Technologies For Bioethanol Production Research Articles

Advances and challenges in pretreatment technologies for bioethanol production: A comprehensive review

Bioethanol production from biomass is a promising avenue for sustainable energy, yet the high cost of pretreatment processes poses significant economic challenges. This paper explores the critical role of pretreatment in enhancing bioethanol yield and reducing production costs. Various pretreatment methods, including physical, chemical, physicochemical, and biological techniques, are reviewed and further analyzed for their effectiveness in breaking down lignocellulosic biomass into fermentable sugars. Emphasis is placed on recent technological advancements and innovations that improve efficiency and cost-effectiveness. The paper reviews the latest research on combined pretreatment approaches that have shown potential in overcoming recalcitrance and increasing sugar yield. Also, the role of nanotechnology in biomass pretreatment has been discussed. The economic implications of different pretreatment strategies are discussed, highlighting cost-benefit analyses and the potential for scalability. By addressing the complexities and advancements in pretreatment technologies, this study aims to provide a comprehensive understanding of the role of optimizing pretreatment processes in significantly enhancing hydrolysis efficiency. The findings underscore the importance of continued research and development to achieve better economic viability and environmental sustainability in bioethanol production.

A Review of the Technological Aspects and Process Optimization of Bioethanol Production From Corn Stover Biomass: Pretreatment Process, Hydrolysis, Fermentation, Purification Process, and Future Perspective

ABSTRACTBioethanol, a sustainable energy solution derived from renewable biomass, has gained prominence, with corn stover emerging as a substantial biomass resource in Indonesia. Corn stover, a corn residue, is one of the top three agricultural wastes worldwide and is abundantly available. However, a significant portion of corn stover is burned in fields rather than utilized for bioethanol production, whereas it has potential as a bioethanol feedstock. As the world strives to realize sustainable and environmentally friendly energy security, bioethanol production from corn stover can be one of the solutions to be developed. Nonetheless, the current immaturity of bioethanol production technology is one of the causes of large‐scale production failure. The present paper comprehensively reviews the technological aspects and process optimization of bioethanol production using corn stover as a feedstock comprising pretreatment, hydrolysis, fermentation, and bioethanol purification processes. According to our critical review, ammonia fiber expansion (AFEX) pretreatment is the most effective conventional pretreatment, with glucose yield up to 90%. Moreover, ultrasound appears to be the most viable option for nonconventional pretreatment of corn stover for producing bioethanol. However, combining ultrasound pretreatment and dilute aqueous ammonia produced 80.6% sugar output. Furthermore, enzymatic hydrolysis emerges as the most effective saccharification, yielding up to 81.39%. Moreover, the fermentation process of corn stover with the saccharification and co‐fermentation (SScF) method and the process optimization with response surface methodology (RSM) could produce bioethanol with a concentration of up to 59.8 g/L and 92.07% ethanol yield, respectively. This review also reveals that pervaporation for the purification process is the best choice for producing bioethanol with high purity up to > 99%. In addition, this method could reduce the energy used by 6.6% lower, 24.2% lower carbon footprint, and have the lowest total capital and production costs compared to conventional molecular sieves and extractive distillation. We believe this review article can provide a reference for selecting the best bioethanol production process from corn stover for further research.

Bioethanol production from cassava fed-batch fermentation in pervaporation membrane bioreactor with permeate fractional condensation

A new type pervaporation membrane bioreactor was developed by coupling cassava-based fed-batch fermentation and pervaporation membrane separation technology for bioethanol production. Membrane separation slowed down broth accumulation rate and mitigated ethanol product inhibition. The fermentation time, average sugar consumption rate, ethanol production and ethanol productivity were 131h, 6.6 gL-1h-1, 149.4 gL-1 and 2.5 gL-1h-1, respectively. They were improved by 55.9 %, 73.2 %, 32.3 % and 49.7 %, respectively, compared to those of conventional fed-batch fermentation. The average membrane flux and separation factor were 711.3 gm-2h-1 and 6.5, respectively, with an ethanol concentration of 24.4 wt% in the permeate. Throughout fermentation, the total mass transfer coefficient remained constant at 9.6 × 10-6 ms-1, with the convection mass transfer coefficient decreasing as the broth viscosity increasing while the membrane mass transfer coefficient slightly increasing. A two-stage condensation downstream the membrane achieved fractional vapor recovery. The primary condensate with low ethanol concentration (1.6 wt%) can be used for cassava hydrolyzation, saving 14.0 % of water requirement. Recovering ethanol from the high-concentration (32.6 wt%) secondary condensate required lower energy (46 %) compared to direct recovery from the total permeate.

Economic evaluation of elements of corn cultivation technology for grain and bioethanol production

Economic evaluation of elements of corn cultivation technology for grain and bioethanol production

Optimization of Bioethanol Production from Cassava through Fermentation Stimulant with Addition of Alpha-Amylase Enzyme

Bioethanol, as a substitute for fuel, presents significant advantages such as environmentally friendly exhaust emissions, high octane value, and a reduction in the use of hazardous additives. The utilization of carbohydrate-rich alternatives as bioethanol feedstock is gaining prominence, particularly root vegetables like cassava. The objective of this research is to obtain bioethanol from cassava through a fermentation stimulant process involving cellulase enzyme and Saccharomyces caravisiase. In the long term, the overarching goal is to establish an alternative energy source with bioethanol production technology derived from cassava. This study comprises three treatments, incorporating the addition of alpha-amylase enzyme at 0.5, 0.1, and 0.15 mL, with a fermentation duration of 56 hours. The research findings reveal that the addition of 0.5 mL of alpha-amylase enzyme produces optimal bioethanol with the highest yield. These results not only underscore the potential of cassava as a primary bioethanol feedstock but also make a significant contribution to the development of efficient and sustainable bioethanol production technology.

Geospatial environmental techno-economic assessment of pretreatment technologies for bioethanol production

Second-generation biofuels, starting from lignocellulosic biomass, are considered as a renewable alternative for fossil fuels with lower environmental impact and potentially higher supply and energy security. The economic and environmental performance of second-generation bioethanol production from corn stover in the European Union (EU) is studied, starting in Belgium as base case. A comparative environmental techno-economic assessment has been conducted, with process simulations in Aspen Plus and corn stover availability data in thirteen EU countries to calculate minimum ethanol selling prices (MESP) and Greenhouse gas emissions (GHGe). In this analysis, the emphasis is on the comparison of different pretreatment technologies, namely (i) dilute acid, (ii) alkaline, (iii) steam explosion and (iv) liquid hot water. Dilute acid showed the best economic and environmental performance for the base case scenario. Within the EU, Hungary and Romania presented the lowest MESP for the steam explosion model at 0.39 and 0.43 EUR/L respectively. Poland showed the lowest GHGe, at 0.46 kg CO2eq/L for the alkaline model, mainly due to the avoided product allocation on electricity and its high carbon intensity in the electricity generation sector. The second lowest GHGe were obtained in France for the dilute acid model and are attributed to its low agricultural emissions intensity. This study identifies a location-dependence of the economic and environmental performance of pretreatment technologies, which can be extrapolated from the EU to other large regions around the world and should be taken into consideration by decision-makers.

Simultaneous bioconversion of rice straw into an intermediate product using ionic liquid and native extracellular hydrolytic enzyme from indigenous actinomycetes

Bioethanol production technology using lignocellulosic substrates has become a focus to overcome the limited supply of fossil fuels in the current century. Simultaneous saccharification requires an understanding of suitable efficient procedures in bioconversion row material into fermented sugar. In this study, the effect of pre-treated rice straws using ionic liquid on enzymatic saccharification by isolated actinomycetes was investigated. Ionic liquid to rice straw in a ratio (IL/RS) was set up 0 to 3 (g/g), and the remaining of the ionic liquids in pre-treated biomass was examined for their effect on the hydrolytic enzyme activity of the actinomycetes. Three actinomycetes were isolated from decomposed rice straw and were purified and screened for their cellulolytic and xylanolytic activity; one strain, namely ActRS-4, was selected as an optimum isolate for further hydrolysis examination. Both cellulase and xylanase activity exhibit a peak at a ratio IL/RS of 1 (g/g), the activity was 27.72 and 66.16 U/ml, respectively. The highest yield of sugar was also achieved at this IL/RS ratio for 8 days of incubation. The pretreatment indicates that it could promote an increase in the yield of glucose and xylose by 28% and 37% respectively. This study was promising to develop a one-pot conversion of lignocellulosic biomass into bioethanol using the biological process.

Environmental assessment of the valorization of glycerol for the production of hyperthermophilic β-glucosidase under a biorefinery approach

Bioethanol production technologies from lignocellulosic biomass are not yet optimized and do not compete economically with first-generation bioethanol production. Strategies have been investigated to produce more active, stable and temperature-tolerant enzymes to be used for biomass hydrolysis such as the hyperthermophilic β-glucosidase produced by Yarrowia lipolytica. The use of this strain offers an additional competitive advantage, as it can use glycerol stream from the biodiesel process as a carbon source. In this way, not only is a by-product of biofuel production used, but the enzyme could be applied in the production of lignocellulosic ethanol, increasing the value chain by closing the bioeconomy cycle. To this end, large-scale process modelling of β-glucosidase production has been developed to collect the inventory data needed for life cycle assessment methodology. The fermentation stage is the largest contributor to environmental impacts, with electricity being the main hotspot identified, contributing more than 50% in most impact categories. Residual glycerol has also been identified as a critical input, with a significant contribution in some categories. To improve the environmental profile, a sensitivity analysis has been carried out considering reductions in electricity and heat consumption, and other alternative oil-based resources for the production of biodiesel. This analysis identified that large environmental reductions could be achieved, which makes the valorization of the glycerol obtained as a side stream of biodiesel production more realistic.

Key prospects and major development of hydrogen and bioethanol production

Cheap Production of bioethanol from renewable lignocellulosic waste has the imperative potential to economically cut burgeoning world dependency on fossils while reducing net emission of carbon dioxide (CO2), a principal greenhouse gas (GHGs). This paper highlights key benefits and status of bioethanol production technologies, aiming mainly on recent developments and its key potentials in Pakistan. Most sector of Pakistan economy heavily rely on the energy and power that is being produced using traditional approaches like from oil and hydel. However, the sedimentation in dams cut-down the energy generation and overwhelmed severe energy crisis that are witnessed since last decade. Thus, Pakistan must go to avail alternative sources of energy like hydro, biomass and solar so that energy security can be ensured to recover the tremendous loss of economy. Renewable biomass is abundantly available in Pakistan which can be used to produce bioethanol and electricity. Currently, 22 distilleries are producing the ethanol from sugar cane bagasse and out of these only 8 distillation units are producing motor fuel grade ethanol. The current bioethanol production of country is about 403,500 tons/year along with 2423 tons of biodegradable waste available in major cities. In addition, Pakistan produces 6.57, 0.5, 0.66, and 2.66 million tons of sugarcane, corn, rice, and wheat straw per annum, respectively. This biomass can produce 1.6 million liters of bioethanol which can produce approximately 38% of Pakistan's electricity annually. Despite having large potential, Pakistan is still producing a few volumes of ethanol from sugarcane bagasse. The production of bioethanol can be boosted using (I) pretreatment of agricultural biomass by alkali (II) enzymatic and bacteria-based hydrolysis of the biomass (III) post-hydrolysis using pressurized steam above 100 °C (IV) Fermentation of the biomass@ 7–10 h and (V) and (VI) distillation of bioethanol. This study recommends (1) increase R&D capacities mainly in the west and central regions of Pakistan, (2) initiate mega-projects to promote integrated bio-ethanol production at agriculture farms by providing 1/3 subsides, (3) purchase of bioethanol directly from the major agricultural farms, (4) produce bioethanol related manpower from the key research institutes as specified in this study.

Hydrolysis of coffee pulp as raw material for bioethanol production: sulfuric acid variations

Indonesia has enormous biomass resources due to its land territory is mostly surrounded by forests and agricultural area. One of the main agricultural commodities is Gayo Arabica coffee. Coffee agro-residue such as coffee-pulp contains glucose, organic matter, protein, nitrogen and high minerals. Therefore, coffee pulp can be a potential raw material for bioethanol production. In order to develop an effective technology for bioethanol production from coffee-pulp, it is necessary to investigate in early the way of glucose can be effectively prepared. In this preliminary investigation, glucose products ware prepared using two methods, i.e. method-I under several main-stages including extraction, delignification, and hydrolysis. While, under method-II, the sample was directly hydrolyzed at 100°C for 4 h. Under both methods, hydrolysis process to get glucose was performed by adding sulfuric acid (H2SO4) at various concentrations (8 wt.%, 10 wt.% and 12 wt.%). Based on analysis results, the highest glucose level, i.e. 17 % was obtained from method-II by adding 8 wt.% sulfuric acid. The less the amount of sulfuric acid added, the higher the glucose level produced. No difference in pH was found from both methods. The color of glucose produced under method-I is clearer compared to those prepared under method-II.

Carbon footprint analysis of sweet sorghum-based bioethanol production in the potential saline - Alkali land of northwest China

Available saline-alkali land could be used to plant bioenergy crops for biofuel stocks, retaining productive land for food crops. Sweet sorghum is a promising candidate for bioethanol production due to its ability to tolerate environmental stresses. This study estimated the available saline-alkali land for sweet sorghum planting in northwest China using a multi-factorial analysis, quantified its bioethanol potential, and assessed the carbon footprint of sweet sorghum stalk (SSS)-based bioethanol production on this land using a life cycle assessment. The results revealed 9.33 × 105 ha saline-alkali land available for sweet sorghum planting, or 11.47% of the total saline-alkali land in the study area, with a potential yield of 6.87 × 107 t sweet sorghum stalk, producing 4.29 × 106 t bioethanol. The carbon footprint of SSS-based bioethanol production ranged from 2.21 to 2.25 t CO2 eq t−1 bioethanol across selected districts. Sweet sorghum cultivation accounted for most of the carbon footprint in each district (40.18–45.30%). Compared to gasoline, the carbon footprint for pure bioethanol (E100) made from SSS in the selected districts declined by 33.42–49.94% with or without reusing the bagasse co-product. The carbon footprint of E10 (10% bioethanol from SSS and 90% gasoline) declined by 2.68–4.49%. Thus, it is possible to cultivate sweet sorghum on the selected saline-alkali land in northwest China for bioethanol production. However, future studies are needed to (1) improve sweet sorghum genotypes and identify optimal agronomic management for feedstock, (2) advance technologies for bioethanol production, (3) develop bioethanol-tolerant yeast and bacteria strains, and (4) stimulate policy support for growers and industrialists to accelerate cleaner production.

Development and comparison of membrane separation schemes for byproduct recovery from Egyptian rice straw black liquor

BackgroundRecovery of valuable ingredients from black liquor could lead to an environmentally and economically sound bioethanol production technology. In this work, two schemes comprising hybrid membrane systems incorporating ultrafiltration (UF) and nanofiltration (NF) are developed for the recovery of lignin, silica rich and cellulose/hemicellulose hydrolysates byproducts from alkaline pretreated rice straw.MethodsThe first scheme (I) comprises UF, NF and thermal vapor compression (TVC), while, the second scheme (II) includes UF, 2 stages of NF and 2 TVC units. Further treatments are suggested to produce solid byproducts with an economic value. Furthermore, material balance of the two schemes based on 1000 m3/d of black liquor and the main design features and comparative direct cost indicators of the main adopted units were deduced using WT Cost II© software.ResultsResults revealed that about (80–90%) yield of recovered byproducts from both schemes with equivalent amounts of 9.5, 5.5 and 18.5 ton/d of lignin, silica rich and cellulose/hemicellulose hydrolysates dry products, respectively. Moreover, reusable water recovery approaches 26% and 70% for schemes (I) and (II), respectively.ConclusionsFurther, the wastewater generated from scheme (II) is 2.9 times folds scheme (I) which improves the environmental impact of the former. Preliminary cost indicators revealed that both schemes have almost the same total direct capital cost.

Growth rate measurements of Chlorella vulgaris in a photobioreactor by Neubauer-improved counting chamber and densitometer

The depletion of fossil fuel sources and increased CO2 emissions has triggered intensive research to discover renewable energy sources. With the Low Carbon Scenario, the role of renewable energy will increase to 58% in 2050. As a renewable energy source, bioethanol is environmentally friendly which can substitute gasoline. Currently, the third-generation bioethanol production technology from microalgae is still being developed. Chlorella vulgaris is one of the microalgae types with high carbohydrate content and is easy and fast to cultivate. This study aims to evaluate the growth rate of C. vulgaris cultivated in a bubble column photobioreactor using artificial seawater aerated with pure CO2. Two LED tube lights were used with 12 h light and 12 dark cycles for 12 - 13 days. Microalgae culture population was measured every 24 h using a Neubauer-improved counting chamber and a microscope equipped with a digital camera. The results showed that the maximum specific growth rate,/max, was found to be 0.344 d1, and the highest concentration of 1.88 x107 cells mL1 occurred on day 7. Moreover, the microalgae populations were also measured using a densitometer. Since the calculation of the cell population used secondary data from the literature, the results were less accurate than those of the counting chamber.

A Preliminary Life Cycle Analysis of Bioethanol Production Using Seawater in a Coastal Biorefinery Setting

Bioethanol has many environmental and practical benefits as a transportation fuel. It is one of the best alternatives to replace fossil fuels due to its liquid nature, which is similar to the gasoline and diesel fuels traditionally used in transportation. In addition, bioethanol production technology has the capacity for negative carbon emissions, which is vital for solving the current global warming dilemma. However, conventional bioethanol production takes place based on an inland site and relies on freshwater and edible crops (or land suitable for edible crop production) for production, which has led to the food vs. fuel debate. Establishing a coastal marine biorefinery (CMB) system for bioethanol production that is based on coastal sites and relies on marine resources (seawater, marine biomass and marine yeast) could be the ultimate solution. In this paper, we aim to evaluate the environmental impact of using seawater for bioethanol production at coastal locations as a step toward the evaluation of a CMB system. Hence, a life cycle assessment for bioethanol production was conducted using the proposed scenario, named Coastal Seawater, and compared to the conventional scenario, named Inland Freshwater (IF). The impact of each scenario in relation to climate change, water depletion, land use and fossil depletion was studied for comparison. The Coastal Seawater scenario demonstrated an improvement upon the conventional scenario in all the selected impact categories. In particular, the use of seawater in the process had a significant effect on water depletion, showing an impact reduction of 31.2%. Furthermore, reductions were demonstrated in natural land transformation, climate change and fossil depletion of 5.5%, 3.5% and 4.2%, respectively. This indicates the positive impact of using seawater and coastal locations for bioethanol production and encourages research to investigate the CMB system.

Biotransformation Methods of Paddy Straw into Bioethanol

Bio-fuel production can be categorized into biodiesel and bioethanol and the most common renewable fuel today is ethanol derived from sugar. Future large-scale use for ethanol will most certainly have to be based on production from lignocellulosic materials due to its abundance in food crop waste. This article gives an overview on paddy straw biotransformation into ethanol. Rice straw has lignocellulosic material for bioethanol production since it is one of the most abundant renewable resources. Paddy straw especially, has favorable characteristics such as high hemicellulose and cellulose content that can be readily hydrolyzed into fermentable sugars. However, one of the major challenges in developing technology for bioethanol production from paddy straw is selection of an appropriate pre-treatment and fermentation method.

Recyclable cascading of arsenic phytoremediation and lead removal coupled with high bioethanol production using desirable rice straws

Crop straws provide enormous lignocellulose residues convertible to biofuels, whereas Arsenic (As) and lead (Pb) pollute agricultural soil and water source. Hence, it becomes important to explore a compelling biomass process technology for both bioethanol production and trace metal remediation. In this study, we selected classic rice cultivars that distinctively accumulated As from 10.25 to 16.18 μg/g in their mature straws from the As-polluted farming soils, being up to 10-fold higher than those of the previously-reported rice straws and other crops. By performing various chemical pretreatments with the As-accumulated rice straws, this study sorted out that the optimal two-step 2%H2SO4 and 2%NaOH pretreatments could cause almost complete biomass enzymatic saccharification for high bioethanol production in all rice straws examined, along with a full As release for As recycling as potential high-value crystallized chemical. Furthermore, all remaining lignin-rich solid resides were finally examined to act as active biosorbent for Pb adsorption, with the optimal Pb adsorption conditions established (1 g/L adsorbent dose at pH6.0 and room temperature). Hence, this study has not only demonstrated a cascading-like strategy for efficient As and Pb remediation in agricultural soil and water source, but it has also provided a value-added approach for complete utilization of crop straws towards high bioethanol production.

Design, Fabrication and Performance Test of a Pilot Scale Bioethanol Plant with Fractional Distillation Unit

This study presents the design and development of a pilot scale bioethanol plant. The pilot plant was designed to produce an average of 20 liters/day of ethanol from a 60 litre volume of brut/beer from agricultural waste materials. The design of the bioethanol plant covers the stages of concept formation to the production of specification sheets for components parts and equipment, the design consideration for the plant was also included. The pilot plant consists of the fermentation pot, radiator, water pot, ethanol collection pot, fractional distillation unit, boiler, reboiler, condenser, pumps, electrical components, frame and base of the plant and tyres for mobility. The materials used for the development of the plant are mainly stainless steel, mild steel and copper. A performance test was carried out on the bioethanol plant with fractional distillation unit. Agricultural waste material was used for the testing of the plant. The feedstock was processed and allowed to undergo fermentation during which physicochemical parameters like pH, sugar content, alcoholic content, conductivity and specific gravity was carried out for a period of four days. The fermented beer/brut was then distilled to produce an average of 79% alcohol. The equipment was locally fabricated in the National Centre for Energy and Environment, University of Benin, Benin City, Edo State Nigeria using about 85% local content. The pilot plant has proven the availability of local technology for bioethanol production in Nigeria.

Environmental assessment of different technologies for bioethanol production from Cynara cardunculus: A Life Cycle Assessment study

Waste biomass for biofuels production can contribute to reduce dependence on fossil fuels and consequently, a decrease of CO2 emissions. In this work, the environmental feasibility of cardoon-to-bioethanol process was evaluated using Life Cycle Assessment (LCA). For this purpose, three processes involving different biomass pretreatments (dilute acid (DA), single steam explosion (SE) and steam explosion + alkaline extraction (SE + AE)) were simulated by using SuperPro Designer 9.5. Simulation results and literature data were used to perform LCA by using Gabi 6.0 software. LCA results showed that the pretreatment step is the main contributor to the overall impact in the dilute acid case due to the large energy requirements. The use of steam-explosion-based pretreatments drastically reduce environmental impacts regarding to DA process, being fertilizers, chemicals and enzyme production the main important contributors. By combining single steam explosion and subsequent alkaline extraction, the environmental performance is improved compared to single steam explosion due to a reduction of the energy consumption. However, higher toxicity impacts were obtained mainly because of the larger amount of enzyme and chemicals required. GHG emissions and energy balance of bioethanol from cardoon falls within the values reported for similar lignocellulosic raw materials. Finally, the comparative study of bioethanol from cardoon and fossil gasoline indicates that steam explosion-based processes are environmentally superior in most impact categories, obtaining a dramatic reduction of the primary energy demand (80%) and the GHG emissions (45%).

The Technology Used for Synthetic Polyploid Production of Miscanthus as Cellulosic Biofuel Feedstock

Background: The contemporary bioethanol production technologies are based on the utilization of plant lignocellulosic biomass. These technologies require conducting regular search, breeding, and creation of new energy crops. In particular, significant attention is paid to plants of the genus Miscanthus - perennial grasses that have a great potential as renewable energy sources. The main advantages of representatives of this species are considered to be high biomass yield, cold tolerance, a low requirement to soil conditions, long-term use of plantation, etc. M. × giganteus is the most promising species of the genus. The last is a sterile allotriploid originated through the hybridization of M. sinensis and M. sacchariflorus. Due to the problem with sexual reproduction, there is a lack of genotypes necessary for plant breeding programs to improve this species. Thus, polyploidization is an indispensable approach for obtaining new genotypes of M. × giganteus. Objective: The aim of this work is to review the attempts and methodologies employed to induce polyploidy in plants belonging to the genus Miscanthus. Methods: For this purpose, the concentrations and duration of treatment with different antimitotic agents in species, within this genus, have been considered. Methods for ploidy level determination and evaluation of biological and biochemical traits in the resulting polyploids have also been reported. Results: The application of antimitotic agents in vitro is the most effective and commonly used method of polyploidization in Miscanthus. The most effective antimitotic compounds appeared to be the well-known dinitroanilines, such as oryzalin and trifluralin, as well as new dinitroanilines with significantly lower phytotoxicity level. Conclusion: Polyploidization in Miscanthus has been investigated by various research groups worldwide. Currently, polyploid forms of M. sinensis, M. sacchariflorus and M. × giganteus have been obtained. The biological and biochemical traits of the obtained polyploids differ significantly from their original forms. However, the challenge of fertility restoration of M. × giganteus has not been resolved yet.

Saccharification of water hyacinth biomass by a combination of steam explosion with enzymatic technologies for bioethanol production.

In the present work, bioethanol was produced by sugar fermentation obtained from water hyacinth using a novelty hybrid method composed of steam explosion and enzymatic hydrolysis, using hydrolytic enzymes produced by solid-state fermentation and water hyacinth as substrate. The highest activity, 42 U for xylanase and 2 U for cellulase per gram of dry matter, respectively, was obtained. Steam explosion pretreatment was performed at 190℃ for 1, 5, and 10min, using water hyacinth sampled from the Maria Lizamba Lagoon, the Arroyo Hondo and the Amapa River. The highest amounts of reducing sugars of water hyacinth were obtained form the samples from the lagoon (5.4g/50g of dry matter) after 10min of treatment. Steamed biomass was hydrolysed using the enzymes obtained by solid-state fermentation, obtained reducing sugars (maximum 15.5g/L); the efficiency of enzymatic hydrolysis was 0.51g of reducing sugars per gram of water hyacinth. Finally, reducing sugars were fermented using Saccharomyces cerevisiae for conversion to ethanol, with the highest ethanol concentration (7.13g/L) and an ethanol yield of 0.23g/g of dry matter.