CP/Pt electrocatalyst, the CP/TiO 2 /Pt electrocatalysts (i) oxidize ethanol at much lower potentials, (ii) display superior current peak densities of more than 2.5 times higher by voltammetry, and (iii) steady state current density during long-term stability up to 8 times greater. For portable electronic applications, the binder-free and hierarchical structures of the CP/TiO 2 /Pt electrocatalyst with its planar deposition make it very attractive as anode for direct ethanol fuel cells. [ABSTRACT FROM AUTHOR]

Abstract: This study uses Life Cycle Assessment (LCA) to assess the environmental profiles and greenhouse gas (GHG) emissions for bioethanol production from waste papers and to compare them with the alternative waste management options of recycling or incineration with energy recovery. Bioethanol production scenarios both with and without pre-treatments were conducted. It was found that an oxidative lime pre-treatment reduced GHG emissions and overall environmental burdens for a newspaper-to-bioethanol process whereas a dilute acid pre-treatment raised GHG emissions and overall environmental impacts for an office paper-to-bioethanol process. In the comparison of bioethanol production systems with alternative management of waste papers by different technologies, it was found that the environmental profiles of each system vary significantly and this variation affects the outcomes of the specific comparisons made. Overall, a number of configurations of bioethanol production from waste papers offer environmentally favourable or neutral profiles when compared with recycling or incineration. [Copyright &y& Elsevier]

Ample interest for more efficient utilization of bio-based residues has emerged in the Nordic pulp and paper (P&P) industry, which uses virgin wood as feedstock. Although different bioenergy retrofit technologies for production of liquid, solid, and gaseous bioenergy products have been applied in the existing P&P mills, the number of installations remains small. The lack of profound knowledge of existing bioenergy retrofits hinders the replication and market uptake of potential technologies. This review synthesises the existing knowledge of European installations and identifies the key drivers and barriers for implementation to foster the market uptake of potential technologies. The bioenergy retrofits were reviewed in terms of technical maturity, drivers, barriers and market potential. Based on this evaluation, common drivers and barriers towards wider market uptake were outlined from political, economic, social, technical, environmental, and legal perspective. Technologies already commercially applied include anaerobic fermentation of sludge, bark gasification, tall oil diesel and bioethanol production, whereas lignin extraction, biomethanol production, hydrothermal liquefaction and hydrothermal carbonization are being demonstrated or first applications are under construction. The findings of this review show that a stable flow of residues at P&P mills creates a solid base for retrofitting. New innovative bio-based products would allow widening the companies' product portfolios and creating new businesses. Also, European Union's (EU) legislation drives towards advanced biofuels production. Wider uptake of the retrofitting technologies requires overcoming the barriers related to uncertainty of economic feasibility and unestablished markets for new products rather than technical immaturity. • Bioenergy retrofits can widen the product portfolio of the pulp and paper industry. • Bioenergy retrofits in Europe were comprehensively reviewed for the first time. • Drivers and barriers for the market uptake were assessed from different perspectives. • Retrofits support the REDII targets for advanced biofuels in transport sector. • Utilization of residues for bioenergy products improves mills' resource efficiency. [ABSTRACT FROM AUTHOR]

[Display omitted] • Key SSF variables were optimized for PHP-pretreated PM wood at two thermal levels. • SSF process at 35 °C is preferable compared to a higher trade-off level of 38 °C. • With optimal SSF at 35 °C, high ethanol titer (77 g/L) and yield (84%) were gained. • Optimal SSF at 35 °C can reduce energy demand while increasing ethanol production. The optimization of key simultaneous saccharification and fermentation (SSF) parameters for bioethanol production from phosphoric acid plus hydrogen peroxide pretreated paper mulberry wood was carried out under two isothermal scenarios; the yeast optimum and trade-off temperatures of 35 and 38 °C, respectively. The optimal conditions established for SSF at 35 °C (solid loading: 16%; enzyme dosage: 9.8 mg protein/g glucan; and yeast concentration: 6.5 g/L) achieved high ethanol titer and yield of 77.34 g/L and 84.60% (0.432 g/g), respectively. These corresponded to 1.2 and 1.3-folds increases, compared to the results of the optimal SSF at a relatively higher temperature of 38 °C. The information from this study would prove beneficial in reducing process energy demands to some extent, while also helping to achieve high levels of both ethanol concentration and yield that are desired in cellulosic ethanol production. [ABSTRACT FROM AUTHOR]

A new process for the production of bioethanol from paper mill sludge (PMS) is described in this work. PMS biomass feedstock was processed via the simultaneous saccharification and fermentation (SSF) with and without accelerants. The enzymatic hydrolysis and fermentation were first evaluated, and the energy demand was 2.2 MJ/L of produced ethanol. When the enzymatic hydrolysis and fermentation were combined, the energy demand was reduced to 1.0 MJ/L ethanol, the sugars production increased, and the overall capital cost of the process decreased. The sugar yield was improved by adding accelerant and selecting the optimal fiber recovery method. The accelerant improved the enzymatic hydrolysis via a pathing/bridging mechanism. The SSF with the chemical fiber recovery method coupled with accelerant addition would be the best process configuration. Upon this combination, the glucose profile was enhanced from 9.8 g/L to 17.0 g/L. The sludge fiber conversion by SSF was improved by selecting an efficient fiber recovery method combined with the accelerant addition. SSF in chemical fiber recovery with accelerant addition was the best process by a 10% improvement of ethanol yield. The proposed process configuration offers a lower cost and sustainable process and contributes to the circular economy of zero waste discharges. • A combined SSF process using PMS feedstock to produce bioethanol was developed. • The energy saving in an integrated process was 1.2 MJ/L ethanol. • The optimal fiber recovery from paper mill sludge was achieved via acid treatment. • The optimal fiber recovery increased fractional glucose by 27%. • The cationic accelerant improved the enzymatic hydrolysis by 10% due to the patching mechanism. [ABSTRACT FROM AUTHOR]

Abstract: The treatment and reutilization of paper sludge (PS) is a worldwide issue. In this study, PS without any pretreatment was used for bioethanol production through simultaneous saccharification and fermentation (SSF) using hyper producer of cellulase and thermotolerant yeast. For saccharification of PS cellulose, cellulase activity was improved from 1.28 × 107 FPU m−3 (wild type) up to 1.52 × 107 FPU m−3 by mutation of Acremonium cellulolyticus C-1 and its carboxymethyl cellulase (CMCase) activity increased 5-fold compared to that of the wild type. In the SSF process, using A. cellulolyticus origin cellulase the highest level of ethanol production was 11.80 and 11.34 kg m−3 from 50 kg m−3 untreated PS in 250 cm3 and 2 dm3 flask scales, respectively. Ethanol yield based on consumed glucose was 80%. This result exhibits a high ethanol production yield from untreated PS, without using a commercial cellulase, nor any pretreatment of PS during SSF process. [Copyright &y& Elsevier]

Mechanical-biological treatment plants treat municipal solid waste to recover recyclable materials, nutrients and energy. Waste paper and cardboard (WP), the second main compound in municipal solid waste (∼30% in weight basis), is typically used for biogas generation. However, its recovery is gaining attention as it can be used to produce add-value products like bioethanol and residual derived fuel. Nevertheless, WP suppression or replacement will impact anaerobic digestion in terms of biogas production, process stability and digestate management. Two lab-scale reactors were used to assess the impact of WP in anaerobic digestion performance. A control reactor was only fed with biowaste (BioW), while a second reactor was fed with two different mixtures of BioW and WP, i.e. 85/15% and 70/30% (weight basis). Results indicate that either replacing half of the WP by BioW or removing half of the WP has little impact on the methane production. When removing half of the WP, methane production could be sustained by a larger waste biodegradability. The replacement of all WP by BioW increased the reactor methane production (∼37%), while removing all WP would have reduced the methane production about 15%. Finally, replacing WP loading rate by BioW led to a system less tolerant to instability periods and with poorer digestate quality. [ABSTRACT FROM AUTHOR]

This work evaluates the environmental performance of using pulp and paper sludge as feedstock for the production of second generation ethanol. An ethanol plant for converting 5400 tons of dry sludge/year was modelled and evaluated using a cradle-to-gate life cycle assessment approach. The sludge is a burden for pulp and paper mills that is mainly disposed in landfilling. The studied system allows for the valorisation of the waste, which due to its high polysaccharide content is a valuable feedstock for bioethanol production. Eleven impact categories were analysed and the results showed that enzymatic hydrolysis and neutralisation of the CaCO 3 are the environmental hotspots of the system contributing up to 85% to the overall impacts. Two optimisation scenarios were evaluated: (1) using a reduced HCl amount in the neutralisation stage and (2) co-fermentation of xylose and glucose, for maximal ethanol yield. Both scenarios displayed significant environmental impact improvements. [ABSTRACT FROM AUTHOR]

• Steam followed by alkaline treatment enhanced enzyme accessibility of PPS cellulose. • Reducing sugar yield was maximized during batch hydrolysis by optimized conditions. • High solid fed-batch hydrolysis was developed by ideal enzyme addition strategies. • Fed-batch S-SSCF with specified pre-hydrolysis was developed for high ethanol titer. The current study investigated an integrated fermentation process for efficient conversion of pulp and paper sludge (PPS) material to bio-ethanol. To achieve maximum yield of reducing sugar from the pretreated PPS, most influencing parameters such as enzyme dosages, surfactant dosages on PPS loadings were optimized in a batch saccharification process using response surface methodology. The experimental validation studies under optimal conditions of 6% (w/w) solid loading condition, 0.16% (w/w) of surfactant concentration and 158 FPU/gm of enzyme loading resulted in a maximum reducing sugar yield of 45 ± 3.75% (w/w). Separate batch saccharification studies were conducted with 4% to 7% (w/w) solid loading to formulate best operating conditions for fed-batch saccharification with 13% (w/w), 18% (w/w) and 22% (w/w) high solid loading. The PPS solid loading of 18% (w/w) in fed-batch saccharification resulted in maximal release of glucose and xylose of 79.56 g/L and 8.65 g/L respectively at 60 h. Further improvement in the conversion of PPS to bioethanol was established through adoption of fed-batch semi-simultaneous saccharification and co-fermentation (S-SSCF) process. Fermentation using co-cultivation of two yeast species namely P. stipitis NCIM 3499 and Baker's yeast resulted in maximum ethanol concentration of 42.34 g/L with 0.53 g/g yield from 18% (w/w) solid loading. Thus, the current study demonstrated the potential application of PPS waste as a feedstock material for ethanol production, which can be adopted by industries as an environment-friendly alternative to common solid waste management. [ABSTRACT FROM AUTHOR]

Much of the hemicellulose fraction of pulp mill feedstock is released into black liquor during the pulping process, and it is combusted to recover chemicals and energy in the form of steam and electricity. It is technically feasible to recover this fraction of carbohydrates and convert it into value-added products. In this study, a portion of the hemicellulose in pulp feed was hydrolyzed to soluble sugars by hot-water treatment. The sugars (mixtures of pentose, hexose, and their oligomers) were then converted to ethanol by simultaneous saccharification and fermentation (SSF) employing pectinase and the ethanologenic microorganism, Saccharomyces cerevisiae. The prehydrolysate produced from wood also contained toxins, primarily lignin and sugar degradation products, which strongly inhibited the microbial and the enzymatic reactions. Detoxification of the prehydrolysates was achieved by over-liming (addition of excess CaO). The total sugar concentration in the prehydrolysate obtained from softwood was below 4 wt%, which is roughly equivalent to 2 wt% ethanol, far below the acceptable level for downstream processing. In our previous study (Kang et al. 2010), a certain amount of water is added to attain fluidity required for SSF operation. In this study, prehydrolysate, in place of water, was added into the bioreactor along with the sludge. The proposed scheme has proven that total sugar concentration as well as product concentration in the bioreactor can be significantly increased above that of the sludge-alone operation. [ABSTRACT FROM AUTHOR]

Paper sludge (PS) from the paper and pulp industry consists primarily of cellulose and ash and has significant potential for ethanol production. Thirty-seven PS samples from 11 South African paper and pulp mills exhibited large variation in chemical composition and resulting ethanol production. Simultaneous saccharification and fermentation (SSF) of PS in fed-batch culture was investigated at high solid loadings and low enzyme dosages. Water holding capacity and viscosity of the PS influenced ethanol production at elevated solid loadings of PS. High viscosity of PS from virgin pulp mills restricted the solid loading to 18% (w/w) at an enzyme dosage of 20 FPU/gram dry PS (gdPS), whereas an optimal solid loading of 27% (w/w) was achieved with corrugated recycle mill PS at 11 FPU/gdPS. Ethanol concentration and yield of virgin pulp and corrugated recycle PS were 34.2 g/L at 66.9% and 45.5 g/L at 78.2%, respectively. [ABSTRACT FROM AUTHOR]

Abstract: This study evaluates acid pretreated waste paper hydrolyzate as feedstock for bioethanol production. The presence of 70.12±4.88% carbohydrates (holocellulose) makes waste paper a prospective and renewable biomass for bioethanol production. The waste paper was found to contain α-cellulose (61.5±3.49%), pentosans (7.42±0.36%), lignin (16.33±0.96%), ash (12.50±0.33%) and moisture (8.28±0.63%). Conditions for the dilute acid pretreatment of waste paper were optimized by varying solid/liquid ratio 1:8–1:14 (w/v), reaction time 01–06h, and sulfuric acid concentration 0.005–1.00N at 120°C in an autoclave. The conditions optimized for acid hydrolysis of waste paper were 0.50N H2SO4 at 120°C for 02h reaction time keeping biomass:acid ratio 1:10 (w/v) for recovery of reducing sugars from waste paper hydrolyzate. Fermentation of acid hydrolyzate of waste paper with Pichia stipitis under optimum condition resulted in ethanol production 3.73±0.16g/l with 77.54±4.47% of fermentation efficiency. [Copyright &y& Elsevier]

Waste banknote paper is a residue from the banking industry that cannot be recycled due to the presence of ink, microbial load and special coating that provides protection against humidity. As a result, waste banknote paper ends up being burned or buried, which brings environmental impacts, mainly caused by the presence of heavy metals in its composition. To minimize the environmental impacts that come from the disposal of waste banknote paper, this study proposes to produce value-added products (bioethanol and biogas) from waste banknote paper. For this, the effect of ink and pretreatment conditions on bioethanol and biomethane yields were analyzed. Waste banknote paper provided by the Central Bank of Iran was used. The raw material with ink (WPB) and without ink (WPD) was pretreated using sulfuric acid at different concentrations (1%, 2%, 3%, and 4%) and the nitrogen explosive decompression (NED) at different temperatures (150 °C, 170 °C, 190 °C, and 200 °C). The results show that the use of NED pretreatment in WPD resulted in the highest glucose concentration of all studies (13 ± 0.19 g/L). The acid pretreatment for WPB showed a correlation with the acid concentration. The highest ethanol concentration was obtained from the fermentation using WPD pretreated with NED (6.36 ± 0.72 g/L). The maximum methane yields varied between 136 ± 5 mol/kg TS (2% acid WPB) and 294 ± 4 mol/kg TS (3% acid WPD). Our results show that the presence of ink reduces bioethanol and biogas yields and that the chemical-free NED pretreatment is more advantageous for bioethanol and biogas production than the acid pretreatment method. Waste banknote paper without ink is a suitable feedstock for sustainable biorefinery processes. [ABSTRACT FROM AUTHOR]

Here we developed a flow-based system resulting in improved performance of enzyme cascade-based biofuel cells. A paper-based biofuel cell with passive laminar flow was build to show the impact of flow on the performance of two different enzyme cascades – methanol and ethanol cascade. Both cascades demonstrated enhanced electrochemical output as a consequence of the decreased diffusion path of reaction intermediates identifying the intermediates diffusion in between enzymatic active sites as the rate limiting step in cascade operating systems. [ABSTRACT FROM AUTHOR]

Ethanol as a renewable fuel has been applied in fuel vehicles (FVs), and it is promising in hybrid electric vehicles (HEVs). This work aims to investigate the emission characteristics of ethanol applied in both FVs and plug-in hybrid electric vehicles (PHEVs). The paper conducted a real-road test of an internal combustion FV and PHEV, respectively, based on the world light vehicle test cycle (WLTC) by using gasoline and regular gasoline under different temperature conditions. The use of E10 and E20 in FVs has been effective in reducing the conventional emissions of the vehicles. At 23 °C, E10 and E20 reduced the conventional emissions including carbon monoxide (CO), total hydrocarbon compound (THC), non-methane hydrocarbon compound (NMHC), particulate matter (PM), and particulate number (PN) by 15.40–31.11% and 11.00–44.13% respectively. At 6 °C, E10 and E20 reduced conventional emissions including THC, CO, and PM by 2.15–8.61% and 11.02–13.34%, respectively. However, nitrogen oxide (NOX) emissions increased to varying degrees. The reduction trend of non-conventional emissions including methane (CH4), nitrous oxide (N2O), and carbon dioxide (CO2) from FVs fueled with E10 and E20 is not significant for vehicles. Overall, the emission reduction effect of E20 is better than that of E10, and the emission reduction effect of ethanol gasoline on vehicle emissions is reduced at low temperatures. Lower ambient temperatures increase vehicle emissions in the low-speed segment but decrease vehicle emissions in the ultra-high-speed segment. HEV emissions of THC, CO, PN, and PM are reduced by 25.28%, 12.72%, 77.34%, and 64.59%, respectively, for E20 compared to gasoline, and the use of E20 in HEVs contributes to the reduction of overall vehicle emissions. [ABSTRACT FROM AUTHOR]

The surge in global biofuel demand is propelled by intensifying concerns over climate change and effective waste management. Government mandates on biofuel blending further boost this trend, underlining the significance of selecting renewable feedstocks, such as bioethanol and biodiesel, for biofuel production. The importance of selecting an efficient biomass pretreatment method cannot be overstated, given its status as the most energy-intensive and chemical-reliant step in the biofuel production chain. Thus, pretreatment becomes a crucial determinant in the feasibility and economic viability of biofuel technologies. Amid a wide array of pretreatment strategies, identifying a method that is both effective and sustainable is crucial for advancing biofuel commercialization. This review aims to rigorously evaluate both traditional and novel pretreatment techniques and their environmental footprints, leveraging life cycle assessment (LCA) studies from existing literature. By examining the sustainability of various pretreatment methods, this paper provides a holistic and clear view, serving as an essential resource for policymakers and industry stakeholders. It outlines the challenges faced in each phase of an LCA and proposes viable solutions. Additionally, the review furnishes valuable insights, recommendations, and directions for future research in achieving sustainable biofuel production. [ABSTRACT FROM AUTHOR]

Year after year, there are alarming data concerning the excessive release of greenhouse gases into the atmosphere, especially CO2 from the burning of fossil fuels. In this context, the development of renewable energy sources has evolved considerably, mainly due to the incentive use of biofuels, such as bioethanol. The second-generation bioethanol production from lignocellulosic biomasses has interesting potential to meet this energy demand. The Eucalyptus tree stands as a primary example of cultivated hardwoods, owing to its lignocellulosic structure and the biomass residues generated during its processing, where these attributes make it a significant candidate for the production of fuels. The industrial potential of these materials can be explored in the fractionation of their components to reduce their recalcitrance due to the triad formed by cellulose, hemicellulose, and lignin, for further processing and obtaining the products of interest. This paper comprehensively gathers the current technological progress employed for processing Eucalyptus wood biomasses for second-generation bioethanol production. Discussion regarding their chemical composition, the main forms of pretreatments that are being applied, and ways to minimize the generation of fermentative inhibitors during these processes is addressed. Finally, recent researches focused on Eucalyptus biomass-based bioethanol production and techno-economic considerations are discussed. The feasibility of the process is closely tied to the comprehensive utilization of products derived from this biomass. While production appears relatively effective at the laboratory scale, further research is required to develop a cost-effective process that fully harnesses the potential of the biomass. [ABSTRACT FROM AUTHOR]

Reducing the carbon footprint of energy production is one of the most pressing challenges facing humanity today. Lignocellulosic biomass residues from fruit production industries show promise as a viable energy source. This paper presents a study of the Italian context concerning the utilization of orchard lignocellulosic residues for energy production as electricity or bioethanol. The potential of various orchard residues was assessed through chemical and physical analyses, and an equivalent electrical energy of about 6441.62 GWh or an amount of 0.48 Mt/y of bioethanol was obtained based on the average annual dry residue mass availability of about 3.04 Mt/y. These data represent 9.30% of the national electrical energy production from renewable sources, as well as 6.21% of the Italian demand for gasoline in 2022. Electricity generation from these residues has shown its potential as a reliable and sustainable baseload power source, as well as a source of renewable transportation fuel. The studied process could be a valuable reference to expand these concepts on a global scale to achieve a greener and more sustainable energy future. [ABSTRACT FROM AUTHOR]

In the last decades, the production of fuel ethanol from corn has spread as a valid renewable alternative to pursue sustainability goals. However the uncertain nature of both input (corn) and output (gasoline) prices, together with price dependent operational decisions, combine to make this difficult plant valuation require a real options approach. Moreover, this project is characterized by various sequential stages that contribute to increase its valuation difficulties. The purpose of this paper is to provide a reliable valuation methodology of a corn ethanol plant project able to consider the characteristics of the project. We apply the compound Real Options Approach to price a corn ethanol plant project considering that the corn and gasoline prices both follow a skew-geometric Brownian motion. We also propose a case study to show a real implementation of our theoretical model. The results show that the corn ethanol plant is financially attractive as renewable investment since the uncertainties inherent in the project add value, via managerial flexibility, to the real option valuation. [ABSTRACT FROM AUTHOR]

The conversion of lignocellulosic agricultural waste into biofuels and other economically valuable compounds can reduce dependence on fossil fuels, reduce harmful gas emissions, support the sustainability of natural resources, including water, and minimize the amount of waste in landfills, thus reducing environmental degradation. In this paper, the conversion of agricultural wastes into biomethane, biohydrogen, biodiesel, bioethanol, biobutanol, and bio-oil is reviewed, with special emphasis on primary and secondary agricultural residues as substrates. Some novel approaches are mentioned that offer opportunities to increase the efficiency of waste valorization, e.g., hybrid systems. In addition to physical, chemical, and biological pretreatment of waste, some combined methods to mitigate the negative effects of various recalcitrant compounds on waste processing (alkali-assisted thermal pretreatment, thermal hydrolysis pretreatment, and alkali pretreatment combined with bioaugmentation) are evaluated. In addition, the production of volatile fatty acids, polyhydroxyalkanoates, biochar, hydrochar, cellulosic nanomaterials, and selected platform chemicals from lignocellulosic waste is described. Finally, the potential uses of biofuels and other recovered products are discussed. [ABSTRACT FROM AUTHOR]

• Shrub-like pt-rh catalysts with different metallic ratios on carbon paper were prepared by laser ablation. • The catalysts displayed higher tolerance to CO and higher catalytic activity towards ethanol oxidation. • Pt-Rh catalysts demonstrated long-term poisoning rates eight times lower than pt. Plasmas techniques are novel routes for the preparation of complex nanostructured materials for catalysis and clean hydrogen energy such as fuel cells. CBPLD technique allows enhanced interaction between the catalyst and the support and improved catalytic properties. Herein, a highly active and durable vertically aligned nanostructured shrub-like bimetallic Pt x Rh 100-x alloys with atomic ratios close to nominal values are grown on carbon paper substrate. The tolerance to CO poisoning and ethanol electrooxidation reactions are studied over these new types of shrub-like bimetallic Pt x Rh 100-x /CP catalysts, demonstrating that such structures effectively facilitate both processes and very low long-term poisoning rates. Such high catalytic activity accounts for two mechanisms: Rh a highly oxophilic transition metal activates water dissociation at lower potentials than Pt (bifunctional mechanism), and the ligand effect where Rh alters the electronic structure of the neighboring Pt suggesting a faster supply in OH ads. Image, graphical abstract [ABSTRACT FROM AUTHOR]

Paper mill sludge (PMS) solids are predominantly comprised of cellulosic fibers and fillers rejected during the pulping or paper making process. Most sludges are dewatered and discharged into landfills or land spread at a cost to the mill; creating large economic and environmental burdens. This lignocellulosic residual stream can be used as a source of sugars for microbial fermentation to renewable chemicals. The aim of this study was to determine the possibility of converting mill sludge to sugars and then fermentation to either isoprene or ethanol. Chemical analysis indicated that the cellulosic fiber composition between 28 to 68% and hemicellulose content ranged from 8.4 to 10.7%. Calcium carbonate concentration in the sludge ranged from 0.4 to 34%. Sludge samples were enzyme hydrolyzed to convert cellulose fibers to glucose, percent conversion ranged from 10.5 to 98%. Calcium carbonate present with the sludge resulted in low hydrolysis rates; washing of sludge with hydrochloric acid to neutralize the calcium carbonate, increased hydrolysis rates by 50 to 88%. The production of isoprene "very low" (190 to 470 nmol) because the isoprene yields were little. Using an industrial yeast strain for fermentation of the sludge sugars obtained from all sludge samples, the maximum conversion efficiency was achieved with productivity ranging from 0.18 to 1.64 g L−1 h−1. Our data demonstrates that PMS can be converted into sugars that can be fermented to renewable chemicals for industry. [ABSTRACT FROM AUTHOR]

Municipal wastes have become a severe problem in developed and developing countries during the last century, paper being the main constituent. Not all of the waste paper can be recycled, and therefore alternative procedures for the use of the remaining material should be pursued. The aim of the present work was the application of cellulases for waste paper treatment and the subsequent glucose production and optimization of the conditions for such treatment. Glucose thereafter can be utilized for production of ethanol or other chemicals by specific microbial cultures. The work focused in the stabilization of cellulases by cross-linking or by the addition of specific crown ether based compounds to improve glucose production. The results indicated that enzymatic treatment of waste paper is of particular interest, since it may be an alternative way to carry out municipal wastes treatment and concomitant glucose production. By the application of the proposed procedure, the total amounts of municipal wastes can be greatly reduced and production of bioethanol can be achieved. [ABSTRACT FROM AUTHOR]

To use residual biomass in industrial plants it is necessary to fulfill conditions that have proven challenging when developing production processes based on renewable sources. Relatively recent efforts to produce second‐generation ethanol (2GE) have led to some caveats regarding obstacles that can arise in the large‐scale conversion of residual lignocellulosic biomass to biofuel. Even after years of research to develop technological packages that would make the production of 2GE feasible, the first plants installed could not operate continuously within the design, and they failed to meet market expectations. By interviewing managers from the 2GE pioneer plants, the research reported in this paper identified the methods used by the 2GE pioneers, from decision‐making processes to startup and plant operation. Analyzing the challenges they faced and their relationships with innovation processes, it found that industrial handling of lignocellulosic biomass was the main reason for the relative operational failure of the pioneer 2GE production plants. It also found that changes of policy and lack of efficient communication between the equipment suppliers and the users might also lead to the failure of the pioneer plants. Based on these findings, this paper considers the significance of these projects for biobased industries using lignocellulosic biomass in pioneer plants. The conclusions suggest that filling the knowledge gap related to the industrial handling of lignocellulosic biomass, as well as understanding that new relationships between biorefineries and their equipment suppliers may generate new paths for innovation processes, should be fundamental for the implementation of first‐of‐a‐kind plants within the scope of bioeconomy. [ABSTRACT FROM AUTHOR]

The production of energy, food, water, and other utensils by fossil fuels generates pollution that causes constant climate change. To minimize and avoid this phenomenon, opting for less polluting energy production sources is increasingly necessary. Green hydrogen (H 2), a renewable and clean fuel, is analyzed in bibliometric terms in the present work, emphasizing photosynthetic H 2. The data were obtained through the journal database list in Web of Science, in which a total of 1507 was published between January 2010 to September 2022, dealing with the production of photosynthetic green hydrogen. The country with the most significant publication is China, with respectively 24.50% of the publications, and the Chinese Academy of Sciences has 60 co-authored papers, the largest in co-authorship—most papers published in the international journal of hydrogen energy, with 19.49% of the publications. The raw materials identified as emerging are cyanobacteria and microalgae, Rhodobacter capsulatus , synechocystis sp pcc6803 and Chlamydomonas reinhardtii pointed out as the microalgae of most significant interest. However, it is necessary to improve them, given the decrease in inactivity provided by the Calvin-Benson cycle. Life cycle assessment studies are needed, as well as H 2 storage. There is a need to reduce the levelized cost of H 2 production, which is around 9.65–25.22 USD/gallon. Studies also point to using cyanobacteria and microalgae to produce other biofuels (bioethanol biodiesel) and materials (supercapacitors, batteries, and polymers). [Display omitted] • Evaluation of the photosynthetic production of green hydrogen. • Analysis of 1507 papers from the Web of Science with CiteSpace, Vosviwer and Exell. • Advanced bibliometric analysis of future trends in the production of green hydrogen. • Using photosynthetic methods to produce biofuels. • Polymer production uses carbon dioxide and green hydrogen. [ABSTRACT FROM AUTHOR]

Paper mill sludge (PMS) can be efficiently utilized to produce fuels and chemicals. However, wastewater is usually generated during the de-ashing step of the PMS for fibrous materials recovery. Per process requirements, the wastewater stream must be treated which results in an increase in the overall process production cost. Therefore, this research aims at reusing the wastewater produced during the de-ashing step as a substitute for freshwater addition during the conversion of PMS into ethanol. The advantages of this approach include reducing the amount of wastewater produced and enhancing the overall efficiency of the process. It will contribute to the circular economy of zero waste discharges. The results showed that 30% of the process wastewater can be recycled without affecting the enzymatic hydrolysis and ethanol fermentation. Hence, the amount of wastewater that needs to be treated is reduced by 30% resulting in a cost reduction of 22.5%. The results also showed that wastewater recycling minimized the energy demands in the distillation and evaporation units by 1206 kJ/kg. The energy reduction is due to the increase of metals and total soluble solids in the broth stream after fermentation. This process configuration enhanced the process economy, saved energy and managed waste streams. • Reuse of wastewater in the paper mill sludge conversion. • A certain degree of recycling has no impact on the glucose yield. • Wastewater recycling reduced the energy demand of the process by 1251 kJ/kg metric tons wastewater. • Cost-saving of wastewater treatment by 22.5% when a 30% recycling degree achieved. [ABSTRACT FROM AUTHOR]

The current study was designed to isolate and identify superior cellulose-degrading fungi from Egyptian soils reached with cellulosic compounds, then production of bioethanol from paper wastes using this isolate. Among 9 fungal isolates, one isolate was selected as the highest cellulases producer. This isolate was identified by morphological and genetic characteristics as Aspergillus niger MK543209. Basal mineral salt medium amended with 1% rice straw was the best medium for cellulose-degrading enzymes production under submerged fermentation (SmF). Additionally, bagasse at 30% and urea at 2% were the best carbon and nitrogen sources, respectively. In respect to the environmental conditions, the optimum temperature, pH and incubation period were 45 °C, 5.5 and 4 days, respectively. The optimized conditions were applied to produce reducing sugars from paper wastes, followed by production of bioethanol as a renewable energy. A 0.9 g/l/h of ethanol were produced as the best value. This study may be considered the initial point for production of renewable energy and protection of environment from wastes. [ABSTRACT FROM AUTHOR]

We examined the efficient conversion of waste biomass to bioethanol by the marine-derived yeast Saccharomyces cerevisiae (C19 strain). In this study, two kinds of cellulose biomass, (A) waste from Undaria pinnatifida processing, and (B) paper shredder scrap, were utilized as raw materials. The hydrolysate of (A), and (B) were separately saccharified with enzymes, followed by an approximately five-fold concentration, using an evaporator. Both of the concentrated, saccharified solutions from (A) and (B) were mixed in various ratios and used as substrates containing glucose at 200-300 g/l for yeast fermentation. S. cerevisiae C19 produced bioethanol at 40-90 g/l from 100 ml of the substrates, and the optimum mixing ratio of the biomass in the substrates was found to be (A):(B) = 3:7 in dried weight. Using 3.0 l of the substrate at a ratio of (A):(B) = 3:7, and glucose at 235.0 g/l, fermentation was carried out at 30 °C and a pH of 7.0 by S. cerevisiae C19 in a jar fermentor (10 l), producing 87.7 g/l of bioethanol in 5 days. The fermented solution was fractionated with a distillation apparatus and 331 ml of ethanol purified to 788.0 g/l was produced. [ABSTRACT FROM AUTHOR]

Abstract: This paper presents an alternative analytical method employing energy dispersive X-ray fluorescence (EDXRF) to determine copper, iron, nickel and zinc ions in ethanol fuel samples after a pre-concentration procedure. Our pre-concentration strategy utilizes analyte retention on cation exchange chromatography paper, a convenient substrate for direct EDXRF measurements. The repeatability, expressed in terms of RSD of standard solutions containing 0.25μgmL−1 of Cu, Fe, Ni and Zn, and calculated from fifteen consecutive measurements, was 2.5, 2.8, 3.0, and 2.7%, respectively. The limits of detection (LOD), defined as the analyte concentration that gives a response equivalent to three times the standard deviation of the blank (n =10), were found to be 13, 15, 15 and 12μgL−1 for Cu, Fe, Ni and Zn, respectively. The proposed method was applied to Cu, Fe, Ni and Zn determination in hydrated ethanol fuel samples collected from different gas stations. [Copyright &y& Elsevier]

[Display omitted] • First report on the optimization of citric acid (CA) using banana pseudostem. • The optimized process gave a maximum CA concentration of 14.408 g/L. • Kinetics were determined on fresh water, wastewater and standard medium. • The wastewater-based bioprocess demonstrated only a 9.11% lower CA concentration. • Findings facilitate the development of waste-based lignocellulosic bioprocesses. This study optimized the simultaneous saccharification and citric acid (CA) production from banana pseudostem (BP). Thereafter, kinetic assessment of Aspergillus brasiliensis growth and CA production were determined for the optimum conditions using fresh water (SSF optimizedFW) or dairy wastewater (SSF DWW) and compared to Sabouraud Dextrose Emmon's medium modified with BP (SSF SDEmodified). The optimized conditions gave a CA concentration of 14.408 g/L. Kinetic assessment revealed the same maximum specific growth rates (μ max) (0.05 h−1) for all three bioprocesses, while the SSF SDEmodified process resulted in the highest maximum potential CA concentration (P m) (13.991 g/L) in comparison to the SSF DWW (P m = 13.095 g/L) and SSF optimizedFW (P m = 12.967 g/L) systems. Findings from this study facilitates the implementation of waste-based lignocellulosic bioprocesses that may eradicate the use of expensive pretreatment chemicals, fermentation medium constituents, and resources, in keeping with the water, energy and food nexus towards developing a circular bioeconomy. [ABSTRACT FROM AUTHOR]

Pulping and papermaking of Leucoena diversifolia by soda-anthraquinone-ethanol was studied using an experimental design in order to investigate the effects of cooking variables: temperature, time, soda concentration, ethanol concentration and wash-disintegrate temperature on the pulp yield and the physico-chemical characteristics of paper sheets (tensile index, burst index, tear index and brightness). Previously, in order to assess the potential of plants of this raw material grown over short periods, its results were compared with those of other leucaena varieties and the best crop among three grown for 1-3 years was selected. The results were evaluated using the response surface methodology with a view to identifying the most suitable operating conditions. In accordance with biomass production and the features of the raw materials and cellulose pulp obtained, the L. diversifolia grown for 2 years was found to be the most suitable choice for obtaining pulp and paper among the five leucaena varieties examined. Suitable physical characteristics of paper sheets (tensile index, burst and tear index) and acceptable yield pulping and brightness could be obtained by operating at medium temperature, active alkali concentration, pulping time, ethanol concentration and wash-disintegrate temperature. [ABSTRACT FROM AUTHOR]

The article presents a research which investigates the bioconversion of paper sludge (PS) into bioethanol by simultaneous saccharification and fermentation (SSF) using a PS based cellulase from Acremonium cellulolyticus and thermotolerant Saccharomyces cerevisiae TJ14. It is stated that using cellulase of PS origin minimized biofuel production costs, as the culture broth containing cellulase can be used directly. Results showed that ethanol concentration increased with increasing PS organic material (PSOM) concentration, up to 150 g/l. An increase in cellulase concentration or the yeast inoculum did not result in significant improvement in ethanol yield.

Cryptococcus albidusandSaccharomyces cerevisiaewas used for separate hydrolysis and fermentation of sugar cane bagasse for production of ethanol. Lignocellulolytic enzymes, CMCase (34 U/ml), FPase (3 U/ml), β-glucosidase (2.3 U/ml), laccase (32 U/ml), and xylanase (12 U/ml), were assayed by fungus, however, after optimization of process parameters, an increase of 1.5-fold sugar (375 mg/g) from bagasse and production of lignocellulolyic enzymes were determined. The sugar produced by sugar cane bagasse was subsequently treated bySaccharomyces cerevisiae, indicating enhanced production of ethanol at 40 h was 38.4 g/L, reached to a maximum at 50 h, and then it was decreased. [ABSTRACT FROM PUBLISHER]

This review paper examines acid and alkaline pretreatments on perennial grasses for second-generation (2G) bioethanol production, a relatively unexplored area in this field. It compares the efficiency of these pretreatments in producing fermentable sugar and bioethanol yield. This study finds that alkaline pretreatment is more effective than acidic pretreatment in removing lignin and increasing sugar yield, leading to higher ethanol yields. However, it is costlier and requires longer reaction times than acidic pretreatment, while acidic pretreatment often leads to the formation of inhibitory compounds at higher temperatures, which is undesirable. The economic and environmental impacts of lignocellulosic biomass (LCB) are also assessed. It is revealed that LCB has a lower carbon but higher water footprint and significant costs due to pretreatment compared to first-generation biofuels. This review further explores artificial intelligence (AI) and advanced technologies in optimizing bioethanol production and identified the gap in literature regarding their application to pretreatment of perennial grasses. This review concludes that although perennial grasses hold promise for 2G bioethanol, the high costs and environmental challenges associated with LCB necessitate further research. This research should focus on integrating AI to optimize the pretreatment of LCB, thereby improving efficiency and sustainability in 2G biofuel production. [ABSTRACT FROM AUTHOR]

A previous study demonstrated that paper sludges with high ash contents can be converted to ethanol by simultaneous saccharification and fermentation (SSF) or simultaneous saccharification and co-fermentation (SSCF). High ash content in the sludge, however, limited solid loading in the bioreactor, causing low product concentration. To overcome this problem, sludges were de-ashed before SSF and SSCF. Low ash content in sludges also increased the ethanol yield to the extent that the enzyme dosage required to achieve 70% yield in the fermentation process was reduced by 30%. High solid loading in SSF and SSCF decreased the ethanol yield. High agitation and de-ashing of the sludges were able to restore part of the yield loss caused by high solid loading. Substitution of the laboratory fermentation medium (peptone and yeast extract) with corn steep liquor did not bring about any adverse effects in the fermentation. Fed-batch operation of the SSCF and SSF using low-ash content sludges was effective in raising the ethanol concentration, achieving 47.8 g/L and 60.0 g/L, respectively. [ABSTRACT FROM AUTHOR]