| 1. |
- Abtahi, Z., et al.
(författare)
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Ethanol production by Mucor indicus at high glucose and ethanol concentrations
- 2010
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Ingår i: Minerva Biotecnologica. - : Edizioni Minerva Medica. - 1120-4826 .- 1827-160X. ; 22:3-4, s. 83-89
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Tidskriftsartikel (refereegranskat)abstract
- Mucor indicus was cultivated under aerobic and anaerobic conditions to study its tolerance against high concentration of glucose up to 350 g/L and ethanol up to 120 g/L present in the medium. The fungus could grow well even in 350 g/L glucose and produce ethanol, but it was able to assimilate the entire glucose when its concentration was less than 200 g/L. On the other hand, M. indicus produced ethanol as the main product with yield and concentration up to 0.45 g/g and 73 g/L, respectively, while glycerol, its only major byproduct, was produced up to 24 g/L. However, the fungus was not so tolerant against exogenously added ethanol, and it could not grow with more than 40 g/L added ethanol to the culture. Under aerobic conditions, M. indicus displayed different morphology, switching from long filamentous to yeast-like growth forms by increasing initial glucose concentration. This implies that yeast-like growth can be induced by growing M. indicus at high glucose concentration. Under anaerobic conditions, only one yeast-like form was observed.
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| 2. |
- Bazooyar, Faranak, 1972, et al.
(författare)
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Molecular Modelling of Cellulose Dissolution
- 2013
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Ingår i: Journal of Computational and Theoretical Nanoscience. - : American Scientific Publishers. - 1546-1955 .- 1546-1963. ; 10:11, s. 2639-2646
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Tidskriftsartikel (refereegranskat)abstract
- In this work we present computational studies that shed light on the molecular mechanism of the initial stages of cellulose dissolution in saturated steam, which is an important pretreatment step in the conversion of lignocellulose to biofuel. The COMPASS, Dreiding and Universal molecular mechanics force fields and the B3LYP density functional with 6-311G, 6-311++G(d, p) and 6-311++G(2d, 2p) basis sets were used to study systems containing glucose, cellobiose and water. These molecular systems were studied since they are sufficiently small to perform the density functional theory calculations in a tractable time, while also being relevant to the dissolution of cellulose in saturated steam. Comparison of the energies and structures obtained from the three force fields with those obtained from the first principles method showed that the COMPASS force field is preferred to the other two and that this force field gives similar structures obtained from the first principles method. This supports the validity of the COMPASS force field for studying cellulose dissolution in saturated steam, and preliminary simulations were performed using grand canonical Monte Carlo and molecular dynamics simulations of cellulose dissolution in saturated steam at 100 degrees C and 1 bar, 160 degrees C and 6.2 bar, and 250 degrees C and 39.7 bar. The results show that the cellulose crystal dissolves in saturated steam at the higher temperatures and pressures.
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| 3. |
- Chandolias, Konstantinos, 1985-, et al.
(författare)
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Effects of Heavy Metals and pH on the Conversion of Biomass to Hydrogen via Syngas Fermentation
- 2018
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Ingår i: BioResources. - : BioResources. - 1930-2126. ; 13:2, s. 4455-4469
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Tidskriftsartikel (refereegranskat)abstract
- The effects of three heavy metals on hydrogen production via syngas fermentation were investigated within a metal concentration range of 0 to 1.5 mg Cu/L, 0 to 9 mg Zn/L, 0 to 42 mg Mn/L, in media with initial pH of 5, 6, and 7, at 55 degrees C. The results showed that at lower metal concentration, pH 6 was optimum while at higher metal concentrations, pH 5 stimulated the process. More specifically, the highest hydrogen production activity recorded was 155% +/- 12% at a metal concentration of 0.04 mg Cu/L, 0.25 mg Zn/L, and 1.06 mg Mn/L and an initial medium pH of 6. At higher metal concentration (0.625 mg Cu/L, 3.75 mg Zn/L, and 17.5 mg Mn/L), only pH 5 was stimulating for the cells. The results showed that the addition of heavy metals, contained in gasification-derived ash, can improve the production rate and yield of fermentative hydrogen. This could lead to lower costs in gasification process and fermentative hydrogen production and less demand for syngas cleaning before syngas fermentation.
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| 4. |
- Chandolias, Konstantinos, et al.
(författare)
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Protective effect of a reverse membrane bioreactor against toluene and naphthalene in anaerobic digestion
- 2022
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Ingår i: Biotechnology and Applied Biochemistry. - : Wiley. - 1470-8744 .- 0885-4513. ; 69:3, s. 1267 -1274
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Tidskriftsartikel (refereegranskat)abstract
- Raw syngas contains tar contaminants including toluene and naphthalene, which inhibit its conversion to methane. Cell encasement in a hydrophilic reverse membrane bioreactor (RMBR) could protect the cells from hydrophobic contaminants. This study aimed to investigate the inhibition of toluene and naphthalene and the effect of using RMBR. In this work, toluene and naphthalene were added at concentrations of 0.5–1.0 and 0.1–0.2 g/L in batch operation. In continuous operation, concentration of 0–6.44 g/L for toluene and 0–1.28 g/L for naphthalene were studied. The results showed that no inhibition was observed in batch operation for toluene and naphthalene at concentrations up to 1 and 0.2 g/L, respectively. In continuous operation of free cell bioreactors (FCBRs), inhibition of toluene and naphthalene started at 2.05 and 0.63 g/L, respectively. When they were present simultaneously, inhibition of toluene and naphthalene occurred at concentrations of 3.14 and 0.63 g/L, respectively. In continuous RMBRs, no inhibition for toluene and less inhibition for naphthalene were observed, resulting in higher methane production from RMBR than that of FCBR. These results indicated that RMBR system gave a better protection effect against inhibitors compared with FCBR.
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| 5. |
- Christia, Abdi, 1991, et al.
(författare)
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Ethanol production from alkali-pretreated oil palm empty fruit bunch by simultaneous saccharification and fermentation with mucor indicus
- 2016
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Ingår i: International Journal of Green Energy. - : Informa UK Limited. - 1543-5075 .- 1543-5083. ; 13:6, s. 566-572
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Tidskriftsartikel (refereegranskat)abstract
- Oil palm empty fruit bunch (OPEFB) is a potential raw material for production of lignocellulosic bioethanol. The OPEFB was pretreated with 8% sodium hydroxide (NaOH) solution at 100°C for 10 to 90 min. Enzymatic digestion was carried out using cellulase and β-glucosidase at 45°C for 24 h. It was then inoculated with Mucor indicus spores suspension and fermented under anaerobic conditions at 37°C for 96 h. Sodium hydroxide pretreatment effectively removed 51–57% of lignin in the OPEFB and also its hemicellulose (40–84%). The highest glucan digestibility (0.75 g/g theoretical glucose) was achieved in 40-min NaOH pretreatment. Fermentation by M. indicus resulted in 68.4% of the theoretical ethanol yield, while glycerol (16.2–83.2 mg/g), succinic acid (0–0.4 mg/g), and acetic acid (0–0.9 mg/g) were its by-products. According to these results, 11.75 million tons of dry OPEFB in Indonesia can be converted into 1.5 billion liters of ethanol per year.
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| 6. |
- Dasa, Kris, 1989, et al.
(författare)
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Inhibitory Effect of Long-Chain Fatty Acids on Biogas Production and the Protective Effect of Membrane Bioreactor
- 2016
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Ingår i: BioMed Research International. - : Hindawi Limited. - 2314-6133 .- 2314-6141. ; 2016:ID:7263974, s. 9 pages-
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Tidskriftsartikel (refereegranskat)abstract
- Anaerobic digestion of lipid-containing wastes for biogas production is often hampered by the inhibitory effect of long-chain fatty acids (LCFAs). In this study, the inhibitory effects of LCFAs (palmitic, stearic, and oleic acid) on biogas production as well as the protective effect of a membrane bioreactor (MBR) against LCFAs were examined in thermophilic batch digesters. The results showed that palmitic and oleic acid with concentrations of 3.0 and 4.5 g/L resulted in >50% inhibition on the biogas production, while stearic acid had an even stronger inhibitory effect. The encased cells in the MBR system were able to perform better in the presence of LCFAs. This system exhibited a significantly lower percentage of inhibition than the free cell system, not reaching over 50% at any LCFA concentration tested.
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| 7. |
- Ferreira, Jorge A., et al.
(författare)
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Spent sulphite liquor for cultivation of an edible Rhizopus sp.
- 2012
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Ingår i: BioResources. - : North Carolina State University: College of Natural Resources. - 1930-2126. ; 7:1, s. 173-188
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Tidskriftsartikel (refereegranskat)abstract
- Spent sulphite liquor, the major byproduct from the sulphite pulp production process, was diluted to 50% and used for production of an edible zygomycete Rhizopus sp. The focus was on production, yield, and composition of the fungal biomass composition. The fungus grew well at 20 to 40°C, but 32°C was found to be preferable compared to 20 and 40°C in terms of biomass production and yield (maximum of 0.16 g/g sugars), protein content (0.50-0.60 g/g), alkali-insoluble material (AIM) (ca 0.15 g/g), and glucosamine content (up to 0.30 g/g of AIM). During cultivation in a pilot airlift bioreactor, the yield increased as aeration was raised from 0.15 to 1.0 vvm, indicating a high demand for oxygen. After cultivation at 1.0 vvm for 84 h, high yield and production of biomass (up to 0.34 g/g sugars), protein (0.30-0.50 g/g), lipids (0.02-0.07 g/g), AIM (0.16-0.28 g/g), and glucosamine (0.22-0.32 g/g AIM) were obtained. The fungal biomass produced from spent sulphite liquor is presently being tested as a replacement for fishmeal in feed for fish aquaculture and seems to be a potential source of nutrients and for production of glucosamine.
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| 8. |
- Forgács, Gergely, 1983, et al.
(författare)
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Metahne Production from citrus waste: Process development and cost estimation
- 2012
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Ingår i: Journal of Chemical Technology and Biotechnology. - : Wiley. - 1097-4660 .- 0268-2575. ; 87:2, s. 250-255
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Tidskriftsartikel (refereegranskat)abstract
- AbstractLignocellulosic biomass can be utilized to produce ethanol, a promising alternative energy source for the limited crude oil. There are mainly two processes involved in the conversion: hydrolysis of cellulose in the lignocellulosic biomass to produce reducing sugars, and fermentation of the sugars to ethanol. The cost of ethanol production from lignocellulosic materials is relatively high based on current technologies, and the main challenges are the low yield and high cost of the hydrolysis process. Considerable research efforts have been made to improve the hydrolysis of lignocellulosic materials. Pretreatment of lignocellulosic materials to remove lignin and hemicellulose can significantly enhance the hydrolysis of cellulose. Optimization of the cellulase enzymes and the enzyme loading can also improve the hydrolysis. Simultaneous saccharification and fermentation effectively removes glucose, which is an inhibitor to cellulase activity, thus increasing the yield and rate of cellulose hydrolysis.
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| 9. |
- Forgács, Gergely, et al.
(författare)
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Methane production from feather waste pretreated with Ca(OH)2: Process development and economical analysis
- 2014
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Ingår i: Waste and Biomass Valorization. - : Springer Netherlands. - 1877-2641 .- 1877-265X. ; 5:1, s. 65-73
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Tidskriftsartikel (refereegranskat)abstract
- This study investigated the industrial application of feather waste as a substrate for anaerobic digestion. Feather was pretreated with 0–0.2 Ca(OH)2 g/g TSfeather (total solids of feathers) for 30–120 min at 100–120 °C, in order to increase the digestibility, and to enhance the methane yield in a subsequent digestion at 55 °C. Based on the results of the batch digestion, an industrial process was developed, which can achieve 0.40 Nm3/kg VSfeather (volatile solids of feathers) methane yield from the pretreated feathers, while it fulfills the animal by-product hygenization requirements as well. This base case of the industrial pretreatment process was designed using SuperPro Designer® for utilizing 2,500 tons of feathers per year, which is the waste stream from an average slaughterhouse with a capacity of 60,000 broilers per day. The production cost of the methane is estimated to be 0.475 EUR/Nm3, while the investments on the pretreatment unit requires 0.97 million EUR as total capital investment, and 0.25 million EUR/year for operating cost. However, the process is sensitive to the plant capacity. Changing the plant capacity from 625 to 10,000 tons of feather per year, results in reducing the biogas production cost from 1.177 to 0.203 EUR/Nm3. In addition, sensitivity analysis was performed on the base case to investigate the effect of the value of the incoming feather on the overall process profitability. The results showed that the proposed investment could be considered as being financially viable in the case of production of upgraded biomethane even without the current gate fee system.
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| 10. |
- Isroi, Isroi, 1974, et al.
(författare)
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Structural Changes of Oil Palm Empty Fruit Bunch (OPEFB) after Fungal and Phosphoric Acid Pretreatment
- 2012
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Ingår i: Molecules. - : MDPI AG. - 1420-3049 .- 1420-3049 .- 1431-5157. ; 17:12, s. 14995-15012
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Tidskriftsartikel (refereegranskat)abstract
- Oil palm empty fruit bunch (OPEFB) was pretreated using white-rot fungus Pleurotus floridanus, phosphoric acid or their combination, and the results were evaluated based on the biomass components, and its structural and morphological changes. The carbohydrate losses after fungal, phosphoric acid, and fungal followed by phosphoric acid pretreatments were 7.89%, 35.65%, and 33.77%, respectively. The pretreatments changed the hydrogen bonds of cellulose and linkages between lignin and carbohydrate, which is associated with crystallinity of cellulose of OPEFB. Lateral Order Index (LOI) of OPEFB with no pretreatment, with fungal, phosphoric acid, and fungal followed by phosphoric acid pretreatments were 2.77, 1.42, 0.67, and 0.60, respectively. Phosphoric acid pretreatment showed morphological changes of OPEFB, indicated by the damage of fibre structure into smaller particle size. The fungal-, phosphoric acid-, and fungal followed by phosphoric acid pretreatments have improved the digestibility of OPEFB's cellulose by 4, 6.3, and 7.4 folds, respectively.
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