Thermophilic fermentations of lignocellulosic substrates and economics of biofuels: prospects in Pakistan

Ahmad, Qurat‐ul‐Ain; Qazi, Javed Iqbal

doi:10.1007/s40095-014-0094-4

Cited by 13 publications

(8 citation statements)

References 94 publications

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“…On the basis of cellulose equivalence in biomass to pure cellulose (70 g/L) used in this experiment, when 110 g/L of differently pretreated SCBs were used. The pretreatment chemicals included 2% H 2 SO 4 , 3% H 3 PO 3 , 1% HCl, and 1N NaOH, selected for SCB pretreatment on the basis of maximum cellulose enrichment, as previously reported 37 were assessed for the ethanol and hydrogen coproduction by C. thermocellum DSMZ 1313.…”

Section: Resultsmentioning

confidence: 99%

Bench‐scale fermentation for second generation ethanol and hydrogen production by Clostridium thermocellum DSMZ 1313 from sugarcane bagasse

Ahmad

Manzoor

Chaudhary

et al. 2020

Env Prog and Sustain Energy

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Exploration of eco‐friendly energy resources substituting conventional fossil fuels is the real challenge globally. Prospectively, current investigation accentuates the fermentative conversion of low‐cost lignocellulosic biomass waste, sugarcane bagasse (SCB) into bioethanol and biohydrogen exploiting thermophilic cellulolytic bacterium Clostridium thermocellum DSMZ 1313. Initially, the optimization of some key fermentation factors for bioethanol and biohydrogen productions was done in 150 ml serum bottles employing Taguchi orthogonal array L27 (3̂13) experimental design. Results elucidated that the most suitable factors for ethanologenesis were 70 g/L cellulose, 10 g/L corn‐steep liquor (CSL), 15 mg/L ferrous sulfate (FeSO4·6H2O), 1 g/L magnesium chloride (MgCl2·6H2O), pH 7, and 5 days incubation whereas for hydrogen fermentation were 60 g/L cellulose, 30 g/L CSL, 5 mg/L FeSO4·6H2O, 2 g/L MgCl2·6H2O, pH 7, and 3 days incubation. Quantitatively, 7.422 g/L ethanol and 56.891/50 ml hydrogen were produced from cellulose while 6.352 g/L ethanol and 51.685/50 ml hydrogen with H2SO4‐pretreated SCB (substituted with cellulose). Scaled‐up suspended‐cell fermentations in bench‐scale stirred‐tank bioreactor resulted in 11.77% increased ethanol yield (0.239 g ethanol/g of glucose) and twofold higher hydrogen volumes (106.88 ml hydrogen/g of glucose). The employment of SCB directly as substrate for biofuels production has appeared sustainable to meet the high global energy demands.

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Section: Resultsmentioning

confidence: 99%

Bench‐scale fermentation for second generation ethanol and hydrogen production by Clostridium thermocellum DSMZ 1313 from sugarcane bagasse

Ahmad

Manzoor

Chaudhary

et al. 2020

Env Prog and Sustain Energy

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“…Ethanol yield of 0.909 mol of ethanol/mol of sugars consumed was obtained after 84 h of incubation, corresponding to 0.279 g ethanol/g of sugars consumed. Though reduced ethanol yield in comparison with the yield by mesophilic yeast, S. cerevisiae (as shown in Additional file 2 ) was obtained, but the use of thermophilic fermentative bacteria is considered more advantageous where LCB is used as fuels’ feed as unlike most mesophilic yeasts, the thermophilic fermentative bacteria are able to ferment hexoses as well as pentoses to ethanol [ 36 , 46 ]. The percent reduction of substrate was 98.5 showing significant conversion of substrate into product with ethanol titer of 11.301 g/L.…”

Section: Discussionmentioning

confidence: 99%

Moderate alkali-thermophilic ethanologenesis by locally isolated Bacillus licheniformis from Pakistan employing sugarcane bagasse: a comparative aspect of aseptic and non-aseptic fermentations

Ahmad

Yang

Manzoor

et al. 2017

Biotechnol Biofuels

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BackgroundBiofuels obtained from first-generation (1G) sugars-starch streams have been proven unsustainable as their constant consumption is not only significantly costly for commercial scale production systems, but it could potentially lead to problems associated with extortionate food items for human usage. In this regard, biofuels’ production in alkali-thermophilic environs from second-generation (2G) bio-waste would not only be markedly feasible, but these extreme conditions might be able to sustain aseptic fermentations without spending much for sterilization.ResultsPresent investigation deals with the valuation of ethanologenic potential of locally isolated moderate alkali-thermophilic fermentative bacterium, Bacillus licheniformis KU886221 employing sugarcane cane bagasse (SCB) as substrate. A standard 2-factor central composite response surface design was used to estimate the optimized cellulolytic and hemicellulolytic enzymatic hydrolysis of SCB into maximum fermentable sugars. After elucidation of optimized levels of fermentation factors affecting ethanol fermentation using Taguchi OA L27 (3^13) experimental design, free cell batch culture was carried out in bench-scale stirred-tank bioreactor for ethanol fermentation. Succeeding fermentation modifications included subsequent substrate addition, immobilized cells fibrous-bed bioreactor (FBB) incorporation to the basic setup, and performance of in situ gas stripping for attaining improved ethanol yield. Highest ethanol yield of 1.1406 mol ethanol/mol of equivalent sugars consumed was obtained when gas stripping was performed during fed-batch fermentation involving FBB under aseptic conditions. Despite the fact that under non-aseptic conditions, 30.5% lesser ethanol was formed, still, reduced yield might be considered influential as it saved the cost of sterilization for ethanol production.ConclusionEffectual utilization of low-priced abundantly available lignocellulosic waste sugarcane bagasse under non-aseptic moderate alkali-thermophilic fermentation conditions as directed in this study has appeared very promising for large-scale cost-effective bioethanol generation processes.Electronic supplementary materialThe online version of this article (doi:10.1186/s13068-017-0785-1) contains supplementary material, which is available to authorized users.

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“…The proposed approach is expected to give more consistent conditions at which the oxidation process occurs if compared to the conventional methods. 32,33,34 In the latter cases, an average between wall and cylinder gas temperature is assumed to control post-oxidation kinetics, and the concentrations of the species are referred to the entire cylinder volume.…”

Section: Unburned Hydrocarbon Model Descriptionmentioning

confidence: 99%

A phenomenological model for the description of unburned hydrocarbons emission in ultra-lean engines

Malfi

Bellis

Bozza

et al. 2021

International Journal of Engine Research

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The adoption of lean-burn concepts for internal combustion engines working with a homogenous air/fuel charge is under development as a path to simultaneously improve thermal efficiency, fuel consumption, nitric oxides, and carbon monoxide emissions. This technology may lead to a relevant emission of unburned hydrocarbons (uHC) compared to a stoichiometric engine. The uHC sources are various and the relative importance varies according to fuel characteristics, engine operating point, and some geometrical details of the combustion chamber. This concern becomes even more relevant in the case of engines supplied with natural gas since the methane has a global warming potential much greater than the other major pollutant emissions. In this work, a simulation model describing the main mechanisms for uHC formation is proposed. The model describes uHC production from crevices and flame wall quenching, also considering the post-oxidation. The uHC model is implemented in commercial software (GT-Power) under the form of “user routine”. It is validated with reference to two large bore engines, whose bores are 31 and 46 cm (engines named accordingly W31 and W46). Both engines are fueled with natural gas and operated with lean mixtures (λ > 2), but with different ignition modalities (pre-chamber device or dual fuel mode). The engines under study are preliminarily schematized in the 1D simulation tool. The consistency of 1D engine schematizations is verified against the experimental data of BMEP, air flow rate, and turbocharger rotational speed over a load sweep. Then, the uHC model is validated against the engine-out measurements. The averaged uHC predictions highlight an average error of 7% and 10 % for W31 and W46 engines, respectively. The uHC model reliability is evidenced by the lack of need for a case-dependent adjustment of its tuning constants, also in presence of relevant variations of both engine load and ring pack design.

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Thermophilic fermentations of lignocellulosic substrates and economics of biofuels: prospects in Pakistan

Cited by 13 publications

References 94 publications

Bench‐scale fermentation for second generation ethanol and hydrogen production by Clostridium thermocellum DSMZ 1313 from sugarcane bagasse

Bench‐scale fermentation for second generation ethanol and hydrogen production by Clostridium thermocellum DSMZ 1313 from sugarcane bagasse

Moderate alkali-thermophilic ethanologenesis by locally isolated Bacillus licheniformis from Pakistan employing sugarcane bagasse: a comparative aspect of aseptic and non-aseptic fermentations

A phenomenological model for the description of unburned hydrocarbons emission in ultra-lean engines

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