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Potential Cellulosic Ethanol Production from Organic Residues of Agro-Based Industries in Nepal  [PDF]
Ram Kailash P. Yadav,Arbindra Timilsina,Rupesh K. Yadawa,Chandra P. Pokhrel
ISRN Renewable Energy , 2014, DOI: 10.1155/2014/305695
Abstract: With the objective of exploring the potential of bioethanol production from lignocellulosic wastes from major agro-based industries in Nepal, four types of major industries using raw materials from agriculture are selected as sources of lignocellulosic residues. They include a sugar industry, a paper industry, a tobacco industry, and a beer industry. Data from secondary/primary sources were used to record organic residues from these industries and estimates were made of potential production of bioethanol from them. About 494892.263 tons of dry bagasse could be produced if the total production of sugarcane in Nepal is taken to the sugar industry which means that about 138569.833?KL of bioethanol could be produced (in the year 2011/12). Similarly, the dry biomass residue produced from the paper mill is 86.668?ton/year that could produce 24.267?KL of bioethanol. The lignocellulosic residue from tobacco field in Nepal is approximately 18.826?ton/year that has potential to produce 5.836?KL of bioethanol. The dry biomass residue produced in beer industry amounts to 155.0596?ton/year that can yield about 63.5744?KL of bioethanol. It is estimated that about 57,841.3754?KL of bioethanol could be produced when these residues are fully utilized in producing bioethanol. If E10 is used in total import of petrol, about 20246.7?KL of bioethanol could be utilized, and the rest 37,594.6754?KL of bioethanol could be utilized for many other purposes. 1. Introduction The world’s economy today highly depends on fossil energy sources of which crude oils have been the major resource to meet the increased energy demand [1]. The utilization of these depletable sources in the long run is not considered to be sustainable. So, many countries around the world are shifting their focus toward renewable alternative sources for power production [2]. One renewable solution concerning the depletion of fossil fuels and the atmospheric pollution derived from their combustion is the use of biomass (bioenergy). The conversion of biomass into biofuels represents an important option for both the exploitation of an alternative source of energy and the reduction of polluting gases, mainly carbon dioxide [3, 4]. A variety of fuels can be produced from biomass resources that also include liquid fuels such as ethanol and methanol [5]. Liquid biofuels have several advantages [6]. Growing environmental concerns over the use and depletion of nonrenewable fuel sources, together with the increasing price of oil and instability in the oil market, have recently stimulated interest in optimizing
Pretreatment of oil palm residues by dilute alkali for cellulosic ethanol production

张海燕,周玉杰,李晋平,戴玲妹,刘德华,张建安,Yuen May Choo,Soh Kheang Loh
生物工程学报 , 2013,
Abstract: In the study, we used oil palm residues (empty fruit bunch, EFB) as raw material to produce cellulosic ethanol by pretreatment, enzymatic hydrolysis and fermentation. Firstly, the pretreatment of EFB with alkali, alkali/hydrogen peroxide and the effects on the components and enzymatic hydrolysis of cellulose were studied. The results show that dilute alkali was the suitable pretreatment method and the conditions were first to soak the substrate with 1% sodium hydroxide with a solid-liquid ratio of 1:10 at 40 °C for 24 h, and then subjected to 121 °C for 30 min. Under the conditions, EFB solid recovery was 74.09%, and glucan, xylan and lignin content were 44.08%, 25.74% and 13.89%, respectively. After separated with alkali solution, the pretreated EFB was washed and hydrolyzed for 72 h with 5% substrate concentration and 30 FPU/g dry mass (DM) enzyme loading, and the conversion of glucan and xylan reached 84.44% and 89.28%, respectively. We further investigated the effects of substrate concentration and enzyme loading on enzymatic hydrolysis and ethanol batch simultaneous saccharification and fermentation (SSF). The results show that when enzyme loading was 30 FPU/g DM and substrate concentration was increased from 5% to 25%, ethanol concentration were 9.76 g/L and 35.25 g/L after 72 h fermentation with Saccharomyces cerevisiae (inoculum size 5%, V/V), which was 79.09% and 56.96% of ethanol theory yield.
Optimization for the Production of Cellulase Enzyme from Municipal Solid Waste Residue by Two Novel Cellulolytic Fungi  [PDF]
S. P. Gautam,P. S. Bundela,A. K. Pandey,Jamaluddin Khan,M. K. Awasthi,S. Sarsaiya
Biotechnology Research International , 2011, DOI: 10.4061/2011/810425
Abstract: The main purpose of this study is to reduce the production cost of cellulase by optimizing the production medium and using an alternative carbon source such as municipal solid waste residue. In the present investigation, we aim to isolate the two novel cellulase producing fungi (Aspergillus niger and Trichoderma sp.) from municipal solid waste. Municipal solid waste residue (4-5% (w/v)) and peptone and yeast extract (1.0% (w/v)) were found to be the best combination of carbon and nitrogen sources for the production of cellulase by A. niger and Trichoderma sp. Optimum temperature and pH of the medium for the cellulase production by A. niger were 40°C and 6-7, whereas those for the production of cellulase by Trichoderma sp. were 45°C and 6.5. Cellulase production from A. niger and Trichoderma sp. can be an advantage as the enzyme production rate is normally higher as compared to other fungi. 1. Introduction Ethanol production from municipal solid waste biomass is emerging as one of the most important technologies for sustainable fuels. major constrains in enzymatic hydrolysis of cellulosic materials for the production of fermentation sugar are low productivity and the cost of cellulases [1]. Municipal solid waste (MSW) is the largest group of waste present on this planate causing environmental pollutions [2]. It was estimated that the photosynthetic material annually with respect to carbon of which about 50% is cellulose. It is a fibrous, insoluble, high molecular weight, crystalline polysaccharides composted of repeating D-glucose units linked by β-1,4- glucosidic bonds and being the most abundant carbohydrate polymer on earth [3, 4]. Cellulases are consortium of free enzymes which comprise of endoglucanases (β-1, 4-D-glucan-4-glucanohydrolase, EC, carboxymethyl cellulase, EC), exoglucanases (β-1,4-D-glucan-4-glucohydrolase, EC, cellobiohydrolase, CBH), and cellobiases (β-D-glucoside glucohydrolase, EC, β-1,4-D-glucosidase) which are found in many of the 57 glycosyl hydrolase families [5]. The right proportion of these enzyme acts synergistically for maximum saccharification. Endoglucanase cleaves internal β-1,4-glucan chain links in cellulose randomly [6] and opens the molecules for cellobiohydrolases which hydrolyze the bonds at nonreducing end of crystalline cellulosic chain producing cellobiose cellobiases which split the disaccharide units and convert cellobiose into glucose and thus complete the cellulolysis [7]. MSW containing organic substances is an ideal habitat for different species of fungi. Cellulolytic fungi
Cellulosic hydrolysate toxicity and tolerance mechanisms in Escherichia coli
Tirzah Y Mills, Nicholas R Sandoval, Ryan T Gill
Biotechnology for Biofuels , 2009, DOI: 10.1186/1754-6834-2-26
Abstract: Governments around the world are calling for increased production of renewable transportation fuels in light of massive increases in energy consumption [1-5]. The United States has mandated the production of 36 billion gallons of biofuels by 2022, with even greater increases of up to 60 billion gallons by 2030 proposed by the new administration [1,6]. A major challenge is that current production methods based on corn ethanol are limited to 10 to 15 billion gallons per year [7]. Moreover, corn ethanol has recently come under criticism for its potential to increase greenhouse gas emissions when compared to fossil fuels and negative impact on food markets [8-10]. These findings stipulate that new feedstocks and processes capable of producing 20 to 50 billion gallons per year, while not increasing greenhouse gas emissions, must be responsibly developed and commercialized within the next two decades. Biofuels derived from lignocellulosic biomass hold promise for making up a significant fraction of this market.Lignocellulosic feedstocks, such as switchgrass, poplar, and corn stover, provide greenhouse gas savings of 65 to 100% in comparison to petrol [11]. When land-use changes are considered, cellulosic ethanol still has the ability to reduce overall greenhouse gas emissions depending on the source of biomass and associated land-use change [8]. Feedstocks that do not require a substantial change in land-use include crop and municipal wastes, fall grass harvests, and algae [8]. Other potential feedstocks include waste from pulp and paper mills, construction debris, and animal manures [1]. These feedstocks are of extreme interest because they require no additional land-use conversion [8].Many processes exist and have been recently reviewed for the pretreatment of lignocellulosic biomass to produce a fermentable hydrolysate [12-16]. The overall goal of pretreatment is to better expose cellulose for downstream hydrolysis, convert hemicellulose to pentoses, and to remove lign
Qijun Wang,Yuanxin Wu,Shengdong Zhu
BioResources , 2011,
Abstract: Cellulosic ethanol production has drawn much attention in recent years. However, there remain significant technical challenges before such production can be considered as economically feasible at an industrial scale. Among them, the efficient conversion of carbohydrates in lignocellulosic biomass into fermentable sugars is one of the most challenging technical difficulties in cellulosic ethanol production. Use of ionic liquids has opened new avenues to solve this problem by two different pathways. One is pretreatment of lignocellulosic biomass using ionic liquids to increase its enzymatic hydrolysis efficiency. The other is to transform the hydrolysis process of lignocellulosic biomass from a heterogeneous reaction system to a homogeneous one by dissolving it into ionic liquids, thus improving its hydrolysis efficiency.
Chemical Pretreatment Methods for the Production of Cellulosic Ethanol: Technologies and Innovations  [PDF]
Edem Cudjoe Bensah,Moses Mensah
International Journal of Chemical Engineering , 2013, DOI: 10.1155/2013/719607
Abstract: Pretreatment of lignocellulose has received considerable research globally due to its influence on the technical, economic and environmental sustainability of cellulosic ethanol production. Some of the most promising pretreatment methods require the application of chemicals such as acids, alkali, salts, oxidants, and solvents. Thus, advances in research have enabled the development and integration of chemical-based pretreatment into proprietary ethanol production technologies in several pilot and demonstration plants globally, with potential to scale-up to commercial levels. This paper reviews known and emerging chemical pretreatment methods, highlighting recent findings and process innovations developed to offset inherent challenges via a range of interventions, notably, the combination of chemical pretreatment with other methods to improve carbohydrate preservation, reduce formation of degradation products, achieve high sugar yields at mild reaction conditions, reduce solvent loads and enzyme dose, reduce waste generation, and improve recovery of biomass components in pure forms. The use of chemicals such as ionic liquids, NMMO, and sulphite are promising once challenges in solvent recovery are overcome. For developing countries, alkali-based methods are relatively easy to deploy in decentralized, low-tech systems owing to advantages such as the requirement of simple reactors and the ease of operation. 1. Introduction Cellulosic or second generation (2G) bioethanol is produced from lignocellulosic biomass (LB) in three main steps: pretreatment, hydrolysis, and fermentation. Pretreatment involves the use of physical processes (e.g., size reduction, steaming/boiling, ultrasonication, and popping), chemical methods (e.g., acids, bases, salts, and solvents), physicochemical processes (e.g., liquid hot water and ammonium fibre explosion or AFEX), biological methods (e.g., white-rot/brown-rot fungi and bacteria), and several combinations thereof to fractionate the lignocellulose into its components. It results in the disruption of the lignin seal to increase enzyme access to holocellulose [1, 2], reduction of cellulose crystallinity [3, 4], and increase in the surface area [5, 6] and porosity [7, 8] of pretreated substrates, resulting in increased hydrolysis rate. In hydrolysis, cellulose and hemicelluloses are broken down into monomeric sugars via addition of acids or enzymes such as cellulase. Enzymatic hydrolysis offers advantages over acids such as low energy consumption due to the mild process requirements, high sugar yields, and no unwanted wastes.
The Potential of Cellulosic Ethanol Production from Grasses in Thailand
Jinaporn Wongwatanapaiboon,Kunn Kangvansaichol,Vorakan Burapatana,Ratanavalee Inochanon,Pakorn Winayanuwattikun,Tikamporn Yongvanich,Warawut Chulalaksananukul
Journal of Biomedicine and Biotechnology , 2012, DOI: 10.1155/2012/303748
Abstract: The grasses in Thailand were analyzed for the potentiality as the alternative energy crops for cellulosic ethanol production by biological process. The average percentage composition of cellulose, hemicellulose, and lignin in the samples of 18 types of grasses from various provinces was determined as 31.85–38.51, 31.13–42.61, and 3.10–5.64, respectively. The samples were initially pretreated with alkaline peroxide followed by enzymatic hydrolysis to investigate the enzymatic saccharification. The total reducing sugars in most grasses ranging from 500–600 mg/g grasses (70–80% yield) were obtained. Subsequently, 11 types of grasses were selected as feedstocks for the ethanol production by simultaneous saccharification and cofermentation (SSCF). The enzymes, cellulase and xylanase, were utilized for hydrolysis and the yeasts, Saccharomyces cerevisiae and Pichia stipitis, were applied for cofermentation at 35°C for 7 days. From the results, the highest yield of ethanol, 1.14 g/L or 0.14 g/g substrate equivalent to 32.72% of the theoretical values was obtained from Sri Lanka ecotype vetiver grass. When the yields of dry matter were included in the calculations, Sri Lanka ecotype vetiver grass gave the yield of ethanol at 1,091.84 L/ha/year, whereas the leaves of dwarf napier grass showed the maximum yield of 2,720.55 L/ha/year (0.98 g/L or 0.12 g/g substrate equivalent to 30.60% of the theoretical values).
Effect of Moisture Content on Anaerobic Methanization of Municipal Solid Waste

QU Xian,HE Pin-jing,SHAO Li-ming,
,何品晶,邵立明,Bouchez Théodore

环境科学 , 2009,
Abstract: Biogas production,gas and liquid characteristics were investigated for comparing the effect of moisture content on methanization process of MSW with different compositions of food waste and cellulosic waste.Batch reactors were used to study the anaerobic methanization of typical Chinese and French municipal solid waste(MSW) and cellulosic waste with different moisture content,as 35%,field capacity(65%-70%),80%,and saturated state(>95%).The results showed that for the typical Chinese and French waste,which c...
"Challenges of cellulosic ethanol production from xylose-extracted corncob residues,"  [PDF]
BioResources , 2015,
Direct ethanol production from cellulosic materials using a diploid strain of Saccharomyces cerevisiae with optimized cellulase expression
Ryosuke Yamada, Naho Taniguchi, Tsutomu Tanaka, Chiaki Ogino, Hideki Fukuda, Akihiko Kondo
Biotechnology for Biofuels , 2011, DOI: 10.1186/1754-6834-4-8
Abstract: The engineered diploid strain, which contained multiple copies of three cellulase genes integrated into its genome, was precultured in molasses medium (381.4 mU/g wet cell), and displayed approximately six-fold higher phosphoric acid swollen cellulose (PASC) degradation activity than the parent haploid strain (63.5 mU/g wet cell). When used to ferment PASC, the diploid strain produced 7.6 g/l ethanol in 72 hours, with an ethanol yield that achieved 75% of the theoretical value, and also produced 7.5 g/l ethanol from pretreated rice straw in 72 hours.We have developed diploid yeast strain optimized for expression of cellulolytic enzymes, which is capable of directly fermenting from cellulosic materials. Although this is a proof-of-concept study, it is to our knowledge, the first report of ethanol production from agricultural waste biomass using cellulolytic enzyme-expressing yeast without the addition of exogenous enzymes. Our results suggest that combining multigene expression optimization and diploidization in yeast is a promising approach for enhancing ethanol production from various types of lignocellulosic biomass.Dwindling supplies of petroleum and growing environmental concerns over its use has led to increasing interest in developing biomass as a feedstock for liquid fuels. In particular, bioethanol produced from biomass represents a promising alternative fuel or gasoline extender. Currently, the main feedstock for bioethanol production is starch-rich biomass, as it is rapidly hydrolyzed by amylases, giving high yields of glucose. However, lignocellulosic biomass (such as rice straw, which is one of the most abundant lignocellulosic waste materials), is regarded as a promising starting material for bioethanol production, because it is abundant, inexpensive, renewable and has favorable environmental properties [1]. Despite these advantages, lignocellulosic biomass is much more expensive to process than grains because of the need for extensive pretreatment and
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