Separate Hydrolysis And Fermentation Process Research Articles

Simultaneous saccharification and fermentation for biobutanol production from corn starch via ABE fermentation

The preparation of bio-butanol from corn starch requires saccharification and fermentation processes. In view of the fact that the pH value at the later stage of fermentation is applicable to the enzymatic hydrolysis of glucoamylase, the effects of simultaneous saccharification and fermentation (SSF) and separate hydrolysis and fermentation (SHF) were compared in this paper. 11.2 g/L butanol and 21.5 g/L total solvent could be obtained by the SSF process, while the yield was 9.74 g/L butanol and 17.2 g/L total solvent in the SHF process. The SSF process required a shorter overall process time (120 h) than the SHF process (144 h) and resulted in a large increase of 38.9% in butanol productivity (2.25 g/Ld for SSF compared to 1.62 g/Ld for SHF). These results show that the application of SSF can reduce the fermentation overall time, simplify the fermentation process, and reduce equipment investment and operating costs.

Biotechnology process for microbial lipid synthesis from enzymatic hydrolysate of pre-treated sugarcane bagasse for potential bio-oil production

Sugarcane bagasse is a lignocellulosic biomass waste produced from sugar and alcohol production. The aim of this study was to produce cellular lipids from sugarcane bagasse with a biotechnology process using microbial enzymes and lipid-accumulating yeast. Sugarcane bagasse, pre-treated with a steam explosion method, was subjected to enzymatic hydrolysis by a separate hydrolysis and fermentation (SHF) system, using crude enzymes from a new strain of Trichoderma SG2 (T. SG2) with or without supplementation with a commercial enzyme (Cellic CTec2). The mixture of both enzymes produced substantial amounts of sugar from pretreated sugarcane bagasse. In a multistage SHF process, in the second stage (21 + 21 h), a total of 26.92 g L−1 of sugar was converted. In another stage-wise process (21 + 21+21 h) of hydrolysis of residual biomass, 26.23 g L−1 of sugar was recorded; thus maximizing the production of fermentable sugars from bagasse. The cultivation of Rhodotorula sp. R1 in sugarcane bagasse enzymatic hydrolysate (BH) for lipid production was evaluated. The enrichment of the hydrolysate with d-glucose, Y-yeast extract, and P-peptone (BH + P20D20/N0.93) and (BH + Y10D20/N0.2) produced 7.69% and 10.50% of lipids, respectively. Similar to vegetable oils and other yeasts, the lipids accumulated by Rhodotorula R1 contain mainly elaidic acid, palmitic acid, stearic acid, linoleic acid, and a lower percentage of other fatty acids, indicating a suitable composition for biodiesel production.

Polish Varieties of Industrial Hemp and Their Utilisation in the Efficient Production of Lignocellulosic Ethanol.

Nowadays, more and more attention is paid to the development and the intensification of the use of renewable energy sources. Hemp might be an alternative plant for bioenergy production. In this paper, four varieties of Polish industrial hemp (Białobrzeskie, Tygra, Henola, and Rajan) were investigated in order to determine which of them are the most advantageous raw materials for the effective production of bioethanol. At the beginning, physical and chemical pretreatment of hemp biomass was carried out. It was found that the most effective is the alkaline treatment with 2% NaOH, and the biomasses of the two varieties were selected for next stages of research: Tygra and Rajan. Hemp biomass before and after pretreatment was analyzed by FTIR and SEM, which confirmed the effectiveness of the pretreatment. Next, an enzymatic hydrolysis process was carried out on the previously selected parameters using the response surface methodology. Subsequently, the two approaches were analyzed: separated hydrolysis and fermentation (SHF) and a simultaneous saccharification and fermentation (SSF) process. For Tygra biomass in the SHF process, the ethanol concentration was 10.5 g∙L−1 (3.04 m3·ha−1), and for Rajan biomass at the SSF process, the ethanol concentration was 7.5 g∙L−1 (2.23 m3·ha−1). In conclusion, the biomass of Polish varieties of hemp, i.e., Tygra and Rajan, was found to be an interesting and promising raw material for bioethanol production.

Augmented ethanol production from alkali-assisted hydrothermal pretreated cassava peel waste

ABSTRACT Cassava peel is a by-product produced at large amounts in starch-based agro industries and could be a major feedstock for bioethanol in most of the Asian countries. In this work, we aimed to evaluate two fermentation strategies for bioethanol production from alkali-assisted hydrothermal pretreated cassava peel by thermotolerant Kluyveromyces marxianus MTCC 4139 strain. Initially, milled cassava peel was subjected to alkali-assisted hydrothermal pretreatment at different autoclaving temperatures (110°C − 130°C) and residence times (15 − 30 min) in the presence of different NaOH concentrations (0.25%−1.0% w/v NaOH). On subsequent enzymatic hydrolysis of pretreated cassava peel (1% NaOH at 120°C for 30 min) with different optimal enzyme loadings (α-amylase, glucoamylase and cellulase) showed maximum 670.58 ± 10.13 mg/g reducing sugar yield with 81.25% ± 3.20% saccharification efficiency. Furthermore, SHF (separate hydrolysis and fermentation) and SSF (simultaneous saccharification and fermentation) of cassava hydrolyzates were studied for improved ethanol yield and fermentation efficiencies. SSF of hydrothermal pretreated cassava hydrolyzate with K. marxianus strain showed higher ethanol yield (0.44 g/g) with 86.11% fermentation efficiency as compared to SHF process (0.41 g/g; 80.24% fermentation efficiency).

Comparison of Enzymatic and Acidic Fractionation of Corn Fiber for Glucose-rich Hydrolysate and Bioethanol Production by Candida boidinii

Corn fiber is a by-product of the corn wet milling process and a promising raw material to produce bioethanol in a bio-refinery process. In this study, enzymatic and acidic fractionations of corn fiber were compared with particular attention to produce glucose-rich hydrolyzates. The acidic fractionation contained two, sequential, sulphuric acid-catalyzed, hydrolysis steps based on our previous study. In the enzymatic fractionation process, corn fiber was pre-treated by soaking in aqueous ammonia (18.5 % (w/w) dry matter, 15 % (w/w) ammonia solution, 24 hours) and then hydrolyzed by using Hemicellulase (NS 22002) enzyme cocktail. The cellulose part of the solid residues obtained after the acidic and enzymatic fractionation processes was enzymatically hydrolyzed by using Cellic Ctec2 and Novozymes 188 (12.5 % (w/w) dry matter, 50 °C, 72 hours). Cellulose hydrolysis after the acidic and enzymatic fractionation resulted in a supernatant containing 64 g/L and 25 g/L glucose, respectively. Therefore, ethanol fermentation experiments were performed in Separated Hydrolysis and Fermentation (SHF) and Simultaneous Saccharification and Fermentation (SSF) configurations after the acidic fractionation of corn fiber. SHF configuration was found to be more advantageous regarding the achievable ethanol yield. Although the fermentation with Candida boidinii NCAIM Y.01308 was accomplished within longer time (43 hours) compared to Saccharomyces cerevisiae (5 hours), the achieved ethanol yields were similar (79%) during the SHF process. It was concluded that acidic fractionation is more efficient to produce glucose-rich hydrolyzate from corn fiber compared to enzymatic fractionation, and Candida boidinii is suitable for ethanol fermentation on the glucose-rich hydrolyzate.

Ethanol Production from Alkaline-treated Rice Straw via Separate Hydrolysis and Fermentation (SHF) using K. marxianus UniMAP 1-1

The decreasing reserves of non-renewable energy especially fossil fuel has led to an urgent need to establish alternative fuels. Ethanol is one of the energies explored, which can be generated by fermentation method. The use of environmentally friendly material such as lignocellulosic biomass to develop a biofuel is significant. Ethanol production at high temperature was preferred as it will significantly reduce the cooling cost involved. Thus, the use of thermotolerant strain in the fermentation process was recommended. In this study, separate hydrolysis and fermentation (SHF) was employed to produce ethanol from 2% sodium hydroxide-treated rice straw using cellulase enzyme, and fermented by a thermotolerant K. marxianus UniMAP 1-1 strain. The fermentation process was done at two different temperatures, 37°C and 50°C, at pH 4.8. The ethanol yield from both 37°C and 50°C was 0.36 g/g and 0.38 g/g, respectively. K. marxianus UniMAP 1-1 showed a good production of ethanol at elevated temperature. This is the first study reporting ethanol production from rice straw using K. marxianus UniMAP 1-1. Thus, this study can improve our understanding of the development of thermotolerant yeast accountable to the SHF process for ethanol production.

Development of a green liquor dregs pretreatment for enhanced glucose recovery from corn cobs and kinetic assessment on various bioethanol fermentation types

This study optimized a novel pretreatment of corn cob wastes (CCW) using green liquor dregs (GLD), a waste product from the chemical kraft pulping industry. Subsequently, the microbial growth and ethanol production kinetics of different bioprocess types were comparatively evaluated using the logistic and modified Gompertz models respectively. The optimized GLD pretreatment conditions released a maximum glucose yield of 0.42 g/g. Separate hydrolysis and fermentation (SHF), simultaneous saccharification and fermentation (SSF) and SSF with pre hydrolysis (PSSF) processes were assessed and gave comparable kinetic data. The SHF and PSSF processes displayed slightly higher microbial and bioethanol kinetic coefficients compared to the SSF system. Implications from this study provide major insights for reducing energy, time and costs incurred with lignocellulosic substrate pretreatment, bioethanol process design and scale up. Additionally, the study demonstrates a possible route for beneficiation of waste material such as GLD.

Effect of residual extractable lignin on acetone\u2013butanol\u2013ethanol production in SHF and SSF processes

BackgroundLignin plays an important role in biochemical conversion of biomass to biofuels. A significant amount of lignin is precipitated on the surface of pretreated substrates after organosolv pretreatment. The effect of this residual lignin on enzymatic hydrolysis has been well understood, however, their effect on subsequent ABE fermentation is still unknown.ResultsTo determine the effect of residual extractable lignin on acetone–butanol–ethanol (ABE) fermentation in separate hydrolysis and fermentation (SHF) and simultaneous saccharification and fermentation (SSF) processes, we compared ABE production from ethanol-washed and unwashed substrates. The ethanol organosolv pretreated loblolly pine (OPLP) was used as the substrate. It was observed that butanol production from OPLP-UW (unwashed) and OPLP-W (washed) reached 8.16 and 1.69 g/L, respectively, in SHF. The results showed that ABE production in SHF from OPLP-UW prevents an “acid crash” as compared the OPLP-W. In SSF process, the “acid crash” occurred for both OPLP-W and OPLP-UW. The inhibitory extractable lignin intensified the “acid crash” for OPLP-UW and resulted in less ABE production than OPLP-W. The addition of detoxified prehydrolysates in SSF processes shortened the fermentation time and could potentially prevent the “acid crash”.ConclusionsThe results suggested that the residual extractable lignin in high sugar concentration could help ABE production by lowering the metabolic rate and preventing “acid crash” in SHF processes. However, it became unfavorable in SSF due to its inhibition of both enzymatic hydrolysis and ABE fermentation with low initial sugar concentration. It is essential to remove extractable lignin of substrates for ABE production in SSF processes. Also, a higher initial sugar concentration is needed to prevent the “acid crash” in SSF processes.

Bioconversion of hazelnut shell using near critical water pretreatment for second generation biofuel production

The global energy deficiency and depletion of fossil fuels have raised concerns leading to a wide scale examination of alternative and renewable energy sources. Lignocellulosic biomass that is one of the renewable energy sources has major potential in the world and it has a wide variety of sources including agricultural residues such as cotton stalk, corn stover, wheat straw, etc. Including over 65% cellulose and hemicelluloses content, these materials can be hydrolyzed into monomeric sugars and then can be converted into biofuels and other industrial products.The main objective of this study is bioethanol production with bioconversion of lignocellulosic biomass, namely hazelnut shell. In order to efficiently utilize this raw material for ethanol production by degrading the lignocellulosic structure, an effective pretreatment is required. LHW, a near critical water pretreatment method, is chosen for this particular research due to its unique environmental and economic properties. The experiment design was prepared with Response Surface Estimation Method (RSM) by Design Expert software. The experiment parameters were selected as temperature (100–200 °C), pressure (80–200 bar) and flow rate (2–8 ml/min). The optimum condition (OC) for the process was determined as 138 °C, 2 ml/min and 200 bar according to the Dinitrosaliclic acid (DNS) method. Additionally, in order to achieve maximum ethanol concentration, the condition producing maximum reducing sugar content is determined. Separated hydrolysis and fermentation (SHF) process was used for bioethanol production. Enzymatic hydrolysis was conducted with a part of solid residue obtained from the maximum ethanol condition (MEC) for bioethanol production. MEC is 200 °C, 2 ml/min and 200 bar. Under MEC, at the end of the fermentation process maximum ethanol yield was 44.89% with 0.5 g of solid loading.The main purpose of the study is to determine the effects of different solid loading rates in the enzymatic hydrolysis stage of SHF process to ethanol production as a result of fermentation. There are several pretreatment methods for this process. It is concluded that the superior qualities of LHW pretreatment in means of environmental friendliness, non-toxic and non-corrosive byproducts, water usage instead of other chemical additives, degradation of lignocellulosic structure and low cost were suitable for the intended purpose of bioethanol production using hazelnut shell.

Bioethanol production from rice straw through an enzymatic route mediated by enzymes developed in-house from Aspergillus fumigatus

This study concerns the in-house development of enzymes from Aspergillus fumigatus and their application in separate hydrolysis and fermentation (SHF) processes for bioethanol production from pretreated rice straw. The cellulase and hemicellulase activities of A. fumigatus cultivated in NaOH-pretreated rice straw were much higher than those of A. fumigatus cultivated in raw rice straw. A. fumigatus cultivated in raw rice straw exhibited no lignin-degrading manganese peroxidase (MnP) or laccase enzymatic activity. However, A. fumigatus cultivated in NaOH-pretreated rice straw exhibited high lignin-degrading MnP and laccase enzymatic activity. A. fumigatus completely degraded 1.0% NaOH-pretreated rice straw, yielding 27.89 g/L reducing sugar upon loading of 50 g/L rice straw (based on the original amount of rice straw that went to pretreatment). Saccharification of 1.0% NaOH-pretreated rice straw using 200 FPU/mL crude enzyme released 22.15 g/L reducing sugars in 20 h. The SHF processes resulted in an ethanol concentration and yield of 9.45 g/L and 83.5%, respectively, with Saccharomyces tanninophilus.

Bioethanol production from oil palm empty fruit bunch with SSF and SHF processes using Kluyveromyces marxianus yeast

This research aimed to study bioethanol production from Oil Palm Empty Fruit Bunches (OPEFB) with Simultaneous Saccharification and Fermentation (SSF) and Separate Hydrolysis and Fermentation (SHF) by Klyveromyces marxinus. The basic steps for bioethanol production from lignocellulosic biomass are (1) pretreatment for delignification, which is necessary to liberate cellulose and hemicellulose; (2) hydrolysis of cellulose and hemicellulose to generate fermentable sugars; and (3) fermentation of bioethanol from sugars. In step (1) OPEFB was subjected to acid–alkali pretreatment with a dilute acid solution (at substrate loading 12.50%w/v, sulfuric acid concentration 0.2 M, at 121 °C for 53 min) followed by an alkali solution (NaOH 5%w/v, at 121 °C for 20 min), which resulted in 72.10%wt cellulose yield with hemicellulose and lignin yields of 3.24%wt and 17.60%wt, respectively. Then the optimal conditions for ethanol production by SSF process were investigated by Response Surface Methodology. The four manipulated factors were temperature (30–45 °C), substrate loading (5–15% w/v), pH (4–6), and yeast concentration (1–5%v/v), and the maximal 0.281 g/g bioethanol yield was found at 12.24%w/v, pH 4.5, yeast concentration 2.04%v/v, and 36.94 °C. In SHF, hydrolysis and fermentation steps were conducted at the optimal conditions for SSF, giving 0.584 g/g reducing sugar and 0.258 g/g bioethanol yield. The results demonstrate that an acid–alkali pretreatment could remove hemicellulose and lignin from lignocellulosic biomass, increasing cellulose yield, while SSF performed better than SHF with both quicker processing and higher bioethanol concentration.

A comparison of methods of ethanol production from sweet sorghum bagasse

Ethanol production from sweet sorghum bagasse (SSB) is reported. A two-step pretreatment with hydrogen peroxide followed by NaOH at 121 °C for 20 min, was used prior to enzymatic treatment. Enzymatic treatment was carried out using a commercial cellulase. Enzymatic hydrolysis for 72 h resulted in a hydrolysate containing xylose (5.1 g L−1), glucose (75.3 g L−1) and cellobiose (1.4 g L−1). This hydrolysate was used to produce ethanol by a 72-h fermentation with the yeast Saccharomyces cerevisiae TISTR 5606 at 30 °C. This separate hydrolysis and fermentation (SHF) method was compared with a simultaneous saccharification and fermentation (SSF) method. The SSF process used the pretreated SSB and was carried out in two different ways: (1) In the first method, the enzyme, the substrate and the yeast inoculum were mixed and SSF fermentation took place at 37 °C for 72-h, to produce a final ethanol concentration of 22.3 g L−1; (2) in the second method, termed the ‘delayed simultaneous-saccharification fermentation’ or DSSF, the pretreated SSB was enzymatically hydrolyzed at 50 °C for 6-h, cooled to 37 °C, and then inoculated with the yeast to commence a 66-h fermentation. This gave a final ethanol concentration of 28.3 g L−1. The ethanol productivity was 0.31 g L−1 h−1 for the SHF and SSF processes, but the DSSF had a ∼26% higher productivity.

Detoxification of Hydrolysates of the Red Seaweed Gelidium amansii for Improved Bioethanol Production

In this study, bioethanol was produced from the seaweed Gelidium amansii as biomass through separate hydrolysis and fermentation (SHF) processes. The SHF processes examined in this study include thermal acid hydrolysis pretreatment, enzymatic saccharification, detoxification, and fermentation. Thermal acid hydrolysis pretreatment was conducted using H2SO4, with a slurry content of 8-16% and treatment time of 15-75min. The optimal conditions for thermal acid hydrolysis pretreatment were 12% (w/v) seaweed slurry content and 180mM H2SO4 at 121°C for 45min, at which 26.1g/L galactose and 6.8g/L glucose were produced. A monosaccharide (mainly glucose) was also obtained from the enzymatic saccharification of thermal acid hydrolysate using 16U/mL Celluclast 1.5L enzyme at 45°C for 36h. Detoxification was performed using the adsorption method with activated carbon, the overliming method with Ca (OH)2, and the ion exchange method with polyethyleneimine. Among those detoxification methods, activated carbon showed the best performance for hydroxymethylfurfural removal. Ethanol fermentation was performed using 12% (w/v) seaweed hydrolysate with Saccharomyces cerevisiae adapted to galactose as well as various detoxification treatments.

Different schemas of saccharification and fermentation for bioethanol production from Opuntia ficus-indica cladode flour with wild strains

In the present work, two wild microorganisms were studied for saccharification and fermentation. A wild Acinetobacter pittii isolated from decaying cladodes (Opuntia ficus-indica) was capable of producing extracellular cellulases and a wild yeast Kluyveromyces marxianus isolated from termite was capable of producing alcohol. In Mexico, there are surpluses of cladode production and where it is essential to take advantage and use this carbon source for alcohol production due to currently fossil fuels depletion. Separate hydrolysis and fermentation (SHF), simultaneous saccharification and fermentation (SSF) and semi-simultaneous saccharification and fermentation (SSSF) for cellulase and alcohol production using Opuntia ficus-indica cladode as a unique carbon source was evaluated. In SHF process the best conditions for FPase activity (Filter paper activity for total cellulases) were 37 °C and pH 6.5 obtaining 0.67±0.02 U/ml and 0.61±0.03 U/ml for Acinetobacter pittii and Kluyveromyces marxianus, respectively. For alcohol production, the best conditions were 40 °C and pH 5.5 obtaining 12.95±0.3 g/L with K. marxianus while A. pittii did not produce significant alcohol concentration. Both processes were made with agitation (200 rpm). The SSF process was made with both microorganisms inoculated at the same time at 37 °C and without agitation. The maximum FPase activity of 0.28±0.004 U/ml and the maximum alcohol concentration was 7.5±0.27 g/L. Finally, an SSSF was performed, initially with A. pittii at 37 °C and after 8 h K. marxianus was then inoculated with temperature switched to 40 °C, the all process was performed without agitation. The maximum FPase activity was 0.45±0.001 U/ml, and the maximum alcohol concentration was 11.7±0.02 g/L. There was a significant difference (ANOVA) between SHF and SSSF in alcohol production. The best process for FPase activity and alcohol production is separate hydrolysis and fermentation using only yeast Kluyveromyces marxianus.

Optimization of cellulolytic enzyme components through engineering Trichoderma reesei and on-site fermentation using the soluble inducer for cellulosic ethanol production from corn stover

BackgroundCellulolytic enzymes produced by Trichoderma reesei are widely studied for biomass bioconversion, and enzymatic components vary depending on different inducers. In our previous studies, a mixture of glucose and disaccharide (MGD) was developed and used to induce cellulase production. However, the enzymatic profile induced by MGD is still not defined, and further optimization of the enzyme cocktail is also required for efficient ethanol production from lignocellulosic biomass.ResultsIn this study, cellulolytic enzymes produced by T. reesei Rut C30 using MGD and alkali-pretreated corn stover (APCS) as inducer were compared. Cellular secretome in response to each inducer was analyzed, which revealed a similar enzyme profile. However, significant difference in the content of cellulases and xylanase was detected. Although MGD induction enhanced β-glucosidase production, its activity was still not sufficient for biomass hydrolysis. To overcome such a disadvantage, aabgl1 encoding β-glucosidase in Aspergillus aculeatus was heterologously expressed in T. reesei Rut C30 under the control of the pdc1 promoter. The recombinant T. reesei PB-3 strain showed an improved β-glucosidase activity of 310 CBU/mL in the fed-batch fermentation, 71-folds higher than that produced by the parent strain. Meanwhile, cellulase activity of 50 FPU/mL was detected. Subsequently, the crude enzyme was applied for hydrolyzing corn stover with a solid loading of 20% through separate hydrolysis and fermentation (SHF) and simultaneous saccharification and fermentation, respectively, for ethanol production. Better performance was observed in the SHF process, through which a total of 119.9 g/L glucose was released within 12 h for concomitant ethanol production of 54.2 g/L.ConclusionsThe similar profile of cellulolytic enzymes was detected under the induction of MGD and APCS, but higher amount of cellulases was present in the crude enzyme induced by MGD. However, β-glucosidase activity induced by MGD was not sufficient for hydrolyzing lignocellulosic biomass. High titers of cellulases and β-glucosidase were achieved simultaneously by heterologous expression of aabgl1 in T. reesei and fed-batch fermentation through feeding MGD. We demonstrated that on-site cellulase production by T. reesei PB-3 has a potential for efficient biomass saccharification and ethanol production from lignocellulosic biomass.

Enzymatic Conversion of Sugar Beet Pulp: A Comparison of Simultaneous Saccharification and Fermentation and Separate Hydrolysis and Fermentation for Lactic Acid Production.

This study compares the efficiency of lactic acid production by separate hydrolysis and fermentation (SHF) or simultaneous saccharification and fermentation (SSF) of sugar beet pulp, a byproduct of industrial sugar production. In experiments, sugar beet pulp was hydrolyzed using five commercial enzymes. A series of shake flask fermentations were conducted using five selected strains of lactic acid bacteria (LAB). The differences in the activities of the enzymes for degrading the principal sugar beet pulp components were reflected in the different yields of total reducing sugars. The highest yields after hydrolysis and the lowest quantities of insoluble residues were obtained using a mixture (1:1) of Viscozyme® and Ultraflo® Max. In the SHF process, only a portion of the soluble sugars released by the enzymes from the sugar beet pulp was assimilated by the LAB strains. In SSF, low enzyme loads led to reduction in the efficiency of sugar accumulation. The risk of carbon catabolic repression was reduced. Our results suggest that SSF has advantages over SHF, including lower processing costs and higher productivity. Lactic acid yield in SSF mode (approx. 30 g/L) was 80-90% higher than that in SHF.

Pretreatment of Starch-Free Sugar Palm Trunk (Arenga pinnata) to Enhance Saccharification in Bioethanol Production

Starch-Free Sugar Palm Trunk (Arenga pinnata) can be utilized to produce bioethanol because of their high lignocellulosic contents. Production of bioethanol from lignocellulosic materials consist of pre-treatment, saccharification and fermentation processes. In this work, conversion of starch-free sugar palm trunk (Arenga pinnata) to fermentable sugar and bioethanol was carried out through g pretreatment, saccharification and fermentation processes. The pretreatment was carried out by addition of 1% (v/v) HNO3 and NH4OH for 30 min and 60 min, respectively. The saccharification was carried out at enzyme celullase loadings of 10 and 20 FPU/g and substrate loadings of 10 and 20 g for NH4OH pretreated samples. Fermentation was carried out using two methods i.e. separated hydrolysis and fermentation (SHF) and simultaneous saccharification and fermentation (SSF) techniques. The results showed that pretreatment using NH4OH was more effective than HNO3for 60 minutes. IFurthermore, the results also presented the reduction of the lignin content of 9.44% and the increase of cellulose content to 18.56% for 1% (v/v) NH4OH 60 min of pretreatment. The increase of enzyme cellulase (20 FPU/g substrate) and substrate loading (20 g) could produce more reducing sugar (17.423 g/L and 19.233 g/L) than that at 10 FPU/g substrate and 10 g substrate (11.423 g/L and 17.423 g/L), respectively. The comparison of SHF and SSF showed that SHF process yielded higher ethanol (8.11 g/L) as compared to SSF (3.95 g/L) and nontreatment process (0.507 g/L) for 72 h..

The comprehensive analysis of sorghum cultivated in Poland for energy purposes: Separate hydrolysis and fermentation and simultaneous saccharification and fermentation methods and their impact on bioethanol effectiveness and volatile by-products from the grain and the energy potential of sorghum straw

The aim of this work was to study the potential of sorghum crop cultivated in European climate as an energy material. The investigation showed strong interaction between the fermentation method and the sorghum cultivar. It was also noted that the cultivar with the highest grain yield showed the highest yield of ethanol per hectare, achieving 1269 L/ha in SHF (separate hydrolysis and fermentation) and 1248 L/ha in SSF (simultaneous saccharification and fermentation). Chromatographic analysis of raw spirits showed that smaller amounts of impurities are formed in the SSF process than in the SHF process. The calorific value of sorghum straw was also measured, and amounted to 16,050–16,840 kJ/kg. The results have demonstrated the high value of sorghum as grain for bioethanol production and as straw as a valuable feedstock for forming pellets or briquettes.

Evaluation of dilute acid pretreatment for bioethanol fermentation from sugarcane bagasse pith

Sugarcane bagasse pith is the most abundant agricultural waste in Thailand and an attractive raw material for biosugar production using dilute acid pretreatment and enzymatic hydrolysis. In this study, the raw material was pretreated at 121 °C with different sulfuric acid concentrations (0%, 1%, 2%, 3% or 4% volume per volume, v/v) and pretreatment times (30, 60 or 90 min). The pretreated solid was hydrolyzed using a commercial enzyme (Celluclast® 1.5L). The maximum total sugars yield (53.7 g/100 g dry bagasse pith) was achieved at 1–2% v/v H2SO4 for 90 min, representing 67% of total sugars in the bagasse pith. For ethanol production, simultaneous saccharification and fermentation (SSF) and separate hydrolysis and fermentation (SHF) processes were employed using Pichia stipitis JCM 10742. The results indicated that both the ethanol concentration and productivity using SSF were higher than from the SHF process. The ethanol concentration and productivity using SSF were 3.70 g/L and 0.15 g/L/hr in 24 h fermentation, respectively, while for the SHF process the results were 2.58 g/L and 0.09 g/L/hr in 30 h fermentation, respectively.

Process alternatives for bioethanol production from mango stem bark residues

Three alternatives for bioethanol production from pretreated mango stem bark after maceration (MSBAM) were evaluated as a biorefinery component for the mango agroindustry. These included separate hydrolysis and fermentation (SHF), simultaneous saccharification and fermentation (SSF), and pre-saccharification followed by simultaneous saccharification and fermentation (PSSF). The effects on ethanol concentration, yield and productivity of pretreated MSBAM solids loading, Tween 20 addition, and temperature were used for process comparisons. The highest yields for the SHF, SSF, and PSSF process alternatives were 58.8, 81.6, and 84.5%, respectively. Since saccharification and fermentation are carried out in the same vessel in the SSF alternative, and no significant SSF and PSSF differences in ethanol concentration were observed, SSF is recommended as the best process configuration.