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  • 1.
    Chandolias, Konstantinos
    University of Borås, Faculty of Textiles, Engineering and Business.
    Lignocellulosic Biorefinery for Biohydrogen and Carboxylic Acids Production in Flexible Membrane Bioreactor and Two-stage System2017In: 7th Nordic Wood Biorefinery Conference. 28-30 March 2017. Stockholm, 2017Conference paper (Other academic)
    Abstract [en]

    Lignocellulosic biorefineries can produce numerous biofuels and chemicals via the anaerobic digestion process. Although several works have been recently conducted on this field, the technology is considered new and more research efforts are required towards industrialisation. In this work, wheat straw was digested after hydrolysis with dilute phosphoric acid. The substrate was biologically converted into carboxylic acids and biohydrogen at different OLRs (4.42-17.95 g COD/L.d). The semi-continuous experiments took place at 55 °C, both in reactors with free-cells or mixed free and membrane-encased cells, According to the results, the optimum biohydrogen, acetic and isobutyric acid yields were obtained at OLR of 4.42 g COD/L.d. Moreover, the highest lactic acid production was recorded at OLR of 9.33 g COD/L.d. Furthermore, a reactor containing both free and membrane-encased cells showed 60% higher lactic acid production (at OLR of 13.42 g COD/L.d) in comparison to the conventional free cell reactor. In addition, the production of acetic and isobutyric acid was greatly improved by a two-stage system. The use of both free and encased cells in a flexible membrane system along with the two-stage system for the optimisation of the process is the main novelty of this work.

  • 2.
    Chandolias, Konstantinos
    et al.
    University of Borås, Faculty of Textiles, Engineering and Business. Research Centre for Resource Recovery.
    Pardaev, Sindor
    University of Borås, Faculty of Textiles, Engineering and Business. University of Samarkand.
    Taherzadeh, Mohammad
    University of Borås, Faculty of Textiles, Engineering and Business. Research Centre for Resource Recovery.
    Biohydrogen and carboxylic acids production from wheat straw hydrolysate2016In: Bioresource Technology, ISSN 0960-8524, E-ISSN 1873-2976Article in journal (Refereed)
  • 3.
    Chandolias, Konstantinos
    et al.
    University of Borås, Faculty of Textiles, Engineering and Business.
    Pekgenc, Enise
    Department of Environmental Engineering, Istanbul Technical University.
    Taherzadeh, Mohammad J
    University of Borås, Faculty of Textiles, Engineering and Business.
    Floating membrane bioreactors with high gas hold-up for syngas-to-biomethane conversion2019In: Energies, ISSN 1996-1073, E-ISSN 1996-1073, Vol. 12, no 6Article in journal (Refereed)
    Abstract [en]

    The low gas-to-liquid mass transfer rate is one of the main challenges in syngas biomethanation. In this work, a new concept of the floating membrane system with high gas hold-up was introduced in order to enhance the mass transfer rate of the process. In addition, the effect of the inoculum-to-syngas ratio was investigated. The experiments were conducted at 55 °C with an anaerobic mixed culture in both batch and continuous modes. According to the results from the continuous experiments, the H2 and CO conversion rates in the floating membrane bioreactor were approximately 38% and 28% higher in comparison to the free (suspended) cell bioreactors. The doubling of the thickness of the membrane bed resulted in an increase of the conversion rates of H2 and CO by approximately 6% and 12%, respectively. The highest H2 and CO consumption rates and CH4 production rate recorded were approximately 22 mmol/(L·d), 50 mmol/(L·d), and 34.41 mmol/(L·d), respectively, obtained at the highest inoculum-to-syngas ratio of 0.2 g/mL. To conclude, the use of the floating membrane system enhanced the syngas biomethanation rates, while a thicker membrane bed resulted in even higher syngas conversion rates. Moreover, the increase of the inoculum-to-syngas ratio of up to 0.2 g/mL favored the syngas conversion.

  • 4.
    Chandolias, Konstantinos
    et al.
    University of Borås, Faculty of Textiles, Engineering and Business.
    Richards, Tobias
    University of Borås, Faculty of Textiles, Engineering and Business.
    Taherzadeh, Mohammad J
    University of Borås, Faculty of Textiles, Engineering and Business.
    Combined gasification-fermentation process in waste biorefinery2018In: Waste Biorefinery: Potential and Perspectives, Elsevier, 2018Chapter in book (Refereed)
    Abstract [en]

    Thermal processes of wastes lead to production of energy in form of electricity and/or heat. However, if the goal is to produce materials, thermochemical processes can be applied. These processes via e.g. gasification produce raw syngas that is a mixture of principally H2, CO and CO2, with some impurities. This raw syngas is traditionally cleaned and catalytically treated via chemical processes such as Fischer-Tropsch. However, as there is a variety of microorganisms that can assimilate syngas, this gas can be used as a substrate to produce different chemicals via biochemical routes. This chapter is dedicated to describe an efficient thermochemical-biochemical route of waste treatment. The gasification process, the design and the factors that affect the syngas composition are firstly described. Thereafter, the microbiology, biochemical reactions, metabolic pathways and process conditions toward production of several metabolic products from syngas such as carboxylic acids, ethanol, butanol, 2,3-butanediol, methane and biopolymers are presented. 

  • 5.
    Chandolias, Konstantinos
    et al.
    University of Borås, Faculty of Textiles, Engineering and Business.
    Wainaina, Steven
    Niklasson, Claes
    Chalmers Technical University.
    Taherzadeh, Mohammad J
    University of Borås, Faculty of Textiles, Engineering and Business.
    Effects of Heavy Metals and pH on the Conversion of Biomass to Hydrogen via Syngas Fermentation2018In: BioResources, ISSN 1930-2126, E-ISSN 1930-2126Article in journal (Refereed)
    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.

  • 6.
    Chandolias, Konstantinos
    et al.
    University of Borås, Faculty of Textiles, Engineering and Business.
    Youngsukkasem, Supansa
    University of Borås, Faculty of Textiles, Engineering and Business.
    Taherzadeh, Mohammad
    University of Borås, Faculty of Textiles, Engineering and Business.
    Rapid Bio-methanation of Syngas by High Cell-density in Reverse Membrane Bioreactor (RMBR)2015In: Advanced Membrane Technology VI: Water, Energy and New Frontiers / [ed] Dibakar Bhattacharyya (University of Kentucky, USA), Benny Freeman (University of Texas, USA), 2015Conference paper (Other academic)
  • 7.
    Patinvoh, Regina
    et al.
    University of Borås, Faculty of Textiles, Engineering and Business.
    Osalie, Alex
    University of Borås, Faculty of Textiles, Engineering and Business.
    Chandolias, Konstantinos
    University of Borås, Faculty of Textiles, Engineering and Business.
    Sarvari Horvath, Ilona
    Taherzadeh, Mohammad
    University of Borås, Faculty of Textiles, Engineering and Business.
    Innovative Pretreatment Strategies for Biogas Production2016In: Bioresource Technology, ISSN 0960-8524, E-ISSN 1873-2976, Vol. NovArticle in journal (Refereed)
    Abstract [en]

    Biogas or biomethane is traditionally produced via anaerobic digestion, or recently bythermochemical or a combination of thermochemical and biological processes viasyngas (CO and H2) fermentation. However, many of the substrates feedstocks haverecalcitrant structure and difficult to digest (e.g., lignocelluloses or keratins), or theyhave toxic compounds (such as fruit flavors or high ammonia content), or not digestibleat all (e.g., plastics). To overcome these challenges, innovative strategies for enhancedand economically favorable biogas production were proposed in this review. Thestrategies considered are commonly known physical pretreatment, rapid decompression,autohydrolysis, acid- or alkali pretreatments, solvents (e.g. for lignin or cellulose)pretreatments or leaching, supercritical, oxidative or biological pretreatments, as well ascombined gasification and fermentation, integrated biogas production and

  • 8.
    Youngsukkasem, Supansa
    et al.
    University of Borås, Faculty of Textiles, Engineering and Business.
    Chandolias, Konstantinos
    University of Borås, Faculty of Textiles, Engineering and Business.
    Taherzadeh, Mohammad
    University of Borås, Faculty of Textiles, Engineering and Business.
    Syngas Biomethanation in a Semi-Continuous Reverse Membrane Bioreactor (RMBR)2016In: Fermentation, MDPI, ISSN 2311-5637, Vol. 2, no 2, article id 8Article in journal (Refereed)
    Abstract [en]

    Syngas biomethanation is a potent bio-conversion route, utilizing microorganisms to assimilate intermediate gases to produce methane. However, since methanogens have a long doubling time, the reactor works best at a low dilution rate; otherwise, the cells can be washed out during the continuous fermentation process. In this study, the performance of a practical reverse membrane bioreactor (RMBR) with high cell density for rapid syngas biomethanation as well as a co-substrate of syngas and organic substances was examined in a long-term fermentation process of 154 days and compared with the reactors of the free cells (FCBR). The RMBR reached maximum capacities of H2, CO, and CO2 conversion of 7.0, 15.2, and 4.0 mmol/Lreactor.day, respectively, at the organic loading rate of 3.40 gCOD/L.day. The highest methane production rate from the RMBR was 186.0 mL/Lreactor.day on the 147th day, compared to the highest rate in the FCBR, 106.3 mL/Lreactor.day, on the 58th day. The RMBR had the ability to maintain a high methanation capacity by retaining the microbial cells, which were at a high risk for cell wash out. Consequently, the system was able to convert more syngas simultaneously with the organic compounds into methane compared to the FCBR.

  • 9.
    Youngsukkasem, Supansa
    et al.
    University of Borås, Faculty of Textiles, Engineering and Business.
    Chandolias, Konstantinos
    University of Borås, Faculty of Textiles, Engineering and Business.
    Taherzadeh, Mohammad J
    University of Borås.
    Rapid bio-methanation of syngas in a reverse membrane bioreactor: membrane encased microorganisms2015In: Bioresource Technology, ISSN 0960-8524, E-ISSN 1873-2976, Vol. 178, p. 334-40Article in journal (Refereed)
    Abstract [en]

    The performance of a novel reverse membrane bioreactor (RMBR) with encased microorganisms for syngas bio-methanation as well as a co-digestion process of syngas and organic substances was examined. The sachets were placed in the reactors and examined in repeated batch mode. Different temperatures and short retention time were studied. The digesting sludge encased in the PVDF membranes was able to convert syngas into methane at a retention time of 1 day and displayed a similar performance as the free cells in batch fermentation. The co-digestion of syngas and organic substances by the RMBR (the encased cells) showed a good performance without any observed negative effects. At thermophilic conditions, there was a higher conversion of pure syngas and co-digestion using the encased cells compared to at mesophilic conditions.[on SciFinder (R)]

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