| 1. |
- Pour Bafrani, Mohammad, 1981, et al.
(author)
-
Production of biofuels, limonene and pectin from citrus wastes
- 2010
-
In: Bioresource Technology. - : Elsevier BV. - 0960-8524 .- 1873-2976. ; 101:11, s. 4246-4250
-
Journal article (peer-reviewed)abstract
- Production of ethanol, biogas, pectin and limonene from citrus wastes (CWs) by an integrated process was investigated. CWs were hydrolyzed by dilute-acid process in a pilot plant reactor equipped with an explosive drainage. Hydrolysis variables including temperature and residence time were optimized by applying a central composite rotatable experimental design (CCRD). The best sugar yield (0.41 g/g of the total dry CWs) was obtained by dilute-acid hydrolysis at 150 degrees C and 6 min residence time. At this condition, high solubilization of pectin present in the CWs was obtained, and 77.6% of total pectin content of CWs could be recovered by solvent recovery. Degree of esterification and ash content of produced pectin were 63.7% and 4.23%, respectively. In addition, the limonene of the CWs was effectively removed through flashing of the hydrolyzates into an expansion tank. The sugars present in the hydrolyzates were converted to ethanol using baker's yeast, while an ethanol yield of 0.43 g/g of the fermentable sugars was obtained. Then, the stillage and the remaining solid materials of the hydrolyzed CWs were anaerobically digested to obtain biogas. In summary, one ton of CWs with 20% dry weight resulted in 39.641 ethanol, 45 m(3) methane, 8.91 limonene, and 38.8 kg pectin.
|
|
| 2. |
- Chandolias, Konstantinos, et al.
(author)
-
Protective effect of a reverse membrane bioreactor against toluene and naphthalene in anaerobic digestion
- 2022
-
In: Biotechnology and Applied Biochemistry. - : Wiley. - 1470-8744 .- 0885-4513. ; 69:3, s. 1267 -1274
-
Journal article (peer-reviewed)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.
|
|
| 3. |
- Dasa, Kris, 1989, et al.
(author)
-
Inhibitory Effect of Long-Chain Fatty Acids on Biogas Production and the Protective Effect of Membrane Bioreactor
- 2016
-
In: BioMed Research International. - : Hindawi Limited. - 2314-6133 .- 2314-6141. ; 2016:ID:7263974, s. 9 pages-
-
Journal article (peer-reviewed)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.
|
|
| 4. |
- Gmoser, Rebecca, 1990-, et al.
(author)
-
From stale bread and brewers spent grain to a new food source using edible filamentous fungi
- 2020
-
In: Bioengineered Bugs. - : Informa UK Limited. - 2165-5979 .- 2165-5987. ; 11:1, s. 582-598
-
Journal article (peer-reviewed)abstract
- By-products from the food sector with a high load of organic matter present both a waste-handling problem related to expenses and to the environment, yet also an opportunity. This study aims to increase the value of stale bread and brewers spent grain (BSG) by re-introducing these residues to the food production chain by converting them to new protein-enriched products using the edible filamentous fungi Neurospora intermedia and Rhizopusoryzae. After 6 days of solid state fermentation (at 35°C, with a95% relative humidity and moisture content of 40% in the substrate) on stale bread, a nutrient-rich fungal-fermented product was produced. The total protein content, as analyzed by total amino acids, increased from 16.5% in stale sourdough bread to 21.1% (on dry weight basis) in the final product with an improved relative ratio of essential amino acids. An increase in dietary fiber, minerals (Cu, Fe, Zn) and vitamin E, as well as an addition of vitamin D2 (0.89 µg/g dry weight sample) was obtained compared with untreated stale bread. Furthermore, addition of BSG to the sourdough bread with the aim to improve textural changes after fermentation showed promising outcomes. Cultivation of N. intermedia or R. oryzae on stale sourdough bread mixed with 6.5% or 11.8% BSG, respectively, resulted in fungal-fermented products with similar textural properties to a commercial soybean burger. Bioconversion of stale bread and BSG by fungal solid state fermentation to produce a nutrient-enriched food product was confirmed to be a successful way to minimize food waste and protein shortage.
|
|
| 5. |
- Kurniawan, Tonny, et al.
(author)
-
Semi-continuous reverse membrane bioreactor in two-stage anaerobic digestion of citruswaste
- 2018
-
In: Materials. - : MDPI AG. - 1996-1944. ; 11:8
-
Journal article (peer-reviewed)abstract
- The presence of an antimicrobial compound called D-Limonene in citrus waste inhibits methane production from such waste in anaerobic digestion. In this work, a two-stage anaerobic digestion method is developed using reverse membrane bioreactors (rMBRs) containing cells encased in hydrophilic membranes. The purpose of encasement is to retain a high cell concentration inside the bioreactor. The effectiveness of rMBRs in reducing cell washout is evaluated. Three different system configurations, comprising rMBRs, freely suspended cells (FCs), and a combination of both (abbreviated to rMBR-FCs), are incubated at three different organic loading rates (OLRs) each, namely 0.6, 1.2, and 3.6 g COD/(L cycle). Incubation lasts for eight feeding cycles at 55 °C. Methane yield and biogas composition results show that rMBRs perform better than rMBR-FCs and FCs at all three OLRs. Volatile fatty acid profiles and H2production show that the reactors are working properly and no upset occurs. Additionally, a short digestion time of 4 days can be achieved using the rMBR configuration in this study.
|
|
| 6. |
- Lennartsson, Patrik R, 1983, et al.
(author)
-
Ethanol production from lignocellulose by the dimorphic fungus Mucor indicus
- 2008
-
In: World Bioenergy. Jönköping, Sweden, 27-29 May, 2008.
-
Conference paper (other academic/artistic)abstract
- Ethanol production from dilute-acid hydrolyzate by the dimorphic fungus Mucor indicus was investigated. A mixture of different forest wood chips dominated by spruce was hydrolyzed with 0.5 g/L sulfuric acid at 15 bar for 10 min, yielding different sugars including galactose, glucose, mannose, and xylose, but also different fermentation inhibitors such as acetic acid, furfural, hydroxymethyl furfural (HMF), and phenolic compounds. We induced different morphological growth of M. indicus from purely filamentous, mostly filamentous, mostly yeast-like to purely yeast-like. The different forms were then ysed to ferment the hydrolyzate. They tolerated the presence of the inhibitors under anaerobic batch cultivation well and the ethanol yield was 430-440 g/kg consumed sugars. The ethanol productivity depended on the morphology. Judging from these results, we conclude that M. indicus is useful for ethanol production from toxic substrates independent of its morphology.
|
|
| 7. |
- Lukitawesa, Lukitawesa, et al.
(author)
-
Effect of effluent recirculation on biogas production using two-stage anaerobic digestion of citrus waste
- 2018
-
In: Molecules. - : MDPI AG. - 1420-3049 .- 1420-3049 .- 1431-5157. ; 23:12
-
Journal article (peer-reviewed)abstract
- Citrus waste is a promising potential feedstock for anaerobic digestion, yet the presence of inhibitors such as D-limonene is known to limit the process. Effluent recirculation has been proven to increase methane yield in a semi-continuous process for recalcitrant material, but it has never been applied to toxic materials. This study was aimed to investigate the effect of recirculation on biogas production from citrus waste as toxic feedstock in two-stage anaerobic digestion. The first digestion was carried out in a stirred tank reactor (STR). The effluent from the first-stage was filtered using a rotary drum filter to separate the solid and the liquid phase. The solid phase, rich in hydrophobic D-limonene, was discarded, and the liquid phase containing less D-limonene was fed into the second digester in an up-flow anaerobic sludge bed (UASB) reactor. A high organic loading rate (OLR 5 g VS/(L·day)) of citrus waste was fed into the first-stage reactor every day. The effluent of the first-stage was then fed into the second-stage reactor. This experiment was run for 120 days. A reactor configuration without recirculation was used as control. The result shows that the reactor with effluent recirculation produced a higher methane yield (160–203 NmL/g·VS) compared to that without recirculation (66–113 NmL/g·VS). More stable performance was also observed in the reactor with recirculation as shown by the pH of 5–6, while without recirculation the pH dropped to the range of 3.7–4.7. The VS reduction for the reactor with recirculation was 33–35% higher than that of the control without recirculation. Recirculation might affect the hydrolysis-acidogenesis process by regulating pH in the first-stage and removing most of the D-limonene content from the substrate through filtration.
|
|
| 8. |
- Lukitawesa, Lukitawesa, et al.
(author)
-
Inhibition of patchouli oil for anaerobic digestion and enhancement in methane production using reverse membrane bioreactors.
- 2017
-
In: Renewable energy. - : Elsevier Ltd.. - 0960-1481 .- 1879-0682.
-
Journal article (peer-reviewed)abstract
- Patchouli oil is an essential oil extd. from arom. crop Pogostemon cablin and is widely used in perfumery industry, food industry, and/or even as medicine. The leaves have 4.6% oil that is extd. by steam, but remains an enormous amt. of wastes contg. ca 0.8% oil. Patchouli waste is an interesting substrate for methane prodn. However, the oil has been found to have antibacterial activity. The inhibition of patchouli oil on anaerobic digestion was investigated in this study under thermophilic conditions (55 °C). The patchouli oil showed antibacterial effect, where addn. of 0.05, 0.5 and 5 g/L patchouli oil reduced biogas prodn. by 16.2%, 27.2% and 100% resp. As patchouli oil is a lipophilic compd., hydrophilic polyvinylidene difluoride (PVDF) membrane was used to protect the microorganisms against this inhibitor in a reverse membrane bioreactor (rMBR) system. The methane yield of fresh plant and waste were 86 and 179 NmL CH4/gVS, resp. when using free cells. Although using solely an rMBR did not give significant rise to methane yield, the combination rMBR and free cell strategy to protect part of the digesting microorganisms against this inhibitor considerably enhanced the methane prodn. by 73% for fresh patchouli plant, compared to digestion using free cells. [on SciFinder(R)]
|
|
| 9. |
- Marhendraswari, M. B.D., et al.
(author)
-
Production of edible fungal (Rhizopus delemar CBS 145940) biomass from organosolv-pretreated oil palm empty fruit bunch (OPEFB) in submerged fermentation
- 2020
-
In: IOP Conference Series: Materials Science and Engineering. - : Institute of Physics (IOP). - 1757-8981 .- 1757-899X. ; 991:1
-
Conference paper (peer-reviewed)abstract
- Accumulation of oil palm empty fruit bunches (OPEFB) from palm oil industry poses challenges for the disposal process, which leads to environmental damage. For this reason, valorization of OPEFB fractions to produce edible fungal biomass was carried out in this research. The fungus was Rhizopus delemar CBS 145940, which is an edible fungus, Indonesian indigenous, and is favorable for the production of several end products. Organosolv pretreatment was first conducted on OPEFB using ethanol (50%) as the solvent. Enzymatic hydrolysis was then performed using Cellic® Ctec3 on the pretreated-OPEFB fractions. Hydrolyzates from cellulose-rich fraction, slurry (a mixture of cellulose-rich fraction and hemicellulose-rich fraction), and hemicellulose-rich fraction were used as the cultivation media for fungal growth. The corresponding yield of fungal biomass from each medium was 0.62 ± 0.07 g/g glucose; 0.41 ± 0.02; and 0.61 ± 0.13 g/g fermentable sugars, respectively. These results showed that Rhizopus delemar CBS 145940 could be grown in all the hydrolyzates from the OPEFB fractions. Nevertheless, in order to obtain higher fungal biomass, supplementation of nutrition was needed.
|
|
| 10. |
- Millati, Ria, 1972, et al.
(author)
-
Anaerobic digestion of citrus waste using two-stage membrane bioreactor
- 2018
-
In: IOP Conference Series: Materials Science and Engineering. - 1757-8981 .- 1757-899X. ; 316:1
-
Conference paper (peer-reviewed)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.
|
|
