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Fermentative hydrogen and methane productions using membrane bioreactors
University of Borås, Faculty of Textiles, Engineering and Business.
2015 (English)Doctoral thesis, comprehensive summary (Other academic)
Sustainable development
The content falls within the scope of Sustainable Development
Abstract [en]

The role of energy as a stimulant for economic growth and environmental sustainabilityof any nation has made the focus on green fuels, including fermentative hydrogen (bioH2) andmethane (bioCH4), to be a priority for the World’s policy makers. Nigeria, as the most populousAfrican country, with worsening energy crisis, can benefit from the introduction of the bioH2 andbioCH4 technologies into the country’s energy mix, since such technologies have the potential ofgenerating energy from organic wastes such as fruit waste.Fruit waste was studied in detail in this work because of its great economic andenvironmental potential, as large quantities of the wastes (10–65% of raw fruit) are generatedfrom fruit consumption and processing. Meanwhile, bioH2 and bioCH4 productions involvinganaerobic microorganisms in direct contact with organic wastes have been observed to result insubstrate and product inhibitions, which reduce the gas yields and limit the application of thetechnologies on an industrial scale. For example, in this study, the first experimental work todetermine the effects of hydraulic retention times and fruit mixing on bioH2 production fromsingle and mixed fruits revealed the highest cumulative bioH2 yield to be equivalent to 30% ofthe theoretical yield. However, combining the fermentation process with the application ofmembrane encapsulated cells and membrane separation techniques, respectively, could reducesubstrate and product inhibitions of the microorganisms. This study, therefore, focused on theapplication of membrane techniques to enhance the yields of bioH2 and bioCH4 productions fromthe organic wastes.The second experimental work which focused on reduction of substrate inhibition,involved the investigation of the effects of the PVDF membrane encapsulation techniques on thebioH2 and bioCH4 productions from nutrient media with limonene, myrcene, octanol and hexanalas fruit flavours. The results showed that membrane encapsulated cells produced bioCH4 fasterand lasted longer, compared to free cells in limonene. Also, about 60% membrane protectiveeffect against myrcene, octanol and hexanal inhibitions was obtained. Regarding bioH2production, membrane encapsulated cells, compared to free cells, produced higher average dailyyields of 94, 30 and 77% with hexanal, myrcene and octanol as flavours, respectively. The finalpart of the study, which was aimed at reducing product inhibition, involved the study of theeffects of membrane permeation of volatile fatty acids (VFAs) on the bioreactor hydrodynamicsin relation to bioH2 production. The investigation revealed that low transmembrane pressure of104Pa was required to achieve a 3L h-1m-2 critical flux with reversible fouling mainly due to cakelayer formation, and bioH2 production was also observed to restart after VFAs removal.The results from this study suggest that membrane-based techniques could improve bioH2and bioCH4 productions from fermentation media with substrate and product inhibitions.

Place, publisher, year, edition, pages
Borås: Högskolan i Borås, 2015. , 72 p.
Series
Skrifter från Högskolan i Borås, ISSN 0280-381X ; 72
Keyword [en]
Encapsulation, Inhibition, hydrodynamics, hydrogen, methane, fruit flavour, Membrane bioreactor
National Category
Environmental Biotechnology
Research subject
Resource Recovery
Identifiers
URN: urn:nbn:se:hb:diva-671ISBN: 978-91-87525-73-5 (print)ISBN: 978-91-87525-74-2 (print)OAI: oai:DiVA.org:hb-671DiVA: diva2:849071
Public defence
2015-10-28, E310, Allegatan 1, Borås, 10:00 (English)
Available from: 2015-09-21 Created: 2015-08-27 Last updated: 2015-12-18Bibliographically approved
List of papers
1. Development and Dissemination Strategies for Accelerating Biogas Production in Nigeria
Open this publication in new window or tab >>Development and Dissemination Strategies for Accelerating Biogas Production in Nigeria
2014 (English)In: BioResources, ISSN 1930-2126, E-ISSN 1930-2126, Vol. 9, no 3Article in journal (Refereed)
Abstract [en]

Following the worsening energy crisis of unreliable electricity and unaffordable petroleum products coupled with the increase number of poverty-stricken people in Nigeria, the populace is desperately in need of cheap alternative energy supplies that will replace or complement the existing energy sources. Previous efforts by the government in tackling the challenge by citizenship sensitization of the need for introduction of biofuel into the country’s energy mix have not yielded the expected results because of a lack of sustained government effort. In light of the shortcomings, this study assesses the current potential of available biomass feedstock for biogas production in Nigeria, and further proposes appropriate biogas plants, depending on feedstock type and quantity, for the six geopolitical zones in Nigeria. Besides, the study proposes government-driven biogas development systems that could be effectively used to harness, using biogas technology, the estimated 270 TWh of potential electrical energy from 181 million tonnes of available biomass, in the advancement of electricity generation and consequent improvement of welfare in Nigeria.

Place, publisher, year, edition, pages
NCSU, 2014
Keyword
Biogas, available feedstock, Nigerian’s prospect, Biogas-consultancy, Biogas-consultancy, Resource Recovery
National Category
Industrial Biotechnology
Research subject
Resource Recovery
Identifiers
urn:nbn:se:hb:diva-1872 (URN)000344184300158 ()2320/13766 (Local ID)2320/13766 (Archive number)2320/13766 (OAI)
Available from: 2015-11-13 Created: 2015-11-13 Last updated: 2016-03-03
2. Evaluation of Fermentative Hydrogen Production from Single and Mixed Fruit Wastes
Open this publication in new window or tab >>Evaluation of Fermentative Hydrogen Production from Single and Mixed Fruit Wastes
2015 (English)In: Energies, ISSN 1996-1073, E-ISSN 1996-1073, Vol. 8, no 5, 4253-4272 p.Article in journal (Refereed) Published
Abstract [en]

The economic viability of employing dark fermentative hydrogen from wholefruit wastes as a green alternative to fossil fuels is limited by low hydrogen yield due to theinhibitory effect of some metabolites in the fermentation medium. In exploring means ofincreasing hydrogen production from fruit wastes, including orange, apple, banana, grapeand melon, the present study assessed the hydrogen production potential of singly-fermentedfruits as compared to the fermentation of mixed fruits. The fruit feedstock was subjected tovarying hydraulic retention times (HRTs) in a continuous fermentation process at 55 °C for47 days. The weight distributions of the first, second and third fruit mixtures were 70%,50% and 20% orange share, respectively, while the residual weight was shared equally bythe other fruits. The results indicated that there was an improvement in cumulativehydrogen yield from all of the feedstock when the HRT was five days. Based on the resultsobtained, apple as a single fruit and a fruit mixture with 20% orange share have the mostimproved cumulative hydrogen yields of 504 (29.5% of theoretical yield) and 513 mL/gvolatile solid (VS) (30% of theoretical yield ), respectively, when compared to other fruits.

Place, publisher, year, edition, pages
MDPI AG, 2015
Keyword
whole fruit wastes; singly-digested fruits, mixing proportion, biohydrogen, retention time, significant effect
National Category
Industrial Biotechnology
Research subject
Resource Recovery
Identifiers
urn:nbn:se:hb:diva-3736 (URN)10.3390/en8054253 (DOI)000356879600048 ()2-s2.0-84930807156 (Scopus ID)
Available from: 2015-12-06 Created: 2015-12-06 Last updated: 2017-05-04Bibliographically approved
3. Enhanced Fermentative Hydrogen and Methane Production from an Inhibitory Fruit-Flavored Medium with Membrane-Encapsulated Cells.
Open this publication in new window or tab >>Enhanced Fermentative Hydrogen and Methane Production from an Inhibitory Fruit-Flavored Medium with Membrane-Encapsulated Cells.
2015 (English)In: Membranes, ISSN 2077-0375, E-ISSN 2077-0375, Vol. 5, no 4Article in journal (Refereed) Published
Abstract [en]

This study focused on the possibility of improving fermentative hydrogen and methane production from an inhibitory fruit-flavored medium using polyvinylidene fluoride (PVDF) membrane-encapsulated cells. Hexanal, myrcene, and octanol, which are naturally produced in fruits such as apple, grape, mango, orange, strawberry, and plum, were investigated. Batch and semi-continuous fermentation processes at 55 °C were carried out. Presence of 5 g/L of myrcene, octanol, and hexanal resulted in no methane formation by fermenting bacteria, while encapsulated cells in the membranes resulted in successful fermentation with 182, 111, and 150 mL/g COD of methane, respectively. The flavor inhibitions were not serious on hydrogen-producing bacteria. With free cells in the presence of 5 g/L (final concentration) of hexanal-, myrcene-, and octanol-flavored media, average daily yields of 68, 133, and 88 mL/g COD of hydrogen, respectively, were obtained. However, cell encapsulation further improved these hydrogen yields to 189, 179, and 198 mL/g COD. The results from this study indicate that the yields of fermentative hydrogen and methane productions from an inhibitory medium could be improved using encapsulated cells.

Keyword
encapsulated bacteria, fruit flavors, membrane, hydrogen, methane, inhibition
National Category
Industrial Biotechnology
Research subject
Resource Recovery
Identifiers
urn:nbn:se:hb:diva-3726 (URN)10.3390/membranes5040616 (DOI)26501329 (PubMedID)
Available from: 2015-12-06 Created: 2015-12-06 Last updated: 2017-05-04Bibliographically approved
4. Membrane bioreactors’ potential for ethanol and biogas production: A review
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, 1711-1723 p.Article 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
Keyword
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: 2016-07-14Bibliographically approved
5. Biogas production by encased bacteria in synthetic membranes: Protective effects in toxic media and high loading rates
Open this publication in new window or tab >>Biogas production by encased bacteria in synthetic membranes: Protective effects in toxic media and high loading rates
2013 (English)In: Environmental technology, ISSN 0959-3330, E-ISSN 1479-487X, Vol. 34, no 13-14, 2077-2084 p.Article in journal (Refereed) Published
Abstract [en]

A bioreactor including encased digesting bacteria for biogas production was developed, and its performance in toxic media and under high organic loading rates (OLRs) was examined and compared with traditional digestion reactors. The bacteria (3 g) were encased and sealed in 3 × 6cm 2 PVDF (polyvinylidene fluoride) membranes with a pore size of 0.1 μ m, and then several sachets were placed in the reactors. They were then examined in toxic medium containing up to 3% limonene as a model inhibitor in batch reactors, and OLRs of up to 20 g COD / L.day in semi-continuous digestions. The free and encased cells with an identical total bacterial concentration of 9 g in a medium containing 2% limonene produced at most 6.56 and 23.06 mL biogas per day, respectively. In addition, the digestion with free cells completely failed at an OLR of 7.5 g COD / L.day, while the encased cells were still fully active with a loading of 15 g COD / L.day.

Place, publisher, year, edition, pages
Tailor & Francis, 2013
Keyword
Resource Recovery
National Category
Industrial Biotechnology
Research subject
Resource Recovery
Identifiers
urn:nbn:se:hb:diva-1649 (URN)10.1080/09593330.2013.770555 (DOI)000325389900038 ()24350461 (PubMedID)2320/12929 (Local ID)2320/12929 (Archive number)2320/12929 (OAI)
Available from: 2015-11-13 Created: 2015-11-13 Last updated: 2016-07-14Bibliographically approved

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