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  • 1.
    Amiri, Shahnaz
    et al.
    Linköping University, Department of Management and Engineering, Energy Systems. Linköping University, The Institute of Technology. Linköping University, Biogas Research Center.
    Henning, Dag
    Linköping University, Department of Management and Engineering, Energy Systems. Linköping University, The Institute of Technology. Linköping University, Biogas Research Center.
    Karlsson, Björn
    Linköping University, Department of Management and Engineering, Energy Systems. Linköping University, The Institute of Technology. Linköping University, Biogas Research Center.
    Simulation and introduction of a CHP plant in a Swedish biogas system2013In: Renewable energy, ISSN 0960-1481, E-ISSN 1879-0682, Vol. 49, no SI, p. 242-249Article in journal (Refereed)
    Abstract [en]

    The objectives of this study are to present a model for biogas production systems to help achieve a more cost-effective system, and to analyse the conditions for connecting combined heat and power (CHP) plants to the biogas system. The European electricity market is assumed to be fully deregulated. The relation between connection of CHP. increased electricity and heat production, electricity prices, and electricity certificate trading is investigated. A cost-minimising linear programming model (MODEST) is used. MODEST has been applied to many energy systems, but this is the first time the model has been used for biogas production. The new model, which is the main result of this work, can be used for operational optimisation and evaluating economic consequences of future changes in the biogas system. The results from the case study and sensitivity analysis show that the model is reliable and can be used for strategic planning. The results show that implementation of a biogas-based CHP plant result in an electricity power production of approximately 39 GW h annually. Reduced system costs provide a profitability of 46 MSEK/year if electricity and heat prices increase by 100% and electricity certificate prices increase by 50%. CO2 emission reductions up to 32,000 ton/year can be achieved if generated electricity displaces coal-fired condensing power.

  • 2.
    Ammenberg, Jonas
    et al.
    Linköping University, Department of Management and Engineering, Environmental Technology and Management. Linköping University, Biogas Research Center. Linköping University, Faculty of Science & Engineering. Linköping University, Biogas Research Center (BRC).
    Anderberg, Stefan
    Linköping University, Department of Management and Engineering, Environmental Technology and Management. Linköping University, Biogas Research Center. Linköping University, Faculty of Science & Engineering.
    Lönnqvist, Tomas
    Division of Energy Processes, Department of Chemical Engineering and Technology, Royal Institute of Technology, Stockholm, Sweden.
    Grönkvist, Stefan
    Division of Energy Processes, Department of Chemical Engineering and Technology, Royal Institute of Technology, Stockholm, Sweden.
    Sandberg, Thomas
    Department of Industrial Economics and Management, Royal Institute of Technology, Stockholm, Sweden.
    Biogas in the transport sector: Actor and policy analysis focusing on the demand side in the Stockholm region2018In: Resources, Conservation and Recycling, ISSN 0921-3449, E-ISSN 1879-0658, Vol. 129, p. 70-80Article in journal (Refereed)
    Abstract [en]

    Sweden has ambitions to phase out fossil fuels and significantly increase the share of biofuels it uses. This articlefocuses on Stockholm County and biogas, with the aim to increase the knowledge about regional preconditions.Biogas-related actors have been interviewed, focusing on the demand side. Biogas solutions play an essentialrole, especially regarding bus transports and taxis. Long-term development has created well-functioning sociotechnicalsystems involving collaboration. However, uncertainties about demand and policy cause hesitation andsigns of stagnating development.Public organizations are key actors regarding renewables. For example, Stockholm Public Transport procuresbiogas matching the production at municipal wastewater treatment plants, the state-owned company Swedaviasteers via a queuing system for taxis, and the municipalities have shifted to “environmental cars”.There is a large interest in electric vehicles, which is expected to increase significantly, partially due tosuggested national policy support. The future role of biogas will be affected by how such an expansion comesabout. There might be a risk of electricity replacing biogas, making it more challenging to reach a fossil-freevehicle fleet. Policy issues strongly influence the development. The environmental car definition is of importance,but its limited focus fails to account for several different types of relevant effects. The dynamic policylandscape with uncertainties about decision makers’ views on biogas seems to be one important reason behindthe decreased pace of development. A national, long-term strategy is missing. Both the European Union andSweden have high ambitions regarding a bio-based and circular economy, which should favor biogas solutions.

    The full text will be freely available from 2019-10-20 10:58
  • 3.
    Ammenberg, Jonas
    et al.
    Linköping University, Department of Management and Engineering, Environmental Technology and Management. Linköping University, Faculty of Science & Engineering. Linköping University, Biogas Research Center.
    Bohn, Irene
    Den Kgl. Veterinær- og Landbohøjskole, Denmark.
    Feiz, Roozbeh
    Linköping University, Department of Management and Engineering, Environmental Technology and Management. Linköping University, Faculty of Science & Engineering. Linköping University, Biogas Research Center.
    Systematic assessment of feedstock for an expanded biogas production: A multi-criteria approach2017Report (Other academic)
    Abstract [en]

    Biogas solutions can contribute to more renewable and local energy systems, and also involve other essential aspects such as nutrient recycling. From a theoretical feedstock perspective there is a great biogas potential in Sweden, but the development has been relatively slow as many biogas producers face challenges of different types. Among the many influencing factors, the choice of feedstocks (biomass) is of strategic importance. Within the Biogas Research Center (BRC), hosted by Linköping University in Sweden, a research project focused on feedstock has been ongoing for several years. It has involved researchers, biogas and biofertilizer producers, agricultural organizations and others. The main aim has been to develop a method to assess the suitability of feedstock for biogas and biofertilizer production, and to apply this method on a few selected feedstocks. A multi-criteria method has been developed that covers potential, feasibility and resource efficiency, operationalized via 17 indicators directed towards cost efficiency, technological feasibility, energy and environmental performance, accessibility, competition, policy and other issues. Thus the method it is relatively comprehensive, yet hopefully simple enough to be used by practitioners.

    The main ambition, applying the method, has been to collect and structure relevant information to facilitate strategic overviews, communication and informed decision making. This is relevant for development within the biogas and biofertilizer industry, for policymakers, to define and prioritize among essential research projects, etc. This report presents some essential parts of this project, focusing on the multi-criteria method and results regarding ley crops, straw, farmed blue mussels and food waste (and stickleback to some extent). It clarifies how the method can be applied and highlights barriers, drivers and opportunities for each feedstock. Comparisons are also made. The results indicate that biogas production from food waste and ley crops is the most straightforward, and for straw and farmed blue mussels there are more obstacles to overcome. For all of them, the dynamic and very uncertain policy landscape is a barrier. In the final chapter, some conclusions about the method and its application are drawn.

  • 4.
    Ammenberg, Jonas
    et al.
    Linköping University, Department of Management and Engineering, Environmental Technology and Management. Linköping University, The Institute of Technology. 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, Magnus
    Linköping University, Department of Management and Engineering, Energy Systems. Linköping University, Biogas Research Center.
    Svensson, Niclas
    Linköping University, Department of Management and Engineering, Environmental Technology and Management. Linköping University, The Institute of Technology. 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.
    Karlsson, Martin
    Linköping University, Department of Physics, Chemistry and Biology, Chemistry. Linköping University, The Institute of Technology. Linköping University, Biogas Research Center.
    Tonderski, Karin
    Linköping University, Department of Physics, Chemistry and Biology, Biology. Linköping University, The Institute of Technology. Linköping University, Biogas Research Center.
    Eklund, Mats
    Linköping University, Department of Management and Engineering, Environmental Technology and Management. Linköping University, The Institute of Technology. Linköping University, Biogas 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.

  • 5.
    Björn, Annika
    et al.
    Linköping University, The Tema Institute, Department of Water and Environmental Studies. Linköping University, Biogas Research Center.
    Shakeri Yekta, Sepehr
    Linköping University, The Tema Institute, Department of Water and Environmental Studies. Linköping University, Biogas Research Center.
    Ojong, Pascal
    Linköping University, The Tema Institute, Department of Water and Environmental Studies. Linköping University, Biogas Research Center.
    Karlsson, Anna
    Linköping University, Biogas Research Center. Scandinavian Fuels AB, Stockholm, Sweden.
    Ejlertsson, Jörgen
    Linköping University, The Tema Institute, Department of Water and Environmental Studies. Linköping University, Biogas Research Center.
    Svensson, Bo H.
    Linköping University, The Tema Institute, Department of Water and Environmental Studies. Linköping University, Biogas Research Center.
    Extracellular polymers (EPS) and soluble microbial products (SMP) in reactor liquids of 12 full-scale biogas reactors2013In: Proceedings of 13th World Congress on Anaerobic Digestion, Santiago de Compostella: Lapices , 2013Conference paper (Refereed)
  • 6.
    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.

  • 7.
    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)
  • 8.
    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)
  • 9.
    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 digestion of kraft mill fibre sludge by CSTRs with sludge recirculation.2016In: 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.

  • 10.
    Ekstrand, Eva-Maria
    et al.
    Linköping University, Department of Thematic Studies, Department of Water and Environmental Studies. Linköping University, Faculty of Arts and Sciences. Linköping University, Biogas Research Center.
    Larsson, Madeleine
    Linköping University, Department of Thematic Studies, 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 AB, Sweden.
    Cardell, Lina
    Linköping University, Biogas Research Center. Scandinavian Biogas Fuels AB, Sweden .
    Borgström, Ylva
    Linköping University, Biogas Research Center. Pöyry Sweden AB, Sweden .
    Björn, Annika
    Linköping University, Department of Thematic Studies, Department of Water and Environmental Studies. Linköping University, Faculty of Arts and Sciences. Linköping University, Biogas Research Center.
    Ejlertsson, Jörgen
    Linköping University, Department of Thematic Studies, Department of Water and Environmental Studies. 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, Department of Water and Environmental Studies. Linköping University, Faculty of Arts and Sciences. Linköping University, Biogas Research Center.
    Nilsson, Fredrik
    Linköping University, Biogas Research Center. Pöyry Sweden AB, Sweden .
    Karlsson, Anna
    Linköping University, Biogas Research Center. Scandinavian Biogas Fuels AB, Sweden .
    Methane potentials of the Swedish pulp and paper industry - A screening of wastewater effluents2013In: Applied Energy, ISSN 0306-2619, E-ISSN 1872-9118, Vol. 112, p. 507-517Article in journal (Refereed)
    Abstract [en]

    With the final aim of reducing the energy consumption and increase the methane production at Swedish pulp and paper mills, the methane potential of 62 wastewater effluents from 10 processes at seven pulp and/or paper mills (A-G) was determined in anaerobic batch digestion assays. This mapping is a first step towards an energy efficient and more sustainable utilization of the effluents by anaerobic digestion, and will be followed up by tests in lab-scale and pilot-scale reactors. Five of the mills produce kraft pulp (KP), one thermo-mechanical pulp (TMP), two chemical thermo-mechanical pulp (CTMP) and two neutral sulfite semi-chemical (NSSC) pulp. Both elementary and total chlorine free (ECF and TCF, respectively) bleaching processes were included. The effluents included material from wood rooms, cooking and oxygen delignification, bleaching (often both acid- and alkali effluents), drying and paper/board machinery as well as total effluents before and after sedimentation. The results from the screening showed a large variation in methane yields (percent of theoretical methane potential assuming 940 NmL CH4 per g TOC) among the effluents. For the KP-mills, methane yields above 50% were obtained for the cooking effluents from mills D and F, paper machine wastewater from mill D, condensate streams from mills B, E and F and the composite pre-sedimentation effluent from mill D. The acidic ECF-effluents were shown to be the most toxic to the AD-flora and also seemed to have a negative effect on the yields of composite effluents downstream while three of the alkaline ECF-bleaching effluents gave positive methane yields. ECF bleaching streams gave higher methane yields when hardwood was processed. All TCF-bleaching effluents at the KP mills gave similar degradation patterns with final yields of 10-15% of the theoretical methane potential for four of the five effluents. The composite effluents from the two NSSC-processes gave methane yields of 60% of the theoretical potential. The TMP mill (A) gave the best average yield with all six effluents ranging 40-65% of the theoretical potential. The three samples from the CTMP process at mill B showed potentials around 40% while three of the six effluents at mill G (CTMP) yielded 45-50%.

  • 11.
    Ekstrand, Eva-Maria
    et al.
    Linköping University, The Tema Institute, Department of Water and Environmental Studies. Linköping University, Biogas Research Center.
    Åhrman, Sofia
    Linköping University, The Tema Institute, Department of Water and Environmental Studies. Linköping University, Biogas Research Center.
    Truong, Xu-bin
    Linköping University, Biogas Research Center. Scandinavian Fuels AB, Stockholm, Sweden.
    Bastviken, David
    Linköping University, The Tema Institute, Department of Water and Environmental Studies. Linköping University, Biogas Research Center.
    Ejlertsson, Jörgen
    Linköping University, The Tema Institute, Department of Water and Environmental Studies. Linköping University, Biogas Research Center.
    Svensson, Bo H.
    Linköping University, The Tema Institute, Department of Water and Environmental Studies. Linköping University, Biogas Research Center.
    Karlsson, Anna
    Linköping University, Biogas Research Center. Scandinavian Fuels AB.
    Björn, Annika
    Linköping University, The Tema Institute, Department of Water and Environmental Studies. Linköping University, Biogas Research Center.
    Biogas potential in fibre residues from pulp and paper mills2013In: Proceedings of 13th World Congress on Anaerobic Digestion / [ed] Juan M. Lema, Fernando Fdez-Polanco, Marta Caballa, Jorge Rodriguez; Sonia Suarez, Santiago de Compostella: Lapices , 2013Conference paper (Refereed)
  • 12.
    Ersson, Carolina
    et al.
    Linköping University, Department of Management and Engineering, Environmental Technology and Management. Linköping University, The Institute of Technology. Linköping University, Biogas Research Center.
    Ammenberg, Jonas
    Linköping University, Department of Management and Engineering, Environmental Technology and Management. Linköping University, The Institute of Technology. Linköping University, Biogas Research Center.
    Eklund, Mats
    Linköping University, Department of Management and Engineering, Environmental Technology and Management. Linköping University, The Institute of Technology. Linköping University, Biogas Research Center.
    Biofuels for transportation in 2030: feedstock and production plants in a Swedish county2013In: Biofuels, ISSN 1759-7269, E-ISSN 1759-7277, Vol. 4, no 4, p. 379-395Article in journal (Refereed)
    Abstract [en]

    Background: This paper gives insight into whether biofuels for road transport can play an important role in a Swedish county in the year 2030, and contributes to knowledge on how to perform similar studies.

    Methodology: A resource-focused assessment, including feedstock from the waste sector, agricultural sector, forestry sector and aquatic environments, partially considering technological and economic constraints.

    Results: Two scenarios were used indicating that biofuels could cover almost 30 and 50%, respectively, of total energy demand for road transport.

    Conclusion: Without compromising food security, this study suggests that it is possible to significantly increase biofuel production, and to do this as an integrated part of existing society, thereby also contributing to positive societal synergies.

  • 13.
    Ersson, Carolina
    et al.
    Linköping University, Department of Management and Engineering, Environmental Technology and Management. Linköping University, The Institute of Technology. Linköping University, Biogas Research Center.
    Ammenberg, Jonas
    Linköping University, Department of Management and Engineering, Environmental Technology and Management. Linköping University, The Institute of Technology. Linköping University, Biogas Research Center.
    Eklund, Mats
    Linköping University, Department of Management and Engineering, Environmental Technology and Management. Linköping University, The Institute of Technology. Linköping University, Biogas Research Center.
    Connectedness and its dynamics in the Swedish biofuels for transport industry2015In: Progress in Industrial Ecology, An International Journal, ISSN 1476-8917, E-ISSN 1478-8764, Vol. 9, no 3, p. 269-295Article in journal (Refereed)
    Abstract [en]

    Connectedness through cooperation with other sectors regarding feedstock, energy, products and by-products is important for environmental performance of industrial production. The aim of this study is to provide a better understanding of the level of connectedness in the Swedish biofuels for transport industry, involving producers of ethanol, biogas and biodiesel. In interviews, the CEOs of four important companies provided information about current strategies, historic and planned development. The production systems are dynamic and have changed significantly over time, including material and energy exchanges between traditionally separate industries. Interesting development was noted where revised business strategies have led to changed cooperation structures and thus altered material and energy flows. Fuel and raw material prices are very influential and all of the respondents said that political decisions to a large extent affect their competitiveness and emphasised the importance of clear long-term institutional conditions, ironically very much in contrast to the current situation within EU and Sweden.

  • 14.
    Fallde, Magdalena
    Linköping University, The Tema Institute, Technology and Social Change. Linköping University, Faculty of Arts and Sciences. Linköping University, Biogas Research Center.
    Can area managers connect policy and tenants? Implementation and diffusion of a new waste management system in Linkoping, Sweden2015In: Journal of Environmental Planning and Management, ISSN 0964-0568, E-ISSN 1360-0559, Vol. 58, no 5, p. 932-947Article in journal (Refereed)
    Abstract [en]

    Recycling and reducing household waste are political goals internationally, nationally and locally. In Sweden, households in apartment buildings seem to sort their waste to a lesser extent than households in single-family houses. This paper analyses the challenges of the diffusion of a new waste management system in apartment buildings, and focuses on a municipal housing company and the actions of its area managers. It is argued that area managers can be regarded as street-level bureaucrats who act as collectors of tenants everyday practices in the studied implementation process. The study is based on interviews, document analysis and observations.

  • 15.
    Fallde, Magdalena
    et al.
    Linköping University, The Tema Institute, Technology and Social Change. Linköping University, Faculty of Arts and Sciences. Linköping University, Biogas Research Center.
    Eklund, Mats
    Linköping University, Department of Management and Engineering, Environmental Technology and Management. Linköping University, The Institute of Technology. Linköping University, Biogas Research Center.
    Towards a sustainable socio-technical system of biogas for transport: the case of the city of Linköping in Sweden2015In: Journal of Cleaner Production, ISSN 0959-6526, E-ISSN 1879-1786, Vol. 98, p. 17-28Article in journal (Refereed)
    Abstract [en]

    In this article, the development of biogas for transport in the municipality of Linköping, Sweden, is studied in order to contribute to a better understanding of the conditions for socio-technical transitions towards sustainability. Linköping municipality, 1976 [kommunfullmäktige] Motion om utredning angående eldrivna fordon. Dnr 1976.278. Using concepts from multi-level perspectives and socio-technical perspectives on system builders, the study focuses on three time periods: During the first time period (1976–1994), a niche for biogas developed amongst dedicated actors in small networks representing energy and public transport within the municipality. That is, biogas was entirely connected to the vision of a ‘green’ public transport. Second, between the years of 1994 and 2001, the biogas producing company acted as a system builder and initiated a large-scale biogas production through close cooperation in networks with other actors. As a result, biogas reached a phase of technological maturity and also gained some support from national investment programs. Finally, from 2001 the expansion of biogas became clearer as the biogas production spread into a regional arena but also reached for new customers, like personal cars. Unforeseen spin-offs like the formation of new private companies and development of research were important results of the transition. Thereby, the transition is a move towards a new socio-technical regime. A conclusion from the study is that the development of biogas was highly influenced by national support and pressure, but was mainly driven by local actors – system builders – that could steer the processes and had endurance as well as capability to mobilize resources in order to fulfill their purposes.

  • 16.
    Gustavsson, Jenny
    et al.
    Linköping University, The Tema Institute. Linköping University, Faculty of Arts and Sciences. Linköping University, Biogas Research Center.
    Shakeri Yekta, Sepehr
    Linköping University, The Tema Institute, Department of Water and Environmental Studies. Linköping University, Faculty of Arts and Sciences. Linköping University, Biogas Research Center.
    Karlsson, Anna
    Linköping University, Biogas Research Center. Scandinavian Biogas Fuels AB, Sweden .
    Skyllberg, Ulf
    Linköping University, Biogas Research Center. Swedish University of Agriculture Science, Sweden .
    Svensson, Bo
    Linköping University, The Tema Institute, Department of Water and Environmental Studies. Linköping University, Faculty of Arts and Sciences. Linköping University, Biogas Research Center.
    Potential bioavailability and chemical forms of Co and Ni in the biogas process-An evaluation based on sequential and acid volatile sulfide extractions2013In: Engineering in Life Sciences, ISSN 1618-0240, E-ISSN 1618-2863, Vol. 13, no 6, p. 572-579Article in journal (Refereed)
    Abstract [en]

    Several previous studies reported stimulatory effects on biogas process performance after trace metal supplementation. However, the regulation of the bioavailability in relation to chemical speciation, e.g. the role of sulfide is not fully understood. The objective of the present study was to determine the effect of sulfide on chemical speciation and bioavailability of Co and Ni in lab-scale semicontinuous stirred biogas tank reactors treating stillage. The chemical forms and potential bioavailability of Co and Ni were studied by sequential extraction, analysis of acid-volatile sulfide (AVS), and simultaneously extracted metals. The results demonstrated that Ni was completely associated to the organic matter/sulfide fraction and AVS, suggesting low potential bioavailability. Cobalt was predominantly associated to organic matter/sulfide and AVS, but also to more soluble fractions, which are considered to be more bioavailable. Process data showed that both Co and Ni were available for microbial uptake. Although the actual bioavailability of Co could be explained by association to more bioavailable chemical fractions, the complete association of Ni with organic matter/sulfides and AVS implies that Ni was taken up despite its expected low bioavailability. It was concluded that extensive Co- and Ni-sulfide precipitation did not inhibit microbial uptake of Co and Ni in the reactors.

  • 17.
    Gustavsson, Jenny
    et al.
    Linköping University, The Tema Institute. Linköping University, Faculty of Arts and Sciences. Linköping University, Biogas Research Center.
    Shakeri Yekta, Sepehr
    Linköping University, The Tema Institute, Department of Water and Environmental Studies. Linköping University, Faculty of Arts and Sciences. Linköping University, Biogas Research Center.
    Sundberg, Carina
    Linköping University, The Tema Institute, Department of Water and Environmental Studies. Linköping University, Faculty of Arts and Sciences. Linköping University, Biogas Research Center.
    Karlsson, Anna
    Linköping University, Biogas Research Center. Scandinavian Biogas Fuels AB, Sweden .
    Ejlertsson, Jörgen
    Linköping University, The Tema Institute, Department of Water and Environmental Studies. Linköping University, Faculty of Arts and Sciences. Linköping University, Biogas Research Center.
    Skyllberg, Ulf
    Linköping University, Biogas Research Center. Swedish University of Agriculture Science, Sweden .
    Svensson, Bo
    Linköping University, The Tema Institute, Department of Water and Environmental Studies. Linköping University, Faculty of Arts and Sciences. Linköping University, Biogas Research Center.
    Bioavailability of cobalt and nickel during anaerobic digestion of sulfur-rich stillage for biogas formation2013In: Applied Energy, ISSN 0306-2619, E-ISSN 1872-9118, Vol. 112, p. 473-477Article in journal (Refereed)
    Abstract [en]

    Addition of Co and Ni often improves the production of biogas during digestion of organic matter, i.e. increasing CH4-production, process stability and substrate utilization which often opens for higher organic loading rates (OLRs). The effect of Co and Ni addition was evaluated by measuring methane production, volatile solids reduction, pH and concentration of volatile fatty acids (VFAs). A series of six lab-scale semi-continuously fed biogas tank reactors were used for this purpose. The chemical forms and potential bioavailability of Co and Ni were examined by sequential extraction, acid volatile sulfide extraction (AVS) and simultaneously extracted metals. Furthermore, the sulfur speciation in solid phase was examined by sulfur X-ray absorption near edge structure spectroscopy. The effect of Co and Ni deficiency on the microbial community composition was analyzed using quantitative polymerase chain reaction and 454-pyrosequencing. The results showed that amendment with Co and Ni was necessary to maintain biogas process stability and resulted in increased CH4-production and substrate utilization efficiency. 10-20% of the total Co concentration was in dissolved form and should be regarded as easily accessible by the microorganisms. In contrast, Ni was entirely associated with organic matter/sulfides (mainly AVS) and regarded as very difficult to take up. Still Ni had stimulatory effects suggesting mechanisms such as dissolution of NiS to be involved in the regulation of Ni availability for the microorganisms. The microbial community structure varied in relation to the occurrence of Ni and Co. The acetate-utilizing Methanosarcinales dominated during stable process performance, i.e. when both Co and Ni were supplied, while hydrogenotrophic Methanomicrobiales increased together with VFA concentrations under Co or Ni deficiency. The increase was more pronounced at Co limitation. This study demonstrates that there are good possibilities to improve the performance of biogas processes digesting sulfur-rich substrates by supplementation of Co and Ni.

  • 18.
    Hjalmarsson, Linnea
    Linköping University, Department of Thematic Studies. Linköping University, The Tema Institute, Technology and Social Change. Linköping University, Biogas Research Center.
    Biogas as a boundary object for policy integration - the case of Stockholm2015In: Journal of Cleaner Production, ISSN 0959-6526, E-ISSN 1879-1786, Vol. 98, p. 185-193Article in journal (Refereed)
    Abstract [en]

    Policy integration between autonomous policy sectors is a tool for managing interdependent technical systems to avoid suboptimization. Biogas, regarded as a renewable energy carrier usable in the energy and transport systems, is produced from organic material such as municipal organic waste (MOW). It is connected to a number of systems and policy sectors, making biogas management an instructive case for studying policy integration processes. Swedish biogas production has increased in recent years, and in the Stockholm region there has been enormous interest in biogas production for vehicle use since the early 2000s. In this paper biogas will be discussed in the perspective that it is or has potential to be a vital part of three systems: waste, energy, and transportation. The aim is to analyse whether policy integration occurs between the systems and to explore if boundary objects can play a role when understanding policy integration processes. In examining the biogas development process, regional policy documents and interviews with stakeholders in the biogas process are used. The results indicate consensus among regional actors that biogas should be used in vehicles and that MOW should be collected for this purpose, indicating congruence of understanding of biogas. Biogas functions as a boundary object in these cases and contributes to high policy integration between the energy and waste systems. Despite consensus that biogas should be used in the transport system, there is little policy integration between the energy and transport sectors. The policy sectors of transport infrastructure and spatial planning are not concerned with fuel or biogas issues. Public transport policy focuses on the use of biogas for their vehicles, but even if biogas serves as a boundary object it is not developing into policy integration processes. The conclusion is that biogas development has resulted in integrated policymaking between the energy and waste sectors and biogas has served as a strong boundary object which has spurred that development. Between the energy and transport sectors there is little policy integration, and biogas is not a boundary object in the cases of transport infrastructure and spatial planning policy sectors. What this case shows is that if there is a lack of presence of a boundary object it suggests no preconditions for policy integration processes to start.

  • 19.
    Johansson, Maria
    et al.
    Linköping University, Department of Management and Engineering, Energy Systems. Linköping University, Faculty of Science & Engineering. Linköping University, Biogas Research Center.
    Lindkvist, Emma
    Linköping University, Department of Management and Engineering, Energy Systems. Linköping University, Faculty of Science & Engineering. Linköping University, Biogas Research Center.
    Rosenqvist, Jakob
    Tranås Energi, Sweden.
    Methodology for Analysing Energy Demand in Biogas Production Plants: A Comparative Study of Two Biogas Plants2017In: Energies, ISSN 1996-1073, E-ISSN 1996-1073, Vol. 10, no 11, article id 1822Article in journal (Refereed)
    Abstract [en]

    Biogas production through anaerobic digestion may play an important role in a circular economy because of the opportunity to produce a renewable fuel from organic waste. However, the production of biogas may require energy in the form of heat and electricity. Therefore, resource-effective biogas production must consider both biological and energy performance. For the individual biogas plant to improve its energy performance, a robust methodology to analyse and evaluate the energy demand on a detailed level is needed. Moreover, to compare the energy performance of different biogas plants, a methodology with a consistent terminology, system boundary and procedure is vital. The aim of this study was to develop a methodology for analysing the energy demand in biogas plants on a detailed level. In the methodology, the energy carriers are allocated to: (1) sub-processes (e.g., pretreatment, anaerobic digestion, gas cleaning), (2) unit processes (e.g., heating, mixing, pumping, lighting) and (3) a combination of these. For a thorough energy analysis, a combination of allocations is recommended. The methodology was validated by applying it to two different biogas plants. The results show that the methodology is applicable to biogas plants with different configurations of their production system.

  • 20.
    Karlsson, Anna
    et al.
    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.
    Sepehr, Shakeri Yekta
    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.
    Improvement of the Biogas Production Process: Explorative project (EP1)2014Report (Other academic)
    Abstract [en]

    There are several ways to improve biogas production in anaerobic digestion processes and a number of strategies may be chosen. Increased organic loading in existing plants will in most cases demand the introduction of new substrate types. However, to substantially increase the Swedish biogas production new, large-scale biogas plants digesting new substrate types need to be established.

    Better utilization of existing digester volumes can be linked to: 

    • Increase of organic loading rates and/or reduced hydraulic retention time
    • Optimizing the anaerobic microbial degradation by identifying rate-limitations, its causes and possible remedies such as:
    • Nutrient and trace element balances
    • Needs and availability of trace element
    • Process design aiming at an increase of the active biomass (e.g. recirculation of reactor material, two stage processes)
    • Process inhibition (enzymatically regulated product inhibition and toxicity)
    • Improved pre-treatment to increase degradation rates and VS-reduction
    • Mixing and rheology
    • Better monitoring and control
    • Co-digestion with more high-potential substrates

    The present report reviews a number of fields that are linked to improvements in the biogas production process as based on the bullets above.

    A well-working, active biomass is a prerequisite for efficient biogas production processes, why factors affecting microbial growth are crucial to obtain stable processes at the highest possible organic load/lowest possible hydraulic retention time.

    The microorganisms need nutrients, i.e. carbon, nitrogen, phosphorus, calcium, potassium, magnesium and iron as well as trace elements such as cobalt, nickel, manganese, molybdenum, selenium and tungsten for growth. The need of nutrients and trace elements varies with the substrate digested, the organic loading rate, the process design (e.g. the reactor configuration, the degree of recirculation etc). In addition, the complexity of the chemical reactions controlling the bioavailability of the trace metals is wide, why optimal addition strategies for trace elements needs to be developed.

    Substrates as food wastes, sewage sludge, cattle manure, certain energy crops and algae are good bases to obtain processes with good nutrient- and trace element balances. These kinds of substrates can often be implemented for “mono-substrate” digestion, while substrates dominated by carbohydrates or fats needs to be co-digested or digested in processes modified by  e.g. nutrient- and trace element additions, sludge recirculation, etc. Protein-rich substrates often include enough nutrients, but can give other process problems (see below).

    Iron, cobalt and nickel are the nutrients/trace elements given most attention so far. However, molybdenum, selenium and tungsten have also, among others, been shown effective in different AD applications. The effects have, however, mainly been shown on turnover of VFAs and hydrogen (resulting in increased methane formation), while just a few studies have addressed their direct effect on rates of hydrolysis, protein-, fat- and carbohydrate degradation. Selenium- and cobalt-containing enzymes are known to be involved in amino acid degradation, while selenium and tungsten are needed in fat- and long chain fatty acid degradation. Enzymes active in hydrolysis of cellulose have been shown to be positively affected by cobalt, cupper, manganese, magnesium and calcium. This implies that trace element levels and availability will directly affect the hydrolysis rates as well as rates and degradation pathways for digestion of amino acids, long chain fatty acids and carbohydrates. However, their effect on hydrolysis seems neglected, why studies are needed to map the metals present in active sites and co-factors of enzymes mediating these primary reactions in AD. Further investigations are then needed to elucidate the importance of the identified metals on the different degradation steps of AD aiming at increased degradation rates of polymeric and complex substrates. It should also be noted that the degradation routes for amino acid degradation in AD-processes, factors governing their metabolic pathways, and how ATP is gained in the different pathways seem unknown. The different routes may result in different degradation efficiencies, why a deeper knowledge within this field is called for.

    Trace metals added to biogas reactors have positive effects on the process only if they are present in chemical species suitable for microbial uptake. Interaction of biogenic sulfide with trace metals has been identified as the main regulator of trace metal speciation during AD. Fe, Co and Ni instantaneously form strong sulfide precipitates in biogas reactors but at the same time show very different chemical speciation features. The soluble fraction of Co widely exceeded the levels theoretically possible in equilibrium with inorganic sulfide. The high level of soluble Co is likely due to association with dissolved organic compounds of microbial origin. Fe and Ni speciation demonstrated a different pattern dominated by low solubility products of inorganic metal sulfide minerals, where their solubility was controlled mainly by the interactions with different dissolved sulfide and organic ligands. To our knowledge, the information about chemical speciation of other trace metals (Se, Mo, and W among others) and its effects on the bioavailability in anaerobic digestion environments is rare. Providing information on the metal requirements by processes linked to their bioavailability in biogas reactors is identified as a key knowledge needed for maximizing the effect of metals added to biogas reactors. Further research is also needed for development and design of proper metal additive solutions for application in full scale biogas plants. A practical approach is to supplement trace metals in specific chemical forms, which are either suitable for direct bio-uptake or will hamper undesirable and bio-uptake-limiting reactions (e.g. mineral precipitation).

    Recirculation of reactor material as a way to enrich and maintain an active microbial biomass (and, thus, an increase in the substrate turnover rate) in tank reactors has been tested for digestion of fat within BRCs project DP6. The methane yield increased from 70 to 90% of the theoretical potential at a fat-loading rate of 1.5 g VS/L and day. The same strategy has been successful during digestion of fiber sludge from the pulp and paper industry, i.e. the recirculation has been crucial in establishment of low hydraulic retention times. Also degradation of sewage sludge (SS) would likely be improved by recirculation as the retention time of the solid SS is prolonged in such a system. However, this remains to be tested. The recirculation concept also needs to be evaluated in larger scale reactors to form a base to include extra costs and energy consumption vs. the benefits from increased yields.

    To divide the anaerobic digestion process into two phases, where the hydrolytic/acidogenic and the syntrophic/methanogenic stages of anaerobic digestion are separated, might be a way to enhance degradation of lignocellulosic materials as the hydrolysis of these compounds may be inhibited by the release of soluble sugars. It should be noted that the natural AD of ruminates is phase-separated and improvements in AD can likely be achieved using these natural systems as a starting point. Also the degradation of aromatic and chlorinated species is likely enhanced by phase separation. One way to obtain such systems is to combine a leached bed for hydrolysis of insoluble material with a methanogenic reactor treating the leachate. Plug flow reactors might be another possibility as well as membrane reactors, which physically separates the hydrolyzing and methanogenic phases.

    Inhibition caused by toxic levels of ammonia (protein- and ammonia rich substrates), fat-rich substrates and long chain fatty acids (LCFAs), aromatic compounds, salts etc. have been reported in many cases and some remedies are suggested. Ammonia can be stripped off as a measure to overcome too high levels. Another option is to adjust pH of the reactor liquid by addition of acid shifting the ammonia-ammonium balance in the system towards less free ammonia. A decrease in alkalinity by acid addition might also affect the availability of trace elements as solubility of trace metal mineral phases is generally higher at lower pH. LCFA degradation has been shown to benefit from periodic additions of fat and is, thus, an effective strategy to minimize inhibition by the release of the LCFA. Adsorption to zeolites has also been shown to abate the inhibition by LCFA. The best way to avoid inhibition is, however, to keep the processes nutritionally well balanced and using concepts suitable for the actual substrate mix digested (i.e. sludge recirculation, phase separation etc.) in order to obtain the highest possible degradation rate for problematic compounds, thus, avoiding accumulation of inhibitory components such as LCFA and aromatics. High ammonia and salt levels can often be regulated by the substrate mix.

    The hydrolysis is often reported as rate limiting in digestion of complex polymers in balanced anaerobic digestion systems, while the methanogensis is regarded as rate-limiting for more easily degraded substrates. As mentioned above the effect on methane formation rates by the addition of trace elements have been shown in numerous studies, while their effect on the hydrolysis and acidogenic AD steps are much less studied. Thus, the effects of the trace elements on the early steps in the AD-chain need to be investigated further.

    To obtain high-rate hydrolysis, effective and energy efficient pre-treatment methods are crucial for a large number of substrates. The rate of hydrolysis is to a large extent dependent on the properties of the organic compounds in the substrate e.g. carbohydrates, proteins, fat or lignocellulosic material as well as particle size and pre-treatment methods applied. The establishment and colonization by sessile microorganisms and biofilms is highly important for efficient and high rate hydrolysis. Microbial formation of organic compounds and the availability of surfaces are factors influencing these key processes, which in turn are tightly coupled to the growth conditions for the hydrolyzing microorganisms. This is an area recently brought up as an issue for detailed research.

    Mixing is mostly needed for effective high-rate biogas production, but too extensive mixing can destroy the syntrohpic interactions necessarily taking place during AD. However, the efficiency of the mixing system design in relation to colonization, presences of dead zones, changes in viscosity/rheology, etc. seem unclear and this area thus calls for further attention. 

    In high-loaded efficient processes a monitoring program following parameters e.g. organic loading rate, gas-production, VS-reduction, pH and VFA-levels is needed. This can be achieved through sampling and analysis off line, but there are of course benefits with on-line monitoring. A number of different methods have been suggested and tested, and some titration- and spectroscopic methods are applied, but none seems commonly in use. The reasons for the low interest to apply these methods may be the need for expertise on calibration, validation and multivariate analysis of most on-line methods, high maintenance demands (cost and time), and l functional problems related to fouling, gas bubbles, sensor location, disturbing particles etc.

    New substrates with the highest potential for use in existing or new biogas plants seem to be forestry-based biomass, certain energy crops and macro-algae. Both the energy crops and the macro-algae can be chosen to give nutritionally well balanced AD-processes, while AD on forestry biomass demands nutrient supplements. For both the energy crops and the macro-algae sustainable cultivation systems need to be developed. Crop rotation systems should be employed to minimize tillage as well as fertilization- and pesticide utilization at highest possible TS-yields. System analyses aiming at sustainability and economy of TS and methane yields per ha including needs of nutrient supplements should therefore be performed.

    In all three cases (forestry biomass, energy crops and algae) pre-treatment methods to create high internal surface areas are needed. However, the pre-treatment methods chosen need to be highly energy- and resource efficient to obtain sustainable systems (a positive energy balance). New plants will for profitability likely need to be large with highly developed infrastructure for substrates supply and distribution of the produced biogas/electricity nearby. Process concepts aiming at highest possible loading rates at shortest possible retention time will be needed, which likely are met by including both phase-separated process systems and systems for sludge recirculation.

    It should also be noted that the lignin in substrates from forestry biomass needs to be used for production of e.g. polymeric materials or as a fuel to obtain reasonable energy balances for AD of lignocellulose. Pre-treatment methods obtaining separation of lignin is therefore needed. A substantial research and development is in progress within this field.

    The possibilities for AD within the pulp and paper industry are interesting, especially if specific effluents within the pulp- and paper production units are selected and the raw material for the pulp and paper production is chosen considering the biogas yields of the residues.

  • 21.
    Karlsson, Magnus
    et al.
    Linköping University, Department of Management and Engineering, Energy Systems. Linköping University, The Institute of Technology. Linköping University, Biogas Research Center.
    Ivner, Jenny
    Linköping University, Department of Management and Engineering, Energy Systems. Linköping University, The Institute of Technology. Linköping University, Biogas Research Center.
    Söderström, Mats
    Linköping University, Department of Management and Engineering, Energy Systems. Linköping University, The Institute of Technology. Linköping University, Biogas Research Center.
    Final report for BRC EP3 (New industries)2015Report (Other academic)
    Abstract [en]

    In BRC EP3 focus has been on new industries. The goal has been to find some new industries where biogas production is a resource‐efficient way to take advantage of material flows that are not used today. From this goal seven activities were formulated and are in short: (A1) Present biogas solutions, (A2) Overview of new industrial sectors in Sweden regarding biogas production, (A3) Possibilities and impossibilities process‐wise, (A4) Energy and environmental impacts, (A5) Societal aspects, (A6) Selection of case studies, and (A7) Case study design. These activities needed different angles of approach and therefore a variety of methods were used in the project, e.g. literature studies, calculations, measurements, interviews and workshops. The results from the activities are presented in short below.

    A1: International comparison of biogas production at industrial sites, for example, is impossible to carry out as different classifications are used in different countries. In A1 a way to categorize biogas plants is proposed and discussed.

    A2: By screening and geographically pin‐pointing the food industry, eight clusters were chosen for deeper studies. A mapping of biogas potential was thereafter carried out in these clusters. The activity shows great potentials for some of the clusters regarding biogas production.

    A3: Process‐related feasibility for opportunities for the clusters studied in A2 is targeted. The general conclusion is that there are no severe aspects that imply that one should not continue working with a specific cluster or a specific substrate found in those clusters, regarding biogas production.

    A4: Each cluster found in A2 is assessed in terms of environmental aspects (climate, acidification and eutrophication), energy balance and economy, which were found being the most important assessment criteria when it comes to efficient biogas solutions. The results show, for example, that even though some of the clusters hold a large potential for biogas production some of these clusters do not imply profitable solutions or environmental advantages compared to the present situation of using the substrates. Moreover, the study shows that the end use of the biogas (electricity, heat and vehicle fuel) has significant influence on the results. It is shown that each cluster has a unique combination of substrates and unique alternatives for use of both substrates and produced biogas, implying different beneficial solutions. Sometimes the beneficial solutions differ dependent on what assessment criterion used.

    A5: Societal aspects were explored for each cluster found in A2. It is shown that there are differences between the clusters regarding institutional and organizational prerequisites. Important areas have been identified on both a national level (e.g. taxes) and regional level (e.g. cooperation between public and private sectors).

    A6: When selecting case studies it is found that the following aspects needs to be considered: (1) biogas potential, (2) character of substrates and other materials, (3) environmental aspects (climate, acidification and eutrophication), (4) influence on energy balances (5) economy, (6) use of biogas, and (7) societal aspects.

    A7: When designing case studies the same aspects as for A6 applies. However, when designing the case study it is also vital to consider where to put the system border and also consider the localization of the production unit (e.g. internal at a company or detached).

    Moreover, integration of biogas solutions with other types of material or energy flows has to be considered.

    All the stated parts in “Motivation and aim” are addressed in the project. Consequently, the target of the project is achieved.

  • 22.
    Larsson, Madeleine
    Linköping University, The Tema Institute, Tema Environmental Change. Linköping University, Faculty of Arts and Sciences. Linköping University, Biogas Research Center.
    Anaerobic Digestion of Wastewaters from Pulp and Paper Mills: A Substantial Source for Biomethane Production in Sweden2015Doctoral thesis, comprehensive summary (Other academic)
    Abstract [en]

    The Swedish pulp and paper industry is the third largest exporter of pulp and paper products worldwide. It is a highly energy-demanding and water-utilising industry, which generates large volumes of wastewater rich in organic material. These organic materials are to different extents suitable for anaerobic digestion (AD) and production of energy-rich biomethane. The implementation of an AD process within the wastewater treatment plant of a mill would increase the treatment capacity and decrease the overall energy consumption due to less aeration and lower sludge production and in addition produce biomethane. Despite the many benefits of AD it is only applied at two mills in Sweden today. The reason for the low implementation over the years may be due to problems encountered linked to the complexity and varying composition of the wastewaters. Due to changes in market demands many mills have broadened their product portfolios and turned towards more refined products. This has increased both the complexity and the variations of the wastewaters´ composition even further, as the above changes can imply an increased pulp bleaching and utilisation of more diverse raw materials within the mills.

    The main aim of this thesis was therefore to generate knowledge needed for an expansion of the biomethane production within the pulp and paper industry. As a first step to achieve this an evaluation of the biomethane potential and the suitability for AD of wastewaters within a range of Swedish pulp and paper mills was performed. Thus, around 70 wastewater streams from 11 different processes at eight mills were screened for their biomethane potential. In a second step, the impact of shifts in wood raw material and bleaching on the AD process and the biomethane production was investigated and further evaluated in upflow anaerobic sludge bed (UASB) reactors.

    The screening showed that the biomethane potential within the Swedish pulp and paper industry could be estimated to 700 GWh, which corresponds to 40% of the Swedish biomethane production during 2014. However, depending on the conditions at each specific mill the strategy for the establishment of AD needs to differ. For mills producing kraft pulp the potential is mainly found in wastewaters rich in fibres, alkaline kraft bleaching wastewaters and methanol-rich condensates. The biomethane potential within thermo-mechanical pulp- (TMP) and chemical thermo-mechanical pulp (CTMP) mills is mainly present in the total effluents after pre-sedimentation and in the bleaching effluents as these holds high concentrations of dissolved organic material. The screening further showed that the raw material used for pulp production is an important factor for the biomethane potential of a specific wastewater stream, i.e. hardwood (HW) wastewaters have higher potentials than those from softwood (SW) pulp production. This was confirmed in the lab-scale UASB reactor experiments, in which an alkaline kraft bleaching wastewater and a composite pulping and bleaching CTMP wastewater were used as substrates. AD processes were developed and maintained stable throughout shifts in wastewater composition related to changes in the wood raw materials between SW and HW for the kraft wastewater and spruce, aspen and birch for the CTMP wastewater. The lower biomethane production from SW- compared to HW wastewaters was due to a lower degradability together with a higher ratio of sulphuric compounds per TOC for the SW case. The impact of shifts between bleached and unbleached CTMP production could not be fully  evaluated in the continuous process mainly due to technical problems. However, due to the large increase in dissolved organic material when bleaching is applied, the potential biomethane production will increase during the production of bleached pulp compared to unbleached pulp. Based on the biomethane potentials obtained for one of the included CTMP mills, their yearly production of biomethane was estimated to 5-27 GWh with the lowest and the highest value corresponding to the production of unbleached spruce pulp vs. bleached birch pulp.

    Thus, the results of the investigations presented in this thesis show that the UASBreactor is suitable for AD of wastewaters within the pulp and paper industry. The results also show that challenges related to variations in the organic material composition of the wastewaters due to variations in wood raw materials could be managed. The outcome of the thesis work also imply that the production of more refined products, which may include the introduction of an increased number of raw materials and extended bleaching protocols, could increase the potential biomethane production, especially if the pulp production will make use of more HW.

    List of papers
    1. Methane potentials of the Swedish pulp and paper industry - A screening of wastewater effluents
    Open this publication in new window or tab >>Methane potentials of the Swedish pulp and paper industry - A screening of wastewater effluents
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    2013 (English)In: Applied Energy, ISSN 0306-2619, E-ISSN 1872-9118, Vol. 112, p. 507-517Article in journal (Refereed) Published
    Abstract [en]

    With the final aim of reducing the energy consumption and increase the methane production at Swedish pulp and paper mills, the methane potential of 62 wastewater effluents from 10 processes at seven pulp and/or paper mills (A-G) was determined in anaerobic batch digestion assays. This mapping is a first step towards an energy efficient and more sustainable utilization of the effluents by anaerobic digestion, and will be followed up by tests in lab-scale and pilot-scale reactors. Five of the mills produce kraft pulp (KP), one thermo-mechanical pulp (TMP), two chemical thermo-mechanical pulp (CTMP) and two neutral sulfite semi-chemical (NSSC) pulp. Both elementary and total chlorine free (ECF and TCF, respectively) bleaching processes were included. The effluents included material from wood rooms, cooking and oxygen delignification, bleaching (often both acid- and alkali effluents), drying and paper/board machinery as well as total effluents before and after sedimentation. The results from the screening showed a large variation in methane yields (percent of theoretical methane potential assuming 940 NmL CH4 per g TOC) among the effluents. For the KP-mills, methane yields above 50% were obtained for the cooking effluents from mills D and F, paper machine wastewater from mill D, condensate streams from mills B, E and F and the composite pre-sedimentation effluent from mill D. The acidic ECF-effluents were shown to be the most toxic to the AD-flora and also seemed to have a negative effect on the yields of composite effluents downstream while three of the alkaline ECF-bleaching effluents gave positive methane yields. ECF bleaching streams gave higher methane yields when hardwood was processed. All TCF-bleaching effluents at the KP mills gave similar degradation patterns with final yields of 10-15% of the theoretical methane potential for four of the five effluents. The composite effluents from the two NSSC-processes gave methane yields of 60% of the theoretical potential. The TMP mill (A) gave the best average yield with all six effluents ranging 40-65% of the theoretical potential. The three samples from the CTMP process at mill B showed potentials around 40% while three of the six effluents at mill G (CTMP) yielded 45-50%.

    Place, publisher, year, edition, pages
    Elsevier, 2013
    Keywords
    Biogas; Anaerobic digestion; Kraft pulp; Chemical thermo-mechanical pulp; Neutral sulfite semi-chemical pulp; Bleaching
    National Category
    Social Sciences
    Identifiers
    urn:nbn:se:liu:diva-104129 (URN)10.1016/j.apenergy.2012.12.072 (DOI)000329377800053 ()
    Available from: 2014-02-07 Created: 2014-02-07 Last updated: 2018-03-26
    2. Anaerobic digestion of alkaline bleaching wastewater from a Kraft pulp and paper mill using UASB technique
    Open this publication in new window or tab >>Anaerobic digestion of alkaline bleaching wastewater from a Kraft pulp and paper mill using UASB technique
    Show others...
    2015 (English)In: Environmental technology, ISSN 0959-3330, E-ISSN 1479-487X, Vol. 36, no 12, p. 1489-1498Article in journal (Refereed) Published
    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.

    Place, publisher, year, edition, pages
    Taylor & Francis: STM, Behavioural Science and Public Health Titles, 2015
    Keywords
    UASB; alkaline kraft ECF bleaching wastewater; anaerobic digestion; hardwood; softwood
    National Category
    Water Engineering
    Identifiers
    urn:nbn:se:liu:diva-114883 (URN)10.1080/09593330.2014.994042 (DOI)000350448200002 ()25441833 (PubMedID)
    Funder
    Swedish Energy Agency
    Available from: 2015-03-05 Created: 2015-03-05 Last updated: 2018-10-05
    3. Anaerobic digestion of wastewater from the production of bleached chemical thermo-mechanical pulp: higher methane production for hardwood than softwood
    Open this publication in new window or tab >>Anaerobic digestion of wastewater from the production of bleached chemical thermo-mechanical pulp: higher methane production for hardwood than softwood
    Show others...
    2017 (English)In: Journal of chemical technology and biotechnology (1986), ISSN 0268-2575, E-ISSN 1097-4660, Vol. 2, no 1, p. 140-151Article in journal (Refereed) Published
    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.

    Place, publisher, year, edition, pages
    John Wiley & Sons, 2017
    Keywords
    biogas, wastewater treatment, UASB, CTMP, softwood, hardwood
    National Category
    Water Engineering
    Identifiers
    urn:nbn:se:liu:diva-122338 (URN)10.1002/jctb.4980 (DOI)000389443600017 ()
    Funder
    Swedish Energy Agency, 32802–1
    Note

    At the time for thesis presentation publication was in status: Manuscript

    At the time for thesis presentation manuscript was named: Anaerobic digestion of wastewater from the production of bleached chemical thermo-mechanical pulp: The effect of changes in raw material composition

    Funding agencies: Swedish Energy Agency [32802-1]; Scandinavian Biogas Fuels AB; Poyry Sweden AB; BillerudKorsnas AB; Purac AB; SCA

    Available from: 2015-10-29 Created: 2015-10-29 Last updated: 2018-10-05Bibliographically approved
    4. The biomethane potential of chemical thermo-mechanical pulp wastewaters in relation to their chemical composition
    Open this publication in new window or tab >>The biomethane potential of chemical thermo-mechanical pulp wastewaters in relation to their chemical composition
    Show others...
    2015 (English)Manuscript (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.

    Keywords
    CTMP; bleaching; softwood; hardwood; biomethane potential; dissolved lignin; carbohydrates; wood extractives
    National Category
    Water Engineering
    Identifiers
    urn:nbn:se:liu:diva-122339 (URN)
    Available from: 2015-10-29 Created: 2015-10-29 Last updated: 2016-05-04Bibliographically approved
  • 23.
    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.

  • 24.
    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.

  • 25.
    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.

  • 26.
    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)
  • 27.
    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, M.
    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.

  • 28.
    Moestedt, Jan
    et al.
    Linköping University, Biogas Research Center. SLU.
    Nordell, Erik
    Linköping University, Biogas Research Center. Tekniska Verken i Linköping.
    Lundgren, Jesper
    Linköping University, Biogas Research Center.
    Genero Marti, Magali
    Linköping University, Biogas Research Center.
    Sundberg, Carina
    Linköping University, Department of Thematic Studies, Department of Water and Environmental Studies. 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.
    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 waste2014Conference paper (Refereed)
  • 29.
    Moestedt, Jan
    et al.
    Linköping University, Biogas Research Center. Tekniska Verken i Linköping.
    Nordell, Erik
    Linköping University, Biogas Research Center. Tekniska Verken i Linköping.
    Shakeri Yekta, Sepehr
    Linköping University, The Tema Institute, Tema Environmental Change. Linköping University, Faculty of Arts and Sciences. Linköping University, Biogas Research Center.
    Lundgren, Jesper
    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.
    Ejlertsson, Jörgen
    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.
    The combined effects of iron, cobalt and nickel additions on anaerobicco-digestion of food and slaughterhouse waste2014Conference paper (Refereed)
  • 30.
    Nordell, Erik
    et al.
    Linköping University, Biogas Research Center. Tekniska Verken Linkoping AB Publ, Dept Biogas RandD, SE-58115 Linkoping, Sweden .
    B Hansson, Anna
    Linköping University, Biogas Research Center. Tekniska Verken Linkoping AB Publ, Dept Biogas RandD, SE-58115 Linkoping, Sweden .
    Karlsson, Martin
    Linköping University, Department of Physics, Chemistry and Biology, Chemistry. Linköping University, The Institute of Technology. Linköping University, Biogas Research Center. Tekniska Verken Linkoping AB Publ, Dept Biogas RandD, SE-58115 Linkoping, Sweden .
    Zeolites relieves inhibitory stress from high concentrations of long chain fatty acids2013In: Waste Management, ISSN 0956-053X, E-ISSN 1879-2456, Vol. 33, no 12, p. 2659-2663Article in journal (Refereed)
    Abstract [en]

    Protein and fat rich slaughterhouse waste is a very attractive waste stream for the production of biogas because of the high biochemical methane potential of the substrate. The material has however some drawbacks as the sole material for biogas production due to the production of several process disturbing metabolites such as ammonia, sulfides and long chain fatty acids. We can in this work present results that show that zeolites have the potential to relieve inhibitory stress from the presence of long chain fatty acids. Moreover, the results strongly indicate that it is mainly acetic acid consumers that are most negatively affected by long chain fatty acids and that the mechanism of stress relief is an adsorption of long chain fatty acids to the zeolites. In addition to this, it is shown that the effect is immediate and that only a small amount of zeolites is necessary to cancel the inhibitory effect of long chain fatty acids.

  • 31.
    Olsson, Linda
    et al.
    Linköping University, Department of Management and Engineering, Energy Systems. Linköping University, The Institute of Technology. Linköping University, Biogas Research Center.
    Fallde, Magdalena
    Linköping University, The Tema Institute, Technology and Social Change. Linköping University, Faculty of Arts and Sciences. Linköping University, Biogas Research Center.
    Waste(d) potential: a socio-technical analysis of biogas production and use in Sweden2015In: Journal of Cleaner Production, ISSN 0959-6526, E-ISSN 1879-1786, Vol. 98, p. 107-115Article in journal (Refereed)
    Abstract [en]

    This paper takes a socio-technical perspective on Swedish biogas production and use, in order to identify characteristics which may improve and increase biogas production. Biogas could potentially reduce greenhouse gas (GHG) emissions from Swedish road transport by 25%, and to that end transport policy endorses the use of biogas as vehicle fuel. Currently, however, only a small fraction of the biogas production potential is utilised. By analysing how social and technological context has influenced production and use of biogas over the past 70 years, using concepts from the theory of Large Technical Systems (LTS), features of importance for increasing biogas production are identified. Biogas is shown to be a complex issue, with different functions within the energy, transport and waste management systems. As there is not one coherent biogas system but many individual systems, with different objectives, local and sectorial measures are required in order to increase biogas production. In particular, the importance of biogas production as waste management is identified. In order to utilise the biogas potential and reduce GHG emissions from road transport, policy-makers and researchers are advised to address the plurality in biogas systems.

  • 32.
    Shakeri Yekta, Sepehr
    et al.
    Linköping University, The Tema Institute, Department of Water and Environmental Studies. Linköping University, Biogas Research Center.
    Skyllberg, Ulf
    Linköping University, Biogas Research Center. Department of Forest Ecology and Management, Swedish University of Agricultural Sciences, Umeå, Sweden.
    Björn, Annika
    Linköping University, The Tema Institute, Department of Water and Environmental Studies. Linköping University, Biogas Research Center.
    Gustavsson, Jenny
    Linköping University, The Tema Institute, Department of Water and Environmental Studies. Linköping University, Biogas Research Center.
    Karlsson, Anna
    Linköping University, Biogas Research Center. Scandinavian Fuels AB, Stockholm, Sweden.
    Svensson, Bo H.
    Linköping University, The Tema Institute, Department of Water and Environmental Studies. Linköping University, Biogas Research Center.
    Sulfur and metal speciation in biogas reactors2013In: Proceedings of 13th World Congress on Anaerobic Digestion: 25th-28th June 2013, Santiago de Compostella, Spain, Santiago de Compostella: Lapices , 2013Conference paper (Refereed)
  • 33.
    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)
  • 34.
    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.
    Willén, Magnus
    Björn, Annika
    Linköping University, The Tema Institute, Tema Environmental Change. Linköping University, Faculty of Arts and Sciences.
    Ryan, Ziels
    University of Washington, USA.
    Ojong, Pascal
    Linköping University, The Tema Institute, Tema Environmental Change. Linköping University, Faculty of Arts and Sciences.
    Svedlund, Matilda
    Karlsson, Anna
    Scandinavian Biogas Fuels AB.
    Ejlertsson, Jörgen
    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.
    Effects of sulfide on anaerobic digestion of primary and activatedbiosludge: A multi-approach study2014Conference paper (Refereed)
  • 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.
    Svensson, Bo H.
    et al.
    Linköping University, The Tema Institute, Tema Environmental Change. Linköping University, Biogas Research Center.
    Karlsson, Anna
    Linköping University, Biogas Research Center. Scandinavian Biogas Fuels AB.
    Sundberg, Carina
    Linköping University, The Tema Institute, Tema Environmental Change. Linköping University, Biogas Research Center.
    Ziels, Ryan
    Linköping University, Biogas Research Center. University of Washington, USA.
    Gustavsson, Jenny
    Linköping University, The Tema Institute, Tema Environmental Change. Linköping University, Biogas Research Center.
    Larsson, Madeleine
    Linköping University, The Tema Institute, Tema Environmental Change. Linköping University, Biogas Research Center.
    Shakeri Yekta, Sepehr
    Linköping University, The Tema Institute, Tema Environmental Change. Linköping University, Biogas Research Center.
    Abu Al-Soud, Waleed
    Linköping University, Biogas Research Center.
    Sörensen, Sören
    Linköping University, Biogas Research Center.
    Björn, Annika
    Linköping University, The Tema Institute, Tema Environmental Change. Linköping University, Biogas Research Center.
    Skyllberg, Ulf
    Linköping University, Biogas Research Center. Umeå Universitet.
    Micronutrients and microorganisms in biogas processes: fundamentals and experiences2014Conference paper (Other academic)
  • 37.
    Ziels, Ryan
    et al.
    Linköping University, Biogas Research Center. University of Washington, USA.
    Gustavsson, Carl
    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.
    Karlsson, Anna
    Linköping University, Biogas Research Center. Scandinavian Biogas Fuels AB.
    Shakeri Yekta, Sepehr
    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.
    Ejlertsson, Jörgen
    Linköping University, The Tema Institute, Tema Environmental Change. Linköping University, Faculty of Arts and Sciences. Linköping University, Biogas Research Center.
    Impacts of co-digestion waste vegetable oil with primary and wasteactivated sludge on microbial community and process performance2014Conference paper (Refereed)
  • 38.
    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 acidconversion during anaerobic codigestion of fats, oils, and grease withmunicipal 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.

  • 39.
    Ziels, Ryan M.
    et al.
    Department of Civil Engineering, The University of British Columbia, Vancouver, BC, Canada.
    Svensson, Bo H
    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 Management and Engineering, Environmental Technology and Management. Linköping University, Faculty of Arts and Sciences.
    Larsson, Madeleine
    Linköping University, Department of Thematic Studies, Tema Environmental Change. Linköping University, Faculty of Arts and Sciences. Linköping University, Biogas Research Center.
    Karlsson, Anna
    Scandinavian Biogas Fuels AB, Stockholm, 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.
    Microbial rRNA gene expression and co-occurrence profiles associate with biokinetics and elemental composition in full-scale anaerobic digesters2018In: Microbial Biotechnology, ISSN 1751-7907, E-ISSN 1751-7915, Vol. 11, no 4, p. 694-709Article in journal (Refereed)
    Abstract [en]

    This study examined whether the abundance and expression of microbial 16S rRNA genes were associated with elemental concentrations and substrate conversion biokinetics in 20 full-scale anaerobic digesters, including seven municipal sewage sludge (SS) digesters and 13 industrial codigesters. SS digester contents had higher methane production rates from acetate, propionate and phenyl acetate compared to industrial codigesters. SS digesters and industrial codigesters were distinctly clustered based on their elemental concentrations, with higher concentrations of NH3-N, Cl, K and Na observed in codigesters. Amplicon sequencing of 16S rRNA genes and reverse-transcribed 16S rRNA revealed divergent grouping of microbial communities between mesophilic SS digesters, mesophilic codigesters and thermophilic digesters. Higher intradigester distances between Archaea 16S rRNA and rRNA gene profiles were observed in mesophilic codigesters, which also had the lowest acetate utilization biokinetics. Constrained ordination showed that microbial rRNA and rRNA gene profiles were significantly associated with maximum methane production rates from acetate, propionate, oleate and phenyl acetate, as well as concentrations of NH3-N, Fe, S, Mo and Ni. A co-occurrence network of rRNA gene expression confirmed the three main clusters of anaerobic digester communities based on active populations. Syntrophic and methanogenic taxa were highly represented within the subnetworks, indicating that obligate energy-sharing partnerships play critical roles in stabilizing the digester microbiome. Overall, these results provide new evidence showing that different feed substrates associate with different micronutrient compositions in anaerobic digesters, which in turn may influence microbial abundance, activity and function.

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