| 1. |
- 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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| 2. |
- Harmini, Sri, et al.
(författare)
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Fungal Pretreatment of Oil Palm Empty Fruit Bunch : Effect of Manganese and Nitrogen
- 2013
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Ingår i: Cellulose Chemistry and Technology. - : Editura Academiei Romane. - 0576-9787. ; 47:9-10, s. 751-757
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Tidskriftsartikel (refereegranskat)abstract
- Oil palm empty fruit bunch (OPEFB) was biologically pretreated using Pleurotus floridanus LIPIMC996 supplemented with various concentrations of manganese and nitrogen and incubated for 35 days at 30°C, and enzyme activities of manganese peroxidase (MnP) and laccase were examined. When OPEFB was supplemented with manganese, the highest lignin reduction was achieved up to 25.0±5.6% at the addition of 200 μg Mn2+/g OPEFB.In addition, Pleurotus floridanus LIPIMC996 grew best on OPEFB supplemented with 800 μg Mn2+/g OPEFB. When OPEFB was supplemented with nitrogen, the highest lignin reduction was achieved up to 27.2± 3.5% at the addition of 20 mM nitrogen. The best growth of Pleurotus floridanus was also achieved with the addition of 20 mM nitrogen. The addition of nitrogen and manganese on OPEFB did not significantly affect the activity of MnP and laccase.
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| 3. |
- Millati, R, et al.
(författare)
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2nd Generation Ethanol by Zygomycetes Fungi at Elevated Temperature
- 2013
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Konferensbidrag (refereegranskat)abstract
- Seven zygomycetes tempe isolates were screened for ethanol production at 40oC, 45oC, 50oC. All the isolates were able to produce ethanol at 40oC and three isolates were able to produce ethanol at 45oC. The corresponding ethanol yields were 0.39-0.47 g/g on glucose and 0.22- 0.26 g/g on glucose. No isolate could grow and produce ethanol at 50oC. One isolate was selected and used for ethanol production from untreated and fungal-pretreated oil palm empty fruit bunch (OPEFB), untreated and fungal-pretreated oat straw as well as Avicel by nonisothermal simultaneous saccharification and fermentation (NSSF). This NSSF included hydrolysis with cellulase and -glucosidase for 24 h at 45oC, followed by simultaneous saccharification and fermentation with the selected isolate at 40oC for 96 h. The NSSF of untreated and fungal-pretreated OPEFB, untreated and fungal-pretreated oat straw, and Avicel resulted in 14.10%, 14.25%, 27.28%, 49.88%, and 63.77% ethanol compared to the theoretical yield.
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| 4. |
- Purwandari, F. A., et al.
(författare)
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Pretreatment of oil palm empty fruit bunch (OPEFB) by N-methylmorpholine-N-oxide (NMMO) for biogas production: Structural changes and digestion improvement
- 2013
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Ingår i: Bioresource Technology. - : Elsevier BV. - 0960-8524 .- 1873-2976. ; 128, s. 461-466
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Tidskriftsartikel (refereegranskat)abstract
- Pretreatment of OPEFB (oil palm empty fruit bunch) by NMMO (N-methylmorpholine-N-oxide) on its subsequent digestions was investigated. The pretreatments were carried out at 90 and 120 degrees C for 1, 3, and 5 h in three different modes of dissolution (by 85% NMMO solution), ballooning (79% NMMO solution), and swelling (73% NMMO solution). The total solid recovery after the pretreatment was 89-94%. The pretreatment process did not have a major impact on the composition of OPEFB, other than a reduction of ash from 5.4% up to 1.3%. The best improvement in biogas production was achieved by a dissolution mode pretreatment of OPEFB, using conditions of 85% NMMO, 3 h, and 120 degrees C. It resulted in 0.408 Nm(3)/kg VS methane yield and 0.032 Nm(3) CH4/kg VS/day initial methane production rate, which correspond in improving by 48% and 167% compared to the untreated OPEFB, respectively.
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| 5. |
- Wikandari, R., et al.
(författare)
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Biogas production from citrus waste by membrane bioreacto
- 2014
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Ingår i: Membranes. - : MDPIAG. - 2077-0375. ; 4:3, s. 596-607
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Tidskriftsartikel (refereegranskat)abstract
- Rapid acidification and inhibition by d-limonene are major challenges of biogas production from citrus waste. As limonene is a hydrophobic chemical, this challenge was encountered using hydrophilic polyvinylidine difluoride (PVDF) membranes in a biogas reactor. The more sensitive methane-producing archaea were encapsulated in the membranes, while freely suspended digesting bacteria were present in the culture as well. In this membrane bioreactor (MBR), the free digesting bacteria digested the citrus wastes and produced soluble compounds, which could pass through the membrane and converted to biogas by the encapsulated cell. As a control experiment, similar digestions were carried out in bioreactors containing the identical amount of just free cells. The experiments were carried out in thermophilic conditions at 55 °C, and hydraulic retention time of 30 days. The organic loading rate (OLR) was started with 0.3 kg VS/m3/day and gradually increased to 3 kg VS/m3/day. The results show that at the highest OLR, MBR was successful to produce methane at 0.33 Nm3/kg VS, while the traditional free cell reactor reduced its methane production to 0.05 Nm3/kg VS. Approximately 73% of the theoretical methane yield was achieved using the membrane bioreactor.
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| 6. |
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| 7. |
- 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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| 8. |
- 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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| 9. |
- Harmini, S, et al.
(författare)
-
Fungal Pretreatment of Oil Palm Empty Fruit Bunch: Effect of Manganese and Nitrogen
- 2013
-
Ingår i: Cellulose Chemistry and Technology. - 0576-9787. ; 47:9-10, s. 751-757
-
Tidskriftsartikel (refereegranskat)abstract
- Oil palm empty fruit bunch (OPEFB) was biologicallypretreated usingPleurotus floridanusLIPIMC996 supplementedwith various concentrations of manganese and nitrogen and incubated for 35 days at 30°C, and enzyme activities ofmanganese peroxidase (MnP) and laccase were examined. When OPEFB was supplemented with manganese, thehighest lignin reduction was achieved up to 25.0±5.6% at the addition of 200 μg Mn2+/g OPEFB.In addition,PleurotusfloridanusLIPIMC996 grew best on OPEFB supplemented with 800μg Mn2+/g OPEFB. When OPEFB wassupplemented with nitrogen, the highest lignin reduction was achieved up to 27.2± 3.5% at the additionof 20 mMnitrogen. The best growth ofPleurotus floridanuswas also achieved with the addition of 20 mM nitrogen. The additionof nitrogen and manganese on OPEFB did not significantly affect the activity of MnP and laccase.
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| 10. |
- Millati, Ria, 1972, et al.
(författare)
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2nd Generation Ethanol by Zygomycetes Fungi at Elevated Temperatures
- 2014
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Ingår i: Energy Procedia. - : Elsevier BV. - 1876-6102. ; 52, s. 104-109
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Konferensbidrag (refereegranskat)abstract
- Seven zygomycetes tempe isolates were screened for ethanol production at 40oC, 45oC, 50oC. All the isolates were able to produce ethanol at 40oC with the yields of 0.39-0.47 g/g on glucose and three isolates were able to produce ethanol at 45oC with the yields of 0.22-0.26 g/g on glucose. No isolate could grow and produce ethanol at 50oC. One isolate was selected and used for ethanol production from untreated and fungal-pretreated oil palm empty fruit bunch (OPEFB), untreated and fungal-pretreated oat straw as well as Avicel by non-isothermal simultaneous saccharification and fermentation (NSSF). This NSSF included hydrolysis with cellulase and β-glucosidase for 24 h at 45oC, followed by simultaneous saccharification and fermentation using the selected isolate at 40oC for 96 h. The NSSF of untreated and fungal-pretreated OPEFB, untreated and fungal-pretreated oat straw, and Avicel resulted in 14.10%, 14.25%, 27.28%, 49.88%, and 63.77% ethanol compared to the theoretical yield.
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| 11. |
- Millati, Ria, 1972, et al.
(författare)
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Anaerobic digestion of citrus waste using two-stage membrane bioreactor
- 2018
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Ingår i: IOP Conference Series: Materials Science and Engineering. - 1757-8981 .- 1757-899X. ; 316:1
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Konferensbidrag (refereegranskat)abstract
- Anaerobic digestion is a promising method to treat citrus waste. However, the presence of limonene in citrus waste inhibits anaerobic digestion process. Limonene is an antimicrobial compound and could inhibit methane forming bacteria that takes a longer time to recover than the injured acid forming bacteria. Hence, volatile fatty acids will be accumulated and methane production will be decreased. One way to solve this problem is by conducting anaerobic digestion process into two stages. The first step is aimed for hydrolysis, acidogenesis, and acetogenesis reactions and the second stage is aimed for methanogenesis reaction. The separation of the system would further allow each stage in their optimum conditions making the process more stable. In this research, anaerobic digestion was carried out in batch operations using 120 ml-glass bottle bioreactors in 2 stages. The first stage was performed in free-cells bioreactor, whereas the second stage was performed in both bioreactor of free cells and membrane bioreactor. In the first stage, the reactor was set into 'anaerobic' and 'semi-aerobic' conditions to examine the effect of oxygen on facultative anaerobic bacteria in acid production. In the second stage, the protection of membrane towards the cells against limonene was tested. For the first stage, the basal medium was prepared with 1.5 g VS of inoculum and 4.5 g VS of citrus waste. The digestion process was carried out at 55°C for four days. For the second stage, the membrane bioreactor was prepared with 3 g of cells that were encased and sealed in a 3×6 cm 2 polyvinylidene fluoride membrane. The medium contained 40 ml basal medium and 10 ml liquid from the first stage. The bioreactors were incubated at 55°C for 2 days under anaerobic condition. The results from the first stage showed that the maximum total sugar under 'anaerobic' and 'semi-aerobic' conditions was 294.3 g/l and 244.7 g/l, respectively. The corresponding values for total volatile fatty acids were 3.8 g/l and 2.9 g/l, respectively. Methane production of citrus waste taken from the first stage under 'anaerobic' condition in membrane and free-cells bioreactors was 11.2 Nml and 7.2 Nml, respectively. Whereas, methane production of citrus waste taken from the first stage under 'semi-aerobic' condition in membrane and free-cells bioreactors was 8.8 Nml and 5.7 Nml, respectively. It can be seen from the results of the first stage that volatile fatty acids from 'anaerobic' condition was higher than that of 'semi-aerobic' condition. The absence of oxygen provides the optimal condition for growth and metabolism of facultative and obligatorily anaerobic bacteria in the first stage. Furthermore, polyvinylidene fluoride membrane was able to protect the cells from antimicrobial compounds.
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