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  • 1.
    Oliveira, Helena Rodrigues
    et al.
    Univ Fed Rio de Janeiro, Brazil.
    Kozlowsky-Suzuki, Betina
    Univ Fed Estado Rio de Janeiro, Brazil.
    Björn, Annika
    Linköping University, Department of Thematic Studies, Tema Environmental Change. Linköping University, Faculty of Arts and Sciences. Linköping University, Biogas Solutions Research Center.
    Shakeri Yekta, Sepehr
    Linköping University, Department of Thematic Studies, Tema Environmental Change. Linköping University, Faculty of Arts and Sciences. Linköping University, Biogas Solutions Research Center.
    Caetano, Cristiane Fonseca
    Univ Fed Rio de Janeiro, Brazil.
    Pinheiro, Erika Flavia Machado
    Univ Fed Rural Rio de Janeiro, Brazil.
    Marotta, Humberto
    Univ Fed Fluminense, Brazil.
    Bassin, Joao Paulo
    Univ Fed Rio de Janeiro, Brazil.
    Oliveira, Luciano
    Environm Dept, Brazil.
    Reis, Marcelo de Miranda
    Inst Mil Engn IME, Brazil.
    Schultz, Mario Sergio
    Univ Fed Rio de Janeiro, Brazil.
    Mangiavacchi, Norberto
    Univ Estado Rio De Janeiro, Brazil.
    Ferreira-Leitao, Viridiana Santana
    Minist Sci Technol & Innovat MCTI, Brazil; Univ Fed Rio de Janeiro, Brazil.
    Fasheun, Daniel Oluwagbotemi
    Minist Sci Technol & Innovat MCTI, Brazil; Univ Fed Rio de Janeiro, Brazil.
    Silva, Fernanda Geraldo
    Univ Estado Rio De Janeiro, Brazil.
    Taveira, Igor
    Univ Fed Rio de Janeiro, Brazil.
    Alves, Ingrid Roberta de Franca Soares
    Inst Mil Engn IME, Brazil.
    Castro, Julia
    Univ Fed Rio de Janeiro, Brazil.
    Durao, Juliana Velloso
    Environm Dept, Brazil.
    Guimaraes, Juliana
    Univ Fed Rio de Janeiro, Brazil.
    Rocha, Mariana Erthal
    Univ Estado Rio De Janeiro, Brazil.
    Tomasini, Marina
    Minist Sci Technol & Innovat MCTI, Brazil; Univ Fed Rio de Janeiro, Brazil.
    Martins, Pedro Vitor de Oliveira
    Minist Sci Technol & Innovat MCTI, Brazil.
    Presciliano, Rogerio
    Univ Fed Rio de Janeiro, Brazil.
    Santos, Stella Buback dos
    Minist Sci Technol & Innovat MCTI, Brazil; Univ Fed Rio de Janeiro, Brazil.
    Faria, Tamires Marques
    Univ Sao Paulo, Brazil.
    Correa, Tarcisio
    Univ Fed Rio de Janeiro, Brazil.
    Linde, Thiago de Nuno Mendes Pery de
    Univ Fed Fluminense, Brazil.
    Abreu, Fernanda
    Univ Fed Rio de Janeiro, Brazil; Univ Fed Rio de Janeiro, Brazil.
    Enrich Prast, Alex
    Linköping University, Department of Thematic Studies, Tema Environmental Change. Linköping University, Faculty of Arts and Sciences. Linköping University, Biogas Solutions Research Center. Univ Fed Rio de Janeiro, Brazil; Fed Univ Sao Paulo IMar UNIFESP, Brazil.
    Biogas potential of biowaste: A case study in the state of Rio de Janeiro, Brazil2024In: Renewable energy, ISSN 0960-1481, E-ISSN 1879-0682, Vol. 221, article id 119751Article in journal (Refereed)
    Abstract [en]

    Anaerobic digestion has been widely applied for waste treatment, renewable energy generation , biofertilizer production. The biogas potential in Brazil is sizable, but the state of Rio de Janeiro is largely dependent on fossil fuels , there is a lack of biogas potential assessments in the state. Thus, this study evaluated biomethane, electricity and biofertilizer potentials in the region. Three different scenarios of biomass supply were considered for four major biowaste streams: sewage sludge; cattle manure; sugarcane processing waste; and food waste. Biomethane generation from the assessed sources could reach 0.6-1.3 billion Nm(3) year(-1), corresponding to 1,768-3,961 GWh year(-1) of electricity , 1.6-3.3 million Mg year- 1 of biofertilizer. Cattle manure was responsible for 73-84% of the projected biomethane production, presenting an opportunity to reduce the sig-nificant emissions from livestock farming. The estimated biofertilizer production could meet the demands of the state , the produced electricity could offset up to 10% of the demand. The gas grid could facilitate the dis-tribution of upgraded biomethane, and 10-22% of the natural gas demand could be met. The findings of this work highlight the high potential for biogas generation in Rio de Janeiro, which is up to seven times larger than the current production.

  • 2.
    Anacleto, Thuane Mendes
    et al.
    Univ Fed Rio de Janeiro, Brazil; Univ Fed Rio de Janeiro, Brazil.
    Kozlowsky-Suzuki, Betina
    Fed Univ State Rio De Janeiro, Brazil; Fed Univ State Rio De Janeiro, Brazil; Fed Univ State Rio De Janeiro, Brazil.
    Björn, Annika
    Linköping University, Department of Thematic Studies, Tema Environmental Change. Linköping University, Faculty of Arts and Sciences. Linköping University, Biogas Solutions Research Center.
    Shakeri Yekta, Sepehr
    Linköping University, Department of Thematic Studies, Tema Environmental Change. Linköping University, Faculty of Arts and Sciences. Linköping University, Biogas Solutions Research Center.
    Masuda, Laura Shizue Moriga
    Ch Mendes Inst Biodivers Conservat ICMBio, Brazil.
    de Oliveira, Vinicius Peruzzi
    Univ Fed Rio de Janeiro, Brazil.
    Enrich Prast, Alex
    Linköping University, Department of Thematic Studies, Tema Environmental Change. Linköping University, Faculty of Arts and Sciences. Linköping University, Biogas Solutions Research Center. Univ Fed Rio de Janeiro, Brazil; Fed Univ Sao Paulo IMar UNIFESP, Brazil.
    Methane yield response to pretreatment is dependent on substrate chemical composition: a meta-analysis on anaerobic digestion systems2024In: Scientific Reports, E-ISSN 2045-2322, Vol. 14, no 1, article id 1240Article in journal (Refereed)
    Abstract [en]

    Proper pretreatment of organic residues prior to anaerobic digestion (AD) can maximize global biogas production from varying sources without increasing the amount of digestate, contributing to global decarbonization goals. However, the efficiency of pretreatments applied on varying organic streams is poorly assessed. Thus, we performed a meta-analysis on AD studies to evaluate the efficiencies of pretreatments with respect to biogas production measured as methane yield. Based on 1374 observations our analysis shows that pretreatment efficiency is dependent on substrate chemical dominance. Grouping substrates by chemical composition e.g., lignocellulosic-, protein- and lipid-rich dominance helps to highlight the appropriate choice of pretreatment that supports maximum substrate degradation and more efficient conversion to biogas. Methane yield can undergo an impactful increase compared to untreated controls if proper pretreatment of substrates of a given chemical dominance is applied. Non-significant or even adverse effects on AD are, however, observed when the substrate chemical dominance is disregarded.

  • 3.
    Safaric, Luka
    et al.
    Linköping University, Department of Thematic Studies, Tema Environmental Change. Linköping University, Faculty of Arts and Sciences. Linköping University, Biogas Solutions Research Center.
    Björn (Fredriksson), Annika
    Linköping University, Department of Thematic Studies, Tema Environmental Change. Linköping University, Faculty of Arts and Sciences. Linköping University, Biogas Solutions Research Center.
    Svensson, Bo H
    Linköping University, Department of Thematic Studies, Tema Environmental Change. Linköping University, Faculty of Medicine and Health Sciences. Linköping University, Biogas Solutions Research Center. Linköping University, Faculty of Arts and Sciences.
    Bastviken, David
    Linköping University, Department of Thematic Studies, Tema Environmental Change. Linköping University, Faculty of Arts and Sciences.
    Shakeri Yekta, Sepehr
    Linköping University, Department of Thematic Studies, Tema Environmental Change. Linköping University, Faculty of Arts and Sciences. Linköping University, Biogas Solutions Research Center.
    Rheology, Micronutrients, and Process Disturbance in Continuous Stirred-Tank Biogas Reactors2023In: Industrial & Engineering Chemistry Research, ISSN 0888-5885, E-ISSN 1520-5045, Vol. 62, no 43, p. 17372-17384Article, review/survey (Refereed)
    Abstract [en]

    Anaerobic digestion (AD) is an important technology for achieving sustainability, but it faces challenges in meeting rising production demands while remaining economically profitable. One difficulty is the lack of a comprehensive understanding of the many interactions within anaerobic digesters, which makes it challenging to fully optimize them. This is particularly notable when considering the interlinked dynamics between micronutrient availability and fluid behavior. This study addresses this gap by focusing on key operational parameters affecting the efficiency of the process in continuous stirred-tank biogas reactors, which are the most used AD technology today. It does so by proposing and evaluating a novel conceptual model of the mechanisms behind how different parts of AD processes interact upon disturbance, highlighting strategies for preventing process failure. This article aims to improve our understanding of the complexity of AD biotechnology and to provide a starting point for developing advanced strategies for operational optimization.

  • 4.
    Liu, Tong
    et al.
    Linköping University, Biogas Research Center. Swedish Univ Agr Sci, Sweden.
    Li, Xiaoxiao
    Linköping University, Department of Thematic Studies, Tema Environmental Change. Linköping University, Faculty of Arts and Sciences. Linköping University, Biogas Research Center. Shanghai Univ Tradit Chinese Med, Peoples R China; East China Univ Sci & Technol, Peoples R China; East China Univ Sci & Technol, Peoples R China.
    Shakeri Yekta, Sepehr
    Linköping University, Department of Thematic Studies, Tema Environmental Change. Linköping University, Faculty of Arts and Sciences. Linköping University, Biogas Research Center.
    Björn, Annika
    Linköping University, Department of Thematic Studies, Tema Environmental Change. Linköping University, Faculty of Arts and Sciences. Linköping University, Biogas Research Center.
    Mu, Bo-Zhong
    East China Univ Sci & Technol, Peoples R China; East China Univ Sci & Technol, Peoples R China.
    Masuda, Laura Shizue Moriga
    Univ Fed Rio de Janeiro UFRJ, Brazil.
    Schnürer, Anna
    Linköping University, Department of Thematic Studies, Tema Environmental Change. Linköping University, Faculty of Arts and Sciences. Linköping University, Biogas Research Center. Swedish Univ Agr Sci, Sweden.
    Enrich Prast, Alex
    Linköping University, Department of Thematic Studies, Tema Environmental Change. Linköping University, Faculty of Arts and Sciences. Linköping University, Biogas Research Center. Univ Fed Rio de Janeiro UFRJ, Brazil.
    Absence of oxygen effect on microbial structure and methane production during drying and rewetting events2022In: Scientific Reports, E-ISSN 2045-2322, Vol. 12, no 1, article id 16570Article in journal (Refereed)
    Abstract [en]

    Natural environments with frequent drainage experience drying and rewetting events that impose fluctuations in water availability and oxygen exposure. These relatively dramatic cycles profoundly impact microbial activity in the environment and subsequent emissions of methane and carbon dioxide. In this study, we mimicked drying and rewetting events by submitting methanogenic communities from strictly anaerobic environments (anaerobic digestors) with different phylogenetic structures to consecutive desiccation events under aerobic (air) and anaerobic (nitrogen) conditions followed by rewetting. We showed that methane production quickly recovered after each rewetting, and surprisingly, no significant difference was observed between the effects of the aerobic or anaerobic desiccation events. There was a slight change in the microbial community structure and a decrease in methane production rates after consecutive drying and rewetting, which can be attributed to a depletion of the pool of available organic matter or the inhibition of the methanogenic communities. These observations indicate that in comparison to the drying and rewetting events or oxygen exposure, the initial phylogenetic structure and the organic matter quantity and quality exhibited a stronger influence on the methanogenic communities and overall microbial community responses. These results change the current paradigm of the sensitivity of strict anaerobic microorganisms to oxygen exposure.

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  • 5.
    Ekstrand, Eva-Maria
    et al.
    Linköping University, Department of Thematic Studies, Tema Environmental Change. Linköping University, Faculty of Arts and Sciences. Linköping University, Biogas Research Center.
    Björn (Fredriksson), Annika
    Linköping University, Department of Thematic Studies, Tema Environmental Change. Linköping University, Faculty of Arts and Sciences. Linköping University, Biogas Research Center.
    Karlsson, Anna
    Linköping University, Biogas Research Center. Scandinavian Biogas Fuels AB, Stockholm, Sweden.
    Schnürer, Anna
    Linköping University, Department of Thematic Studies, Tema Environmental Change. Linköping University, Faculty of Arts and Sciences. Linköping University, Biogas Research Center. Department of Molecular Sciences, Swedish University of Agricultural Sciences, Uppsala BioCenter, Uppsala, Sweden.
    Kanders, Linda
    Linköping University, Biogas Research Center. Purac AB, Lund, Sweden.
    Shakeri Yekta, Sepher
    Linköping University, Department of Thematic Studies, Tema Environmental Change. Linköping University, Faculty of Arts and Sciences. Linköping University, Biogas Research Center.
    Karlsson, Martin
    Linköping University, Department of Physics, Chemistry and Biology, Chemistry. Linköping University, Faculty of Science & Engineering.
    Moestedt, Jan
    Linköping University, Department of Thematic Studies, Tema Environmental Change. Linköping University, Faculty of Arts and Sciences. Linköping University, Biogas Research Center. Department of Biogas R&D, Tekniska verken i Linköping AB, Linköping, Sweden.
    Identifying targets for increased biogasproduction through chemical and organicmatter characterization of digestate from full‑scale biogas plants: what remains and why?2022In: Biotechnology for Biofuels and Bioproducts, E-ISSN 2731-3654, Vol. 15, no 1, article id 16Article in journal (Refereed)
    Abstract [en]

    Background: This study examines the destiny of macromolecules in different full-scale biogas processes. From previousstudies it is clear that the residual organic matter in outgoing digestates can have significant biogas potential,but the factors dictating the size and composition of this residual fraction and how they correlate with the residualmethane potential (RMP) are not fully understood. The aim of this study was to generate additional knowledge of thecomposition of residual digestate fractions and to understand how they correlate with various operational and chemicalparameters. The organic composition of both the substrates and digestates from nine biogas plants operating onfood waste, sewage sludge, or agricultural waste was characterized and the residual organic fractions were linked tosubstrate type, trace metal content, ammonia concentration, operational parameters, RMP, and enzyme activity.

    Results: Carbohydrates represented the largest fraction of the total VS (32–68%) in most substrates. However, inthe digestates protein was instead the most abundant residual macromolecule in almost all plants (3–21 g/kg). Thedegradation efficiency of proteins generally lower (28–79%) compared to carbohydrates (67–94%) and fats (86–91%).High residual protein content was coupled to recalcitrant protein fractions and microbial biomass, either from thesubstrate or formed in the degradation process. Co-digesting sewage sludge with fat increased the protein degradationefficiency with 18%, possibly through a priming mechanism where addition of easily degradable substrates alsotriggers the degradation of more complex fractions. In this study, high residual methane production (> 140 L CH4/kgVS) was firstly coupled to operation at unstable process conditions caused mainly by ammonia inhibition (0.74 mgNH3-N/kg) and/or trace element deficiency and, secondly, to short hydraulic retention time (HRT) (55 days) relative tothe slow digestion of agricultural waste and manure.

    Conclusions: Operation at unstable conditions was one reason for the high residual macromolecule content andhigh RMP. The outgoing protein content was relatively high in all digesters and improving the degradation of proteinsrepresents one important way to increase the VS reduction and methane production in biogas plants. Post-treatment

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  • 6.
    Perman, Ebba
    et al.
    Linköping University, Biogas Research Center. Department of Molecular Sciences, Swedish University of Agricultural Sciences, Uppsala, Sweden.
    Schnürer, Anna
    Linköping University, Biogas Research Center. Department of Molecular Sciences, Swedish University of Agricultural Sciences, Uppsala, Sweden.
    Björn, Annika
    Linköping University, Department of Thematic Studies, Tema Environmental Change. Linköping University, Faculty of Arts and Sciences. Linköping University, Biogas Research Center.
    Moestedt, Jan
    Linköping University, Department of Thematic Studies, Tema Environmental Change. Linköping University, Faculty of Arts and Sciences. Linköping University, Biogas Research Center. Tekniska Verken i Linköping AB, Linköping, Sweden.
    Serial anaerobic digestion improves protein degradation and biogas production from mixed food waste2022In: Biomass and Bioenergy, ISSN 0961-9534, E-ISSN 1873-2909, Vol. 161, article id 106478Article in journal (Refereed)
    Abstract [en]

    Optimization of the biogas generation process is important to achieve efficient degradation and high methane yield, and to reduce methane emissions from the digestate. In this study, serial digester systems with two or three biogas reactors were compared with a single reactor, with the aim of improving degree of degradation and methane yield from food waste and assessing adaptation of microbial communities to different reactor steps. All systems had the same total organic load (2.4 g VS/(L d)) and hydraulic retention time (55 days). Serial systems increased methane yield by >5% compared with the single reactor, with the majority of the methane being obtained from the first-step reactors. Improved protein degradation was also obtained in serial systems, with >20% lower outgoing protein concentration compared with the single reactor and increasing NH4+-N concentration with every reactor step. This resulted in separation of high ammonia (>384 mg NH3-N/L) levels from the main methane production, reducing the risk of methanogen inhibition. Methanosarcina dominated the methanogenic community in all reactors, but increases in the hydrogenotrophic genera Methanoculleus and Methanobacterium were observed at higher ammonia levels. Potential syntrophic acetate-oxidizing bacteria, such as MBA03 and Dethiobacteraceae, followed the same trend as the hydrogenotrophic methanogens. Phylum Bacteroidota family Paludibacteraceae was highly abundant in the first steps and then decreased abruptly, potentially linked to an observed decrease in degradation in the last-step reactors. Nevertheless, the results indicated a trend of increasing relative abundance of the potentially proteolytic genera Proteiniphilum and Fastidiosipila with successive reactor steps.

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  • 7.
    Nordell, Erik
    et al.
    Linköping University, Biogas Research Center. Tekniska Verken i Linköping AB.
    Björn (Fredriksson), Annika
    Linköping University, Department of Thematic Studies, Tema Environmental Change. Linköping University, Faculty of Arts and Sciences. Linköping University, Biogas Research Center.
    Waern, Sandra
    Linköping University, Biogas Research Center. Tekniska Verken i Linköping AB.
    Shakeri Yekta, Sepehr
    Linköping University, Department of Thematic Studies, Tema Environmental Change. Linköping University, Faculty of Arts and Sciences. Linköping University, Biogas Research Center.
    Sundgren, Ingrid
    Linköping University, Department of Thematic Studies, Tema Environmental Change. Linköping University, Faculty of Arts and Sciences. Linköping University, Biogas Research Center.
    Moestedt, Jan
    Linköping University, Department of Thematic Studies, Tema Environmental Change. Linköping University, Faculty of Arts and Sciences. Linköping University, Biogas Research Center. Tekniska Verken i Linköping AB.
    Thermal post-treatment of digestate in order to increase biogas production with simultaneous pasteurization2022In: Journal of Biotechnology, ISSN 0168-1656, E-ISSN 1873-4863, no 344, p. 32-39Article in journal (Refereed)
    Abstract [en]

    Biogas production by anaerobic digestion (AD) of organic wastes is important for the transition to fossil free fuelsin both the transport sector, industries and shipping. The aim of this study was to target the residual organicmatter in the outgoing residue from the AD process, so called digestate, with different thermal treatmentmethods in order to improve digestate degradability and biogas potential upon post-digestion. The thermaltreatment was performed at 55 ◦C in 24 h, 70 ◦C in 1 h and by thermal hydrolysis process (THP; 165 ◦C, 8 bar in0.33 h), and were carefully selected to offer a simultaneous possibility for pasteurization of the digestate accordingto the regulations in Sweden. Digestates from ten full-scale biogas plants were collected, with differentsubstrate profiles including wastewater treatment plant (WWTP), food waste digestion, agriculture digestion andmanure digestion. The results showed that all thermal treatment methods caused increased dissolved organiccarbon concentration (DOC). Four of the thermal treated digestates with the highest increase in DOC weresubsequently tested for the bio-methane potential. Thermal treatments at 70 ◦C and THP, respectively, resulted inthe highest increase in bio-methane potentials, with an increase of 15–39% for one WWTP, 38 – 40% fordigestate from an agriculture digestion plant and 20 – 22% for digestate from a co-digestion plant treating foodwaste. Interestingly, the bio-methane potential from digestate treated with the energy-intense THP method, didnot show any significant difference compared to thermal treatment at 70 ◦C for 1 h. The outcomes of this studysuggest that placing a pasteurization unit between a main digester and a post digester, when applying two-stepdigestion allows for a combined pasteurization and increased biogas production.

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  • 8.
    Calegari, Rubens
    et al.
    Linköping University, Department of Thematic Studies, Tema Environmental Change. Linköping University, Faculty of Arts and Sciences. Linköping University, Biogas Research Center. Center for Nuclear Energy in Agriculture, University of São Paulo, Brazil.
    Šafarič, Luka
    Linköping University, Department of Thematic Studies, Tema Environmental Change. Linköping University, Biogas Research Center. Linköping University, Faculty of Arts and Sciences.
    Shakeri Yekta, Sepehr
    Linköping University, Department of Thematic Studies, Tema Environmental Change. Linköping University, Biogas Research Center. Linköping University, Faculty of Arts and Sciences.
    Björn (Fredriksson), Annika
    Linköping University, Department of Thematic Studies, Tema Environmental Change. Linköping University, Biogas Research Center. Linköping University, Faculty of Arts and Sciences.
    Adiya, P.
    Luiz de Queiroz College of Agriculture, University of São Paulo, Brazil.
    Huang, B.
    Linköping University, Biogas Research Center. Linköping University, Department of Thematic Studies, Tema Environmental Change. Linköping University, Faculty of Arts and Sciences.
    Almeida, G.M.L.L.
    Luiz de Queiroz College of Agriculture, University of São Paulo, Brazil.
    Arthur, V.
    Luiz de Queiroz College of Agriculture, University of São Paulo, Brazil.
    Baptista, A.S.
    Luiz de Queiroz College of Agriculture, University of São Paulo, Brazil.
    Enrich Prast, Alex
    Linköping University, Department of Thematic Studies, Tema Environmental Change. Linköping University, Biogas Research Center. Linköping University, Faculty of Arts and Sciences.
    Anaerobic mono-digestion and anaerobic co-digestion of sugarcane industry residues with iron supplementation2021Conference paper (Other academic)
  • 9.
    Shakeri Yekta, Sepehr
    et al.
    Linköping University, Department of Thematic Studies, Tema Environmental Change. Linköping University, Faculty of Arts and Sciences. Linköping University, Biogas Research Center.
    Liu, Tong
    Linköping University, Biogas Research Center. Swedish Univ Agr Sci, Sweden.
    Mendes Anacleto, Thuane
    Univ Fed Rio de Janeiro, Brazil.
    Axelsson Bjerg, Mette
    Linköping University, Department of Thematic Studies, Tema Environmental Change. Linköping University, Faculty of Arts and Sciences. Linköping University, Biogas Research Center.
    Safaric, Luka
    Linköping University, Department of Thematic Studies, Tema Environmental Change. Linköping University, Faculty of Arts and Sciences. Linköping University, Biogas Research Center.
    Goux, Xavier
    Luxembourg Inst Sci & Technol, Luxembourg.
    Karlsson, Anna
    Linköping University, Department of Thematic Studies, Tema Environmental Change. Linköping University, Faculty of Arts and Sciences. Linköping University, Biogas Research Center. Scandinavian Biogas Fuels AB, Sweden.
    Björn, Annika
    Linköping University, Department of Thematic Studies, Tema Environmental Change. Linköping University, Faculty of Arts and Sciences. Linköping University, Biogas Research Center.
    Schnurer, Anna
    Linköping University, Biogas Research Center. Swedish Univ Agr Sci, Sweden.
    Effluent solids recirculation to municipal sludge digesters enhances long-chain fatty acids degradation capacity2021In: Biotechnology for Biofuels, ISSN 1754-6834, E-ISSN 1754-6834, Vol. 14, no 1, article id 56Article in journal (Refereed)
    Abstract [en]

    Background Slow degradation kinetics of long-chain fatty acids (LCFA) and their accumulation in anaerobic digesters disrupt methanogenic activity and biogas production at high loads of waste lipids. In this study, we evaluated the effect of effluent solids recirculation on microbial LCFA (oleate) degradation capacity in continuous stirred-tank sludge digesters, with the overall aim of providing operating conditions for efficient co-digestion of waste lipids. Furthermore, the impacts of LCFA feeding frequency and sulfide on process performance and microbial community dynamics were investigated, as parameters that were previously shown to be influential on LCFA conversion to biogas. Results Effluent solids recirculation to municipal sludge digesters enabled biogas production of up to 78% of the theoretical potential from 1.0 g oleate l(-1) day(-1). In digesters without effluent recirculation, comparable conversion efficiency could only be reached at oleate loading rates up to 0.5 g l(-1) day(-1). Pulse feeding of oleate (supplementation of 2.0 g oleate l(-1) every second day instead of 1.0 g oleate l(-1) every day) did not have a substantial impact on the degree of oleate conversion to biogas in the digesters that operated with effluent recirculation, while it marginally enhanced oleate conversion to biogas in the digesters without effluent recirculation. Next-generation sequencing of 16S rRNA gene amplicons of bacteria and archaea revealed that pulse feeding resulted in prevalence of fatty acid-degrading Smithella when effluent recirculation was applied, whereas Candidatus Cloacimonas prevailed after pulse feeding of oleate in the digesters without effluent recirculation. Combined oleate pulse feeding and elevated sulfide level contributed to increased relative abundance of LCFA-degrading Syntrophomonas and enhanced conversion efficiency of oleate, but only in the digesters without effluent recirculation. Conclusions Effluent solids recirculation improves microbial LCFA degradation capacity, providing possibilities for co-digestion of larger amounts of waste lipids with municipal sludge.

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  • 10.
    Nordell, Erik
    et al.
    Linköping University, Biogas Research Center. Tekniska verken i Linköping AB, Department of Biogas R&D.
    Moestedt, Jan
    Linköping University, Department of Thematic Studies, Tema Environmental Change. Linköping University, Faculty of Arts and Sciences. Linköping University, Biogas Research Center. Tekniska verken i Linköping AB, Department of Biogas R&D.
    Österman, J.
    Tekniska verken i Linköping AB, Department of Biogas R&D.
    Shakeri Yekta, Sepehr
    Linköping University, Department of Thematic Studies, Tema Environmental Change. Linköping University, Faculty of Arts and Sciences. Linköping University, Biogas Research Center.
    Björn, Annika
    Linköping University, Department of Thematic Studies, Tema Environmental Change. Linköping University, Faculty of Arts and Sciences. Linköping University, Biogas Research Center.
    Sun, Li
    Swedish University of Agricultural Sciences, Department of Molecular Sciences, Biocenter.
    Schnürer, Anna
    Linköping University, Department of Thematic Studies, Tema Environmental Change. Linköping University, Faculty of Arts and Sciences. Swedish University of Agricultural Sciences, Department of Molecular Sciences, Biocenter.
    Post-treatment of dewatered digested sewage sludge by thermophilic high-solid digestion for pasteurization with positive energy output2021In: Waste Management, ISSN 0956-053X, E-ISSN 1879-2456, Vol. 119, p. 11-21Article in journal (Refereed)
    Abstract [en]

    This study investigated the possibility to use thermophilic anaerobic high solid digestion of dewatered digested sewage sludge (DDS) at a wastewater treatment plant (WWTP) as a measure to increase total methane yield, achieve pasteurization and reduce risk for methane emissions during storage of the digestate. A pilot-scale plug-flow reactor was used to mimic thermophilic post-treatment of DDS from a WWTP in Linköping, Sweden. Process operation was evaluated with respect to biogas process performance, using both chemical and microbiological parameters. Initially, the process showed disturbance, with low methane yields and high volatile fatty acid (VFA) accumulation. However, after initiation of digestate recirculation performance improved and the specific methane production reached 46 mL CH4/g VS. Plug flow conditions were assessed with lithium chloride and the hydraulic retention time (HRT) was determined to be 19–29 days, sufficient to reach successful pasteurization. Degradation rate of raw protein was high and resulted in ammonia-nitrogen levels of up to 2.0 g/L and a 30% lower protein content in the digestate as compared to DDS. Microbial analysis suggested a shift in the methane producing pathway, with dominance of syntrophic acetate oxidation and the candidate methanogen family WSA2 by the end of the experiment. Energy balance calculations based on annual DDS production of 10 000 ton/year showed that introduction of high-solid digestion as a post-treatment and pasteurization method would result in a positive energy output of 340 MWh/year. Post-digestion of DDS also decreased residual methane potential (RMP) by>96% compared with fresh DDS.

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  • 11.
    Calegari, Rubens
    et al.
    Linköping University, Department of Thematic Studies, Tema Environmental Change. Linköping University, Biogas Research Center. Linköping University, Faculty of Arts and Sciences. Center for Nuclear Energy in Agriculture, University of São Paulo, Brazil.
    Šafarič, Luka
    Linköping University, Department of Thematic Studies, Tema Environmental Change. Linköping University, Biogas Research Center. Linköping University, Faculty of Arts and Sciences.
    Shakeri Yekta, Sepehr
    Linköping University, Department of Thematic Studies, Tema Environmental Change. Linköping University, Biogas Research Center. Linköping University, Faculty of Arts and Sciences.
    Björn (Fredriksson), Annika
    Linköping University, Department of Thematic Studies, Tema Environmental Change. Linköping University, Biogas Research Center. Linköping University, Faculty of Arts and Sciences.
    Adiya, P.
    Linköping University, Department of Thematic Studies, Tema Environmental Change. Linköping University, Biogas Research Center. Linköping University, Faculty of Arts and Sciences.
    Huang, B.
    Linköping University, Department of Thematic Studies, Tema Environmental Change. Linköping University, Biogas Research Center. Linköping University, Faculty of Arts and Sciences.
    Faria, T.M.
    Nuclear and Energy Research Institute, University of São Paulo, Brazil.
    Arthur, V.
    Center for Nuclear Energy in Agriculture, University of São Paulo, Brazil.
    Babtista, A.S.
    Luiz de Queiroz College of Agriculture, University of São Paulo, Brazil.
    Enrich Prast, Alex
    Linköping University, Department of Thematic Studies, Tema Environmental Change. Linköping University, Biogas Research Center. Linköping University, Faculty of Arts and Sciences.
    Supplementation of trace elements to sulfate-rich substrate and their impact in H2S formation and methane production2021Conference paper (Other academic)
  • 12.
    Safaric, Luka
    et al.
    Linköping University, Department of Thematic Studies, Tema Environmental Change. Linköping University, Faculty of Arts and Sciences.
    Shakeri Yekta, Sepehr
    Linköping University, Department of Thematic Studies, Tema Environmental Change. Linköping University, Faculty of Arts and Sciences.
    Svensson, Bo H.
    Linköping University, Department of Thematic Studies, Tema Environmental Change. Linköping University, Faculty of Arts and Sciences.
    Schnürer, Anna
    Linköping University, Department of Thematic Studies, Tema Environmental Change. Linköping University, Faculty of Arts and Sciences. Department of Molecular Science, Swedish University of Agricultural Science, Uppsala BioCenter, Uppsala, Sweden.
    Bastviken, David
    Linköping University, Department of Thematic Studies, Tema Environmental Change. Linköping University, Faculty of Arts and Sciences.
    Björn (Fredriksson), Annika
    Linköping University, Department of Thematic Studies, Tema Environmental Change. Linköping University, Faculty of Arts and Sciences.
    Effect of Cobalt, Nickel, and Selenium/Tungsten Deficiency on Mesophilic Anaerobic Digestion of Chemically Defined Soluble Organic Compounds2020In: Microorganisms, E-ISSN 2076-2607, Vol. 8, no 4, article id 598Article in journal (Refereed)
    Abstract [en]

    Trace elements (TEs) are vital for anaerobic digestion (AD), due to their role as cofactors in many key enzymes. The aim of this study was to evaluate the effects of specific TE deficiencies on mixed microbial communities during AD of soluble polymer-free substrates, thus focusing on AD after hydrolysis. Three mesophilic (37 degrees C) continuous stirred-tank biogas reactors were depleted either of Co, Ni, or a combination of Se and W, respectively, by discontinuing their supplementation. Ni and Se/W depletion led to changes in methane kinetics, linked to progressive volatile fatty acid (VFA) accumulation, eventually resulting in process failure. No significant changes occurred in the Co-depleted reactor, indicating that the amount of Co present in the substrate in absence of supplementation was sufficient to maintain process stability. Archaeal communities remained fairly stable independent of TE concentrations, while bacterial communities gradually changed with VFA accumulation in Ni- and Se-/W-depleted reactors. Despite this, the communities remained relatively similar between these two reactors, suggesting that the major shifts in composition likely occurred due to the accumulating VFAs. Overall, the results indicate that Ni and Se/W depletion primarily lead to slower metabolic activities of methanogenic archaea and their syntrophic partners, which then has a ripple effect throughout the microbial community due to a gradual accumulation of intermediate fermentation products.

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  • 13.
    Ekstrand, Eva-Maria
    et al.
    Linköping University, Department of Thematic Studies, Tema Environmental Change. Linköping University, Faculty of Arts and Sciences. Linköping University, Biogas Research Center.
    Hedenström, Mattias
    Kemiska institutionen, Umeå universitet.
    Svensson, Bo H
    Linköping University, Department of Thematic Studies, Tema Environmental Change. Linköping University, Faculty of Arts and Sciences. Linköping University, Biogas Research Center.
    Shakeri Yekta, Sepehr
    Linköping University, Department of Thematic Studies, Tema Environmental Change. Linköping University, Faculty of Arts and Sciences. Linköping University, Biogas Research Center.
    Björn (Fredriksson), Annika
    Linköping University, Department of Thematic Studies, Tema Environmental Change. Linköping University, Faculty of Arts and Sciences. Linköping University, Biogas Research Center.
    Methane potentials and organic matter characterization of wood fibres from pulp and paper mills: The influence of raw material, pulping process and bleaching technique2020In: Biomass and Bioenergy, ISSN 0961-9534, E-ISSN 1873-2909, Vol. 143, no 105824Article in journal (Refereed)
    Abstract [en]

    During the process of pulp- and papermaking, large volumes of fibre-rich primary sludge are generated. Anaerobic digestion of primary sludge offers a substantial potential for methane production as an alternative approach to the inefficient energy recoveries by commonly used incineration techniques. However, a systematic study of the importance of upstream process techniques for the methane potential of pulp fibres is lacking. Therefore, biochemical methane potentials were determined at mesophilic conditions for 20 types of fibres processed by a variety of pulping and bleaching techniques and from different raw materials. This included fibres from kraft, sulphite, semi-chemical, chemical thermo-mechanical (CTMP) and thermo-mechanical pulping plants and milled raw wood. The pulping technique was clearly important for the methane potential, with the highest potential achieved for kraft and sulphite fibres (390–400 Nml CH4 g VS− 1 ). For raw wood and CTMP, hardwood fibres gave substantially more methane than the corresponding softwood fibres (240 compared to 50 Nml CH4 g VS− 1 and 300 compared to 160 Nml CH4 g VS− 1 , respectively). Nuclear magnetic resonance characterization of the organic content demonstrated that the relative lignin content of the fibres was an important factor for methane production, and that an observed positive effect of bleaching on the methane potential of softwood CTMP fibres was likely related to a higher degree of deacetylation and improved accessibility of the hemicellulose. In conclusion, fibres from kraft and sulphite pulping are promising substrates for methane production irrespective of raw material or bleaching, as well as fibres from CTMP pulping of hardwood.

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  • 14.
    Ekstrand, Eva-Maria
    et al.
    Linköping University, Department of Thematic Studies, Tema Environmental Change. Linköping University, Faculty of Arts and Sciences.
    Svensson, Bo
    Linköping University, Department of Thematic Studies, Tema Environmental Change. Linköping University, Faculty of Arts and Sciences.
    Safaric, Luka
    Linköping University, Department of Thematic Studies, Tema Environmental Change. Linköping University, Faculty of Arts and Sciences.
    Björn, Annika
    Linköping University, Department of Thematic Studies, Tema Environmental Change. Linköping University, Faculty of Arts and Sciences.
    Viscosity dynamics and the production of extracellular polymeric substances and soluble microbial products during anaerobic digestion of pulp and paper mill wastewater sludges2020In: Bioprocess and biosystems engineering (Print), ISSN 1615-7591, E-ISSN 1615-7605, Vol. 43, no 2, p. 283-291Article in journal (Refereed)
    Abstract [en]

    The production processes of the pulp and paper industry often run in campaigns, leading to large variations in the composition of wastewaters and waste sludges. During anaerobic digestion (AD) of these wastes, the viscosity or the production of extracellular polymeric substances (EPS) and soluble microbial products (SMP) may be affected, with the risk of foam formation, inefficient digester mixing or poor sludge dewaterability. The aim of this study was to investigate how viscosity and production of EPS and SMP during long-term AD of pulp and paper mill sludge is affected by changes in organic loading rate (OLR) and hydraulic retention time (HRT). Two mesophilic lab-scale continuous stirred tank reactors (CSTRs) were operated for 800 days (R1 and R2), initially digesting only fibre sludge, then co-digesting fibre sludge and activated sludge. The HRT was lowered, followed by an increase in the OLR. Reactor fluids were sampled once a month for rheological characterization and analysis of EPS and SMP. The production of the protein fraction of SMP was positively correlated to the OLR, implicating reduced effluent qualities at high OLR. EPS formation correlated with the magnesium content, and during sulphate deficiency, the production of EPS and SMP increased. At high levels of EPS and SMP, there was an increase in viscosity of the anaerobic sludges, and dewatering efficiency was reduced. In addition, increased viscosity and/or the production of EPS and SMP were important factors in sludge bulking and foam formation in the CSTRs. Sludge bulking was avoided by more frequent stirring.

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  • 15.
    Safaric, Luka
    et al.
    Linköping University, Department of Thematic Studies, Tema Environmental Change. Linköping University, Faculty of Arts and Sciences. Linköping University, Biogas Research Center.
    Shakeri Yekta, Sepehr
    Linköping University, Department of Thematic Studies, Tema Environmental Change. Linköping University, Faculty of Arts and Sciences. Linköping University, Biogas Research Center.
    Ejlertsson, Jörgen
    Linköping University, Department of Thematic Studies, Tema Environmental Change. Linköping University, Faculty of Arts and Sciences. Linköping University, Biogas Research Center. Scandinavian Biogas Fuels AB.
    Safari, Mohammad
    Linköping University, Department of Management and Engineering. Linköping University, Faculty of Science & Engineering.
    Nadali Najafabadi, Hossein
    Linköping University, Department of Management and Engineering, Applied Thermodynamics and Fluid Mechanics. Linköping University, Faculty of Science & Engineering.
    Karlsson, Anna
    Linköping University, Biogas Research Center. Scandinavian Biogas Fuels AB.
    Ometto, Francesco
    Linköping University, Biogas Research Center. Scandinavian Biogas Fuels AB.
    Svensson, Bo H
    Linköping University, Department of Thematic Studies, Tema Environmental Change. Linköping University, Faculty of Arts and Sciences.
    Björn, Annika
    Linköping University, Department of Thematic Studies, Tema Environmental Change. Linköping University, Faculty of Arts and Sciences. Linköping University, Biogas Research Center.
    A Comparative Study of Biogas Reactor Fluid Rheology: Implications for Mixing Profile and Power Demand2019In: Processes, ISSN 2227-9717, Processes, ISSN 2227-9717, Vol. 7, no 10Article in journal (Refereed)
    Abstract [en]

    Anaerobic digestion (AD) is an established process for integrating waste management with renewable energy and nutrient recovery. Much of the research in this field focuses on the utilisation of new substrates, yet their effects on operational aspects such as fluid behaviour and power requirement for mixing are commonly overlooked, despite their importance for process optimisation. This study analysed rheological characteristics of samples from 21 laboratory-scale continuous stirred-tank biogas reactors (CSTBRs) digesting a range of substrates, in order to evaluate substrate effect on mixing efficiency and power demand through computational fluid dynamics (CFD). The results show that substrate and process parameters, such as solids content and organic loading, all have a significant effect on CSTBR fluid rheology. The correlation levels between rheological and process parameters were different across substrates, while no specific fluid behaviour patterns could be associated with substrate choice. Substrate should thus be considered an equally important rheology effector as process parameters. Additional substrate-related parameters should be identified to explain the differences in correlations between rheological and process parameters across substrate groups. The CFD modelling revealed that the rheology differences among the AD processes have significant implications for mixing efficiency and power demand of the CSTBRs, highlighting the importance of considering the substrate-induced effects on CSTBR rheology before including a new substrate.

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  • 16.
    Ometto, Francesco
    et al.
    Linköping University, Department of Thematic Studies, Tema Environmental Change. Linköping University, Faculty of Arts and Sciences. Linköping University, Biogas Research Center. Scandinavian Biogas Fuels AB.
    Karlsson, Anna
    Linköping University, Department of Thematic Studies, Tema Environmental Change. Linköping University, Faculty of Arts and Sciences. Linköping University, Biogas Research Center. Scandinavian Biogas Fuels AB.
    Ejlertsson, Jörgen
    Linköping University, Department of Thematic Studies, Tema Environmental Change. Linköping University, Faculty of Arts and Sciences. Linköping University, Biogas Research Center. Scandinavian Biogas Fuels AB.
    Björn (Fredriksson), Annika
    Linköping University, Department of Thematic Studies, Tema Environmental Change. Linköping University, Faculty of Arts and Sciences. Linköping University, Biogas Research Center.
    Shakeri Yekta, Sepehr
    Linköping University, Department of Thematic Studies, Tema Environmental Change. Linköping University, Faculty of Arts and Sciences. Linköping University, Biogas Research Center.
    Anaerobic digestion: an engineered biological process2019In: Substitute natural gas from waste: technical assessment and industrial applications of biochemical and thermochemical processes / [ed] Massimiliano Materazzi, Pier Ugo Foscolo, London: Elsevier , 2019, p. 63-74Chapter in book (Refereed)
    Abstract [en]

    Anaerobic digestion (AD) is a biological process where a variety of microorganisms are the key factors for transforming complex organic structure into biogas, a mixture of methane, carbon dioxide, and other trace gases. Linked to the production of biogas is also the unique possibility to utilize and recycle nutrients released during the digestion. This gives the AD-process a key role in the development of many biorefinery concepts supporting industrial symbiosis and circular economy. The overall process efficiency is linked to the microbial steps which are affected by regulating factors including the characteristic of the substrate and the engineered process layout, together with the targeted outputs (raw biogas, compressed/liquid biogas, fertilizer, and/or other refined products). Between the digestion steps, the hydrolysis, the first microbial step, is often the rate-limiting step in degradation of polymeric substrates. As such, securing efficient and cost-effective hydrolysis represents today the key to process complex biomasses not yet fully utilized within the AD despite its high methane potential.

  • 17.
    Ekstrand, Eva-Maria
    et al.
    Linköping University, Biogas Research Center. Linköping University, Department of Thematic Studies, Tema Environmental Change. Linköping University, Faculty of Arts and Sciences.
    Björn (Fredriksson), Annika
    Linköping University, Biogas Research Center. Linköping University, Department of Thematic Studies, Tema Environmental Change. Linköping University, Faculty of Arts and Sciences.
    Karlsson, Anna
    Linköping University, Department of Thematic Studies, Tema Environmental Change. Linköping University, Faculty of Arts and Sciences. Linköping University, Biogas Research Center. Scandinavian Biogas Fuels AB.
    Magnusson, Björn
    Linköping University, Department of Thematic Studies, Tema Environmental Change. Linköping University, Faculty of Arts and Sciences. Linköping University, Biogas Research Center. Scandinavian Biogas Fuels AB.
    Karlsson, Marielle
    Linköping University, Department of Thematic Studies, Tema Environmental Change. Linköping University, Faculty of Arts and Sciences. Linköping University, Biogas Research Center. Scandinavian Biogas Fuels AB.
    Larsson, Madeleine
    Linköping University, Biogas Research Center. Linköping University, Faculty of Arts and Sciences. Linköping University, Department of Thematic Studies, Tema Environmental Change.
    Truong, Xu-bin
    Linköping University, Department of Thematic Studies, Tema Environmental Change. Linköping University, Faculty of Arts and Sciences. Linköping University, Biogas Research Center. Scandinavian Biogas Fuels AB.
    Svensson, Bo H
    Linköping University, Biogas Research Center. Linköping University, Department of Thematic Studies, Tema Environmental Change. Linköping University, Faculty of Arts and Sciences.
    Ejlertsson, Jörgen
    Linköping University, Department of Thematic Studies, Tema Environmental Change. Linköping University, Faculty of Arts and Sciences. Linköping University, Biogas Research Center. Scandinavian Biogas Fuels AB.
    Anaerobic digestion in the kraft pulp and paper industry – challenges and possibilities for implementation2019Conference paper (Other academic)
  • 18.
    Feiz, Roozbeh
    et al.
    Linköping University, Department of Management and Engineering, Environmental Technology and Management. Linköping University, Faculty of Science & Engineering. Linköping University, Biogas Research Center.
    Ammenberg, Jonas
    Linköping University, Department of Management and Engineering, Environmental Technology and Management. Linköping University, Faculty of Science & Engineering.
    Björn, Annika
    Linköping University, Department of Thematic Studies, Tema Environmental Change. Linköping University, Faculty of Arts and Sciences.
    Yufang, Guo
    School of Environmental Science and Engineering, Guangzhou University, Guangzhou, China.
    Karlsson, Magnus
    Linköping University, Department of Management and Engineering, Energy Systems. Linköping University, Faculty of Science & Engineering.
    Liu, Yonghui
    School of Environmental Science and Engineering, Guangzhou University, Guangzhou, China.
    Liu, Yuxian
    Linköping University. Guangzhou University Research Center on Urban Sustainable Development, Guangzhou University, Guangzhou, China.
    Masuda, Laura Shizue Moriga
    Institute of Biology, Federal University of Rio de Janeiro, Rio de Janeiro, Brazil.
    Enrich-Prast, Alex
    Linköping University, Department of Thematic Studies, Tema Environmental Change. Linköping University, Faculty of Arts and Sciences.
    Rohracher, Harald
    Linköping University, Department of Thematic Studies, Technology and Social Change. Linköping University, Faculty of Arts and Sciences.
    Trygg, Kristina
    Linköping University, Department of Thematic Studies, Technology and Social Change. Linköping University, Faculty of Arts and Sciences.
    Shakeri Yekta, Sepehr
    Linköping University, Department of Thematic Studies, Tema Environmental Change. Linköping University, Faculty of Arts and Sciences.
    Zhang, Fagen
    School of Environmental Science and Engineering, Guangzhou University, Guangzhou, China.
    Biogas Potential for Improved Sustainability in Guangzhou, China: A Study Focusing on Food Waste on Xiaoguwei Island2019In: Sustainability, E-ISSN 2071-1050, Vol. 11, no 6Article in journal (Refereed)
    Abstract [en]

    As a result of rapid development in China and the growth of megacities, large amounts of organic wastes are generated within relatively small areas. Part of these wastes can be used to produce biogas, not only to reduce waste-related problems, but also to provide renewable energy, recycle nutrients, and lower greenhouse gases and air polluting emissions. This article is focused on the conditions for biogas solutions in Guangzhou. It is based on a transdisciplinary project that integrates several approaches, for example, literature studies and lab analysis of food waste to estimate the food waste potential, interviews to learn about the socio-technical context and conditions, and life-cycle assessment to investigate the performance of different waste management scenarios involving biogas production. Xiaoguwei Island, with a population of about 250,000 people, was chosen as the area of study. The results show that there are significant food waste potentials on the island, and that all studied scenarios could contribute to a net reduction of greenhouse gas emissions. Several socio-technical barriers were identified, but it is expected that the forthcoming regulatory changes help to overcome some of them.

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  • 19.
    Šafarič, Luka
    et al.
    Linköping University, Department of Thematic Studies, Tema Environmental Change. Linköping University, Biogas Research Center. Linköping University, Faculty of Arts and Sciences.
    Shakeri Yekta, Sepehr
    Linköping University, Department of Thematic Studies, Tema Environmental Change. Linköping University, Biogas Research Center. Linköping University, Faculty of Arts and Sciences.
    Svensson, Bo H
    Linköping University, Department of Thematic Studies, Tema Environmental Change. Linköping University, Biogas Research Center. Linköping University, Faculty of Arts and Sciences.
    Schnürer, Anna
    Linköping University, Department of Thematic Studies, Tema Environmental Change. Linköping University, Faculty of Arts and Sciences. Linköping University, Biogas Research Center. Molekylära Vetenskaper, SLU.
    Bastviken, David
    Linköping University, Department of Thematic Studies, Tema Environmental Change. Linköping University, Faculty of Arts and Sciences.
    Björn (Fredriksson), Annika
    Linköping University, Department of Thematic Studies, Tema Environmental Change. Linköping University, Biogas Research Center. Linköping University, Faculty of Arts and Sciences.
    Importance of substrate origin for anaerobic sludge rheology in continuous stirred-tank biogas reactors2019Conference paper (Other academic)
  • 20.
    Šafarič, Luka
    et al.
    Linköping University, Department of Thematic Studies, Tema Environmental Change. Linköping University, Biogas Research Center. Linköping University, Faculty of Arts and Sciences.
    Shakeri Yekta, Sepehr
    Linköping University, Department of Thematic Studies, Tema Environmental Change. Linköping University, Biogas Research Center. Linköping University, Faculty of Arts and Sciences.
    Svensson, Bo H
    Linköping University, Department of Thematic Studies, Tema Environmental Change. Linköping University, Biogas Research Center. Linköping University, Faculty of Arts and Sciences.
    Schnürer, Anna
    Linköping University, Department of Thematic Studies, Tema Environmental Change. Linköping University, Biogas Research Center. Linköping University, Faculty of Arts and Sciences. Molekylära Vetenskaper, SLU.
    Bastviken, David
    Linköping University, Department of Thematic Studies, Tema Environmental Change. Linköping University, Faculty of Arts and Sciences.
    Björn (Fredriksson), Annika
    Linköping University, Department of Thematic Studies, Tema Environmental Change. Linköping University, Biogas Research Center. Linköping University, Faculty of Arts and Sciences.
    Importance of substrate origin for anaerobic sludge rheology in continuous stirred-tank biogas reactors2019Conference paper (Other academic)
  • 21.
    Shakeri Yekta, Sepehr
    et al.
    Linköping University, Department of Thematic Studies, Tema Environmental Change. Linköping University, Faculty of Arts and Sciences. Linköping University, Biogas Research Center.
    Hedenström, Mattias
    Department of Chemistry, Umeå University, 901 87 Umeå, Sweden.
    Svensson, Bo
    Linköping University, Department of Thematic Studies, Tema Environmental Change. Linköping University, Faculty of Arts and Sciences. Linköping University, Biogas Research Center.
    Sundgren, Ingrid
    Linköping University, Department of Thematic Studies, Tema Environmental Change. Linköping University, Faculty of Arts and Sciences. Linköping University, Biogas Research Center.
    Dario, Mårten
    Linköping University, Department of Thematic Studies, Tema Environmental Change. Linköping University, Faculty of Arts and Sciences. Linköping University, Biogas Research Center.
    Enrich-Prast, Alex
    Linköping University, Department of Thematic Studies, Tema Environmental Change. Linköping University, Faculty of Arts and Sciences. Linköping University, Biogas Research Center.
    Hertkorn,, Norbert
    Helmholtz Center Munich, German Research Center for Environmental Health, Research Unit Analytical Biogeochemistry, 85764 Neuherberg, Germany.
    Björn, Annika
    Linköping University, Department of Thematic Studies, Tema Environmental Change. Linköping University, Faculty of Arts and Sciences. Linköping University, Biogas Research Center.
    Molecular characterization of particulate organic matter in full scale anaerobic digesters: An NMR spectroscopy study2019In: Science of the Total Environment, ISSN 0048-9697, E-ISSN 1879-1026, Vol. 685, p. 1107-1115Article in journal (Refereed)
    Abstract [en]

    This study assesses the molecular characteristics of particulate organic matter (POM) in agricultural and food waste digesters and elucidates the molecular properties of the recalcitrant POM fraction, which remains in the digestate after AD process. Molecular properties of POM in influent (substrate) and effluent (digestate) of seven full-scale AD plants (three agricultural waste and four food waste digesters) were characterized and compared using solid-state 13C cross-polarization magic angle spinning (CP-MAS) and solution-state 1H,13C heteronuclear single-quantum coherence (HSQC) nuclear magnetic resonance (NMR) spectroscopy. Comparison of the POM structural compositions of substrate and digestate from each AD plant revealed an enrichment of protein structures relative to the carbohydrates in most cases, implying a preferential degradation of the carbohydrates over proteins and/or increase of microbial biomass upon AD of agricultural and food wastes. Distinctive molecular structures of labile and recalcitrant fractions of POM, subjected to AD, were identified by comparing the NMR spectra of all substrate and digestate POM. Accordingly, the labile POM fraction in food and agricultural solid wastes is characterized by structural entities of lipids and starch-like carbohydrates, whereas recalcitrant POM structures resemble alkyl and aromatic subunits of amino acids, lignin, and polysaccharides with β-glycosidic linkages. This information serves as a basis to further explore optimization approaches for improving AD of the underutilized POM and the fate of organic matter in digestate-amended arable lands.

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  • 22.
    Björn (Fredriksson), Annika
    Linköping University, Department of Thematic Studies, Tema Environmental Change. Linköping University, Biogas Research Center. Linköping University, Faculty of Arts and Sciences.
    Process and technology development for sustainable biogas solutions2019Conference paper (Other academic)
  • 23.
    Shakeri Yekta, Sepehr
    et al.
    Linköping University, Department of Thematic Studies, Tema Environmental Change. Linköping University, Faculty of Arts and Sciences.
    Liu, Tong
    Uppsala BioCenter, Swedish University of Agricultural Sciences, Uppsala, Sweden.
    Axelsson Bjerg, Mette
    Linköping University, Department of Thematic Studies, Tema Environmental Change. Linköping University, Faculty of Arts and Sciences.
    Šafarič, Luka
    Linköping University, Department of Thematic Studies, Tema Environmental Change. Linköping University, Faculty of Arts and Sciences.
    Karlsson, Anna
    Scandinavian Biogas Fuels AB, Stockholm, Sweden.
    Björn (Fredriksson), Annika
    Linköping University, Department of Thematic Studies, Tema Environmental Change. Linköping University, Faculty of Arts and Sciences.
    Schnürer, Anna
    Linköping University, Department of Thematic Studies, Tema Environmental Change. Linköping University, Faculty of Arts and Sciences. Uppsala BioCenter, Swedish University of Agricultural Sciences, Uppsala, Sweden.
    Sulfide level in municipal sludge digesters affects microbial community response to long-chain fatty acid loads2019In: Biotechnology for Biofuels, ISSN 1754-6834, E-ISSN 1754-6834, Vol. 12, no 1, article id 259Article in journal (Refereed)
    Abstract [en]

    Background

    Waste lipids are attractive substrates for co-digestion with primary and activated sewage sludge (PASS) to improve biogas production at wastewater treatment plants. However, slow conversion rates of long-chain fatty acids (LCFA), produced during anaerobic digestion (AD), limit the applicability of waste lipids as co-substrates for PASS. Previous observations indicate that the sulfide level in PASS digesters affects the capacity of microbial communities to convert LCFA to biogas. This study assessed the microbial community response to LCFA loads in relation to sulfide level during AD of PASS by investigating process performance and microbial community dynamics upon addition of oleate (C18:1) and stearate (C18:0) to PASS digesters at ambient and elevated sulfide levels.

    Results

    Conversion of LCFA to biogas was limited (30% of theoretical biogas potential) during continuous co-digestion with PASS, which resulted in further LCFA accumulation. However, the accumulated LCFA were converted to biogas (up to 66% of theoretical biogas potential) during subsequent batch-mode digestion, performed without additional substrate load. Elevated sulfide level stimulated oleate (but not stearate) conversion to acetate, but oleate and sulfide imposed a synergistic limiting effect on acetoclastic methanogenesis and biogas formation. Next-generation sequencing of 16S rRNA gene amplicons of bacteria and archaea showed that differences in sulfide level and LCFA type resulted in microbial community alterations with distinctly different patterns. Taxonomic profiling of the sequencing data revealed that the phylum Cloacimonetes is likely a key group during LCFA degradation in PASS digesters, where different members take part in degradation of saturated and unsaturated LCFA; genus W5 (family Cloacimonadaceae) and family W27 (order Cloacimonadales), respectively. In addition, LCFA-degrading Syntrophomonas, which is commonly present in lipid-fed digesters, increased in relative abundance after addition of oleate at elevated sulfide level, but not without sulfide or after stearate addition. Stearate conversion to biogas was instead associated with increasing abundance of hydrogen-producing Smithella and hydrogenotrophic Methanobacterium.

    Conclusions

    Long-chain fatty acid chain saturation and sulfide level are selective drivers for establishment of LCFA-degrading microbial communities in municipal sludge digesters.

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  • 24.
    Ekstrand, Eva-Maria
    et al.
    Linköping University, Department of Thematic Studies, Tema Environmental Change. Linköping University, Biogas Research Center. Linköping University, Faculty of Arts and Sciences.
    Karlsson, Marielle
    Linköping University, Department of Thematic Studies, Tema Environmental Change. Linköping University, Faculty of Arts and Sciences. Linköping University, Biogas Research Center. Scandinavian Biogas Fuels AB.
    Truong, Xu-bin
    Linköping University, Department of Thematic Studies, Tema Environmental Change. Linköping University, Faculty of Arts and Sciences. Linköping University, Biogas Research Center. Scandinavian Biogas Fuels AB.
    Björn (Fredriksson), Annika
    Linköping University, Department of Thematic Studies, Tema Environmental Change. Linköping University, Biogas Research Center. Linköping University, Faculty of Arts and Sciences.
    Karlsson, Anna
    Linköping University, Department of Thematic Studies, Tema Environmental Change. Linköping University, Faculty of Arts and Sciences. Linköping University, Biogas Research Center. Scandinavian Biogas Fuels AB.
    Svensson, Bo H
    Linköping University, Department of Thematic Studies, Tema Environmental Change. Linköping University, Biogas Research Center. Linköping University, Faculty of Arts and Sciences.
    Ejlertsson, Jörgen
    Linköping University, Department of Thematic Studies, Tema Environmental Change. Linköping University, Faculty of Arts and Sciences. Linköping University, Biogas Research Center. Scandinavian Biogas Fuels AB.
    Co-digestion of kraft mill fibre sludge and activated sludge – improving the methane potential by high-rate processes and low activated sludge age2018Conference paper (Refereed)
  • 25.
    Safaric, Luka
    et al.
    Linköping University, Department of Thematic Studies, Tema Environmental Change. Linköping University, Faculty of Arts and Sciences.
    Shakeri Yekta, Sepehr
    Linköping University, Department of Thematic Studies, Tema Environmental Change. Linköping University, Faculty of Arts and Sciences.
    Liu, Tong
    Swedish Univ Agr Sci, Sweden.
    Svensson, Bo
    Linköping University, Department of Thematic Studies, Tema Environmental Change. Linköping University, Faculty of Arts and Sciences.
    Schnürer, Anna
    Linköping University, Department of Thematic Studies, Tema Environmental Change. Linköping University, Faculty of Arts and Sciences. Swedish Univ Agr Sci, Sweden.
    Bastviken, David
    Linköping University, Department of Thematic Studies, Tema Environmental Change. Linköping University, Faculty of Arts and Sciences.
    Björn, Annika
    Linköping University, Department of Thematic Studies, Tema Environmental Change. Linköping University, Faculty of Arts and Sciences.
    Dynamics of a Perturbed Microbial Community during Thermophilic Anaerobic Digestion of Chemically Defined Soluble Organic Compounds2018In: Microorganisms, E-ISSN 2076-2607, Vol. 6, no 4, article id 105Article in journal (Refereed)
    Abstract [en]

    Knowledge of microbial community dynamics in relation to process perturbations is fundamental to understand and deal with the instability of anaerobic digestion (AD) processes. This study aims to investigate the microbial community structure and function of a thermophilic AD process, fed with a chemically defined substrate, and its association with process performance stability. Next generation amplicon sequencing of 16S ribosomal RNA (rRNA) genes revealed that variations in relative abundances of the predominant bacterial species, Defluviitoga tunisiensis and Anaerobaculum hydrogeniformans, were not linked to the process performance stability, while dynamics of bacterial genera of low abundance, Coprothermobacter and Defluviitoga (other than D. tunisiensis), were associated with microbial community function and process stability. A decrease in the diversity of the archaeal community was observed in conjunction with process recovery and stable performance, implying that the high abundance of specific archaeal group(s) contributed to the stable AD. Dominance of hydrogenotrophic Methanoculleus particularly corresponded to an enhanced microbial acetate and propionate turnover capacity, whereas the prevalence of hydrogenotrophic Methanothermobacter and acetoclastic Methanosaeta was associated with instable AD. Acetate oxidation via syntrophic interactions between Coprothermobacter and Methanoculleus was potentially the main methane-formation pathway during the stable process. We observed that supplementation of Se and W to the medium improved the propionate turnover by the thermophilic consortium. The outcomes of our study provided insights into the community dynamics and trace element requirements in relation to the process performance stability of thermophilic AD.

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  • 26.
    Ometto, F.
    et al.
    Research and Development Department , Scandinavian Biogas Fuels AB , Stockholm , Sweden.
    Berg, A.
    Research and Development Department , Scandinavian Biogas Fuels AB , Stockholm , Sweden.
    Björn, Annika
    Linköping University, Department of Thematic Studies, Tema Environmental Change. Linköping University, Faculty of Arts and Sciences.
    Safaric, Luka
    Linköping University, Department of Thematic Studies, Tema Environmental Change. Linköping University, Faculty of Arts and Sciences.
    Svensson, Bo H.
    Linköping University, Department of Thematic Studies, Tema Environmental Change. Linköping University, Faculty of Arts and Sciences.
    Karlsson, A.
    Research and Development Department , Scandinavian Biogas Fuels AB , Stockholm , Sweden.
    Ejlertsson, Jörgen
    Linköping University, Department of Thematic Studies, Tema Environmental Change. Linköping University, Faculty of Arts and Sciences. Research and Development Department , Scandinavian Biogas Fuels AB , Stockholm , Sweden.
    Inclusion of Saccharina latissima in conventional anaerobic digestion systems2018In: Environmental technology, ISSN 0959-3330, E-ISSN 1479-487X, Vol. 39, no 5, p. 628-639Article in journal (Refereed)
    Abstract [en]

    Loading macroalgae into existing anaerobic digestion (AD) plants allows us to overcome challenges such as low digestion efficiencies, trace elements limitation, excessive salinity levels and accumulation of volatile fatty acids (VFAs), observed while digesting algae as a single substrate. In this work, the co-digestion of the brown macroalgae Saccharina latissima with mixed municipal wastewater sludge (WWS) was investigated in mesophilic and thermophilic conditions. The hydraulic retention time (HRT) and the organic loading rate (OLR) were fixed at 19 days and 2.1 g l-1 d-1of volatile solids (VS), respectively. Initially, WWS was digested alone. Subsequently, a percentage of the total OLR (20%, 50% and finally 80%) was replaced by S. latissima biomass. Optimal digestion conditions were observed at medium-low algae loading (=50% of total OLR) with an average methane yield close to [Formula: see text] and [Formula: see text] in mesophilic and thermophilic conditions, respectively. The conductivity values increased with the algae loading without inhibiting the digestion process. The viscosities of the reactor sludges revealed decreasing values with reduced WWS loading at both temperatures, enhancing mixing properties.

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  • 27.
    Shakeri Yekta, Sepehr
    et al.
    Linköping University, Department of Thematic Studies, Tema Environmental Change. Linköping University, Faculty of Arts and Sciences.
    Hedenstrom, Mattias
    Department of Chemistry, Umeå University, Umeå, Sweden.
    Stehr, Jan Eric
    Linköping University, Department of Physics, Chemistry and Biology, Surface Physics and Chemistry. Linköping University, Faculty of Science & Engineering.
    Dario, Mårten
    Linköping University, Department of Thematic Studies, Tema Environmental Change. Linköping University, Faculty of Arts and Sciences.
    Hertkorn, Norbert
    German Res Ctr Environm Hlth, Germany.
    Björn (Fredriksson), Annika
    Linköping University, Department of Thematic Studies, Tema Environmental Change. Linköping University, Faculty of Arts and Sciences.
    Pretreatment,of anaerobic digester samples by hydrochloric acid for solution-state H-1 and C-13 NMR spectroscopic characterization of organic matter2018In: Chemosphere, ISSN 0045-6535, E-ISSN 1879-1298, Vol. 199, p. 201-209Article in journal (Refereed)
    Abstract [en]

    Pretreatment of anaerobic digester samples by hydrochloric acid (HCl) resulted in removal of Fe-based mineral and coordination compounds, attenuating their interferences with solution-state nuclear magnetic resonance (NMR) spectroscopic characterization of the solid phase organic matter. Substrate (influent) and digestate (effluent) samples from two full-scale anaerobic digesters, designated CD (co-digester) and SSD (sewage sludge digester), were investigated. Pretreatment of CD samples with 0.2-2.0 mol l(-1) HCl and pretreatment of SSD samples with 1.0-3.0 mol l(-1) HCl removed 96-100% and 76-80% of total Fe, respectively. Pretreatment declined overall paramagnetic characteristics of digestate samples, manifested by 50% (CD) and 70% (SSD) decrease in electron paramagnetic resonance signal intensities. As a result, meaningful solution-state H-1,C-13 heteronuclear single quantum coherence and H-1 NMR spectra of DMSO-d(6) soluble organic matter could be acquired. Sample pretreatment with the lowest concentration of HCl resulted in alteration of C:N ratios in solid phase, likely due to removal of labile organic and inorganic C- and N-containing compounds, while elevating the HCl concentration did not further change the C:N ratios. Furthermore, sample pretreatment increased the solubility of carbohydrates and proteins in DMSO-d(6), enabling the detection of NMR resonances from certain structural units of carbohydrates (e.g. anomeric O2CH) and proteins (e.g. CH alpha in amino acids). Both attenuation of the paramagnetic matrix as well as art enhanced solubility of carbohydrate and protein fractions of the samples in DMSO-d(6) solvent contributed to an improved molecular characterization of anaerobic digester samples by solution-state NMR analysis.

  • 28.
    Björn, Annika
    et al.
    Linköping University, Department of Thematic Studies, Tema Environmental Change. Linköping University, Faculty of Arts and Sciences.
    Safaric, Luka
    Linköping University, Department of Thematic Studies, Tema Environmental Change. Linköping University, Faculty of Arts and Sciences.
    Karlsson, Anna
    Scandinavian Biogas Fuels AB, Sweden.
    Danielsson, Åsa
    Linköping University, Department of Thematic Studies, Tema Environmental Change. Linköping University, Faculty of Arts and Sciences.
    Ejlertsson, Jörgen
    Linköping University, Department of Thematic Studies, Tema Environmental Change. Linköping University, Faculty of Arts and Sciences. Scandinavian Biogas Fuels AB, Sweden.
    Svensson, Bo
    Linköping University, Department of Thematic Studies, Tema Environmental Change. Linköping University, Faculty of Arts and Sciences.
    Shakeri Yekta, Sepehr
    Linköping University, Department of Thematic Studies, Tema Environmental Change. Linköping University, Faculty of Arts and Sciences.
    Substrate and operational conditions as regulators of fluid properties in full-scale continuous stirred-tank biogas reactors - implications for rheology-driven power requirements2018In: Water Science and Technology, ISSN 0273-1223, E-ISSN 1996-9732, Vol. 78, no 4, p. 814-826Article in journal (Refereed)
    Abstract [en]

    Understanding fluid rheology is important for optimal design and operation of continuous stirred-tank biogas reactors (CSTBRs) and is the basis for power requirement estimates. Conflicting results have been reported regarding the applicability of total solid (TS) and/or total volatile solid (TVS) contents of CSTBR fluids as proxies for rheological properties. Thus, the present study investigates relationships between rheological properties of 12 full-scale CSTBR fluids, their substrate profiles, and major operational conditions, including pH, TS and TVS contents, organic loading rate, hydraulic retention time, and temperature. Rheology-driven power requirements based on various fluid characteristics were evaluated for a general biogas reactor setup. The results revealed a significant correlation only between the rheological fluid properties and TS or TVS contents for sewage sludge digesters and thermophilic co-digesters (CD), but not for mesophilic CD. Furthermore, the calculated power requirements for pumping and mixing, based on the various fluid characteristics of the studied CSTBRs, varied broadly irrespective of TS and TVS contents. Thus, this study shows that the TS and/or TVS contents of digester fluid are not reliable estimators of the rheological properties in CSTBRs digesting substrates other than sewage sludge.

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  • 29.
    Nordell, Erik
    et al.
    Linköping University, Biogas Research Center. Tekniska Verken i Linköping AB.
    Waern, Sandra
    Linköping University, Department of Physics, Chemistry and Biology, Chemistry. Linköping University, Faculty of Science & Engineering. Linköping University, Biogas Research Center. Tekniska Verken i Linköping AB.
    Shakeri Yekta, Sepehr
    Linköping University, Department of Thematic Studies, Tema Environmental Change. Linköping University, Biogas Research Center. Linköping University, Faculty of Arts and Sciences.
    Sundgren, Ingrid
    Linköping University, Department of Thematic Studies, Tema Environmental Change. Linköping University, Biogas Research Center. Linköping University, Faculty of Arts and Sciences.
    Björn (Fredriksson), Annika
    Linköping University, Department of Thematic Studies, Tema Environmental Change. Linköping University, Biogas Research Center. Linköping University, Faculty of Arts and Sciences.
    Moestedt, Jan
    Linköping University, Department of Thematic Studies, Tema Environmental Change. Linköping University, Biogas Research Center. Linköping University, Faculty of Arts and Sciences. Tekniska Verken i Linköping AB.
    Thermal post-treatment of digestate in order to increase biogas production and achieve a pasteurization effect2018Conference paper (Other academic)
  • 30.
    Ekstrand, Eva-Maria
    et al.
    Linköping University, Department of Thematic Studies, Tema Environmental Change. Linköping University, Biogas Research Center. Linköping University, Faculty of Arts and Sciences.
    Svensson, Bo H
    Linköping University, Department of Thematic Studies, Tema Environmental Change. Linköping University, Biogas Research Center. Linköping University, Faculty of Arts and Sciences.
    Björn (Fredriksson), Annika
    Linköping University, Department of Thematic Studies, Tema Environmental Change. Linköping University, Biogas Research Center. Linköping University, Faculty of Arts and Sciences.
    Viscosity dynamics during anaerobic digestion of pulp and paper mill fibre sludge – the dependency on extracellular polymeric substances and soluble microbial products2018Conference paper (Refereed)
    Abstract [en]

    Increased viscosity and the presence of extracellular polymeric substances (EPS) and soluble microbial products (SMP) are important factors that may negatively affect wastewater treatment processes, e.g. foaming, inefficient mixing or poor dewatering. Many industries, including the pulp and paper industry, are running their production processes at shifting conditions, leading to large variations in wastewater composition to downstream treatments. The aim of this study was to investigate how changes in organic loading rate (OLR) and hydraulic retention time (HRT) affect the viscosity and production of EPS and SMP during anaerobic digestion of pulp and paper mill sludge. Two lab-scale continuous stirred tank reactors (CSTRs) were operated for 800 days at 37⁰C. The OLR was increased and the HRT was decreased in steps. Reactor fluid was sampled once a month for rheological characterization and analysis of EPS and SMP.

    Our results demonstrated a clear positive correlation between viscosity and the production of EPS and SMP. OLR, magnesium and potassium were important for EPS and SMP formation and the protein fraction of SMP was negatively correlated to HRT and sludge retention time. The production of EPS and SMP was important in foam formation and sludge bulking, either directly through their surface-active properties, or indirectly by increasing the viscosity. Sludge bulking was avoided by more frequent mixing. In conclusion, rheological measurements and estimates of EPS and SMP contents could prove valuable tools to avoid the severe consequences of sludge bulking and foaming in full-scale applications.

  • 31.
    Larsson, Madeleine
    et al.
    Linköping University, Department of Thematic Studies, Tema Environmental Change. Linköping University, Faculty of Arts and Sciences. Linköping University, Biogas Research Center.
    Truong, Xu-bin
    Linköping University, Biogas Research Center. Scandinavian Biogas Fuels AB, Sweden.
    Björn, Annika
    Linköping University, Department of Thematic Studies, Tema Environmental Change. Linköping University, Faculty of Arts and Sciences. Linköping University, Biogas Research Center.
    Ejlertsson, Jörgen
    Linköping University, Department of Thematic Studies, Tema Environmental Change. Linköping University, Faculty of Arts and Sciences. Linköping University, Biogas Research Center. Scandinavian Biogas Fuels AB, Sweden.
    Svensson, Bo
    Linköping University, Department of Thematic Studies, Tema Environmental Change. Linköping University, Faculty of Arts and Sciences. Linköping University, Biogas Research Center.
    Bastviken, David
    Linköping University, Department of Thematic Studies, Tema Environmental Change. Linköping University, Faculty of Arts and Sciences. Linköping University, Biogas Research Center.
    Karlsson, Anna
    Linköping University, Biogas Research Center. Scandinavian Biogas Fuels AB, Sweden.
    Anaerobic digestion of wastewater from the production of bleached chemical thermo-mechanical pulp: higher methane production for hardwood than softwood2017In: Journal of chemical technology and biotechnology (1986), ISSN 0268-2575, E-ISSN 1097-4660, Vol. 2, no 1, p. 140-151Article in journal (Refereed)
    Abstract [en]

    BACKGROUND: Chemical thermo-mechanical pulp (CTMP) mills holds a large biomethane potential in their wastewater. Their broadened market has involved increased bleaching and utilisation of different raw materials. Therefore, the main aim of this study was to obtain and maintain a stable anaerobic digestion (AD) process, with a high methane yield and total organic carbon (TOC) reduction, when digesting CTMP wastewater, from different production protocols including shifts in raw material and bleaching. A lab-scale upflow anaerobic sludge bed (UASB) reactor was used for the tests.

    RESULTS: The variations in raw material (aspen, birch and spruce) and consequently in TOC-loading (3.6-6.6 kg TOC m-3 and day-1) did not affect the UASB process negatively. Methane production values from 360 to 500 NmL g TOC-1 were obtained, with the highest yield for wastewater from the production of birch- followed by aspenand spruce pulp. The acetic acid and fTOC reduction ranged 90 to 95% and 61 to 73%, respectively.

    CONCLUSIONS: The stable process performance maintained during shifts in raw material for pulp production show that AD is feasible for CTMP mills with a diversified product portfolio. Furthermore, the increased use of hardwood and bleaching will most likely increase their potential as a biomethane producer.

  • 32.
    Shakeri Yekta, Sepehr
    et al.
    Linköping University, Department of Thematic Studies, Tema Environmental Change. Linköping University, Faculty of Arts and Sciences.
    Skyllberg, Ulf
    Swedish University of Agricultural Sciences, Umeå, Sweden.
    Danielsson, Åsa
    Linköping University, Department of Thematic Studies, Tema Environmental Change. Linköping University, Faculty of Arts and Sciences.
    Björn, Annika
    Linköping University, Department of Thematic Studies, Tema Environmental Change. Linköping University, Faculty of Arts and Sciences.
    Svensson, Bo H.
    Linköping University, Department of Thematic Studies, Tema Environmental Change. Linköping University, Faculty of Arts and Sciences.
    Chemical Speciation of Sulfur and Metals in Biogas Reactors - Implications for Cobalt and Nickel Bio-uptake Processes2017In: Journal of Hazardous Materials, ISSN 0304-3894, Vol. 324, p. 110-116Article in journal (Refereed)
    Abstract [en]

    This article deals with the interrelationship between overall chemical speciation of S, Fe, Co, and Ni in relation to metals bio-uptake processes in continuous stirred tank biogas reactors (CSTBR). To address this topic, laboratory CSTBRs digesting sulfur(S)-rich stillage, as well as full-scale CSTBRs treating sewage sludge and various combinations of organic wastes, termed co-digestion, were targeted. Sulfur speciation was evaluated using acid volatile sulfide extraction and X-ray absorption spectroscopy. Metal speciation was evaluated by chemical fractionation, kinetic and thermodynamic analyses. Relative Fe to S content is identified as a critical factor for chemical speciation and bio-uptake of metals. In reactors treating sewage sludge, quantity of Fe exceeds that of S, inducing Fe-dominated conditions, while sulfide dominates in laboratory and co-digestion reactors due to an excess of S over Fe. Under sulfide-dominated conditions, metals availability for microorganisms is restricted due to formation of metal-sulfide precipitates. However, aqueous concentrations of different Co and Ni species were shown to be sufficient to support metal acquisition by microorganisms under sulfidic conditions. Concentrations of free metal ions and labile metal complexes in aqueous phase, which directly participate in bio-uptake processes, are higher under Fe-dominated conditions. This in turn enhances metal adsorption on cell surfaces and bio-uptake rates.

  • 33.
    Wang, Bing
    et al.
    Lund University, Sweden.
    Björn, Annika
    Linköping University, Department of Thematic Studies, Tema Environmental Change. Linköping University, Faculty of Arts and Sciences.
    Strömberg, Sten
    Bioproc Control Sweden AB, Sweden.
    Achu Nges, Ivo
    Lund University, Sweden.
    Nistor, Mihaela
    Bioproc Control Sweden AB, Sweden.
    Liu, Jing
    Lund University, Sweden; Bioproc Control Sweden AB, Sweden.
    Evaluating the influences of mixing strategies on the Biochemical Methane Potential test2017In: Journal of Environmental Management, ISSN 0301-4797, E-ISSN 1095-8630, Vol. 185, p. 54-59Article in journal (Refereed)
    Abstract [en]

    Mixing plays an important role in the Biochemical Methane Potential (BMP) test, but only limited efforts have been put into it. In this study, various mixing strategies were applied to evaluate the influences on the BMP test, i.e., no mixing, shaking in water bath, shake manually once per day (SKM), automated unidirectional and bidirectional mixing. The results show that the effects of mixing are prominent for the most viscous substrate investigated, as both the highest methane production and highest maximal daily methane production were obtained at the highest mixing intensity. However, the organic removal efficiencies were not affected, which might offer evidence that mixing helps the release of gases trapped in digester liquid. Moreover, mixing is required for improved methane production when the digester content is viscous, conversely, mixing is unnecessary or SKM might be sufficient for the BMP test if the digester content is quite dilute or the substrate is easily degraded. (C) 2016 Elsevier Ltd. All rights reserved.

  • 34.
    Björn (Fredriksson), Annika
    et al.
    Linköping University, Department of Thematic Studies, Tema Environmental Change. Linköping University, Faculty of Arts and Sciences. Linköping University, Biogas Research Center.
    Shakeri Yekta, Sepehr
    Linköping University, Department of Thematic Studies, Tema Environmental Change. Linköping University, Faculty of Arts and Sciences. Linköping University, Biogas Research Center.
    Ziels, Ryan
    Linköping University, Biogas Research Center. Department of Civil Engineering, University of British Columbia, Columbia, Canada.
    Karl, Gustafsson
    Linköping University, Department of Thematic Studies, Tema Environmental Change. Linköping University, Faculty of Arts and Sciences. Linköping University, Biogas Research Center.
    Svensson, Bo H
    Linköping University, Department of Thematic Studies, Tema Environmental Change. Linköping University, Faculty of Arts and Sciences. Linköping University, Biogas Research Center.
    Anna, Karlsson
    Linköping University, Biogas Research Center. Scandinavian Biogas Fuels AB, Stockholm, Sweden.
    Feasibility of OFMSW co-digestion with sewage sludge for increasing biogas production at wastewater treatment plants2017In: Euro-Mediterranean Journal for Environmental Integration, ISSN 2365-6433, Vol. 2, no 21Article in journal (Refereed)
    Abstract [en]

    Sweden has the ambition to increase its annual biogas production from the current level of 1.9 to 15 TWh by 2030. The unused capacity of existing anaerobic digesters at wastewater treatment plants is among the options to accomplish this goal. This study investigated the feasibility of utilizing the organic fraction of municipal solid waste (OFMSW) as a co-substrate, with primary and waste-activated sewage sludge (PWASS) for production of biogas, corresponding to 3:1 ratio on volatile solid (VS) basis. The results demonstrated that co-digestion of OFMSW with PWASS at an organic loading rate of 5 gVS l−1 day−1 has the potential to increase the biogas production approximately four times. The daily biogas production increased from 1.0 ± 0.1 to 3.8 ± 0.3 l biogasl−1 day−1, corresponding to a specific methane production of 420 ± 30 Nml methane gVS−1 during the laboratory experiment. Co-digestion of OFMSW with PWASS showed a 50:50 distribution of hydrogenotrophic and aceticlastic methanogens in the digester and enhanced the turnover kinetics of intermediate products (acetate, propionate, and oleate). Practical limitations potentially include the need for sludge dewatering to maintain a sufficient hydraulic retention time (17 days in this study), as well as additional energy consumption for mixing due to an increased sludge apparent viscosity (from 1.8 ± 0.1 to 45 ± 4.8 mPa*s in this study) at elevated OFMSW-loading rates.

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  • 35.
    Shakeri Yekta, Sepehr
    et al.
    Linköping University, Department of Thematic Studies, Tema Environmental Change. Linköping University, Faculty of Arts and Sciences. Linköping University, Biogas Research Center.
    Ziels, Ryan M.
    University of Washington, WA 98195 USA.
    Björn, Annika
    Linköping University, Department of Thematic Studies, Tema Environmental Change. Linköping University, Faculty of Arts and Sciences. Linköping University, Biogas Research Center.
    Skyllberg, Ulf
    Swedish University of Agriculture Science, Sweden.
    Ejlertsson, Jörgen
    Linköping University, Department of Thematic Studies, Tema Environmental Change. Linköping University, Faculty of Arts and Sciences. Linköping University, Biogas Research Center. Scandinavian Biogas Fuels AB, Sweden.
    Karlsson, Anna
    Linköping University, Biogas Research Center. Scandinavian Biogas Fuels AB, Sweden.
    Svedlund, Matilda
    Linköping University, Department of Thematic Studies, Tema Environmental Change. Linköping University, Faculty of Arts and Sciences. Scandinavian Biogas Fuels AB, Sweden.
    Willen, Magnus
    Linköping University, Department of Thematic Studies, Tema Environmental Change. Linköping University, Faculty of Arts and Sciences.
    Svensson, Bo
    Linköping University, Department of Thematic Studies, Tema Environmental Change. Linköping University, Faculty of Arts and Sciences. Linköping University, Biogas Research Center.
    Importance of sulfide interaction with iron as regulator of the microbial community in biogas reactors and its effect on methanogenesis, volatile fatty acids turnover, and syntrophic long-chain fatty acids degradation2017In: Journal of Bioscience and Bioengineering, ISSN 1389-1723, E-ISSN 1347-4421, Vol. 123, no 5, p. 597-605Article in journal (Refereed)
    Abstract [en]

    The inhibitory effects of sulfide on microbial processes during anaerobic digestion have been widely addressed. However, other effects of sulfide are less explored, given that sulfide is a potential sulfur source for microorganisms and its high reactivity triggers a suit of abiotic reactions. We demonstrated that sulfide interaction with Fe regulates the dynamics and activities of microbial community during anaerobic digestion. This was manifested by the S:Fe molar ratio, whose increase adversely influenced the acetoclastic methanogens, Methanosaeta, and turnover of acetate. Dynamics of hydrogenotrophic methanogens, Methanoculleus and Methanobrevibacter, were presumably influenced by sulfide-induced changes in the partial pressure of hydrogen. Interestingly, conversion of the long-chain fatty acid (LCFA), oleate, to methane was enhanced together with the abundance of LCFA-degrading, beta-oxidizing Syntrophomonas at an elevated S:Fe molar ratio. The results suggested that sulfur chemical speciation is a controlling factor for microbial community functions in anaerobic digestion processes. (C) 2016, The Society for Biotechnology, Japan. All rights reserved.

  • 36.
    Björn, Annika
    et al.
    Linköping University, The Tema Institute, Tema Environmental Change. Linköping University, Faculty of Arts and Sciences.
    Borgström, Ylva
    Pöyry Sweden AB, Norrköping, Sweden.
    Ejlertsson, Jörgen
    Linköping University, The Tema Institute, Tema Environmental Change. Linköping University, Faculty of Arts and Sciences.
    Karlsson, Anna
    Scandinavian Biogas Fuels AB, Stockholm, Sweden.
    Nilsson, Fredrik
    Pöyry Sweden AB, Norrköping, Sweden.
    Svensson, Bo
    Linköping University, The Tema Institute, Tema Environmental Change. Linköping University, Faculty of Arts and Sciences.
    Biogasproduktion inom svensk pappers- och massaporduktion : Syntes av möjligheter och begränsningar samt teknisk utvärdering: Bilaga 2 Etablering/effektivisering av biogasproduktion inom svensk pappers- och massaindustri2016Report (Other academic)
    Abstract [sv]

    Linköpings Universitet har tillsammans med Pöyry och Scandinavian Biogas Fuels drivit projektet ”Etablering/effektivisering av  biogasproduktion inom svensk pappers- och massaproduktion”. Potentialen hos det organiska materialet i avloppsvatten från svensk pappers- och massaindustri (PMI) till biogasproduktion skattades vid projektstart till 100 milj. Nm3 metan per år (1 TWh). Denna rapport är en syntes av resultaten från projektet med syfte att ge visa hur de genererade resultaten kan omsättas i teknisk praktik med tillhörande ekonomiska insatser. Syftet är att ge underlag och stöd till PMI-branschen och externa intressenter, som överväger att implementera biogasproduktion inom PMI.

    Substraten för biogasproduktion som återfinns i pappers- och massaindustrins avloppsvatten och slam kännetecknas av stora volymer med låga COD-halter. Detta kräver rötningstekniker, som tillåter mycket korta uppehållstider jämfört med mer traditionellt utformade biogasanläggningar för att inte tankstorleken ska bli för stor. Två tekniker, som utvecklats inom projektet, klarar detta: EGSB (expanded granular sludge bed) och CSTR (completely stirred tank reactor) med slamåterföring. Dessa tekniker har därför utvärderats för tre olika typbruk, ett CTMP-bruk, ett TMP-bruk och ett sulfatmassabruk. Resultaten från dessa experimentella studier är utgångspunkten för i utvärderingen i föreliggande rapport. För varje processkoncept har en grov kostnadsuppskattning (±20 %) gjorts för den investering som krävs för biogasproduktion.

    En EGSB på ett TMP-bruk med ett totalavlopp på 1500 m3/h, där hela blekeriavloppet från peroxidblekningen och en del av det övriga avloppet behandlas i en 4000 m3 reaktor förväntas ge 2,5 milj Nm3 metan/år. Investeringskostnaden för anläggningen uppskattas till 75 milj. SEK (±20 %).

    En EGSB på ett CTMP-bruk med ett totalavlopp på 170 m3/h där hela avloppet behandlas i en 3000 m3 reaktor förväntas ge 1,8 milj Nm3 metan/år. Investeringskostnaden för anläggningen uppskattas till 64 milj. SEK (±20%).

    En CSTR med slamåterföring som körs på bioslam från ett sulfatmassabruk där ett bioslamflöde på 46 m3/h behandlas i en 4000 m3 reaktor förväntas ge 1,0 milj Nm3 metan/år. I denna design är strategin för den aeroba bioreningen ändrad för att producera ett bioslam optimerat för att ge högsta möjliga biogaspotential. Detta innebär produktion av större mängd slam, som i största mån kan rötas till metan, dvs mängd metan per mängd rötat organiskt material samtidigt som COD-reduktionen i vattenreningen bibehålls. Investeringskostnaden för anläggningen uppskattas till 32 milj. SEK (±20%).

    Baserat på de COD-kvantiteter som når de luftade dammarna inom PMIs vattenreningssystem förbrukas årligen ca 0,8 TWh el. Införande av biogasproduktion i massaindustrins spillvattenrening skulle reducera mängden COD med mellan 30-50%, vilket får till följd att den årliga elförbrukningen i samband med den aeroba reningen går ner med ca 0,2-0,4 TWh. Detta innebär alltså ett energitillskott av 0,9 – 1,1 TWh givet att hela den tillgängliga biogaspotentialen skulle byggas ut. Till detta kommer eventuella vinster relaterade till slamhanteringen.

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  • 37.
    Moestedt, J.
    et al.
    Linköping University, Biogas Research Center. Department of R&D Biogas, Tekniska verken i Linköping AB, Linköping, Sweden; Department of Microbiology, BioCenter, University of Agricultural Sciences, Uppsala, Sweden.
    Nordell, E.
    Linköping University, Biogas Research Center. Department of R&D Biogas, Tekniska verken i Linköping AB, Linköping, Sweden.
    Shakeri Yekta, Sepehr
    Linköping University, Department of Thematic Studies, Tema Environmental Change. Linköping University, Faculty of Arts and Sciences. Linköping University, Biogas Research Center.
    Lundgren, J.
    Linköping University, Biogas Research Center. Department of R&D Biogas, Tekniska verken i Linköping AB, Linköping, Sweden.
    Marti, Magali
    Linköping University, Department of Thematic Studies, Tema Environmental Change. Linköping University, Faculty of Arts and Sciences. Linköping University, Biogas Research Center.
    Sundberg, Carina
    Linköping University, Department of Thematic Studies, Tema Environmental Change. Linköping University, Faculty of Arts and Sciences. Linköping University, Biogas Research Center.
    Ejlertsson, Jörgen
    Linköping University, Department of Thematic Studies, Tema Environmental Change. Linköping University, Faculty of Arts and Sciences. Linköping University, Biogas Research Center. Scandinavian Biogas Fuels AB, Sweden.
    Svensson, Bo
    Linköping University, Department of Thematic Studies, Tema Environmental Change. Linköping University, Faculty of Arts and Sciences. Linköping University, Biogas Research Center.
    Björn, Annika
    Linköping University, Department of Thematic Studies, Tema Environmental Change. Linköping University, Faculty of Arts and Sciences. Linköping University, Biogas Research Center.
    Effects of trace element addition on process stability during anaerobic co-digestion of OFMSW and slaughterhouse waste2016In: Waste Management, ISSN 0956-053X, E-ISSN 1879-2456, Vol. 47, no Pt A, p. 11-20Article in journal (Refereed)
    Abstract [en]

    This study used semi-continuous laboratory scale biogas reactors to simulate the effects of trace-element addition in different combinations, while degrading the organic fraction of municipal solid waste and slaughterhouse waste. The results show that the combined addition of Fe, Co and Ni was superior to the addition of only Fe, Fe and Co or Fe and Ni. However, the addition of only Fe resulted in a more stable process than the combined addition of Fe and Co, perhaps indicating a too efficient acidogenesis and/or homoacetogenesis in relation to a Ni-deprived methanogenic population. The results were observed in terms of higher biogas production (+9%), biogas production rates (+35%) and reduced VFA concentration for combined addition compared to only Fe and Ni. The higher stability was supported by observations of differences in viscosity, intraday WA-and biogas kinetics as well as by the 16S rRNA gene and 16S rRNA of the methanogens.(c) 2015 Elsevier Ltd. All rights reserved.

  • 38.
    Ekstrand, Eva-Maria
    et al.
    Linköping University, Department of Thematic Studies, Tema Environmental Change. Linköping University, Biogas Research Center. Linköping University, Faculty of Arts and Sciences.
    Karlsson, Marielle
    Linköping University, Biogas Research Center. Linköping University, Department of Thematic Studies. Linköping University, Faculty of Arts and Sciences. Scandinavian Biogas Fuels AB, Sweden.
    Truong, Xu-Bin
    Linköping University, Biogas Research Center. Scandinavian Biogas Fuels AB, Sweden.
    Björn, Annika
    Linköping University, Department of Thematic Studies, Tema Environmental Change. Linköping University, Biogas Research Center. Linköping University, Faculty of Arts and Sciences.
    Karlsson, Anna
    Linköping University, Biogas Research Center. Scandinavian Biogas Fuels AB, Sweden.
    Svensson, Bo H.
    Linköping University, Department of Thematic Studies, Tema Environmental Change. Linköping University, Biogas Research Center. Linköping University, Faculty of Arts and Sciences.
    Ejlertsson, Jörgen
    Linköping University, Department of Thematic Studies, Tema Environmental Change. Linköping University, Biogas Research Center. Linköping University, Faculty of Arts and Sciences. Scandinavian Biogas Fuels AB, Sweden.
    High-rate anaerobic co-digestion of kraft mill fibre sludge and activated sludge by CSTRs with sludge recirculation2016In: Waste Management, ISSN 0956-053X, E-ISSN 1879-2456, Vol. 56, p. 166-172Article in journal (Refereed)
    Abstract [en]

    Kraft fibre sludge from the pulp and paper industry constitutes a new, widely available substrate for thebiogas production industry, with high methane potential. In this study, anaerobic digestion of kraft fibresludge was examined by applying continuously stirred tank reactors (CSTR) with sludge recirculation.Two lab-scale reactors (4L) were run for 800 days, one on fibre sludge (R1), and the other on fibre sludgeand activated sludge (R2). Additions of Mg, K and S stabilized reactor performance. Furthermore, theCa:Mg ratio was important, and a stable process was achieved at a ratio below 16:1. Foaming was abatedby short but frequent mixing. Co-digestion of fibre sludge and activated sludge resulted in more robustconditions, and high-rate operation at stable conditions was achieved at an organic loading rate of 4 gvolatile solids (VS) L1 day1, a hydraulic retention time of 4 days and a methane production of230 ± 10 Nm L per g VS.

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  • 39.
    Ziels, Ryan
    et al.
    Linköping University, Biogas Research Center. Civil and Environmental Engineering, University of Washington, WA, USA.
    Karlsson, Anna
    Linköping University, Biogas Research Center. Scandinavian Biogas Fuels AB, Sweden.
    Beck, David A.C.
    Science Institute, University of Washington, WA, USA.
    Ejlertsson, Jörgen
    Linköping University, Department of Thematic Studies, Tema Environmental Change. Linköping University, Biogas Research Center. Linköping University, Faculty of Arts and Sciences. Scandinavian Biogas Fuels AB, Sweden.
    Shakeri Yekta, Sepehr
    Linköping University, Department of Thematic Studies, Tema Environmental Change. Linköping University, Biogas Research Center. Linköping University, Faculty of Arts and Sciences.
    Björn, Annika
    Linköping University, Department of Thematic Studies, Tema Environmental Change. Linköping University, Biogas Research Center. Linköping University, Faculty of Arts and Sciences.
    Stensel, H. David
    Civil and Environmental Engineering, University of Washington, WA, USA.
    Svensson, Bo H.
    Linköping University, Department of Thematic Studies, Tema Environmental Change. Linköping University, Biogas Research Center. Linköping University, Faculty of Arts and Sciences.
    Microbial community adaptation influences long-chain fatty acid conversion during anaerobic codigestion of fats, oils, and grease with municipal sludge2016In: Water Research, ISSN 0043-1354, E-ISSN 1879-2448, Vol. 103, p. 372-382Article in journal (Refereed)
    Abstract [en]

    Codigesting fats, oils, and greases with municipal wastewater sludge can greatly improve biomethanerecovery at wastewater treatment facilities. Process loading rates of fats, oils, and greases have beenpreviously tested with little knowledge of the digester microbial community structure, and high transientfat loadings have led to long chain fatty acid (LCFA) accumulation and digester upsets. This studyutilized recently-developed quantitative PCR assays for syntrophic LCFA-degrading bacteria along with16S amplicon sequencing to relate changes in microbial community structure to LCFA accumulationduring transient loading increases to an anaerobic codigester receiving waste restaurant oil andmunicipal wastewater sludge. The 16S rRNA gene concentration of the syntrophic b-oxidizing genusSyntrophomonas increased to ~15% of the Bacteria community in the codigester, but stayed below 3% inthe control digester that was fed only wastewater sludge. Methanosaeta and Methanospirillum were thedominant methanogenic genera enriched in the codigester, and together comprised over 80% of theArchaea community by the end of the experimental period. Constrained ordination showed that changesin the codigester Bacteria and Archaea community structures were related to measures of digester performance.Notably, the effluent LCFA concentration in the codigester was positively correlated to thespecific loading rate of waste oil normalized to the Syntrophomonas 16S rRNA concentration. Specificloading rates of 0e1.5 1012 g VS oil/16S gene copies-day resulted in LCFA concentrations below 30 mg/g TS, whereas LCFA accumulated up to 104 mg/g TS at higher transient loading rates. Based on thecommunity-dependent loading limitations found, enhanced biomethane production from high loadingsof fats, oils and greases can be achieved by promoting a higher biomass of slow-growing syntrophicconsortia, such as with longer digester solids retention times. This work also demonstrates the potentialfor controlling the loading rate of fats, oils, and greases based on the analysis of the codigester communitystructure, such as with quantitative PCR measurements of syntrophic LCFA-degrading bacteriaabundance.

  • 40.
    Larsson, Madeleine
    et al.
    Linköping University, Department of Thematic Studies, Tema Environmental Change. Linköping University, Faculty of Arts and Sciences. Linköping University, Biogas Research Center.
    Truong, Xu-bin
    Linköping University, Biogas Research Center. Scandinavian Biogas Fuels AB, Sweden.
    Björn, Annika
    Linköping University, Department of Thematic Studies, Tema Environmental Change. Linköping University, Faculty of Arts and Sciences. Linköping University, Biogas Research Center.
    Ejlertsson, Jörgen
    Linköping University, Department of Thematic Studies, Tema Environmental Change. Linköping University, Faculty of Arts and Sciences. Linköping University, Biogas Research Center. Scandinavian Biogas Fuels AB, Sweden.
    Bastviken, David
    Linköping University, Department of Thematic Studies, Tema Environmental Change. Linköping University, Faculty of Arts and Sciences. Linköping University, Biogas Research Center.
    Svensson, Bo
    Linköping University, Department of Thematic Studies, Tema Environmental Change. Linköping University, Faculty of Arts and Sciences. Linköping University, Biogas Research Center.
    Karlsson, Anna
    Linköping University, Biogas Research Center. Scandinavian Biogas Fuels AB, Sweden.
    Anaerobic digestion of alkaline bleaching wastewater from a Kraft pulp and paper mill using UASB technique2015In: Environmental technology, ISSN 0959-3330, E-ISSN 1479-487X, Vol. 36, no 12, p. 1489-1498Article in journal (Refereed)
    Abstract [en]

    Anaerobic digestion of alkaline kraft elemental chlorine-free bleaching wastewater in two mesophilic, lab-scale upflow anaerobic sludge bed reactors resulted in significantly higher biogas production (250 ± 50 vs. 120 ± 30 NmL g [Formula: see text]) and reduction of filtered total organic carbon (fTOC) (60 ± 5 vs. 43 ± 6%) for wastewater from processing of hardwood (HW) compared with softwood (SW). In all cases, the gas production was likely underestimated due to poor gas separation in the reactors. Despite changes in wastewater characteristics, a stable anaerobic process was maintained with hydraulic retention times (HRTs) between 7 and 14 h. Lowering the HRT (from 13.5 to 8.5 h) did not significantly affect the process, and the stable performance at 8.5 h leaves room for further decreases in HRT. The results show that this type of wastewater is suitable for a full-scale implementation, but the difference in methane potential between SW and HW is important to consider both regarding process dimensioning and biogas yield optimization.

  • 41.
    Ammenberg, Jonas
    et al.
    Linköping University, Department of Management and Engineering, Environmental Technology and Management. Linköping University, The Institute of Technology. Linköping University, Biogas Solutions Research Center.
    Svensson, Bo
    Linköping University, Department of Thematic Studies, Tema Environmental Change. Linköping University, Faculty of Arts and Sciences. Linköping University, Biogas Solutions Research Center.
    Karlsson, Magnus
    Linköping University, Department of Management and Engineering, Energy Systems. Linköping University, Biogas Solutions Research Center.
    Svensson, Niclas
    Linköping University, Department of Management and Engineering, Environmental Technology and Management. Linköping University, The Institute of Technology. Linköping University, Biogas Solutions Research Center.
    Björn, Annika
    Linköping University, Department of Thematic Studies, Tema Environmental Change. Linköping University, Faculty of Arts and Sciences. Linköping University, Biogas Solutions Research Center.
    Karlsson, Martin
    Linköping University, Department of Physics, Chemistry and Biology, Chemistry. Linköping University, The Institute of Technology. Linköping University, Biogas Solutions Research Center.
    Tonderski, Karin
    Linköping University, Department of Physics, Chemistry and Biology, Biology. Linköping University, The Institute of Technology. Linköping University, Biogas Solutions Research Center.
    Eklund, Mats
    Linköping University, Department of Management and Engineering, Environmental Technology and Management. Linköping University, The Institute of Technology. Linköping University, Biogas Solutions Research Center.
    Biogas Research Center, BRC: Slutrapport för etapp 12015Report (Other academic)
    Abstract [en]

    Biogas Research Center (BRC) is a center of excellence in biogas research funded by the Swedish Energy Agency, Linköping University and a number of external organizations with one-third each. BRC has a very broad interdisciplinary approach, bringing together biogas-related skills from several areas to create interaction on many levels:

    • between industry, academia and society,
    • between different perspectives, and
    • between different disciplines and areas of expertise.

    BRC’s vision is:

    BRC contributes to the vision by advancing knowledge and technical development, as well as by facilitating development, innovation and business. Resource efficiency is central, improving existing processes and systems as well as establishing biogas solutions in new sectors and enabling use of new substrates.

    For BRC phase 1, the first two year period from 2012-2014, the research projects were organized in accordance with the table below showing important challenges for biogas producers and other stakeholders, and how these challenges were tackled in eight research projects. Five of the projects had an exploratory nature, meaning that they were broader, more future oriented and, for example, evaluated several different technology paths (EP1-5). Three projects focused more on technology and process development (DP6-8).

    This final report briefly presents the background and contains some information about competence centers in general. Thereafter follows more detailed information about BRC, for example, regarding the establishment, relevance, organization, vision, corner stones and development. The participating organizations are presented, both the research groups within Linköping University and the partners and members. Further on, there is a more detailed introduction to and description of the challenges mentioned in the table above and a short presentation from each of the research projects, followed by some sections dealing with fulfillment of objectives and an external assessment of BRC. Detailed, listed information is commonly provided in the appendices.

    Briefly, the fulfillment of objectives is good and it is very positive that so many scientific articles have been published (or are to be published) from the research projects and also within the wider center perspective. Clearly, extensive and relevant activities are ongoing within and around BRC. In phase 2 it essential to increase the share of very satisfied partners and members, where now half of them are satisfied and the other half is very satisfied. For this purpose, improved communication, interaction and project management are central. During 2015, at least two PhD theses are expected, to a large extent based on the research from BRC phase 1.

    In the beginning of 2014 an external assessment of BRC was carried out, with the main purpose to assess how well the center has been established and to review the conditions for a future, successful competence center. Generally, the outcome was very positive and the assessors concluded that BRC within a short period of time had been able to establish a well-functioning organization engaging a large share of the participants within relevant areas, and that most of the involved actors look upon BRC as a justifiable and well working investment that they plan to continue to support. The assessment also contributed with several relevant tips of improvements and to clarify challenges to address.

    This report is written in Swedish, but for each research project there will be reports and/or scientific papers published in English.

    The work presented in this report has been financed by the Swedish Energy Agency and the participating organizations.

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  • 42.
    Larsson, Madeleine
    et al.
    Linköping University, The Tema Institute, Tema Environmental Change. Linköping University, Faculty of Arts and Sciences.
    Svedlund, Matilda
    Karlsson, Marielle
    Linköping University, The Tema Institute, Department of Water and Environmental Studies. Linköping University, Faculty of Arts and Sciences.
    Truong, Xu-bin
    Scandinavian Biogas Fuels AB.
    Ejlertsson, Jörgen
    Linköping University, The Tema Institute, Tema Environmental Change. Linköping University, Faculty of Arts and Sciences.
    Björn, Annika
    Linköping University, The Tema Institute, Tema Environmental Change. Linköping University, Faculty of Arts and Sciences.
    Svensson, Bo
    Linköping University, The Tema Institute, Tema Environmental Change. Linköping University, Faculty of Arts and Sciences.
    Karlsson, Anna
    Scandinavian Biogas Fuels AB.
    Effects of temperature on UASB digestion of wastewater from a millproducing recovered fiberbased board2015Conference paper (Refereed)
  • 43.
    Jidesjö, Anders
    et al.
    Linköping University, Department of Thematic Studies, Tema Environmental Change. Linköping University, Faculty of Arts and Sciences.
    Danielsson, Åsa
    Linköping University, Department of Thematic Studies, Tema Environmental Change. Linköping University, Faculty of Arts and Sciences.
    Björn, Annika
    Linköping University, Department of Thematic Studies, Tema Environmental Change. Linköping University, Faculty of Arts and Sciences.
    Interest and Recruitment in Science: A Reform, Gender and Experience Perspective2015In: The XVI International Organisation for Science and Technology Education Symposium (IOSTE Borneo 2014) / [ed] Yoong Suan; Lau Ung Hua, Elsevier, 2015, Vol. 167, no 0, p. 211-216Conference paper (Refereed)
    Abstract [en]

    This paper reports on Swedish results from a worldwide research project concerned with the Interest and Recruitment in Science Education (the IRIS-International study) together with results from a longitudinal national study on girl's views on out of school experience in science and technology in upper secondary education. The studies are framed in the structural situation of the Swedish educational system. The results show that there are reform and policy effects to consider in the discussion of recruiting more students in STEM. Interest in the subject, earlier school experience, achievement and teacher feedback is found to be important for educational choice in STEM. Specifically girls point out societal relevance as important. In addition there are elements outside the school setting with importance for educational choice. Moreover, girls point out visits to a museum and watching films and boys popularized forms of science and computer games. All students consider TV and activities outside school as important for their educational choice in STEM. When trying to implement outside school experience with girls in a longitudinal study in upper secondary education the interplay with school subject teaching is identified as missing. The friction between subject teaching in schools and connections with the surrounding world is proposed as important for future studies.

  • 44.
    Jidesjö, Anders
    et al.
    Linköping University, The Tema Institute, Tema Environmental Change. Linköping University, Faculty of Arts and Sciences.
    Björn, Annika
    Linköping University, The Tema Institute, Tema Environmental Change. Linköping University, Faculty of Arts and Sciences.
    Tydén, Thomas
    Högskolan Dalarna, Akademin Utbildning, hälsa och samhälle.
    Uhrqvist, Ola
    Linköping University, The Tema Institute. Linköping University, Faculty of Arts and Sciences.
    Rapportering av fördjupande forskningsinsatser kopplade till skolutvecklingsprogrammet ”KNUT3”: En berättelse om vad en transformativ inriktning på utbildningens genomförande kan innebära för skolutveckling och möjligheter till meningsfullt lärande2015Report (Other academic)
    Abstract [sv]

    Denna forskningsrapport rapporterar från tre studier genomförda på skolutvecklingsprogrammet ”KNUT3”, som genomfördes under 2014. Forskningen bygger vidare på de resultat som rapporterats i tidigare forskning på samma skolutvecklingsprogram, fast då ”KNUT2” (Jidesjö et al., 2014). Resultaten som rapporteras här vilar således på ett omfattande empiriskt underlag, som korresponderar med verksamheter från förskola upp till och med gymnasieskola. I en övergripande beskrivning handlade ”KNUT” om att hitta sätt att arbeta för att involvera utbildningen mer i verkliga samhällsutmaningar och sätt att arbeta med lärare som sätter avtryck i klassrum och kommer elevernas lärande till del. Områden som arbeten varit koncentrerade till är energi, resurs, klimat och hållbarhetsfrågor. Ett viktigt resultat som identifierades i den förra forskningsrapporten handlar om att bygga skolutveckling inifrån. Det innebär arbeten som utgår ifrån elevers förutsättningar för lärande och ger lärare och elever möjligheter att äga sådana processer. Denna forskningsrapport fördjupar vad ett sådant arbete innebär, vilka förtjänsterna kan vara och hur utmaningar kan hanteras.

    Forskningsinsatserna har i allt arbete som rapporteras här utgått ifrån ett följeforskningsupplägg. Det innebär att forskningen haft två funktioner. Dels att tillse att aktiviteter som genomförs har en relation till forskning och vetenskap. Arbetet handlar då om att ta del av tidigare studier och skapa möten med inblandade lärare och andra aktörer, där dessa resultat kan presenteras på ett sätt att de kan omsättas i pågående arbete. Den andra funktionen handlar om att bedriva ny forskning, som genererar en kunskapsuppbyggnad. Även dessa processer är riggade på ett sätt så att framför allt lärare kan ta del av och även påverka forskningens upplägg och inriktning. Forskningsarbetet bygger således starkt på närvaro under pågående arbete istället för att ha en mer utvärderande karaktär i efterhand.Rapporten bygger på empiriska underlag från tre ingående delstudier.

    Den första återfinns i kapitel två och handlar om lärares perspektiv på utforskande och undersökande arbetssätt i förskola och grundskola. Empirin är genererad via fokusgruppsmetodik med yrkesverksamma lärare som givits möjlighet att reflektera och diskutera kring användandet och implementeringen av material som är mer elevaktiva och öppna i sin karaktär. Resultaten visar att lärares vilja att engagera sig i utvecklingsarbete är kopplat till materialets utformning och rymmer en innehållsdimension samt koppling till samhällsrelevans. Lärarna lyfter också betydelse av involvering av barnens föräldrar i arbetet samt att aktiviteter som utförs har en påverkan på familjelivets handlingar. Breda kontakter med natur och samhälle är ytterligare dimensioner som lyfts fram som viktiga förutsättningar för meningsfullt lärande. Resultaten diskuteras i relation till läraryrkets professionsutveckling, synsätt på undervisning och lärande som förutsättningar för kvalitetsarbete och betydelse av en utbildning som är i takt med tiden.

    Det andra arbetet som rapporteras i kapitel tre, handlar om fördjupande studier kring flickors val av utbildning och hur insatser kan göras för att påverka utbildningsval. Ett rekryteringsperspektiv har genomförts i projektet ”Tjejresan” som pågått i svenska gymnasieskolor. Flickor som valt att studera inom naturvetenskapliga och tekniskt inriktade program har erbjudits möjlighet till aktiviteter där de fått besöka företag och arbetsliv och beretts möjligheter att få inblick i hur andra aktörer utanför skolan arbetar med innehåll. Arbetet har pågått i flera år och forskningsinsatserna har följt utvecklingen. De empiriska underlagen grundar sig i enkätstudier med aktuella elever i kombination med intervjustudier. Till detta har även uppföljande intervjuer genomförts med kvinnor som idag avslutat sin gymnasiala utbildning och befinner sig i olika positioner i samhället. Resultaten indikerar att insatserna haft betydelse, men en begränsad påverkan för utbildningsval. Viktiga faktorer som framkommit rör sig kring intresse för innehållet samt den nära familjens betydelse och att intresse är något som grundlagts betydligt tidigare. Insatserna sent i utbildningssystemet verkar mest ha påverkan för att bibehålla och stimulera intresset genom att skapa relationer mellan skola och arbetsliv och demonstrera karriärvägar. Resultaten är diskuterade i relation till möjligheter att arbeta mer med intresset i grundskolan samt att när det gäller frågan om utbildningsval och rekrytering, öppna upp för möjligheter att föräldrar och den nära familjen är mer involverade i skolarbetet.

    Kapitel fyra innehåller den tredje delstudien och rapporterar ett lärarperspektiv på nätverksarbete och kollegialt lärande. Studien handlar om att öka förståelsen för vad ett nätverk kan vara och innebära. Empirin är genererad från lärare i gymnasieskolan, som ingått i ett nätverk under längre tid och som intervjuats för att kunna delge sina berättelser och reflektioner kring nätverkets och det kollegiala lärandets innebörder. Empirin är sedan framställd kring aktuell teoribildning. Tillsammans identifierar studien ett antal viktiga faktorer, som diskuteras i relation till förtjänster och möjligheter för att stimulera en professionell inriktning på lärararbetet.

    Rapporten är skriven så att delstudierna kan läsas självständiga. För att inordna dem i ett större sammanhang inleds rapporten med ett kapitel där delstudiernas resultat sätts in i ytterligare teoribildning och perspektiv, som hjälper till att tolka innebörder. Aktuell forskning och teoribildning om lärande och kvalitetsarbete har hämtats genom att anlägga historiska, sociologiska och utbildningsvetenskapliga perspektiv. Texten gör inga anspråk på att vara heltäckande och argumenterar inte för en bestämd inriktning. Den är skriven för att bidra som en tolkningsram åt delstudierna och har således empirisk resonans. Forskningsinsatserna har bedrivits utifrån ett följeforskningsperspektiv, som innebär att vetenskaplig och erfarenhetsbaserad kunskap möts för att i gemensamma överläggningar identifiera viktigt arbete där alla kan bidra.

    Det inledande kapitlet lyfter frågor om betydelse av att utvecklingsarbeten i skolan initieras och byggs inifrån elevers förutsättningar för lärande och vidare ut i dynamiska förbindelser med omgivande samhälle. Texten har identifierat traditioner i syn på begåvning, talang och lärande som viktiga att reflektera för att förstå innebörd av andra synsätt. En strävan att åstadkomma en professionell inriktning på utbildningens genomförande har anlagts genom en transformativ inriktning som därpå beskrivs med konkreta dimensioner som kan förstärka och stimulera en sådan inriktning. Sådana dimensioner handlar om egenskaper i ledarskap, barnsyn, samarbete med barns familjer, kontaktytor med natur och samhällsliv, hur grupper sätts samman, hur bedömning byggs upp, egenskaper i arbetsmaterial och betydelse av en lärande gemenskap som innebär att hela skolan arbetar mot gemensamma målsättningar.

    Slutsatser som reflekteras i detta inledande kapitel handlar inte om att problem för utbildningens genomförande handlar om arbeten som tar fram fler resurssidor i form av tips och tricks, som lärare förväntas ta del av och sedan exponera för elever. Kunskaper och drivkrafter för kreativitet i metodik bör istället växa fram som en konsekvens av identifierade problem, så att lärare och deras elever formar och därifrån får stöd som ger insatser som berör deras verkliga bekymmer. I sådana processer kan barnens hemmiljöer, material, bedömning, ledningsfunktioner, forskning och omgivande samhälle träda in och stötta en kunskapsutveckling som successivt introducerar kommande generationer till samhällets utmaningar. En sådan transformativ inriktning gör att samhället på lång sikt blir mer trovärdigt eftersom utbildningen får en förankring i verkliga verksamhetsformer. Annorlunda kan man uttrycka detta som att olika länkar behöver finnas, för att de ska kunna aktiveras vid behov. Exakt när sådana behov uppstår utgör den dynamiska karaktären mellan utbildningens inre och yttre dimensioner, som gör det svårt att fånga innebörden i statiska uttryck. En fastare förankring för utbildningen i samhällslivets vedermödor är identifierad som en viktig fortsättning för kommande studier. Sådana förankringar borde kunna åstadkommas i delvis nya strukturer, med anledning av kommunikationsmediernas allt mer betydande inslag för informationsspridning. Innebörder av hur gestaltningar i det lokala, regionala, nationella och internationella involverar individer och tar sig uttryck, har med produktions- och receptionskontexter att göra och är en trolig viktig fortsättning i förståelse av och för att förstärka den professionella inriktning för lärararbetet, som skisserats i denna forskningsrapport.

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  • 45.
    Larsson, Madeleine
    et al.
    Linköping University, The Tema Institute, Tema Environmental Change. Linköping University, Faculty of Arts and Sciences. Linköping University, Biogas Research Center.
    Ekstrand, Eva-Maria
    Linköping University, The Tema Institute, Tema Environmental Change. Linköping University, Faculty of Arts and Sciences.
    Truong, Xu-bin
    Linköping University, Biogas Research Center. Scandinavian Biogas Fuels AB, Sweden.
    Nilsson, Fredrik
    Pöyry Sweden AB, Norrköping, Sweden.
    Ejlertsson, Jörgen
    Linköping University, The Tema Institute, Tema Environmental Change. Linköping University, Faculty of Arts and Sciences. Linköping University, Biogas Research Center. Scandinavian Biogas Fuels AB, Sweden.
    Svensson, Bo
    Linköping University, The Tema Institute, Tema Environmental Change. Linköping University, Faculty of Arts and Sciences. Linköping University, Biogas Research Center.
    Karlsson, Anna
    Linköping University, Biogas Research Center. Scandinavian Biogas Fuels AB, Sweden.
    Björn, Annika
    Linköping University, The Tema Institute, Tema Environmental Change. Linköping University, Faculty of Arts and Sciences. Linköping University, Biogas Research Center.
    The biomethane potential of chemical thermo-mechanical pulp wastewaters in relation to their chemical composition2015Manuscript (preprint) (Other academic)
    Abstract [en]

    This study evaluates the biomethane potential of composite pulping and bleaching chemical thermo-mechanical pulp (CTMP) wastewaters in relation to their composition of organic compounds, as well as to their sulphur contents. The biomethane potential was determined in batch experiments and the CTMP wastewaters from production of bleached spruce-, birch- and aspen pulp and unbleached spruce pulp were analysed for dissolved lignin, carbohydrates, wood extractives, acetic acid and total sulphur content. The biomethane potential obtained for the wastewaters ranged from 350 to 670 NmL g TOC-1 with the highest yield for wastewater from the production of bleached birch CTMP followed by bleached aspen-, bleached spruce- and unbleached spruce CTMP. The main differences in wastewater composition were related to the raw material used for the pulp production, i.e. softwood vs. hardwood. The compounds mainly promoting the biomethane production were acetic acid, xylose, wood extractives, triglycerides and steryl esters, whereas dissolved lignin, sulphur, arabinose, mannose, lignans and free fatty-/resin acids lowered the potential. However, the individual contribution of each variable was not possible to evaluate due to covariations among them.

  • 46.
    Ekstrand, Eva-Maria
    et al.
    Linköping University, The Tema Institute, Tema Environmental Change. Linköping University, Faculty of Arts and Sciences.
    Karlsson, Marielle
    Linköping University, The Tema Institute, Department of Water and Environmental Studies. Linköping University, Faculty of Arts and Sciences.
    Truong, Xu-Bin
    Scandinavian Biogas.
    Björn, Annika
    Linköping University, The Tema Institute, Tema Environmental Change. Linköping University, Faculty of Arts and Sciences.
    Karlsson, Anna
    Scandinavian Biogas.
    Svensson, Bo H.
    Linköping University, The Tema Institute, Tema Environmental Change. Linköping University, Faculty of Arts and Sciences.
    Ejlertsson, Jörgen
    Scandinavian Biogas.
    The route towards stable and efficient anaerobic digestion of fibrous wastewater from pulp and paper mills in high-rate CSTRs with sludge recirculation2015Conference paper (Other academic)
    Abstract [en]

    The pulp and paper industry carries high costs in wastewater treatment. By combining present techniques with anaerobic digestion (AD), expenses for electricity use and sludge disposal can be reduced. The large wastewater volumes require high-rate systems sensitive to suspended solids, and this has so far excluded treatment of the energy-rich wood fibres. In this study, AD of fibrous wastewater was examined in high-rate CSTRs with sludge recirculation. Two lab-scale reactors (4L) were run for 780 days. Once a day, reactor sludge was withdrawn and centrifuged. The main part of the supernatant was discarded, while the pellet was suspended with the substrate and returned to the reactor. This gave a sludge retention time of 10-16 days and a hydraulic retention time of 4-8 days. One reactor (denoted R1) was fed with fibre sludge, and the second reactor (denoted R2) was co-digesting fibre sludge and activated sludge. Both substrates were taken from a Kraft mill in Sweden. Initially, both reactors experienced frequent drops in pH, and continuous alkali supplements were necessary for process stability. Additions of magnesium and potassium were also needed to obtain stable process performance at an OLR of 3 g VS L-1·day-1. R1 and R2 behaved similarly, but R2 (co-digestion) was more robust with less or no fluctuations in VFA and pH. Addition of activated sludge also to R1 allowed an increase in OLR to 4 g VS L-1·day-1. In summary, stable and efficient operation of a high-rate CSTR with sludge recirculation digesting fibre sludge was achieved at an OLR of 4 g VS L-1·day-1, a HRT of 4 days and a methane production of 260±20 Nml. In addition, co-digestion with activated sludge stabilized the performance at increased OLR and thus gave more methane produced per reactor volume.

  • 47.
    Larsson, Madeleine
    et al.
    Linköping University, The Tema Institute, Department of Water and Environmental Studies. Linköping University, Faculty of Arts and Sciences. Linköping University, Biogas Research Center.
    Truong, Xu-bin
    Linköping University, Biogas Research Center. Scandinavian Biogas Fuels.
    Ejlertsson, Jörgen
    Linköping University, The Tema Institute, Tema Environmental Change. Linköping University, Faculty of Arts and Sciences. Linköping University, Biogas Research Center.
    Bastviken, David
    Linköping University, The Tema Institute, Tema Environmental Change. Linköping University, Faculty of Arts and Sciences. Linköping University, Biogas Research Center.
    Björn, Annika
    Linköping University, The Tema Institute, Tema Environmental Change. Linköping University, Faculty of Arts and Sciences. Linköping University, Biogas Research Center.
    Svensson, Bo
    Linköping University, The Tema Institute, Tema Environmental Change. Linköping University, Faculty of Arts and Sciences. Linköping University, Biogas Research Center.
    Nilsson, Fredrik
    Linköping University, Biogas Research Center. Pöyry AB.
    Karlsson, Anna
    Linköping University, Biogas Research Center. Scandinavian Biogas Fuels AB.
    Anaerobic wastewater treatment and biogas production at TMP and CTMP mills in Sweden.2014Conference paper (Refereed)
  • 48.
    Ejlertsson, Jörgen
    et al.
    Linköping University, The Tema Institute, Tema Environmental Change. Linköping University, Faculty of Arts and Sciences. Linköping University, Biogas Research Center.
    Karlsson, Anna
    Linköping University, Biogas Research Center. Scandinavian Biogas Fuels AB.
    Björn, Annika
    Linköping University, The Tema Institute, Tema Environmental Change. Linköping University, Faculty of Arts and Sciences. Linköping University, Biogas Research Center.
    Nilsson, Fredrik
    Linköping University, Biogas Research Center. Pöyry AB.
    Truong, Xu-bin
    Linköping University, Biogas Research Center. Scandinavian Biogas Fuels.
    Magnusson, Björn
    Linköping University, Biogas Research Center. Scandinavian Biogas Fuels AB.
    Larsson, Madeleine
    Linköping University, The Tema Institute, Department of Water and Environmental Studies. Linköping University, Faculty of Arts and Sciences. Linköping University, Biogas Research Center.
    Ekstrand, Eva-Maria
    Linköping University, The Tema Institute, Tema Environmental Change. Linköping University, Biogas Research Center.
    Karlsson, Marielle
    Linköping University, The Tema Institute, Department of Water and Environmental Studies. Linköping University, Faculty of Arts and Sciences. Linköping University, Biogas Research Center.
    Svensson, Bo
    Linköping University, The Tema Institute, Tema Environmental Change. Linköping University, Faculty of Arts and Sciences. Linköping University, Biogas Research Center.
    Biogas from pulp and paper industry effluents.2014Conference paper (Other academic)
  • 49.
    Ejlertsson, Jörgen
    et al.
    Linköping University, The Tema Institute, Tema Environmental Change. Linköping University, Faculty of Arts and Sciences. Linköping University, Biogas Research Center.
    Karlsson, Anna
    Linköping University, Biogas Research Center. Scandinavian Biogas Fuels AB.
    Björn, Annika
    Linköping University, The Tema Institute, Tema Environmental Change. Linköping University, Faculty of Arts and Sciences. Linköping University, Biogas Research Center.
    Nilsson, Fredrik
    Linköping University, Biogas Research Center. Pöyry AB.
    Truong, Xu-bin
    Linköping University, Biogas Research Center. Scandinavian Biogas Fuels.
    Magnusson, Björn
    Linköping University, Biogas Research Center. Scandinavian Biogas Fuels AB.
    Larsson, Madeleine
    Linköping University, The Tema Institute, Department of Water and Environmental Studies. Linköping University, Faculty of Arts and Sciences. Linköping University, Biogas Research Center.
    Ekstrand, Eva-Maria
    Linköping University, The Tema Institute, Tema Environmental Change. Linköping University, Biogas Research Center.
    Karlsson, Marielle
    Linköping University, The Tema Institute, Department of Water and Environmental Studies. Linköping University, Faculty of Arts and Sciences. Linköping University, Biogas Research Center.
    Svensson, Bo
    Linköping University, The Tema Institute, Tema Environmental Change. Linköping University, Faculty of Arts and Sciences. Linköping University, Biogas Research Center.
    Biogas from pulp andpaper industry effluents.2014Conference paper (Other academic)
  • 50.
    Shakeri Yekta, Sepehr
    et al.
    Linköping University, The Tema Institute, Tema Environmental Change. Linköping University, Faculty of Arts and Sciences. Linköping University, Biogas Research Center.
    Skyllberg, Ulf
    Linköping University, Biogas Research Center. Umeå Universitet.
    Björn, Annika
    Linköping University, The Tema Institute, Tema Environmental Change. Linköping University, Faculty of Arts and Sciences. Linköping University, Biogas Research Center.
    Svensson, Bo
    Linköping University, The Tema Institute, Tema Environmental Change. Linköping University, Faculty of Arts and Sciences. Linköping University, Biogas Research Center.
    Chemical speciation of sulfur and metals in biogas processes2014Conference paper (Other academic)
12 1 - 50 of 86
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