Ongoing biogas projects

Today the biogas process is surveyed by different chemical methods but still it is often difficult to foreseen a disturbance and also to understand the degree of disturbance. In this project we investigate the possibility to use microbial indicators as a complement or alternative to chemical surveillance. The aim is to find a method that can in an early stage can show an upcoming disturbance and also clearly show how the degree of disturbance.

The project run between 2012-2014, was financed though Uppsala BioX and was performed in collaboration with different biogas plants (Göteborg Energy, Uppsala Vatten AB,  Swedish Biogas International, the Biogas plant at Lövsta, SLU and Sötåsens Biogas plant).

However, ammonia also causes instability and low efficiency of the biogas process. We have during many years studied microbial systems coping with high ammonia with the aim to find operational strategies for efficient biogas production from protein rich materials. Through isolations, characterisations and studies in digester systems we today have good knowledge of these microbial systems.

However, at present we do not have enough information to enable controlled operation towards increased growth of these organisms. Through controlled cultivations of pure cultures in under different conditions, as well as digester studies, we aim at finding key parameters for managing the microbial population towards an optimized biogas production.

The project is funded by Formas and will run 2013-2014.

When SAOB grows in pure culture they produce acetate as main end product from a variety of different organic compounds or from hydrogen/carbon dioxide.  In association with a hydrogen consuming partner the same bacteria can reverse its this metabolic pathway and uniquely produce hydrogen and carbon dioxide, as the only end products. The bacteria have been shown to perform this second mechanism in biogas processes, operating with a variety of different organic waste materials. We have in depth knowledge of SAOB from isolated pure cultures, from co-cultures, as well as from community structure analyses but to control and efficiently use SAOB we need to understand the mechanisms regulating acetate versus hydrogen production.

The aim of the proposed project is thus to unlock new and unique knowledge of microbial hydrogen production and its regulation. More specifically we will identify differences in protein and gene expression during growth as acetate producer compared to growth as hydrogen producers and investigate hydrogen production rates in microbial electrolysis cells.

The project is funded by the Energy Agency and run between 2013-2016. The project is run in collaboration between the Department of Microbiology and Animal Genetics as SLU and the Civil and Environmental Engineering at Chalmers.

StandUp for Energy is a collaboration initiative between Uppsala University, The Royal Institute of Technology, The Swedish University of Agricultural Sciences and Luleå University of Technology.

It arose as a result of the Government’s commitment to high quality research in areas of strategic importance to society and the business sector. The overriding aims of the StandUp partnership are to reduce the costs of large-scale production of renewable and environmentally sustainable electricity delivered to the consumer, as well as to develop more cost-effective and energy efficient hybrid and electrical vehicles. Within this program we are performing research concerning biogas production from biomass, at present Salix is in focus. We investigate possibilities for increased biogas production at agricultural sites, where biogas often are converted to electricity.

At SLU the studies are performed in collaboration between three different departments, Microbiology, Plant biology and Forest Genetics and Energy and Technology.

We are in several different project investigating different strategies to improve the biogas production from plant-based material, with straw as a model material. We are evaluating different pre-treatments and reactor configurations and also perform work in order to generate further information about the importance of the microbiology for an efficient degradation. We are studying the cellulose degrading population in different biogas reactors and look for correlations between the microbial community and the degradation efficiency and the gas production. We are also isolating new cellulose degrading bacteria and study their physiology and genetics with the goal to get tools for optimized degradation of lingo-cellulose materials in biogas reactors.

The research is financed by the Swedish Energy Agency, MicroDrivE and CSC (China Scholarship Council). Part of the work is performed in collaboration with AEPi  (Agro-Environmetal  Protection Institute) Tianjin, China.  

Unfortunately, the high levels of nitrogen can also cause problems due to inhibition of the microbiological degradation process, giving rise to biogas. Moreover, stillage as a substrate for biogas typically results in rather high levels of hydrogen sulphide in the gas, that decrease the quality of the biogas and that also bind trace metals, essential for microbial activity. A big portion of the hydrogen sulphide is produced through the action of sulphate reducing bacteria (SRB), using sulphate originating from sulphuric acid used during the ethanol production process. SRB compete with methanogens for their substrate resulting in less methane production. 

In this project we were looking into different operational strategies for increased biogas production from stillage, i.e. to decrease the activity of SRB and to improve the possibility for growth of microbial systems producing methane at high levels of nitrogen.

The project was performed by a industrial PhD student from Tekniska Verken AB and was financed in equal parts by them and by Formas. The project ran between 2011 and 2015. 

Today we have quite good knowledge about the residue as a fertilizing agent but still some question remains to be answered for an optimal usage.  We investigated importance of substrate and operational management for the quality of the residue. The composition of the digestion residue will vary depending on the ingoing material to the biogas plant but also depending on the operational management. For our studies we used residues from different commercial biogas plants but also from more controlled biogas reactors operated in the laboratory. We investigated for example the impact on the substrate C/N quota and the operational temperature on the residue and make comparative analyses with other types of bio-manure, such as cow and swine manure. The studies were focusing on effects of the fertilization on the soil microbial community, of importance for the nitrogen and carbon turnover.

The project was financed by the department of microbiology and Formas and ran between 2010 and 2015.

Crops and agricultural residues such as plant residues and manure, represents an important resource for future bioenergy production, including biogas production.

Thus the interest for farmed based biogas production is high in many countries in Europe and worldwide the number of farm-based plants is increasing. However, many challenges still need to be solved in order to make this technology economical feasible and widely accessible to farmers, particularly for medium and small sized farms.

1. Anaerobic digestion of solid manure at a farm scale biogas plant

The objective was to study the technical, biological and economic conditions for a considerable addition of solid manure (straw-rich cattle/pig manure or nitrogen-rich poultry manure) for co-digestion with liquid manure in a wet digestion process with limited addition of water.

Solid manure contributes to approximately half of the total manure biogas potential in Sweden. Today there is a lack of knowledge on how to efficiently mix solid manure in conventional wet digestion processes. The aim was to demonstrate cost efficient co-digestion of solid manure with liquid manure in a wet digestion process where solids contribute with 60-80% of the total biogas production. The results was disseminated to local farmers with interest for biogas in demonstration activities. The study was accomplished both in a farm scale plant at Sötåsen and in laboratory scale at JTI and SLU. JTI is acted as the project leader and the project was funded by The Swedish Farmers' Foundation for Agricultural Research, Swedish Board of Agriculture, The County Administrative Board of Västra Götaland. Project period: 2012-2014.

2. BIONA - Biogas Reactor Technology for Norwegian Agriculture

The primary objective of this project was to develop cost effective biogas reactor technologies for use in Norwegian agriculture. The AD plant economy can be enhanced by increased biogas production obtained by co-digestion of manure and plant materials with energy rich substrates like fish ensilage, food waste or slaughterhouse waste. However, the AD process is sensitive to high concentrations of the ammonia produced by degradation of these protein-rich substrates. 
Microorganisms that tolerate high concentrations of ammonia can be established but these are slow-growing and can easily be washed out of the biogas reactor. The development of ammonia tolerant biofilms was proposed as a solution to this problem.

In the project the potential role of ammonia tolerant cultures was analyzed and process design criteria for these systems was suggested. The project was divided into three work packages:

1. Ammonia tolerant biogas processes
2. Sensor technology and process optimization
3. High rate biogas reactors of UASB type.

The project was a cooperation between Bioforsk, Norwegian University of Life Sciences (UMB), Telemark University College (TUC), Norweigan University of Sciences and Technology (NTNU), Swedish University of Agricultural Sciences (SLU), Institute of Agricultural and Environmetal Engineering (JTI), Aalborg University, Bondelaget, Lindum, Bioplan Hardanger and FolloRen. The projects ran between 2011-2014 and was financed by the Norweigan research council.