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Wainaina, Steven
Publications (8 of 8) Show all publications
Wainaina, S., Mukesh Kumar, A., Sárvári Horváth, I. & Taherzadeh, M. J. (2020). Anaerobic digestion of food waste to volatile fatty acids and hydrogen at high organic loading rates in immersed membrane bioreactors. Renewable energy
Open this publication in new window or tab >>Anaerobic digestion of food waste to volatile fatty acids and hydrogen at high organic loading rates in immersed membrane bioreactors
2020 (English)In: Renewable energy, ISSN 0960-1481, E-ISSN 1879-0682Article in journal (Refereed) Published
Abstract [en]

The organic loading rate (OLR) is an essential parameter that controls the anaerobic digestion process. This work investigated the performance of immersed membrane bioreactors operated at high OLRs of 4, 6, 8 and 10 g volatile solids (VS)/L/d regarding the fermentation behavior, product recovery and microbial dynamics during the acidogenic fermentation of food waste to volatile fatty acids (VFAs) and hydrogen. The highest yield of 0.52 g VFA/ gVSadded was attained at 6 g VS/L/d, while an optimal hydrogen yield of 14.7 NmL/ gVSadded was obtained at 8 g VS/L/d. The bacterial populations, analyzed using 16S rRNA gene amplicon sequencing, consisted mainly of Firmicutes and Actinobacteria at OLRs 4 and 8 g VS/L/d while Firmicutes, Actinobacteria and Proteobacteria phyla dominated at 6 and 10 g VS/L/d. Moreover, the presence of Clostridium and Lactobacillus genera correlated with the acetate, butyrate, caproate and lactate production.

Keywords
In-situ product recovery Immersed membrane bioreactor High organic loading rate Volatile fatty acids Microbial dynamics
National Category
Engineering and Technology
Research subject
Resource Recovery
Identifiers
urn:nbn:se:hb:diva-22766 (URN)10.1016/j.renene.2020.01.138 (DOI)
Funder
Swedish Agency for Economic and Regional GrowthMoRe ResearchSwedish Research Council
Available from: 2020-02-03 Created: 2020-02-03 Last updated: 2020-02-24Bibliographically approved
Wainaina, S., Mukesh Kumar, A., Sarsaiya, S., Chen, H., Singh, E., Kumar, A., . . . Taherzadeh, M. J. (2020). Resource recovery and circular economy from organic solid waste using aerobic and anaerobic digestion technologies. Bioresource Technology
Open this publication in new window or tab >>Resource recovery and circular economy from organic solid waste using aerobic and anaerobic digestion technologies
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2020 (English)In: Bioresource Technology, ISSN 0960-8524, E-ISSN 1873-2976Article in journal (Refereed) Published
Abstract [en]

With the inevitable rise in human population, resource recovery from waste stream is becoming important for a sustainable economy, conservation of the ecosystem as well as for reducing the dependence on the finite natural resources. In this regard, a bio-based circular economy considers organic wastes and residues as potential resources that can be utilized to supply chemicals, nutrients, and fuels needed by mankind. This review explored the role of aerobic and anaerobic digestion technologies for the advancement of a bio-based circular society. The developed routes within the anaerobic digestion domain, such as the production of biogas and other high-value chemicals (volatile fatty acids) were discussed. The potential to recover important nutrients, such as nitrogen through composting, was also addressed. An emphasis was made on the innovative models for improved economics and process performance, which include co-digestion of various organic solid wastes, recovery of multiple bio-products, and integrated bioprocesses.

Keywords
Resource recovery, Organic solid waste, Circular economy, Anaerobic digestion, Composting
National Category
Engineering and Technology
Research subject
Resource Recovery
Identifiers
urn:nbn:se:hb:diva-22767 (URN)10.1016/j.biortech.2020.122778 (DOI)
Available from: 2020-02-03 Created: 2020-02-03 Last updated: 2020-02-24Bibliographically approved
Mukesh Kumar, A., Sarsaiya, S., Wainaina, S., Rajendran, K., Kumar, S., Quan, W., . . . Jain, A. (2019). A critical review of organic manure biorefinery models toward sustainable circular bioeconomy: Technological challenges, advancements, innovations, and future perspectives. Renewable & sustainable energy reviews, 115-131
Open this publication in new window or tab >>A critical review of organic manure biorefinery models toward sustainable circular bioeconomy: Technological challenges, advancements, innovations, and future perspectives
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2019 (English)In: Renewable & sustainable energy reviews, ISSN 1364-0321, E-ISSN 1879-0690, p. 115-131Article in journal (Refereed) Published
Abstract [en]

Total livestock emissions account for up to 14.5% of man-made greenhouse gas emissions. Counteractive measures, such as circular economy concepts and negative emission technologies are necessary to limit global warming below 1.5 °C. Possible treatment options for organic manure include anaerobic digestion, combustion, gasification, hydrothermal liquefaction and composting. The choice of treatment varies depending on the economics, the requirement of a specific product, and sociocultural factors. Commercialization of these treatments needs a blend of appropriate technology, feasible economics, policy support and agreeable socio-cultural conditions. Key findings of this study include the following: 1. Increasing scientific awareness about manure management and treatment; 2. Building a sustainable cooperative model to commercialize technologies; 3. Creating a market for manure recycling products; 4. The role of policy in supporting technologies and consumers; and 5. The codigestion of substrates for better efficacy. Current trends show minimal actions in place as opposed to the high-rate of acceleration that is necessary.

Keywords
Anaerobic digestion, Organic manure, Pretreatment, Codigestion, Organic loading rate, Bioaugmentation
National Category
Engineering and Technology
Research subject
Resource Recovery
Identifiers
urn:nbn:se:hb:diva-21039 (URN)10.1016/j.rser.2019.05.017 (DOI)000471252700009 ()2-s2.0-85065677454 (Scopus ID)
Available from: 2019-05-21 Created: 2019-05-21 Last updated: 2020-01-29Bibliographically approved
Wainaina, S., Lukitawesa, L., Mukesh Kumar, A. & Taherzadeh, M. J. (2019). Bioengineering of anaerobic digestion for volatile fatty acids, hydrogen or methane production: A critical review. Bioengineered
Open this publication in new window or tab >>Bioengineering of anaerobic digestion for volatile fatty acids, hydrogen or methane production: A critical review
2019 (English)In: Bioengineered, ISSN 2165-5979, E-ISSN 2165-5987, ISSN 2165-5979Article in journal (Refereed) Published
Abstract [en]

Anaerobic digestion (AD) is a well-established technology used for producing biogas or biomethane alongside the slurry used as biofertilizer. However, using a variety of wastes and residuals as substrate and mixed cultures in the bioreactor makes AD as one of the most complicated biochemical processes employing hydrolytic, acidogenic, hydrogen-producing, acetate-forming bacteria as well as acetoclastic and hydrogenoclastic methanogens. Hydrogen and volatile fatty acids (VFAs) including acetic, propionic, isobutyric, butyric, isovaleric, valeric and caproic acid and other carboxylic acids such as succinic and lactic acids are formed as intermediate products. As these acids are important precursors for various industries as mixed or purified chemicals, the AD process can be bioengineered to produce VFAs alongside hydrogen and therefore biogas plants can become biorefineries. The current critical review paper provides the theory and means to produce and accumulate VFAs and hydrogen, inhibit their conversion to methane and to extract them as the final products. The effects of pretreatment, pH, temperature, hydraulic retention time (HRT), organic loading rate (OLR), chemical methane inhibitions, and heat shocking of the inoculum on VFAs accumulation, hydrogen production, VFAs composition, and the microbial community were discussed. Furthermore, this paper highlights the possible techniques for recovery of VFAs from the fermentation media in order to minimize product inhibition as well as to supply the carboxylates for downstream procedures.

Place, publisher, year, edition, pages
Taylor & Francis Group, 2019
Keywords
Anaerobic digestion, Metabolic pathways, Volatile fatty acids, Hydrogen, Biorefineries, Process parameters, Mixed culture fermentation, Inhibiting methanogens
National Category
Natural Sciences
Identifiers
urn:nbn:se:hb:diva-21807 (URN)10.1080/21655979.2019.1673937 (DOI)000490056900001 (PubMedID)2-s2.0-85073183117 (Scopus ID)
Funder
Swedish Research CouncilMoRe ResearchSwedish Agency for Economic and Regional Growth
Available from: 2019-10-03 Created: 2019-10-03 Last updated: 2020-01-31Bibliographically approved
Chandolias, K., Wainaina, S., Niklasson, C. & Taherzadeh, M. J. (2018). Effects of Heavy Metals and pH on the Conversion of Biomass to Hydrogen via Syngas Fermentation. BioResources
Open this publication in new window or tab >>Effects of Heavy Metals and pH on the Conversion of Biomass to Hydrogen via Syngas Fermentation
2018 (English)In: BioResources, ISSN 1930-2126, E-ISSN 1930-2126Article in journal (Refereed) Published
Abstract [en]

The effects of three heavy metals on hydrogen production via syngas fermentation were investigated within a metal concentration range of 0-1.5 mg Cu/L, 0-9 mg Zn/L, 0-42 mg Mn/L, in media with initial pH of 5, 6 and 7, at 55 °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 155.28% ± 12.02% 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 show that the addition of heavy metals, contained in gasification-derived ash, can improve the production rate and yield of fermentative hydrogen. This could lead in lower costs in gasification process and fermentative hydrogen production and less demand for syngas cleaning before syngas fermentation.

Keywords
Gasification; Syngas; Fermentative hydrogen; Heavy metals; pH
National Category
Industrial Biotechnology
Research subject
Resource Recovery
Identifiers
urn:nbn:se:hb:diva-14189 (URN)
Funder
Swedish Research Council
Available from: 2018-05-16 Created: 2018-05-16 Last updated: 2019-10-25Bibliographically approved
Chandolias, K., Wainaina, S., Niklasson, C. & Taherzadeh, M. J. (2018). Effects of Heavy Metals and pH on the Conversion of Biomass to Hydrogen via Syngas Fermentation. BioResources, 13(2), 4455-4469
Open this publication in new window or tab >>Effects of Heavy Metals and pH on the Conversion of Biomass to Hydrogen via Syngas Fermentation
2018 (English)In: BioResources, ISSN 1930-2126, E-ISSN 1930-2126, Vol. 13, no 2, p. 4455-4469Article in journal (Refereed) Published
Abstract [en]

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.

Keywords
gasification, syngas, fermentative hydrogen, heavy metals, pH
National Category
Industrial Biotechnology
Research subject
Resource Recovery
Identifiers
urn:nbn:se:hb:diva-22502 (URN)10.15376/biores.13.2.4455-4469 (DOI)000440518000051 ()
Available from: 2020-01-16 Created: 2020-01-16 Last updated: 2020-01-17Bibliographically approved
Wainaina, S., Mohsen, P., Mahboubi, A., Sárvári Horváth, I. & Taherzadeh, M. J. (2018). Food waste-derived volatile fatty acids platform using an immersed membrane bioreactor. Bioresource Technology, Article ID S0960-8524(18)31650-X.
Open this publication in new window or tab >>Food waste-derived volatile fatty acids platform using an immersed membrane bioreactor
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2018 (English)In: Bioresource Technology, ISSN 0960-8524, E-ISSN 1873-2976, article id S0960-8524(18)31650-XArticle in journal (Refereed) Published
Abstract [en]

Volatile fatty acids (VFAs) are the key intermediates from anaerobic digestion (AD) process that can be a platform to synthesize products of higher value than biogas. However, some obstacles still exist that prevent large-scale production and application of VFAs, key among them being the difficulty in recovering the acids from the fermentation medium and low product yields. In this study, a novel anaerobic immersed membrane bioreactor (iMBR) with robust cleaning capabilities, which incorporated frequent backwashing to withstand the complex AD medium, was designed and applied for production and in situ recovery of VFAs. The iMBR was fed with food waste and operated without pH control, achieving a high yield of 0.54 g VFA/g VSadded. The continuous VFA recovery process was investigated for 40 days at OLRs of 2 gVS/L/d and 4 gVS/L/d without significant change in the permeate flux at a maximum suspended solids concentration of 31 g/L.

Keywords
Food waste, Fouling control, Immersed membrane bioreactor, In situ recovery, Volatile fatty acids
National Category
Engineering and Technology
Research subject
Resource Recovery; Resource Recovery
Identifiers
urn:nbn:se:hb:diva-15420 (URN)10.1016/j.biortech.2018.11.104 (DOI)000454610900041 ()2-s2.0-85057618430 (Scopus ID)
Available from: 2018-12-04 Created: 2018-12-04 Last updated: 2020-01-31Bibliographically approved
Wainaina, S., Sárvári Horváth, I. & Taherzadeh, M. J. (2017). Biochemicals from food waste and recalcitrant biomass via syngas fermentation: A review. Bioresource Technology
Open this publication in new window or tab >>Biochemicals from food waste and recalcitrant biomass via syngas fermentation: A review
2017 (English)In: Bioresource Technology, ISSN 0960-8524, E-ISSN 1873-2976Article in journal (Refereed) Published
Abstract [en]

An effective method for the production of value-added chemicals from food waste and lignocellulosic materials is a hybrid thermal-biological process, which involves gasification of the solid materials to syngas (primarily CO and H2) followed by fermentation. This paper reviews the recent advances in this process. The special focus is on the cultivation methods that involve the use of single strains, defined mixed cultures and undefined mixed cultures for production of carboxylic acids and higher alcohols. A rate limiting step in these processes is the low mass transfer between the gas and the liquid phases. Therefore, novel techniques that can enhance the gas-liquid mass transfer including membrane- and trickle-bed bioreactors were discussed. Such bioreactors have shown promising results in increasing the volumetric mass transfer coefficient (kLa). High gas pressure also influences the mass transfer in certain batch processes, although the presence of impurities in the gas would impede the process.[on SciFinder (R)]

Keywords
co-cultures, food waste, lignocelluloses, reactor design, syngas fermentation
National Category
Industrial Biotechnology
Identifiers
urn:nbn:se:hb:diva-12538 (URN)10.1016/j.biortech.2017.06.075 (DOI)000417046100012 ()28651875 (PubMedID)2-s2.0-85021202351 (Scopus ID)
Available from: 2017-08-27 Created: 2017-08-27 Last updated: 2018-11-28Bibliographically approved

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