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Sepehr Shakeri Yekta

Associate Professor, Head of Division, Docent

I am interested in the interactions between chemical and biological mechanisms involved in complex organic matter degradation during anaerobic digestion, which is important for improving efficiency and stability of biogas production processes.

Trace metals in biogas production processes

Performance of anaerobic digestion processes depend on a balanced supply of trace metals, which are required for the activity of the enzymes driving the metabolic machinery of the anaerobic microorganisms. We study the processes which control the chemical speciation and bio-uptake of trace metals in biogas reactors.


Molecular level characteristics of organic matter in biogas reactors

The nature of organic compounds in anaerobic digestion processes determines the degree of the organic matter conversion to biogas. We study molecular-level characteristics of underutilized organic matter in biogas reactors to further improve their degradability and thus, the biogas production efficiency

Publications

2024

Axel Lindfors, Mats Eklund, Anna Brunzell, Erik Erjeby, Tomas Hirsch, Jonas Ammenberg, Stephanie Cordova, Roozbeh Feiz, Marcus Gustafsson, Maria Johansson, Emma Lindkvist, Thomas Prade, Anna Schnürer, Karin Tonderski, Sepehr Shakeri Yekta (2024) Världens bästa biogassystem: Ett BRC innovationsprojekt
Chen Luo, Gustav Pajala, Sepehr Shakeri Yekta, Sayantan Sarkar, J. Val Klump, Paras Pujari, Joyanto Routh (2024) Soil contamination caused by fly ash from coal-fired thermal power plants in India: Spatiotemporal distribution and elemental leaching potential Applied Geochemistry, Vol. 170, Article 106080 (Article in journal) Continue to DOI
Mette Axelsson Bjerg, Eva-Maria Ekstrand, Ingrid Sundgren, Sepehr Shakeri Yekta, Jan Moestedt, Annika Björn (2024) Moderate thermal post-treatment of digestate to improve biomethane production from agricultural- and food waste Bioresource Technology Reports, Vol. 27, Article 101887 (Article in journal) Continue to DOI
Thuane Mendes Anacleto, Betina Kozlowsky-Suzuki, Annika Björn (Fredriksson), Sepehr Shakeri Yekta, Laura Shizue Moriga Masuda, Vinicius Peruzzi de Oliveira, Alex Enrich Prast (2024) Methane yield response to pretreatment is dependent on substrate chemical composition: a meta-analysis on anaerobic digestion systems Scientific Reports, Vol. 14, Article 1240 (Article in journal) Continue to DOI
Helena Rodrigues Oliveira, Betina Kozlowsky-Suzuki, Annika Björn (Fredriksson), Sepehr Shakeri Yekta, Cristiane Fonseca Caetano, Erika Flavia Machado Pinheiro, Humberto Marotta, Joao Paulo Bassin, Luciano Oliveira, Marcelo de Miranda Reis, Mario Sergio Schultz, Norberto Mangiavacchi, Viridiana Santana Ferreira-Leitao, Daniel Oluwagbotemi Fasheun, Fernanda Geraldo Silva, Igor Taveira, Ingrid Roberta de Franca Soares Alves, Julia Castro, Juliana Velloso Durao, Juliana Guimaraes, Mariana Erthal Rocha, Marina Tomasini, Pedro Vitor de Oliveira Martins, Rogerio Presciliano, Stella Buback dos Santos, Tamires Marques Faria, Tarcisio Correa, Thiago de Nuno Mendes Pery de Linde, Fernanda Abreu, Alex Enrich Prast (2024) Biogas potential of biowaste: A case study in the state of Rio de Janeiro, Brazil Renewable energy, Vol. 221, Article 119751 (Article in journal) Continue to DOI

News

Research & Teaching

Teaching

Teaching in environmental science program and following courses:

  • Biogas process
  • Designing environmental studies
  • Environmental monitoring
  • Global biogeochemical cycles
  • Environmental Chemistry.

Research 

Improved hydrolysis as a means to increase the overall degradability of organic material in anaerobic digestion for biogas production.
Project Leaders: Annika Björn 

Collaborators

  • Biogas Research Center (BRC) Linköping University
  • Swedish Energy Agency
  • BRC partners and members including Scandinavian Biogas Fuels AB, Tekniska Verken i Linköping AB, Nordvästra Skånes Renhållnings AB, Swedish Biogas International AB, Västblekinge Miljö AB

Research projects

Past projects

Trace element availability in biogas reactors - the role of sulphide complexes as regulators of microbial growth and methane yields (PhD project) 

The use of the biogas process for the production of methane, which can be utilized as vehicle fuel or in power plants for electricity production, is strongly established both in Sweden and internationally. The microbiological process is traditionally used to reduce organic waste through digestion. Digested products are used as bio-fertilizers and thus constitute an important component in nutrient circulation, contributing to society’s efforts towards circularity and sustainability. There is an ambition to produce large amounts of biogas efficiently, which means that biogas facilities must be efficient and stable. They need to convert large amounts of substrates per reactor volume and time without disrupting the biological process. This depends, among other things, on how well the growth rate of the microorganisms that carry out anaerobic digestion can be optimized. Microorganisms require a balanced diet, where the availability of macro- and micronutrients is significant for the process. A balanced mixture of protein, fat, and carbohydrates in organic substrates normally provides sufficient levels of nitrogen, phosphorus, potassium, and calcium. However, in high-load reactors, the availability of micronutrients (e.g., iron, nickel, cobalt, tungsten, and selenium) has been shown to be limiting for process performance. By adding these substances, process performance can be improved. We have investigated the possibilities of adding the substances individually and in various combinations. The results show that this is a sustainable method, but both synergistic and antagonistic effects on biogas production occur. The project advanced this area with knowledge about the mechanisms that control the availability of trace metals in the anaerobic environment of the biogas reactors.

The results are presented in the dissertation "Chemical Speciation of Sulfur and Metals in Biogas Reactors: Implications for Cobalt and Nickel Bio-uptake Processes".

Funder: Swedish Energy Agency

Neuclear Magnetic Resonance Spectroscopy for Molecular characterization in biogas and biofertilizer production systems (post-doc project) 

Anaerobic organic matter degradation for biogas production is influenced by the characteristics of the organic substrate, particularly the resistance or reactivity of particulate organic matter (POM) towards microbial hydrolysis as the first step of the anaerobic degradation chain. The POM characteristics are also important for determining the fate of organic matter in agricultural soils where digestate (nutrient-rich rest materials after anaerobic degradation) are applied as fertilizers. This project applies 13C cross-polarization magic-angle spinning (CP-MAS) and two-dimensional 1H,13C heteronuclear single-quantum coherence (HSQC) nuclear magnetic resonance (NMR) spectroscopy to elucidate molecular structures within labile and recalcitrant POM fractions. This foundational information is important for exploring potential optimization strategies to enhance the degradability of underutilized POM for biogas production and the fate of organic matter in soil, where digestate is applied as a biofertilizer.

Relevant publications:

Funder: Swedish Energy Agency through Biogas Research Center