Ethanol Yield Research Articles

Proficient bioconversion of rice straw biomass to bioethanol using a novel combinatorial pretreatment approach based on deep eutectic solvent, microwave irradiation and laccase

Current study is the first report of the combined application of chemical (deep eutectic solvent), physical (microwave irradiation) and biological (laccase) pretreatment strategies for enhancing the enzymatic digestibility of rice straw biomass. Pretreated rice straw biomass was saccharified by cellulase/xylanase from Aspergillus japonicus DSB2 to get a sugar yield of 252.36 mg/g biomass. Design of Experiment based optimization of pretreatment and saccharification variables increased the total sugar yield by 1.67 times (421.5 mg/g biomass, saccharification efficiency 72.6%). Sugary hydrolysate was ethanol-fermented by Saccharomyces cerevisiae and Pichia stipitis to achieve an ethanol yield of 214 mg/g biomass (bioconversion efficiency 72.5%). Structural/chemical aberrations induced in the biomass due to pretreatment were elucidated by X-ray diffraction, scanning electron microscopy, Fourier-transform infrared spectroscopy, and 1H nuclear magnetic resonance techniques to unravel the pretreatment mechanisms. Combined application of various physico-chemical/biological pretreatment may be a promising approach for proficient bioconversion of rice straw biomass.

Optimization of co-culture condition with respect to aeration and glucose to xylose ratio for bioethanol production

ABSTRACT The present study was designed to find a suitable microaerobic condition and ratio of glucose and xylose for maximum ethanol production using co-culture of Saccharomyces cerevisiae and Pichia stipitis. The maximum ethanol concentration and yield were achieved at 0.05 vvm aeration rate and 2:1 glucose/xylose ratio. The co-culture resulted in maximum ethanol concentration, ethanol yield, and volumetric productivity of 12.33 ± 0.10 g/L, 0.43 g/g, and 0.26 g/L/h, respectively. While, the monoculture of P. stipitis resulted in 8.96 ± 0.13 g/L, 0.36 g/g, and 0.19 g/L/h respectively. The fermentation carried out in microaerobic mode delivered 10.68% and 10.56% more ethanol concentration and ethanol yield respectively from glucose compared to the combination of anaerobic and microaerobic mode. Also, the glucose uptake rate increased to 0.83 g/L/h, which corresponds to an improvement of 50.16%, suggesting that the lower microaerophilic condition not only supports P. stipitis metabolism but also does S. cerevisiae to convert glucose faster in a co-culture system. Hence, co-culture cultivation in microaerobic mode would be a better condition to achieve maximum ethanol and productivity.

Fungal pretreatment and acid post-treatment for fractionation and biovalorization of palm biomass wastes into fungal oil, bioethanol, and lactic acid

This research aimed to develop prototype for fully utilizing palm empty fruit brunches (EFB) for production of sugars and biofuels. EFB was biologically pretreated using oleaginous fungus and post-treated using mild acid. This process can remove lignin and fractionate hemicellulose from cellulose pulp, which was confirmed by chemical composition, functional groups, and crystallinity changes. The cellulose pulp was used for ethanol production via simultaneous saccharification and fermentation (SSF). To increase initial sugar concentration prior to ethanol production, repeated-prehydrolysis (RPH) was attempted. The RPH for four cycles gave the maximum sugars of 60.9 ± 1.9 g/L, and the subsequent SSF gave the highest ethanol of 35.2 ± 2.7 g/L with an ethanol yield of 0.40 g/g-sugar. Moreover, during fungal pretreatment the fungus also accumulated lipids with high potential as biodiesel feedstocks, and the hemicellulose hydrolysate obtained after acid post-treatment could be used for lactic acid fermentation. This study has shown a practical biorefinery roadmap for biovalorization of palm biomass wastes into multiple bioproducts, which may greatly contribute to Bio-Circular-Green (BCG) economy.

The Metabolism of Respiring Carbon Sources by Dekkera bruxellensis and Its Relation with the Production of Acetate.

Dekkera bruxellensis has been studied for several aspects of its metabolism over the past years, which has expanded our comprehension on its importance to industrial fermentation processes and uncovered its industrial relevance. Acetate is a metabolite often found in D. bruxellensis aerobic cultivations, whereas its production is linked to decreased ethanol yields. In a previous work, we aimed to understand how acetate metabolism affected the fermentation capacity of D. bruxellensis. In the present work, we evaluated the role of acetate metabolism in respiring cells using ammonium or nitrate as nitrogen sources. Our results showed that galactose is a strictly respiratory sugar and that a relevant part of its carbon is lost, while the remaining is metabolised through the Pdh bypass pathway before being assimilated into biomass. When this pathway was blocked, yeast growth was reduced while more carbon was assimilated to the biomass. In nitrate, more acetate was produced as expected, which increased carbon assimilation, although less galactose was uptaken from the medium. This scenario was not affected by the Pdh bypass inhibition. The confirmation that acetate production was crucial for carbon assimilation was brought by cultivations in pyruvate. All physiological data were connected to the expression patterns of PFK1, PDC1, ADH1, ALD3, ALD5 and ATP1 genes. Other respiring carbon sources could only be properly used by the cells when some external acetate was supplied. Therefore, the results reported herein helped in providing valuable contributions to the understanding of the oxidative metabolism in this potential industrial yeast.

Effective Fermentation of Sugarcane Bagasse Whole Slurries Using Robust Xylose-Capable Saccharomyces cerevisiae

The pre-treatment of lignocellulose material towards cellulosic bioethanol production releases microbial inhibitors that severely limit the fermentation ability of Saccharomyces cerevisiae. This study evaluated to what degree robust xylose-capable strains may improve the fermentability of non-detoxified sugarcane bagasse (SCB) slurries derived from steam explosion (StEX) and further compared this to slurries derived from ammonia fibre expansion (AFEX) pre-treatment. Initial screening in separate hydrolyses and co-fermentation processes using StEx-SCB hydrolysates identified S. cerevisiae TP-1 and CelluXTM4 with higher xylose consumption (≥ 88%) and ethanol concentrations (≥ 50 g/L), and ethanol metabolic yields (≥89% relative to theoretical maximum), even in the presence of approximately 8 g/L of acetic acid. Under industrially relevant pre-hydrolysis simultaneous saccharification and co-fermentation (PSSCF) conditions of high solids loading (15%, w/w) and low enzyme dosage (8 mg protein per gram untreated biomass), the fermentation of StEx-treated SCB whole slurry achieved ethanol yields of 208 and 224 L per Mg raw dry SCB using S. cerevisiae TP-1 and CelluXTM4, respectively. Under the same solids loading and enzyme dosages, the PSSCF of ammonia fibre expansion (AFEXTM) pre-treated SCB achieved ethanol yields of 234 and 251 L per Mg raw dry SCB using TP-1 and CelluXTM4, respectively. The study achieved non-detoxified whole-slurry co-fermentation using StEx pre-treated SCB, with higher ethanol yields than previously reported, by utilising robust xylose-capable strains. The results of this work provide insights into the potential use of inhibitor-tolerant S. cerevisiae strains TP-1 and CelluXTM4 as ethanologens for the fermentation of steam-exploded and undetoxified SCB whole slurries.

Effects of thermo-chemical and enzymatic pre-treatment of tropical seaweeds and freshwater macrophytes on biogas and bioethanol production

AbstractThe use of aquatic biomass as potential sources for bioenergy production has attracted significant attention worldwide. Production of biogas and bioethanol from both marine and freshwater plants using same pre-treatment methods were evaluated and the results indicate that both processes can be potentially enhanced appropriate methods of pre-treatment. In this study, the effects of thermochemical and enzymatic pre-treatment of selected seaweeds and freshwater macrophytes for biogas and bioethanol production were investigated. It was found that methane biogas yield from the anaerobic digestion of selected aquatic plants was highly dependent on the plant species. For example, biomethane yields of 189, 195, 221, 234 mL/g volatile solids were obtained following anaerobic digestion of acid and enzymatic pre-treatment of Laminaria digitata, Sargassum fluitans, Eichhornia crassipies and Pistia stratiotes, respectively. Additionally, alcoholic fermentation by the yeast Saccharomyces cerevisiae (distiller’s strain) was carried out on aquatic plant hydrolysates and the highest ethanol yields (of over 4 g/L) were obtained from Eichhornia crassipies and Pistia stratiotes. Poor fermentation yields from Laminaria digitata, and Sargassum fluitans hydrolysates were attributed to the predominance of un-fermented rhamnose sugars in these plants. The findings demonstrate the importance of reliance on empirical data for each substrate when designing and operating anaerobic digestion and alcohol fermentation systems. The results show that the same pre-treatment methods can be used for both types of bioenergy production, i.e., biogas and bioethanol, from marine and freshwater plants, thereby enhancing the economic viability of both processes in industry-scale applications.

Prediction of ethanol fermentation under stressed conditions using yeast morphological data

A high sugar concentration is used as a starting condition in alcoholic fermentation by budding yeast, which shows changes in intracellular state and cell morphology under conditions of high-sugar stress. In this study, we developed artificial intelligence (AI) models to predict ethanol yields in yeast fermentation cultures under conditions of high-sugar stress using cell morphological data. Our method involves the extraction of high-dimensional morphological data from phase contrast images using image processing software, and predicting ethanol yields by supervised machine learning. The neural network algorithm produced the best performance, with a coefficient of determination (R2) of 0.95, and could predict ethanol yields well even 60min in the future. Morphological data from cells cultured in low-glucose medium could not be used for accurate prediction under conditions of high-glucose stress. Cells cultured in high-concentration glucose medium were similar in terms of morphology to cells cultured under high osmotic pressure. Feeding experiments revealed that morphological changes differed depending on the fermentation phase. By monitoring the morphology of yeast under stress, it was possible to understand the intracellular physiological conditions, suggesting that analysis of cell morphology can aid the management and stable production of desired biocommodities.

Which crop has the highest bioethanol yield in the United States?

Annual U.S. production of bioethanol, primarily produced from corn starch in the U.S. Midwest, rose to 57 billion liters in 2021, which fulfilled the required conventional biofuel target set forth by the Energy Independence and Security Act (EISA) of 2007. At the same time, the U.S. fell short of the cellulosic or advanced biofuel target of 79 billion liters. The growth of bioenergy grasses (e.g., Miscanthus and switchgrass) across the Central and Eastern U.S. has the potential to feed enhanced cellulosic bioethanol production and, if successful, increase renewable fuel volumes. However, water consumption and climate change and its extremes are critical concerns in corn and bioenergy grass productivity. These concerns are compounded by the demands on potentially productive land areas and water devoted to producing biofuels. This is a fundamental Food-Energy-Water System (FEWS) nexus challenge. We apply a computational framework to estimate potential bioenergy yield and conversion to bioethanol yield across the U.S., based on crop field studies and conversion technology analysis for three crops—corn, Miscanthus, and two cultivars of switchgrass (Cave-in-Rock and Alamo). The current study identifies regions where each crop has its highest yield across the Center and Eastern U.S. While growing bioenergy grasses requires more water than corn, one advantage they have as a source of bioethanol is that they control nitrogen leaching relative to corn. Bioenergy grasses also maintain steadily high productivity under extreme climate conditions, such as drought and heatwaves in the year 2012 over the U.S. Midwest, because the perennial growing season and the deeper and denser roots can ameliorate the soil water stress. While the potential ethanol yield could be enhanced using energy grasses, their practical success in becoming a potential source of ethanol yield remains limited by socio-economic and operational constraints and concerns regarding competition with food production.

Food waste valorization applying the biorefinery concept in the Colombian context: Pre-feasibility analysis of the organic kitchen food waste processing

Food waste has been profiled as a potential source of added-value products and energy vectors. Nevertheless, the non-standard composition of food waste has been a bottleneck in proposing different biorefinery configurations. This paper aims to analyze organic kitchen food waste (OKFW) as a source of valuable products by applying the biorefinery concept. A compositional model was proposed considering seven food groups and the consumption trends in Colombia. Biogas and fermentable sugars were produced experimentally. Sugars were considered as feedstock for simulating two scenarios for producing bioethanol and polylactic acid. Finally, a techno-economic assessment was done. As a result, the liquid hot water treatment increases the crystallinity index by 30%, obtaining a fermentable sugar yield of 0.37 kg/kg of dry OKFW. The exhausted solid after saccharification produced 0.42 m3 of biogas/kg of exhausted OKFW. Ethanol and polylactic acid yields were 0.14 kg/kg of dry OKFW and 0.12 kg/kg of dry OKFW. Biogas use in cogeneration units can provide 13.49% and 4.29% of the total plant energy demand. Sugars concentration and downstream processing were the highest energy-demanding sections in the proposed scenarios. In conclusion, OKFW is a promising feedstock to produce added-value products in Colombia. However, biorefineries should be optimized to be robust regardless of the OKFW composition but considering the most representative fractions.

Effect of Laccase Detoxification on Bioethanol Production from Liquid Fraction of Steam-Pretreated Olive Tree Pruning

During lignocellulosic bioethanol production, the whole slurry obtained by steam explosion is filtered, generating a water-insoluble fraction rich in cellulose which is used for saccharification and ethanol fermentation, as well as a liquid fraction containing solubilised glucose and xylose but also some inhibitory by-products (furan derivatives, weak acids and phenols), which limits its use for this purpose. Since utilization of this liquid fraction to ethanol is essential for an economically feasible cellulosic ethanol process, this work studied a laccase from Myceliophthora thermophila to detoxify the liquid fraction obtained from steam-pretreated olive tree pruning (OTP) and to overcome the effects of these inhibitors. Then, the fermentation of laccase-treated liquid fraction was evaluated on ethanol production by different Saccharomyces cerevisiae strains, including the Ethanol Red, with the capacity to ferment glucose but not xylose, and the xylose-fermenting recombinant strain F12. Laccase treatment reduced total phenols content by 87% from OTP liquid fraction, not affecting furan derivatives and weak acids concentration. Consequently, the fermentative behavior of both Ethanol Red and F12 strains was improved, and ethanol production and yields were increased. Moreover, F12 strain was capable of utilizing some xylose, which increased ethanol production (10.1 g/L) compared to Ethanol Red strain (8.6 g/L).

Xylose Metabolization by a Saccharomyces cerevisiae Strain Isolated in Colombia

Saccharomyces cerevisiae (S. cerevisiae) is the most widely used yeast in biotechnology in the world because its well-known metabolism and physiology as well as its recognized ability to ferment sugars such as hexoses. However, it does not metabolize pentoses such as arabinose and xylose, which are present in lignocellulosic biomass. Lignocellulose is a widely available raw material, with xylose content of approximately 35% of total sugars. This xylose fraction could be used to obtain high added-value chemical products such as xylitol. One of these yeasts isolated from a Colombian locality, designated as 202-3, showed interesting properties. 202-3 was identified through different approaches as a strain of S. cerevisiae, with an interesting consumption of xylose metabolizing into xylitol, in addition with excellent ability as a hexose fermenter with high ethanol yields and shows resistance to inhibitors present in lignocellulosic hydrolysates. The xylose metabolization by the 202-3 strain and their kinetics parameters had not been previously reported for any other natural strain of S. cerevisiae. These results suggest the great potential of natural strains for obtaining high value-added chemical products using sugars available in lignocellulosic biomass.

High bioethanol titer and yield from phosphoric acid plus hydrogen peroxide pretreated paper mulberry wood through optimization of simultaneous saccharification and fermentation

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.

Exploring the hybrid route of bio-ethanol production via biomass co-gasification and syngas fermentation from wheat straw and sugarcane bagasse: Model development and multi-objective optimization

Biomass co-gasification and syngas fermentation is one of the least trotted paths in the Indian biofuel production scenario. The aim of the research here is to develop an equilibrium model of biomass co-gasification and syngas fermentation in Aspen plus. Two Indian lignocellulosic biomass namely wheat straw and sugarcane bagasse have been selected as feedstock for this co-gasification process followed by the syngas fermentation. The process shows promising results in terms of ethanol production and energy usage. The effects of gasification process parameters on overall process performance have been analysed. Empirical regression equations were constructed to account for the effects of biomass ratio, which is the ratio of the masses of wheat straw and sugarcane bagasse, gasification temperature and equivalence ratio over ethanol yield, lower heating value of syngas, cold gas efficiency, overall system efficiency, and CO2 emission using response surface methodology. Finally, a multi-objective optimization has been conducted to maximize the ethanol production and overall system efficiency, and to minimize the CO2 emission of the system. Results suggest that the wheat straw and sugarcane bagasse ratio of 4:1, 919.5oC temperature and 0.15 equivalence ratio is the optimum point with an ethanol production rate of 20.917 tonnes/hr, overall efficiency of 52.184%, and a minimum CO2emission of 32669.862 kg/h.

Growth-uncoupled propanediol production in a Thermoanaerobacterium thermosaccharolyticum strain engineered for high ethanol yield

Cocultures of engineered thermophilic bacteria can ferment lignocellulose without costly pretreatment or added enzymes, an ability that can be exploited for low cost biofuel production from renewable feedstocks. The hemicellulose-fermenting species Thermoanaerobacterium thermosaccharolyticum was engineered for high ethanol yield, but we found that the strains switched from growth-coupled production of ethanol to growth uncoupled production of acetate and 1,2-propanediol upon growth cessation, producing up to 6.7 g/L 1,2-propanediol from 60 g/L cellobiose. The unique capability of this species to make 1,2-propanediol from sugars was described decades ago, but the genes responsible were not identified. Here we deleted genes encoding methylglyoxal reductase, methylglyoxal synthase and glycerol dehydrogenase. Deletion of the latter two genes eliminated propanediol production. To understand how carbon flux is redirected in this species, we hypothesized that high ATP levels during growth cessation downregulate the activity of alcohol and aldehyde dehydrogenase activities. Measurements with cell free extracts show approximately twofold and tenfold inhibition of these activities by 10 mM ATP, supporting the hypothesized mechanism of metabolic redirection. This result may have implications for efforts to direct and maximize flux through alcohol dehydrogenase in other species.

Evolving Robust and Interpretable Enzymes for the Bioethanol Industry

AbstractObtaining a robust and applicable enzyme for bioethanol production is a dream for biorefinery engineers. Herein, we describe a general method to evolve an all‐round and interpretable enzyme that can be directly employed in the bioethanol industry. By integrating the transferable protein evolution strategy InSiReP 2.0 (In Silico guided Recombination Process), enzymatic characterization for actual production, and computational molecular understanding, the model cellulase PvCel5A (endoglucanase II Cel5A from Penicillium verruculosum) was successfully evolved to overcome the remaining challenges of low ethanol and temperature tolerance, which primarily limited biomass transformation and bioethanol yield. Remarkably, application of the PvCel5A variants in both first‐ and second‐generation bioethanol production processes (i. Conventional corn ethanol fermentation combined with the in situ pretreatment process; ii. cellulosic ethanol fermentation process) resulted in a 5.7–10.1 % increase in the ethanol yield, which was unlikely to be achieved by other optimization techniques.

Evolving Robust and Interpretable Enzymes for the Bioethanol Industry.

Obtaining a robust and applicable enzyme for bioethanol production is a dream for biorefinery engineers. Herein, we describe a general method to evolve an all-round and interpretable enzyme that can be directly employed in the bioethanol industry. By integrating the transferable protein evolution strategy InSiReP 2.0 (In Silico guided Recombination Process), enzymatic characterization for actual production, and computational molecular understanding, the model cellulase PvCel5A (endoglucanase II Cel5A from Penicillium verruculosum) was successfully evolved to overcome the remaining challenges of low ethanol and temperature tolerance, which primarily limited biomass transformation and bioethanol yield. Remarkably, application of the PvCel5A variants in both first- and second-generation bioethanol production processes (i. Conventional corn ethanol fermentation combined with the in situ pretreatment process; ii. cellulosic ethanol fermentation process) resulted in a 5.7-10.1 % increase in the ethanol yield, which was unlikely to be achieved by other optimization techniques.

Bioethanol production from corn straw pretreated with deep eutectic solvents

BackgroundDeep eutectic solvents (DESs) have gained increasing attention as alternative solvents of environmental unfriendly solvents for biomass pretreatment. ResultsIn this study, bioethanol production from DES-pretreated corn straw was investigated. The results revealed effective lignin removal from corn straw after pretreatment with choline chloride/oxalic acid (C:O), choline chloride/glycerol (C:G), or choline chloride/urea (C:U) DESs. After pretreatment with DESs, cellulose conversion significantly increased to 96.51% from 44.35% in the case of untreated corn straw. The best performance was obtained after the pretreatment of corn straw with C:O with a mass ratio of 1:15 at 120°C for 6 h, and this was mainly attributed to high lignin removal (60.60%). Another experiment showed that corn straw pretreated with C:G had a cellulose conversion of 86.82%, a glucose yield of 63.57%, and an ethanol yield of 54.86%. ConclusionsOverall, this study demonstrated that the pretreatment of corn straw by a suitable DES can lead to efficient bioethanol production.How to cite: Liu J, Wang C, Zhao X, et al. Bioethanol production from corn straw pretreated with deep eutectic solvents. Electron J Biotechnol 2023;62. https://doi.org/10.1016/j.ejbt.2022.12.004.

Integrated biorefinery for production of biodegradable film, bioethanol, and soda pulp from corn stalks

In traditional pulping, black liquor is burned in an alkali recovery system to produce energy. According to the integrated forest biorefinery (IFBR) concept, hemicellulose is partially pre-extracted prior to pulp production to generate value-added products. Corn stalks have a remarkable carbohydrate content (75% w/w), and thus were examined in this study in terms of the IFBR concept. The hemicelluloses were pre-extracted with hot water (90, 120, 135, and 150 °C), NaOH, and NaOH + NaBH4 (50, 70, and 90 °C) for 4 h. NaOH charges of 16.7, 26.7, and 33.3% were explored. The extracts were utilized to produce bioethanol and biodegradable films, and papermaking pulps were produced from the solid fractions. Differences among groups were identified via analysis of variance, and the Duncan’s test was applied to determine those differences that were significant. The results showed that the alkaline pre-extraction (26.7% NaOH at 50 °C) removed 35.6% of the xylose from the stalk structure. The liquid fraction collected from the hot water pre-extraction at 150 °C gave a 14.7% (g/100 g soluble material) yield of bioethanol. Moreover, the theoretical ethanol yield was calculated as 89.4%. The addition of gluten and nanocellulose to the xylan enabled the production of high-quality biodegradable films. Furthermore, the pulps produced from the hot water pre-extracted solid fractions were comparable in yield and pulp properties to the control soda pulp.

Increasing the atom economy of glucose fermentation for bioethanol production in Rubisco-based engineered Escherichia coli

Feedstock accounts for a major portion of bio-based chemical production. While tremendous progress has been made in cellulosic ethanol production over the last few decades, direct conversion of CO2 to biofuels has been under-investigated. Ribulose-1,5-bisphosphate carboxylase/oxygenase (Rubisco) is an enzyme that can fix CO2 by catalyzing the carboxylation. A Rubisco-based Escherichia coli has been constructed that is capable of simultaneously converting glucose and CO2 to bioethanol. Practically homo-fermentative ethanol production can be achieved by FB295A (E. coli BL21(DE3) Δzwf ΔldhA Δfrd ΔpflB harboring pdc, adhB, rbcLS, and prk) in 60 h where the bioethanol yield, concentration, percentage/fermentation product, and CO2 emission/ethanol production were 2.3 ± 0.2 mol/molglucose, 256 ± 19 mM, 100 %, and 0.13 ± 0.02 molCO2/molEtOH, respectively. By a subculture to the second generation, the overall fermentation time was shortened within 30 h and therefore, the bioethanol productivity was improved to 7.1 ± 0.5 mmol⋅L−1⋅h−1 while maintaining an apparent ethanol yield of 2.4 ± 0.1 mol/molglucose. The performance of FB295A reached 100 % theoretical for in situ CO2 recycling. This study presents a new bioethanol production pathway based on in situ CO2 recycling.

Hydrolysis of Blended Cotton/Polyester Fabric from Hospital Waste using Subcritical Water

Currently in Malaysia, most wastes are disposed into poorly managed systems with little or no pollution protection measures. Large amounts of wastes such as textiles are generated through hospitals and health care centers. However, the improper management of these abundantly generated wastes may pose an environmental pollution problems and fire hazard. Cotton textile is a potential biomass for bioethanol production. Subcritical water (Sub-CW) hydrolysis was investigated as an alternative technology for the recycling of cotton textile waste for current health care waste management. The aim of this study was to investigate the possibility of complete conversion of cotton textile waste to ethanol via Sub-CW hydrolysis and fermentation. Sub-CW was carried out to facilitate the hydrolysis of cellulose component in cotton textile (cotton 75%+polyester 25%). The study was divided into two parts; (i) To evaluate the subcritical water parameters such as temperature and time to achieve maximum yield of sugars. (ii) Fermentation of the hydrolysate obtained from Sub-CW hydrolysis to ethanol. Under Sub-CW conditions of temperature (140 °C - 350 °C), reaction time (1-10 min) and water to cotton ratio (3:1) showed that cotton textile treated at 280 °C for 4 min, was optimal for maximizing yield of sugar, which was 0.213 g/g-dry sample. The quantitative analysis by HPLC showed that the soluble carbohydrates in the water phase were mainly composed of glucose. The obtained glucose concentration, 171 mg/L was then fermented at 36 °C for 24 hours by Saccharomyces cerevisae (yeast) to ethanol. Highest yield of ethanol was 0.415 g/g glucose, which was 81.2 % of theoretical yield. Hydrolysis with Sub-CW showed the potential to decompose the cotton textile into simple sugar while keeping sugar degradation to minimal phase and the possibility of complete conversion of cotton textile waste to ethanol via Sub-CW and fermentation.