Biological methanation in biofilm reactor

Duration:
2023 - 2025

Financing:
The Austrian Research Promotion Agency (FFG), opens an external URL in a new window

national partner:

Competence Center CHASE GmbH, opens an external URL in a new window

Contact Person:
Jörg Krampe

Project Staff:
Sebastian Böhler, Joseph Tauber

Links:

https://projekte.ffg.at/projekt/4536647, opens an external URL in a new window

Brief information on the project

By increasing the renewable share in energy production through photovoltaics and wind energy, the fluctuations in production conditions increase the opposition of supply and demand, and consequently the need for long-term storage for a continuous supply of green energy. One possibility to meet this challenge is the methanation of carbon dioxide from digester gas of large wastewater treatment plants, industrial waste gases or from the air using hydrogen from electrolysis, whereby biological processes can also be used here, such as the biological methanation addressed in the project. This represents an opportunity to use existing infrastructures such as the gas grid and storage facilities, to reduce CO2 emissions, and at the same time to relieve the electricity grid and replace fossil natural gas from politically uncertain origins with regionally produced biomethane. The energetic potential of implementation of biological methanation, which is of high interest especially for wastewater treatment plants with existing biogas production, is 220 GWh/a for Austria, or 3% of the renewable electricity production or 1% of the total natural gas demand. The energy potential provided in this way is monetarily about 120 million Euro per year.
For the implementation of biological methanation, water is decomposed into oxygen and hydrogen via water electrolysis using electric power (from renewable energy sources). Subsequently, with the generated hydrogen, carbon dioxide in biogas of wastewater treatment plants is biologically converted to methane by microorganisms (methanized). This not only removes CO2, but also increases the methane content of the biogas from about 65% to almost 100%, which brings with it a wide range of other possible uses. The biomethane produced can be liquefied or compressed and used directly as an energy source or fed into the existing natural gas infrastructure for distribution and storage. The oxygen produced during the electrolysis of the water can be used industrially or, for example, directly on site in wastewater treatment.
In a preliminary project (BioMAra), the basic feasibility of a biological methanation of CO2 in the biogas of wastewater treatment plants could already be demonstrated. However, according to the results of this pre-project, a number of fundamental and crucial factors for the process implementation were defined, which have been insufficiently explored so far. Therefore, in the BioMeFilm (Biological Methanation in Biofilm Reactor) project, the nutrient and trace element requirements as well as the long-term stability and efficiency of a biological methanation plant will be systematically researched in laboratory experiments and the results will be used to create a corresponding digital process model. For this purpose, methods such as 16s-rDNA analysis, HPLC and ICP-OES methods will be used. In addition, the basic requirements for and the effect of biofilm carriers for the bacteria in the hydrogenotrophic biofilm will be explored, which are a key factor for biological process efficiency. Prototypes of the biofilm carrier to be developed using CFD simulation will be manufactured using 3D printing and then tested in real-world trials. Finally, the short- and long-term start-up dynamics (on/off operation) of the biological system will be investigated for using electrolysis to stabilize the grid and to ensure stable long-term plant operation. At the end of the project, all process and procedural fundamentals necessary for a scale-up and implementation on a higher "technical readiness level" should be available to establish and operate biofilm methanation plants at the site of wastewater treatment plants with biogas production.
Operators of large wastewater treatment plants and energy supply companies have expressed their interest in the project and the approach and have promised support. The Vienna University of Technology, Institute for Water Quality and Resource Management and the Competence Center CHASE GmbH will contribute as project partners their complementary know-how in the field of biomethane production and storage by means of Power to Gas or process intensification and will further expand and globally disseminate it, thus expanding Austria as an innovation location in this field.