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Ylitervo, Päivi
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Publications (10 of 18) Show all publications
Sárvári Horváth, I., del Pilar Castillo, M., Schnürer, A., Agnihotri, S., Ylitervo, P. & Edström, M. (2017). Utilization of Straw Pellets and Briquettes as Co-Substrates at Biogas Plants.
Open this publication in new window or tab >>Utilization of Straw Pellets and Briquettes as Co-Substrates at Biogas Plants
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2017 (English)Report (Other academic)
Abstract [en]

Biogas reactors can be utilized more efficiently when straw and food waste are digested together instead of separately. In the present study, straw in the form of pellets and briquettes has been used in experiments and calculations. Co-digestion of different substrates can give a more optimal substrate composition and a more efficient utilization of available digester volume. The pelleting and briquetting process has been shown to be an adequate pretreatment method of the straw. Digesting food waste and straw together showed synergistic effects with improved degradation of the food waste as well as a higher total volumetric methane production as compared to when food waste was used as the sole substrate. Energy produced through increased biogas production was higher than the energy needed for the pelleting and briquetting process. The positive effect in regard to gas production was mainly seen for the straw pellets, results supported by both chemical and microbiological analysis. These effects were observed in both mesophilic and thermophilic conditions. In conclusion, this study illustrates that straw is a suitable co-digestion substrate to food waste and can be used to improve gas yields as well as for more efficient utilization of the digester volume. These results show the biogas potential of straw, today not yet used as a substrate to a large extent.

Publisher
p. 58
Series
EnergiForsk REPORT 2017:438
National Category
Bioenergy
Identifiers
urn:nbn:se:hb:diva-13564 (URN)
Available from: 2018-01-17 Created: 2018-01-17 Last updated: 2018-01-18Bibliographically approved
Mahboubi, A., Ylitervo, P., Doyen, W., De, W. H. & Taherzadeh, M. J. (2016). Reverse membrane bioreactor: Introduction to a new technology for biofuel production. Biotechnology Advances, 34(5), 954-75
Open this publication in new window or tab >>Reverse membrane bioreactor: Introduction to a new technology for biofuel production
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2016 (English)In: Biotechnology Advances, ISSN 0734-9750, E-ISSN 1873-1899, Vol. 34, no 5, p. 954-75Article in journal (Refereed) Published
Abstract [en]

The novel concept of reverse membrane bioreactors (rMBR) introduced in this review is a new membrane-assisted cell retention technique benefiting from the advantageous properties of both conventional MBRs and cell encapsulation techniques to tackle issues in bioconversion and fermentation of complex feeds. The rMBR applies high local cell density and membrane separation of cell/feed to the conventional immersed membrane bioreactor (iMBR) set up. Moreover, this new membrane configuration functions on basis of concentration-driven diffusion rather than pressure-driven convection previously used in conventional MBRs. These new features bring along the exceptional ability of rMBRs in aiding complex bioconversion and fermentation feeds containing high concentrations of inhibitory compounds, a variety of sugar sources and high suspended solid content. In the current review, the similarities and differences between the rMBR and conventional MBRs and cell encapsulation regarding advantages, disadvantages, principles and applications for biofuel production are presented and compared. Moreover, the potential of rMBRs in bioconversion of specific complex substrates of interest such as lignocellulosic hydrolysate is thoroughly studied.[on SciFinder (R)]

Keywords
bioconversion, biofilm, diffusion, fouling, inhibitory compounds, membrane bioreactor, reverse membrane bioreactor, suspended solid
National Category
Industrial Biotechnology
Identifiers
urn:nbn:se:hb:diva-10778 (URN)10.1016/j.biotechadv.2016.05.009 (DOI)000380600200032 ()27238291 (PubMedID)2-s2.0-84973103296 (Scopus ID)
Note

MEDLINE AN 2017046188(Journal; Article; (JOURNAL ARTICLE); General Review; (REVIEW))

Available from: 2016-09-27 Created: 2016-09-27 Last updated: 2018-04-28Bibliographically approved
Ishola, M. M., Ylitervo, P. & Taherzadeh, M. J. (2015). Co-Utilization of Glucose and Xylose for Enhanced Lignocellulosic Ethanol Production with Reverse Membrane Bioreactors.. Membranes, 5(4), 844-856
Open this publication in new window or tab >>Co-Utilization of Glucose and Xylose for Enhanced Lignocellulosic Ethanol Production with Reverse Membrane Bioreactors.
2015 (English)In: Membranes, ISSN 2077-0375, E-ISSN 2077-0375, Vol. 5, no 4, p. 844-856Article in journal (Refereed) Published
Abstract [en]

Integrated permeate channel (IPC) flat sheet membranes were examined for use as a reverse membrane bioreactor (rMBR) for lignocellulosic ethanol production. The fermenting organism, Saccharomyces cerevisiae (T0936), a genetically-modified strain with the ability to ferment xylose, was used inside the rMBR. The rMBR was evaluated for simultaneous glucose and xylose utilization as well as in situ detoxification of furfural and hydroxylmethyl furfural (HMF). The synthetic medium was investigated, after which the pretreated wheat straw was used as a xylose-rich lignocellulosic substrate. The IPC membrane panels were successfully used as the rMBR during the batch fermentations, which lasted for up to eight days without fouling. With the rMBR, complete glucose and xylose utilization, resulting in 86% of the theoretical ethanol yield, was observed with the synthetic medium. Its application with the pretreated wheat straw resulted in complete glucose consumption and 87% xylose utilization; a final ethanol concentration of 30.3 g/L was obtained, which corresponds to 83% of the theoretical yield. Moreover, complete in situ detoxification of furfural and HMF was obtained within 36 h and 60 h, respectively, with the rMBR. The use of the rMBR is a promising technology for large-scale lignocellulosic ethanol production, since it facilitates the co-utilization of glucose and xylose; moreover, the technology also allows the reuse of the yeast for several batches.

National Category
Industrial Biotechnology
Research subject
Resource Recovery
Identifiers
urn:nbn:se:hb:diva-3724 (URN)10.3390/membranes5040844 (DOI)000367793700020 ()26633530 (PubMedID)2-s2.0-84949561398 (Scopus ID)
Available from: 2015-12-06 Created: 2015-12-06 Last updated: 2018-11-29Bibliographically approved
Ylitervo, P. (2014). Concepts for improving ethanol productivity from lignocellulosic materials: encapsulated yeast and membrane bioreactors. (Doctoral dissertation). Chalmers University of Technology
Open this publication in new window or tab >>Concepts for improving ethanol productivity from lignocellulosic materials: encapsulated yeast and membrane bioreactors
2014 (English)Doctoral thesis, comprehensive summary (Other academic)
Abstract [en]

Lignocellulosic biomass is a potential feedstock for production of sugars, which can be fermented into ethanol. The work presented in this thesis proposes some solutions to overcome problems with suboptimal process performance due to elevated cultivation temperatures and inhibitors present during ethanol production from lignocellulosic materials. In particular, continuous processes operated at high dilution rates with high sugar utilisation are attractive for ethanol fermentation, as this can result in higher ethanol productivity. Both encapsulation and membrane bioreactors were studied and developed to achieve rapid fermentation at high yeast cell density. My studies showed that encapsulated yeast is more thermotolerant than suspended yeast. The encapsulated yeast could successfully ferment all glucose during five consecutive batches, 12 h each at 42 °C. In contrast, freely suspended yeast was inactivated already in the second or third batch. One problem with encapsulation is, however, the mechanical robustness of the capsule membrane. If the capsules are exposed to e.g. high shear forces, the capsule membrane may break. Therefore, a method was developed to produce more robust capsules by treating alginate-chitosan-alginate (ACA) capsules with 3-aminopropyltriethoxysilane (APTES) to get polysiloxane-ACA capsules. Of the ACA-capsules treated with 1.5% APTES, only 0–2% of the capsules broke, while 25% of the untreated capsules ruptured within 6 h in a shear test. In this thesis membrane bioreactors (MBR), using either a cross-flow or a submerged membrane, could successfully be applied to retain the yeast inside the reactor. The cross-flow membrane was operated at a dilution rate of 0.5 h-1 whereas the submerged membrane was tested at several dilution rates, from 0.2 up to 0.8 h-1. Cultivations at high cell densities demonstrated an efficient in situ detoxification of very high furfural levels of up to 17 g L-1 in the feed medium when using a MBR. The maximum yeast density achieved in the MBR was more than 200 g L-1. Additionally, ethanol fermentation of nondetoxified spruce hydrolysate was possible at a high feeding rate of 0.8 h-1 by applying a submerged membrane bioreactor, resulting in ethanol productivities of up to 8 g L-1 h-1. In conclusion, this study suggests methods for rapid continuous ethanol production even at stressful elevated cultivation temperatures or inhibitory conditions by using encapsulation or membrane bioreactors and high cell density cultivations.

Place, publisher, year, edition, pages
Chalmers University of Technology, 2014
Series
Skrifter från Högskolan i Borås, ISSN 0280-381X ; 49
Series
Doktorsavhandlingar vid Chalmers tekniska högskola, ISSN 0346-718X ; 3669
Keywords
Encapsulated yeast, Biofuel, S. cerevisiae, Membrane bioreactors, Thermotolerance, Furfural, Acetic acid, Resource Recovery
National Category
Biochemistry and Molecular Biology Other Industrial Biotechnology
Research subject
Resource Recovery
Identifiers
urn:nbn:se:hb:diva-3692 (URN)2320/13505 (Local ID)978-91-7385-988-2 (ISBN)2320/13505 (Archive number)2320/13505 (OAI)
Note

Akademisk avhandling som för avläggande av teknologie doktorsexamen vid Chalmers tekniska högskola försvaras vid offentlig disputation den 4 april 2014, klockan 9:30 i KE-salen, Kemigården 4, Göteborg.

Available from: 2015-12-04 Created: 2015-12-04 Last updated: 2016-08-19Bibliographically approved
Ylitervo, P., Franzen, C. & Taherzadeh, M. (2014). Continuous ethanol production with a membrane bioreactor at high acetic Acid concentrations. Membranes, 4(3), 372-387
Open this publication in new window or tab >>Continuous ethanol production with a membrane bioreactor at high acetic Acid concentrations
2014 (English)In: Membranes, ISSN 2077-0375, E-ISSN 2077-0375, Vol. 4, no 3, p. 372-387Article in journal (Refereed)
Abstract [en]

The release of inhibitory concentrations of acetic acid from lignocellulosic raw materials during hydrolysis is one of the main concerns for 2nd generation ethanol production. The undissociated form of acetic acid can enter the cell by diffusion through the plasma membrane and trigger several toxic effects, such as uncoupling and lowered intracellular pH. The effect of acetic acid on the ethanol production was investigated in continuous cultivations by adding medium containing 2.5 to 20.0 g·L−1 acetic acid at pH 5.0, at a dilution rate of 0.5 h−1. The cultivations were performed at both high (~25 g·L−1) and very high (100–200 g·L−1) yeast concentration by retaining the yeast cells inside the reactor by a cross-flow membrane in a membrane bioreactor. The yeast was able to steadily produce ethanol from 25 g·L−1 sucrose, at volumetric rates of 5–6 g·L−1·h−1 at acetic acid concentrations up to 15.0 g·L−1. However, the yeast continued to produce ethanol also at a concentration of 20 g·L−1 acetic acid but at a declining rate. The study thereby demonstrates the great potential of the membrane bioreactor for improving the robustness of the ethanol production based on lignocellulosic raw materials.

Place, publisher, year, edition, pages
MDPI, 2014
Keywords
Resource Recovery
National Category
Industrial Biotechnology
Research subject
Resource Recovery
Identifiers
urn:nbn:se:hb:diva-1892 (URN)10.3390/membranes4030372 (DOI)2320/14035 (Local ID)2320/14035 (Archive number)2320/14035 (OAI)
Available from: 2015-11-13 Created: 2015-11-13 Last updated: 2017-12-01
Ylitervo, P., Franzén, C. J. & Taherzadeh, M. J. (2014). Continuous Ethanol Production with a Membrane Bioreactor at High Acetic Acid Concentrations. Membranes, 4(3), 372-387
Open this publication in new window or tab >>Continuous Ethanol Production with a Membrane Bioreactor at High Acetic Acid Concentrations
2014 (English)In: Membranes, ISSN 2077-0375, E-ISSN 2077-0375, Vol. 4, no 3, p. 372-387Article in journal (Refereed) Published
Abstract [en]

The release of inhibitory concentrations of acetic acid from lignocellulosic raw materials during hydrolysis is one of the main concerns for 2nd generation ethanol production. The undissociated form of acetic acid can enter the cell by diffusion through the plasma membrane and trigger several toxic effects, such as uncoupling and lowered intracellular pH. The effect of acetic acid on the ethanol production was investigated in continuous cultivations by adding medium containing 2.5 to 20.0 g•L−1 acetic acid at pH 5.0, at a dilution rate of 0.5 h−1. The cultivations were performed at both high (~25 g•L−1) and very high (100–200 g•L−1) yeast concentration by retaining the yeast cells inside the reactor by a cross-flow membrane in a membrane bioreactor. The yeast was able to steadily produce ethanol from 25 g•L−1 sucrose, at volumetric rates of 5–6 g•L−1•h−1 at acetic acid concentrations up to 15.0 g•L−1. However, the yeast continued to produce ethanol also at a concentration of 20 g•L−1 acetic acid but at a declining rate. The study thereby demonstrates the great potential of the membrane bioreactor for improving the robustness of the ethanol production based on lignocellulosic raw materials.

Place, publisher, year, edition, pages
MDPI, 2014
Keywords
acetic acid, membrane bioreactor, bioethanol, cell retention, yeast, Resursåtervinning
National Category
Industrial Biotechnology
Research subject
Resource Recovery
Identifiers
urn:nbn:se:hb:diva-1988 (URN)10.3390/membranes4030372 (DOI)25028956 (PubMedID)2320/14535 (Local ID)2320/14535 (Archive number)2320/14535 (OAI)
Available from: 2015-11-13 Created: 2015-11-13 Last updated: 2017-12-01Bibliographically approved
Ylitervo, P., Doyen, W. & Taherzadeh, M. J. (2014). Fermentation of lignocellulosic hydrolyzate using a submerged membrane bioreactor at high dilution rates. Bioresource Technology
Open this publication in new window or tab >>Fermentation of lignocellulosic hydrolyzate using a submerged membrane bioreactor at high dilution rates
2014 (English)In: Bioresource Technology, ISSN 0960-8524, E-ISSN 1873-2976Article in journal (Refereed) Published
Abstract [en]

A submerged membrane bioreactor (sMBR) was developed to ferment toxic lignocellulosic hydrolyzate to ethanol. The sMBR achieved high cell density of Saccharomyces cerevisiae during continuous cultivation of the hydrolyzate by completely retaining all yeast cells inside the sMBR. The performance of the sMBR was evaluated based on the ethanol yield and productivity at the dilution rates 0.2, 0.4, 0.6, and 0.8 h-1 with the increase of dilution rate. Results show that the yeast in the sMBR was able to ferment the wood hydrolyzate even at high dilution rates, attaining a maximum volumetric ethanol productivity of 7.94 ± 0.10 g L-1 h-1 at a dilution rate of 0.8 h-1. Ethanol yields were stable at 0.44 ± 0.02 g g-1 during all the tested dilution rates, and the ethanol productivity increased from 2.16 ± 0.15 to 7.94 ± 0.10 g L-1 h-1. The developed sMBR systems running at high yeast density demonstrates a potential for a rapid and productive ethanol production from wood hydrolyzate.

Place, publisher, year, edition, pages
Elsevier, 2014
Keywords
Resource Recovery
National Category
Industrial Biotechnology
Research subject
Resource Recovery
Identifiers
urn:nbn:se:hb:diva-1855 (URN)10.1016/j.biortech.2014.04.066 (DOI)000338710500010 ()24836707 (PubMedID)2320/13674 (Local ID)2320/13674 (Archive number)2320/13674 (OAI)
Available from: 2015-11-13 Created: 2015-11-13 Last updated: 2017-12-01
Ylitervo, P., Franzén, C. J. & Taherzadeh, M. (2013). Impact of Furfural on Rapid Ethanol Production Using a Membrane Bioreactor. Energies, 6(3), 1604-1617
Open this publication in new window or tab >>Impact of Furfural on Rapid Ethanol Production Using a Membrane Bioreactor
2013 (English)In: Energies, ISSN 1996-1073, E-ISSN 1996-1073, Vol. 6, no 3, p. 1604-1617Article in journal (Refereed) Published
Abstract [en]

Abstract: A membrane bioreactor was developed to counteract the inhibition effect of furfural in ethanol production. Furfural, a major inhibitor in lignocellulosic hydrolyzates, is a highly toxic substance which is formed from pentose sugars released during the acidic degradation of lignocellulosic materials. Continuous cultivations with complete cell retention were performed at a high dilution rate of 0.5 h−1. Furfural was added directly into the bioreactor by pulse injection or by addition into the feed medium to obtain furfural concentrations ranging from 0.1 to 21.8 g L−1. At all pulse injections of furfural, the yeast was able to convert the furfural very rapidly by in situ detoxification. When injecting 21.8 g L−1 furfural to the cultivation, the yeast converted it by a specific conversion rate of 0.35 g g−1 h−1. At high cell density, Saccharomyces cerevisiae could tolerate very high furfural levels without major changes in the ethanol production. During the continuous cultures when up to 17.0 g L−1 furfural was added to the inlet medium, the yeast successfully produced ethanol, whereas an increase of furfural to 18.6 and 20.6 g L−1 resulted in a rapidly decreasing ethanol production and accumulation of sugars in the permeate. This study show that continuous ethanol fermentations by total cell retention in a membrane bioreactor has a high furfural tolerance and can conduct rapid in situ detoxification of medium containing high furfural concentrations.

Place, publisher, year, edition, pages
M D P I AG, 2013
Keywords
Resursåtervinning
National Category
Industrial Biotechnology Industrial Biotechnology
Research subject
Resource Recovery
Identifiers
urn:nbn:se:hb:diva-1554 (URN)10.3390/en6031604 (DOI)000316604500023 ()2320/12245 (Local ID)2320/12245 (Archive number)2320/12245 (OAI)
Available from: 2015-11-13 Created: 2015-11-13 Last updated: 2017-12-01Bibliographically approved
Ylitervo, P., Franzén, C. J. & Taherzadeh, M. (2013). Mechanically robust polysiloxane: ACA capsules for prolonged ethanol production. Journal of chemical technology and biotechnology (1986), 88(6), 1080-1088
Open this publication in new window or tab >>Mechanically robust polysiloxane: ACA capsules for prolonged ethanol production
2013 (English)In: Journal of chemical technology and biotechnology (1986), ISSN 0268-2575, E-ISSN 1097-4660, Vol. 88, no 6, p. 1080-1088Article in journal (Refereed) Published
Abstract [en]

Fermentation using encapsulated yeast leads to more robust ethanol production from lignocellulose hydrolyzates. Encapsulated yeast is much more tolerant to inhibitors present in hydrolyzates, and fermentation is faster due to increased total cell density. For industrial applications, capsules must be made robust enough to endure long periods and numerous cultivations without breaking. Liquid core alginate–chitosan–alginate (ACA) capsules containing Saccharomyces cerevisiae were produced by the liquid-droplet-forming method and treated with hydrolyzed 3-aminopropyltrietoxysilane (hAPTES) forming very glossy capsules. Capsules produced with 3.0% hAPTES showed the best mechanical robustness but no ethanol could be produced in dilute-acid spruce hydrolyzate using these capsules. Untreated ACA capsules gave the highest ethanol production but demonstrated poor mechanical robustness. 25% of the ACA capsules ruptured within 6 h in the shear test. Capsules treated with 1.5% hAPTES were significantly stronger, since only 0–2% of these capsules broke. Moreover, the ethanol production in the fifth consecutive cultivation in lignocellulose hydrolyzate was nearly as high as for untreated ACA capsules. The mechanical robustness of ACA capsules can be easily improved by treating the capsules with hAPTES. ACA capsules treated with 1.5% hAPTES showed excellent mechanical robustness and a similar ethanol production profile to untreated ACA capsules. © 2012 Society of Chemical Industry

Place, publisher, year, edition, pages
John Wiley & Sons Ltd., 2013
Keywords
3-aminopropyltrietoxysilane, Alginate, Bioethanol production, Chitosan, Encapsulation, Robust capsules, Yeast
National Category
Industrial Biotechnology
Research subject
Resource Recovery
Identifiers
urn:nbn:se:hb:diva-1422 (URN)10.1002/jctb.3944 (DOI)000319020900014 ()2-s2.0-84877923915 (Scopus ID)2320/11742 (Local ID)2320/11742 (Archive number)2320/11742 (OAI)
Available from: 2015-11-13 Created: 2015-11-13 Last updated: 2018-08-01Bibliographically approved
Ylitervo, P., Akinbomi, J. & Taherzadeh, M. (2013). Membrane bioreactors’ potential for ethanol and biogas production: A review. Environmental technology, 34(13-14), 1711-1723
Open this publication in new window or tab >>Membrane bioreactors’ potential for ethanol and biogas production: A review
2013 (English)In: Environmental technology, ISSN 0959-3330, E-ISSN 1479-487X, Vol. 34, no 13-14, p. 1711-1723Article in journal (Refereed) Published
Abstract [en]

Companies developing and producing membranes for different separation purposes, as well as the market for these, have markedly increased in numbers over the last decade. Membrane and separation technology might well contribute to making fuel ethanol and biogas production from lignocellulosic materials more economically viable and productive. Combining biological processes with membrane separation techniques in a membrane bioreactor (MBR) increases cell concentrations extensively in the bioreactor. Such a combination furthermore reduces product inhibition during the biological process, increases product concentration and productivity, and simplifies the separation of product and/or cells. Various MBRs have been studied over the years, where the membrane is either submerged inside the liquid to be filtered, or placed in an external loop outside the bioreactor. All configurations have advantages and drawbacks, as reviewed in this paper. The current review presents an account of the membrane separation technologies, and the research performed on MBRs, focusing on ethanol and biogas production. The advantages and potentials of the technology are elucidated.

Place, publisher, year, edition, pages
Taylor & Francis, 2013
Keywords
Resource Recovery
National Category
Industrial Biotechnology
Research subject
Resource Recovery
Identifiers
urn:nbn:se:hb:diva-1650 (URN)10.1080/09593330.2013.813559 (DOI)000325389900006 ()24350429 (PubMedID)2320/12939 (Local ID)2320/12939 (Archive number)2320/12939 (OAI)
Available from: 2015-11-13 Created: 2015-11-13 Last updated: 2017-12-01Bibliographically approved
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