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  • 51.
    Patinvoh, Regina J.
    et al.
    University of Borås, Faculty of Textiles, Engineering and Business.
    Kalantar Mehrjerdi, Adib
    University of Borås, Faculty of Textiles, Engineering and Business.
    Sarvari, Horvath Ilona
    University of Borås, Faculty of Textiles, Engineering and Business.
    Taherzadeh, Mohammad J
    University of Borås, Faculty of Textiles, Engineering and Business.
    Dry fermentation of manure with straw in continuous plug flow reactor: Reactor development and process stability at different loading rates2017In: Bioresource Technology, ISSN 0960-8524, E-ISSN 1873-2976, Vol. 224, p. 197-205Article in journal (Refereed)
    Abstract [en]

    In this work, a plug flow reactor was developed for continuous dry digestion processes and its efficiency was investigated using untreated manure bedded with straw at 22% total solids content. This newly developed reactor worked successfully for 230days at increasing organic loading rates of 2.8, 4.2 and 6gVS/L/d and retention times of 60, 40 and 28days, respectively. Organic loading rates up to 4.2gVS/L/d gave a better process stability, with methane yields up to 0.163LCH4/gVSadded/d which is 56% of the theoretical yield. Further increase of organic loading rate to 6gVS/L/d caused process instability with lower volatile solid removal efficiency and cellulose degradation.[on SciFinder (R)]

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  • 52.
    Patinvoh, Regina
    et al.
    University of Borås, Faculty of Textiles, Engineering and Business. Department of Chemical and Polymer Engineering, Faculty of Engineering, Lagos State University.
    Lundin, Magnus
    University of Borås, Faculty of Textiles, Engineering and Business.
    Taherzadeh, Mohammad J
    University of Borås, Faculty of Textiles, Engineering and Business.
    Sárvári Horváth, Ilona
    University of Borås, Faculty of Textiles, Engineering and Business.
    Dry Anaerobic Co-Digestion of Citrus Wastes with Keratin and Lignocellulosic Wastes: Batch And Continuous Processes2018In: Waste and Biomass Valorization, ISSN 1877-2641, E-ISSN 1877-265XArticle in journal (Refereed)
    Abstract [en]

    Dry anaerobic co-digestion of citrus wastes (CW) with chicken feather (CF), wheat straw (WS) and manure bedded with straw (MS) was investigated in batch and continuous processes. Experiments were designed with different mixing ratios considering the inhibitory effect of CW, C/N ratio, and total solid content of individual feedstocks. Best mixing ratio (CF:CW:WS:MS) of 1:1:6:0, enhanced methane yield by 14% compared to the expected yield calculated according to the methane yields obtained from the individual fractions. The process performance of this mixture was then investigated in continuous plug flow reactors at different organic loading rates (OLR) with feedstock total solid contents of 21% TS (RTS21) and 32% TS (RTS32). At OLR of 2 gVS/L/d, a methane yield of 362 NmlCH4/gVSadded was obtained from RTS21, which is 13.5% higher than the yield obtained from RTS32 (319 NmlCH4/gVSadded). However, it was not possible to achieve a stable process when the OLR was further increased to 3.8 gVS/L/d; there were increased total VFAs concentrations and a decline in the biogas production.

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  • 53.
    Patinvoh, Regina
    et al.
    University of Borås, Faculty of Textiles, Engineering and Business.
    Osadolor, Osagie Alex
    University of Borås, Faculty of Textiles, Engineering and Business.
    Sárvári Horváth, Ilona
    University of Borås, Faculty of Textiles, Engineering and Business.
    Taherzadeh, Mohammad J
    University of Borås, Faculty of Textiles, Engineering and Business.
    Cost effective dry anaerobic digestion in textile bioreactors: Experimental and economic evaluation2017In: Bioresource Technology, ISSN 0960-8524, E-ISSN 1873-2976, Vol. 245, no Pt A, p. 549-555Article in journal (Refereed)
    Abstract [en]

    The aim of this work was to study dry anaerobic digestion (dry-AD) of manure bedded with straw using textile-based bioreactor in repeated batches. The 90-L reactor filled with the feedstocks (22-30% total solid) and inoculum without any further treatment, while the biogas produced were collected and analyzed. The digestate residue was also analyzed to check its suitability as bio-fertilizer. Methane yield after acclimatization increased from 183 to 290NmlCH4/gVS, degradation time decreased from 136 to 92days and the digestate composition point to suitable bio-fertilizer. The results then used to carry out economical evaluation, which shows dry-AD in textile bioreactors is a profitable method of handling the waste with maximum payback period of 5years, net present value from $7,000 to $9,800,000 (small to large bioreactors) with internal rate of return from 56.6 to 19.3%.

  • 54.
    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 Production2017In: Bioresource Technology, ISSN 0960-8524, E-ISSN 1873-2976, Vol. 224, p. 13-Article 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

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  • 55.
    Pereda Reyes, Ileana
    et al.
    Centro de Estudio de Ingenieria de Procesos Study Center of Process Engineering (CIPRO), High Polytechnic Institute “José Antonio Echeverría”.
    Pagés Díaz, Jhosané
    University of Borås, Faculty of Textiles, Engineering and Business.
    Sárvári Horváth, Ilona
    University of Borås, Faculty of Textiles, Engineering and Business.
    Anaerobic Biodegradation of Solid Substrates from Agroindustrial Activities—Slaughterhouse Wastes and Agrowastes2015In: Biodegradation and Bioremediation of Polluted Systems -: New Advances and Technologies / [ed] Rolando Chamy, Francisca Rosenkranz and Lorena Soler, Croatia: INTECH, 2015, p. 31-64Chapter in book (Other academic)
    Abstract [en]

    Solid wastes from the meat industry are produced in large amounts resulting in a negative impact on the environment if not properly treated. Due to their high content of proteins and fats, these residues are excellent substrates for anaerobic digestion which holds high potential for methane yield. However, possible toxic compounds may be formed during its biodegradation with a consequent failure of the process under long-term operation. The anaerobic co-digestion of such residues with other co-substrates as those generated in agricultural activities has been proposed as a good alternative to overcome these problems. Nevertheless, today there is very little knowledge to assess on mixture interactions connected to wastes composition, biodegradability, and the kinetics of the anaerobic process when complex materials are utilized in ternary and quaternary mixture, specifically when co-digesting solid cattle slaughterhouse waste with agrowaste. It is therefore important to select the right combination of substrates and ratios to obtain synergy instead of antagonism in those mixtures. This chapter aims to provide an overview of the anaerobic digestion of solid slaughterhouse waste and agrowaste, as well as the influence of mixture interactions on its biodegradation.

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  • 56.
    Pinheiro, V. E.
    et al.
    University of Borås, Faculty of Textiles, Engineering and Business. Ribeirão Preto Medical School, São Paulo University, Ribeirão Preto, Brazil.
    Sárvári Horváth, Ilona
    University of Borås, Faculty of Textiles, Engineering and Business.
    Lundin, Magnus
    University of Borås, Faculty of Textiles, Engineering and Business.
    Polizeli, M. D. L. T. D. M.
    Ribeirão Preto Medical School, São Paulo University, Ribeirão Preto, Brazil.
    Screening and cocktail optimization using experimental mixture design: enzymatic saccharification as a biological pretreatment strategy2021In: Biofuels, Bioproducts and Biorefining, ISSN 1932-104X, E-ISSN 1932-1031Article in journal (Refereed)
    Abstract [en]

    Biofuels contribute environment-friendly, renewable energy, minimizing dependence on fossil energy. The pretreatment of biomass is a practical step that accelerates and facilitates the hydrolysis of complex materials. This work aimed to screen, select, and study cocktail formulations for biomass hydrolysis, where the enzymes were provided both from a commercial source (Trichoderma reesei, Novozymes®) and through the cultivation of Aspergillus brasiliensis and Aspergillus tamarii Kita. Experimental mixture designs were used to optimize the enzymatic conversion of substrates into simple sugars. A crude extract rich in amylase (AAB) had a significant favorable influence on cornmeal hydrolysis by maximizing the yield of reducing sugars (RS) (173 μmol mL–1). Celluclast™, rich in cellulase, significantly affected the hydrolysis of banana peel, maximizing the RS yield (175 μmol mL–1). Variable degrees of enzyme synergism were evident from statistical analysis of the biomass hydrolysis.

  • 57.
    Pinheiro, V. E.
    et al.
    São Paulo University, Brazil.
    Wainaina, Steven
    University of Borås, Faculty of Textiles, Engineering and Business.
    Polizeli, M. D. L. T. D. M.
    São Paulo University, Brazil.
    Sárvári Horváth, Ilona
    University of Borås, Faculty of Textiles, Engineering and Business.
    Anaerobic digestion of cornmeal: the effect of crude enzyme extract and co-digestion with cow manure2021In: Biofuels, Bioproducts and Biorefining, ISSN 1932-104X, E-ISSN 1932-1031Article in journal (Refereed)
    Abstract [en]

    This study examined the effect of a crude enzyme extract, containing mainly starch-degrading enzymes, on cornmeal (Zea mays) hydrolysis. This was followed by an investigation of the effect of enzymatic treatment for the anaerobic digestion of this biomass. Cornmeal and cow manure were also co-digested, and both batch and semi-continuous experiments were performed. The enzymatic pretreatment of cornmeal resulted in a yield of 65 ± 5% reducing sugars, with 1:10 w/v (grams of dry substrate per mililiters of enzyme extract) enzyme load at 45 °C for 48 h. There was an 8% enhancement of methane production observed during the batch assays, both when cornmeal hydrolysate was digested and when enzymes were added directly to the digester. Synergetic effects were found when co-digesting cornmeal and cow manure, leading to higher methane yield (280 NmL gVS–1) than that (200 NmL gVS–1) calculated based on the methane potential of the individual substrates. Regarding long-term effects, the laboratory-scale semi-continuous experiments also demonstrated that the co-digestion of cornmeal and cow manure (1:1 volatile solid (VS) basis) led to a stable process reaching an organic loading rate of 3 g VS L day–1 and achieving a daily methane production of 1280.12 ± 99.4 NmL CH4/day. However, when cornmeal was investigated in mono-digestion, and the enzyme extract was directly added during semi-continuous digestion of cornmeal, volatile fatty acid (VFA) accumulation was observed, leading to a decrease in pH, and no significant enhancement of the conversion into methane was observed. © 2021 Society of Chemical Industry and John Wiley & Sons, Ltd. © 2021 Society of Chemical Industry and John Wiley & Sons, Ltd

  • 58.
    Pourbafrani, Mohammad
    et al.
    University of Borås, Faculty of Textiles, Engineering and Business.
    Forgacs, Gergely
    University of Borås, Faculty of Textiles, Engineering and Business.
    Sárvári Horváth, Ilona
    University of Borås, Faculty of Textiles, Engineering and Business.
    Taherzadeh, Mohammad J.
    University of Borås, Faculty of Textiles, Engineering and Business.
    Framställning av mångahanda biprodukter från fasta citrusrester2011Patent (Other (popular science, discussion, etc.))
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  • 59. Pourbafrani, Mohammad
    et al.
    Forgács, Gergely
    Sárvári Horváth, Ilona
    University of Borås, School of Engineering.
    Niklasson, Claes
    Taherzadeh, Mohammad J.
    University of Borås, School of Engineering.
    Production of biofuels, limonene and pectin from citrus wastes2010In: Bioresource Technology, ISSN 0960-8524, E-ISSN 1873-2976, Vol. 101, no 11, p. 4246-4250Article in journal (Refereed)
    Abstract [en]

    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. (C) 2010 Elsevier Ltd. All rights reserved.

  • 60. Purwandari, F. A.
    et al.
    Sanjaya, A. P.
    Millati, R.
    Cahyanto, M.N.
    Sárvári Horváth, Ilona
    University of Borås, School of Engineering.
    Niklasson, C.
    Taherzadeh, M.J.
    University of Borås, School of Engineering.
    Pretreatment of oil palm empty fruit bunch (OPEFB) by N-methylmorpholine-N-oxide (NMMO) for biogas production: Structural changes and digestion improvement2013In: Bioresource Technology, ISSN 0960-8524, E-ISSN 1873-2976, Vol. 128, no 1, p. 461-466Article in journal (Refereed)
    Abstract [en]

    Pretreatment of OPEFB (oil palm empty fruit bunch) by NMMO (N-methylmorpholine-N-oxide) on its subsequent digestions was investigated. The pretreatments were carried out at 90 and 120 °C for 1, 3, and 5 h in three different modes of dissolution (by 85% NMMO solution), ballooning (79% NMMO solution), and swelling (73% NMMO solution). The total solid recovery after the pretreatment was 89–94%. The pretreatment process did not have a major impact on the composition of OPEFB, other than a reduction of ash from 5.4% up to 1.3%. The best improvement in biogas production was achieved by a dissolution mode pretreatment of OPEFB, using conditions of 85% NMMO, 3 h, and 120 °C. It resulted in 0.408 Nm3/kg VS methane yield and 0.032 Nm3 CH4/kg VS/day initial methane production rate, which correspond in improving by 48% and 167% compared to the untreated OPEFB, respectively.

  • 61. Shafiei, Marzieh
    et al.
    Kabir, Maryam M.
    University of Borås, School of Engineering.
    Zilouei, Hamid
    Sárvári Horváth, Ilona
    University of Borås, School of Engineering.
    Karimi, Keikhosro
    Techno-economical study of biogas production improved by steam explosion pretreatment2013In: Bioresource Technology, ISSN 0960-8524, E-ISSN 1873-2976, Vol. 148, p. 53-60Article in journal (Refereed)
    Abstract [en]

    Economic feasibility of steam explosion pretreatment for improvement of biogas production from wheat straw and paper tube residuals was investigated. The process was simulated by Aspen plus®, and the economical feasibility of five different plant capacities was studied by Aspen Process Economic Analyzer. Total project investment of a plant using paper tube residuals or wheat straw was 63.9 or 61.8 million Euros, respectively. The manufacturing cost of raw biogas for these two feedstocks was calculated to 0.36 or 0.48 €/m3 of methane, respectively. Applying steam explosion pretreatment resulted in 13% higher total capital investment while significantly improved the economy of the biogas plant and decreased the manufacturing cost of methane by 36%. The sensitivity analysis showed that 5% improvement in the methane yield and 20% decrease in the raw material price resulted in 5.5% and 8% decrease in the manufacturing cost of methane, respectively.

  • 62.
    Sárvári Horváth, Ilona
    University of Borås, School of Engineering.
    Förbehandling öppnar nya dörrar för biogasen2009Report (Other academic)
  • 63.
    Sárvári Horváth, Ilona
    et al.
    University of Borås, School of Engineering.
    del Pilar Castillo, Maria
    Berglund Odhner, Peter
    Teghammar, Anna
    University of Borås, School of Engineering.
    Kabir, Maryam M.
    University of Borås, School of Engineering.
    Olsson, Marcus
    Ascue, Johnny
    Biogas från lignocellulosa Tekno: ekonomisk utvärdering av förbehandling med NMMO2013Report (Other academic)
    Abstract [en]

    Biogas has been identified as one of the most cost - effective renewable fuels. In order to increase biogas production, yields from traditionally substrates either need to be improved or other alternative substrates must be made available for anaerobic digestion. Cellulose and lignocellulose rich wastes are available in large amounts and have great potential to be utilized for biogas production. This project focused on the opti mization of the pretreatment conditions when using the organic solvent N - methylmorpholine - N - oxide (NMMO) to enhance the methane yield from forest residues and straw. It also focused on a techno - economic evaluation of this pre - treatment technology. NMMO has previously been shown to be effective in dissolving cellulose and, as a consequence, in increasing the methane yield during the subsequent digestion. The goal of this project was to develop a technology that increases energy production from domestic subst rates in a cost - effective and environmentally friendly way. The treatment works well at lower temperatures (90°C), which means that water from the district heating system can advantageously be used in the treatment. The results showed that treatment with NMMO at 90°C doubles the methane yield from forest residues and increases the methane yield from straw by 50 %. For the techno - economic evaluation, the base case was assumed to be a facility with a capacity of 100 000 tones forest residues/year. After a w ashing and filtration step, the treated material will be utilized in a co - digestion process where 33% of the incoming material consists of forest residues and the rest is source - sorted household waste. The scale - up, process design, simulation and calculati ons were made using the software tool Intelligen SuperPro Design ® . The total investment costs were calculated to be about 145 million €, when forest residues or straw are to be used as raw material. Costs for operation (i.e. raw materials, energy, waste ma nagement, maintenance and personnel costs) were set against the incomes from the products (i.e. methane, carbon dioxide and the lignin - rich digested residue) to see if the process was profitable. The internal return rate (IRR), a parameter that indicates w hether a process is profitable or not, indicated that evaluated processes with capacities over 50 000 tons forest residues/year are profitable. However, co - digestion of forest residues with sewage sludge instead of household waste was not profitable. Both the laboratory results and the energy and economic calculations showed that the washing and filtration step is critical for the proposed process. The energy balance calculation resulted in an EROI value of 0.5, which means that the produced methane from fo rest residues counted up only the half of the energy needed for the treatment as well as NMMO separation and recycling. It is important to separate the NMMO well after the treatment, since remaining NMMO at concentrations higher than 0.002% were found to i nhibit the subsequent digestion step. Also it was showed out to be important that the washing step operates with small amounts of water to save energy within the NMMO recovery. A rotary vacuum filtration is therefore recommended for the washing and filtrat ion step, and a mechanical vapor design is recommended for the evaporation, saving up to 70 - 90% energy compared to a conventional design. Treatment of straw with recycled instead of fresh NMMO has also been tested and equal amounts of methane were obtain ed. After a well - functioning washing and filtration step, NMMO could not be detected in the digestate residue.

  • 64.
    Sárvári Horváth, Ilona
    et al.
    University of Borås, School of Engineering.
    del Pilar Castillo, Maria
    Lorén, Anders
    Brive, Lena
    Ekendahl, Susanne
    Nordman, Roger
    Kanerot, Mija
    Förbehandlingsteknikers betydelse för ökat biogasutbyte2012Report (Other academic)
    Abstract [sv]

    Biologisk nedbrytning av organiskt avfall från hushåll och industri till biogas används redan idag. Tekniken är mycket viktig för att kunna uppnå de miljömål som vårt samhälle ställer för en hållbar utveckling. Att erhålla en ökad mängd biogas ur samma mängd substrat har en avgörande ekonomisk betydelse. Samtidigt är alternativa råvaror för biogasproduktion av stort intresse. Syftet med vår studie var att finna lämpliga förbehandlingsmetoder som öppnar molekylstrukturen hos svårnedbrytbara biopolymerer, och på så sätt göra kolet tillgängligt för mikroorganismer inom efterföljande biologisk nedbrytning och rötning till biogas.

  • 65.
    Sárvári Horváth, Ilona
    et al.
    University of Borås, Faculty of Textiles, Engineering and Business.
    del Pilar Castillo, Maria
    RISE-Process and Environmental Engineering.
    Schnürer, Anna
    University of Borås, Faculty of Textiles, Engineering and Business. Swedish University of Agricultural Sciences.
    Agnihotri, Swarnima
    Ylitervo, Päivi
    University of Borås, Faculty of Textiles, Engineering and Business.
    Edström, Mats
    RISE- Process and Environmental Engineering.
    Utilization of Straw Pellets and Briquettes as Co-Substrates at Biogas Plants2017Report (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.

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  • 66.
    Sárvári Horváth, Ilona
    et al.
    University of Borås, Faculty of Textiles, Engineering and Business.
    Tabatabaei, Meisam
    Microbial Biotechnology Department, Agricultural Biotechnology Research Institute of Iran (ABRII.
    Karimi, Keikhosro
    Kumar, Rajeev
    6 Center for Environmental Research and Technology (CE-CERT), Bourns College of Engineering, University of California.
    Recent updates on biogas production-a review2016In: Biofuel Research Journal, Vol. 3, no 2, p. 394-402Article in journal (Refereed)
    Abstract [en]

    One of the greatest challenges facing the societies now and in the future is the reduction of green house gas emissions and thus preventing the climate change. It is therefore important to replace fossil fuels with renewable sources, such as biogas. Biogas can be produced from various organic waste streams or as a byproduct from industrial processes. Beside energy production, the degradation of organic waste through anaerobic digestion offers other advantages, such as the prevention of odor release and the decrease of pathogens. Moreover, the nutrient rich digested residues can be utilized as fertilizer for recycling the nutrients back to the fields. However, the amount of organic materials currently available for biogas production is limited and new substrates as well as new effective technologies are therefore needed to facilitate the growth of the biogas industry all over the world. Hence, major developments have been made during the last decades regarding the utilization of lignocellulosic biomass, the development of high rate systems, and the application of membrane technologies within the anaerobic digestion process in order to overcome the shortcomings encountered. The degradation of organic material requires a synchronized action of different groups of microorganisms with different metabolic capacities. Recent developments in molecular biology techniques have provided the research community with a valuable tool for improved understanding of this complex microbiological system, which in turn could help optimize and control the process in an effective way in the future.

  • 67. Tabatabaei, M.
    et al.
    Karimi, K.
    Kumar, R.
    Sárvári Horváth, Ilona
    University of Borås, Faculty of Textiles, Engineering and Business.
    Renewable energy and alternative fuel technologies2015In: BioMed Research International, article id 245935Article in journal (Refereed)
  • 68.
    Tabatabaei, Meisam
    et al.
    Microbial Biotechnology Department, Agricultural Biotechnology Research Institute of Iran (ABRII.
    Karimi, Keikhosro
    Department of Chemical Engineering, Isfahan University of Technology.
    Kumar, Rajeev
    6 Center for Environmental Research and Technology (CE-CERT), Bourns College of Engineering, University of California.
    Sárvári Horváth, Ilona
    University of Borås, Faculty of Textiles, Engineering and Business.
    Renewable Energy and Alternative Fuel Technologies2015In: BioMed Research International, ISSN 2314-6133, E-ISSN 2314-6141Article in journal (Other academic)
  • 69.
    Tabatabaei, Meisam
    et al.
    Microbial Biotechnology Department, Agricultural Biotechnology Research Institute of Iran (ABRII.
    Karimi, Keikhosro
    Department of Chemical Engineering, Isfahan University of Technology.
    Sárvári Horváth, Ilona
    University of Borås, Faculty of Textiles, Engineering and Business.
    Kumar, Rajeev
    6 Center for Environmental Research and Technology (CE-CERT), Bourns College of Engineering, University of California.
    Recent trends in biodiesel production2015In: Biofuel Research Journal, E-ISSN 2292-8782, Vol. 2, no 3, p. 258-267Article in journal (Refereed)
    Abstract [en]

    This article fully discusses the recent trends in the production of one the most attractive types of biofuels, i.e., biodiesel.with a focus on the existing obstacles for its large scale production. Moreover, recent innovations/improvements under three categories of upstream, mainstream, and downstream processes are also presented. Upstream strategies are mainly focused on seeking more sustainable oil feedstocks and/or enhancing the quality of waste-oriented ones. The mainstream strategies section highlights the numerous attempts made to enhance agitation efficiency including chemical and/or mechanical strategies. Finally, the innovative downstream strategies basically dealing with 1) separation of biodiesel and glycerin, 2) purification of biodiesel and glycerin, and 3) improving the characteristics of the produced fuel, are comprehensively reviewed.

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  • 70.
    Teghammar, A.
    et al.
    University of Borås, School of Engineering. University of Borås, Faculty of Textiles, Engineering and Business.
    Chandra, R.
    Saddler, J.N.
    Taherzadeh, Mohammad J
    University of Borås, Faculty of Textiles, Engineering and Business.
    Sárvári Horváth, Ilona
    University of Borås, Faculty of Textiles, Engineering and Business.
    Substrate characteristic analysis for anaerobic digestion: A study on rice and triticale straw2012In: BioResources, ISSN 1930-2126, E-ISSN 1930-2126, Vol. 7, no 3, p. 3921-3934Article in journal (Refereed)
    Abstract [en]

    Different substrate characteristic analyses have been studied on rice and triticale straw pretreated with NMMO (N-methylmorpholine-N-oxide) prior to biogas production. Simons’ stain, water retention value (WRV), and enzymatic adsorption were used to measure the change in the accessible surface area of the lignocellulosic substrates. FTIR was used to measure the change in cellulosic crystallinity and Time-of-Flight-Secondary-Ion-Spectroscopy (ToF-SIMS) to measure the ratio of cellulose to lignin on the sample surface. All methods showed increased accessible surface area and a decrease in crystallinity after the pretreatments. These qualities were linked to improved biogas production. In the future, the tested methods could replace the time-consuming methane potential analysis to predict the methane production of lignocellulosic materials. Simons’ stain, enzymatic adsorption, and crystallinity measurement by FTIR can be regarded as the recommended methods for the prediction of the improved biogas production as a result of the pretreatment.

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  • 71.
    Teghammar, A.
    et al.
    University of Borås, School of Engineering.
    del Pilar Castillo, M.
    Ascue, J.
    Niklasson, C.
    Sárvári Horváth, Ilona
    University of Borås, School of Engineering.
    Improved Anaerobic Digestion by the addition of paper Tube residuals: Pretreatment, Stabilizing and Synergetic effects2013In: Energy & Fuels, ISSN 0887-0624, E-ISSN 1520-5029, Vol. 27, no 1, p. 277-284Article in journal (Refereed)
    Abstract [en]

    This study deals with the addition of paper tube residuals to a nitrogen rich mixture of organic waste obtained from industrial and municipal activities. This nitrogen rich mixture, called buffer tank substrate (BTS) in the following text, is utilized in a large scale biogas plant. The effects were investigated in semi-continuous co-digestion processes and variations in operational conditions were studied. The addition of paper tubes had stabilizing effects and prevented the failure of the process and made it possible to decrease the hydraulic retention time from 25 to 20 days. Furthermore, synergetic effects were found, with 15-34% higher methane yields, when paper tubes were co-digested with BTS. Moreover, steam explosion pretreatment of the paper tube waste with the addition of 0-2% NaOH were evaluated by batch digestion experiments. Increasing the NaOH concentrations used in the pretreatment resulted in increasing methane yields, with the highest of 403 Nml/gVS methane production corresponding to an increase by 50% compared to that when untreated paper was digested (268 Nml/gVS). The long-term effects of this best pretreatment were further investigated by continuous co-digestion experiments leading to higher methane yield when pretreated paper tubes were utilized in the co-digestion process compared to untreated.

  • 72.
    Teghammar, A.
    et al.
    University of Borås, School of Engineering.
    Forgacs, G.
    University of Borås, School of Engineering.
    Sárvári Horváth, Ilona
    University of Borås, School of Engineering.
    Taherzadeh, M.J.
    University of Borås, School of Engineering.
    Techno-economic study of NMMO pretreatment and biogas production from forest residues2014In: Applied Energy, ISSN 0306-2619, E-ISSN 1872-9118, Vol. 116, p. 125-133Article in journal (Refereed)
    Abstract [en]

    Biogas is nowadays getting more attention as a means for converting wastes and lignocelluloses to green fuels for cars and electricity production. The process of biogas production from N-methylmorpholine oxide (NMMO) pretreated forest residues used in a co-digestion process was economically evaluated. The co-digestion occurs together with the organic fraction of municipal solid waste (OFMSW). The process simulated the milling of the lignocelluloses, NMMO pretreatment unit, washing and filtration of the feedstock, followed by an anaerobic co-digestion, upgrading of the biogas and de-watering of the digestate. The process also took into consideration the utilization of 100,000 DW (dried weight) tons of forest residues and 200,000 DW tons of OFMSW per year. It resulted in an internal rate of return (IRR) of 24.14% prior to taxes, which might be attractive economically. The cost of the chemical NMMO treatment was regarded as the most challenging operating cost, followed by the evaporation of the washing water. Sensitivity analysis was performed on different plant size capacities, treating and digesting between 25,000 and 400,000 DW tons forest residues per year. It shows that the minimum plant capacity of 50,000 DW tons forest residues per year is financially viable. Moreover, different co-digestion scenarios were evaluated. The co-digestion of forest residues together with sewage sludge instead of OFMSW, and the digestion of forest residues only were shown to be non-feasible solutions with too low IRR. Furthermore, biogas production from forest residues was compared with the energy produced during combustion.

  • 73.
    Teghammar, A.
    et al.
    University of Borås, School of Engineering.
    Talebnia, Farid
    University of Borås, School of Engineering.
    Sárvári Horváth, Ilona
    University of Borås, School of Engineering.
    Taherzadeh, M.J.
    University of Borås, School of Engineering.
    Biogas or ethanol from paper tube residuals?2008In: Proceeding 2nd International Simposium on Energy from Biomass and Waste, 17-20 Nov., Venice, Italy, 2008Conference paper (Refereed)
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  • 74.
    Teghammar, Anna
    et al.
    University of Borås, School of Engineering.
    Karimi, Keikhosro
    University of Borås, School of Engineering.
    Sárvári Horváth, Ilona
    University of Borås, School of Engineering.
    Saddler, Jack
    Taherzadeh, Mohammad
    University of Borås, School of Engineering.
    Pretreatment of soft wood spruce and triticale straw by NMMO for enhanced biogas production2010Conference paper (Other academic)
  • 75.
    Teghammar, Anna
    et al.
    University of Borås, School of Engineering.
    Karimi, Keikhosro
    University of Borås, School of Engineering.
    Sárvári Horváth, Ilona
    University of Borås, School of Engineering.
    Taherzadeh, Mohammad
    University of Borås, School of Engineering.
    Enhanced biogas production from rice straw, triticale straw and softwood spruce by NMMO pretreatment2012In: Biomass and Bioenergy, ISSN 0961-9534, E-ISSN 1873-2909, Vol. 36, p. 116-120Article in journal (Refereed)
    Abstract [en]

    Softwoodspruce (chips and milled), ricestraw and triticale (a hybrid of rye and wheat) straw, were pretreated with N-methylmorpholine-N-oxide (NMMO or NMO) prior to anaerobic digestion to produce biogas. The pretreatments were performed at 130 °C for 1–15 h, and the digestions continued for six weeks. The digestions of untreated chips (10 mm) and milled (<1 mm) spruce, ricestraw and triticalestraw resulted in 11, 66, 22 and 30 Nml CH4/g raw material. However, the pretreatments have improved these methane yields by 400–1200%. The best digestion results of the pretreated chips and milled spruce, ricestraw and triticalestraw were 125, 245, 157 and 203 Nml CH4/g raw material (or 202, 395, 328 and 362 Nml CH4/g carbohydrates) respectively, which correspond to 49, 95, 79 and 87% of the theoretical yield of 415 Nml CH4/g carbohydrates. Although the experiments were carried out for six weeks, one and a half weeks was enough to digest the materials.

  • 76.
    Teghammar, Anna
    et al.
    University of Borås, School of Engineering.
    Yngvesson, J.
    Lundin, M.
    Taherzadeh, Mohammad
    University of Borås, School of Engineering.
    Sárvári Horváth, Ilona
    University of Borås, School of Engineering.
    Pretreatment of paper tube residuals for improved biogas production2010In: Bioresource Technology, ISSN 0960-8524, E-ISSN 1873-2976, Vol. 101, no 4, p. 1206-1212Article in journal (Refereed)
    Abstract [en]

    Paper tube residuals, which are lignocellulosic wastes, have been studied as substrate for biogas (methane) production. Steam explosion and nonexplosive hydrothermal pretreatment, in combination with sodium hydroxide and/or hydrogen peroxide, have been used to improve the biogas production. The treatment conditions of temperature, time and addition of NaOH and H2O2 were statistically evaluated for methane production. Explosive pretreatment was more successful than the nonexplosive method, and gave the best results at 220 °C, 10 min, with addition of both 2% NaOH and 2% H2O2. Digestion of the pretreated materials at these conditions yielded 493 N ml/g VS methane which was 107% more than the untreated materials. In addition, the initial digestion rate was improved by 132% compared to the untreated samples. The addition of NaOH was, besides the explosion effect, the most important factor to improve the biogas production.

  • 77.
    Wainaina, Steven
    et al.
    University of Borås, Faculty of Textiles, Engineering and Business.
    Mohsen, Parchami
    University of Borås, Faculty of Textiles, Engineering and Business.
    Mahboubi, Amir
    University of Borås, Faculty of Textiles, Engineering and Business.
    Sárvári Horváth, Ilona
    University of Borås, Faculty of Textiles, Engineering and Business.
    Taherzadeh, Mohammad J
    University of Borås, Faculty of Textiles, Engineering and Business.
    Food waste-derived volatile fatty acids platform using an immersed membrane bioreactor2018In: Bioresource Technology, ISSN 0960-8524, E-ISSN 1873-2976, article id S0960-8524(18)31650-XArticle in journal (Refereed)
    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.

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  • 78.
    Wainaina, Steven
    et al.
    University of Borås, Faculty of Textiles, Engineering and Business.
    Mukesh Kumar, Awasthi
    University of Borås, Faculty of Textiles, Engineering and Business.
    Sárvári Horváth, Ilona
    University of Borås, Faculty of Textiles, Engineering and Business.
    Taherzadeh, Mohammad J
    University of Borås, Faculty of Textiles, Engineering and Business.
    Anaerobic digestion of food waste to volatile fatty acids and hydrogen at high organic loading rates in immersed membrane bioreactors2020In: Renewable energy, ISSN 0960-1481, E-ISSN 1879-0682Article in journal (Refereed)
    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.

  • 79. Wainaina, Steven
    et al.
    Sárvári Horváth, Ilona
    University of Borås, Faculty of Textiles, Engineering and Business.
    Taherzadeh, Mohammad J
    University of Borås, Faculty of Textiles, Engineering and Business.
    Biochemicals from food waste and recalcitrant biomass via syngas fermentation: A review2017In: Bioresource Technology, ISSN 0960-8524, E-ISSN 1873-2976Article in journal (Refereed)
    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)]

  • 80.
    Yangin-Gomec, Cigdem
    et al.
    Department of Environmental Engineering, Istanbul Technical University, Maslak, 34469 Istanbul, Turkey.
    Agnihotri, Swarnima
    University of Borås, Faculty of Textiles, Engineering and Business. Swedish Centre for Resource Recovery.
    Ylitervo, Päivi
    University of Borås, Faculty of Textiles, Engineering and Business. Swedish Centre for Resource Recovery.
    Sárvári Horváth, Ilona
    University of Borås, Faculty of Textiles, Engineering and Business. Swedish Centre for Resource Recovery.
    Assessment of Microbial Diversity during Thermophilic Anaerobic Co-Digestion for an Effective Valorization of Food Waste and Wheat Straw2023In: Energies, E-ISSN 1996-1073, Vol. 16, no 1, article id 15Article in journal (Refereed)
    Abstract [en]

    In this study, predominant bacterial and archaeal populations and their roles during anaerobic mono-digestion of food waste (FW) and co-digestion of FW with straw pellets (SP) at thermophilic temperature (53 ± 1 °C) were assessed by Next Generation Sequencing (NGS) analysis at organic loading rates (OLRs) of 3.0 and 7.0 gVS/L/d. Depending on the seed; results revealed that Firmicutes, Bacteroidetes, and Proteobacteria were, respectively the most prevalent bacterial phyla at both OLRs investigated. On the other hand, Euryarchaeota was dominated by methanogens playing crucial role in biogas production and correlated mainly with the activities of Methanobacteria and Methanomicrobia at class level. Acetoclastic Methanosaetae was the predominant genus at OLR = 3.0 gVS/L/d; however, shared the same predominance with hydrogenotrophic methanogens Methanospirillium at the highest OLR. Although no clear effect in response to straw addition at OLR of 3.0 gVS/L/d could be seen in terms of methanogenic archaea at genus level, hydrogenotrophic methanogens revealed some shift from Methanobacterium to Methanospirillium at higher OLR. Nevertheless, no prominent microbial shift in the presence of wheat straw at increased OLR was likely due to adapted inoculation at start-up which was also demonstrated by relatively stable biogas yields during co-digestion.

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  • 81.
    Yangin-Gomec, Cigdem
    et al.
    Department of Environmental Engineering, Istanbul Technical University, Maslak, 34469 Istanbul, Turkey.
    Sárvári Horváth, Ilona
    University of Borås, Faculty of Textiles, Engineering and Business.
    Martín, Carlos
    Department of Biotechnology, Inland Norway University of Applied Sciences, N-2317 Hamar, Norway; Department of Chemistry, Umeå University, SE-901 87 Umeå, Sweden.
    Energy Production from Biomass Valorization2023In: Energies, E-ISSN 1996-1073, Vol. 16, no 11, article id 4300Article in journal (Refereed)
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  • 82.
    Yarsur, E.
    et al.
    Department of Environmental Engineering, İstanbul Technical University, İstanbul, Turkey.
    Sárvári Horváth, Ilona
    University of Borås, Faculty of Textiles, Engineering and Business.
    Yangin Gömeç, Ç.
    Department of Environmental Engineering, İstanbul Technical University, İstanbul, Turkey.
    Methane yield of paper industry waste in the presence of two compounds from alcohol and aldehyde groups during thermophilic anaerobic digestion2023In: Environmental Research and Technology, Yildiz Technical University , 2023, no 1, p. 54-59Conference paper (Refereed)
    Abstract [en]

    In this study, effect of two chemical compounds (i.e., 1-octanol and hexanal) respectively from the alcohol and aldehyde groups on thermophilic (55±2 °C) anaerobic process digesting the waste produced at a paper industry was investigated. In this scope, possible inhibition was monitored by the cumulative methane (CH4) yields in the batch reactors digesting the paper waste as the feedstock at concentrations of 0.005%, 0.05%, and 0.5% for each compound. Comparing the effects of the two different groups with the control reactor having only the paper waste as the substrate, the results revealed that adding 1-octanol and hexanal up to 0.05% concentrations had some synergistic effect on biogas yield (i.e., from 3% to 12% enhancement). Accordingly, the highest methane yields were 550 and 567 mL/g-VSfed, respectively on average in the presence of 1-octanol and hexanal at a concentration of 0.05% while the cumulative methane yield was observed as 490 mL/g-VSfed for the control reactor. With the exception of 1-octanol at 0.5%, adding both compounds at each investigated concentration was beneficial for the digestion in the batch process. Therefore, the selected alcohol and aldehyde sources did not cause the expected detrimental effect on the methanogens even at the maximum amounts added in this study. Nevertheless, since the effect of the chemical compounds on methane generation has been generally concentration-dependent, the toxic effects of 1-octanol and hexanal would be better observed at higher concentrations (>0.5%), especially when their threshold levels are exceeded in anaerobic reactors digesting paper wastes. 

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