Karlsson AnnaThe biogas research group at WES

The Biogas research group at WES: Jenny Gustavsson, Madeleine Larsson, Jörgen Ejlertsson, Annika Björn, Carina Sundberg, Sepehr Shakeri Yekta, Anna Karlsson and Bo Svensson

The main goal of the biogas research at Water and Environmental studies (WES) is to increase the efficiency of biogas production. The extent of improvement possible within this field is large. For example both substrates and reactor volumes are often used at suboptimal levels. Thus, the biogas production may be enhanced in many existing full scale biogas reactors. However, while optimizing the biogas production for a given system there is a further need of attention to process stability problems, which, thus, need to be considered and controlled in many cases.

The base of the anaerobic production of biogas from organic materials is the microbial community performing the gasification. As all living organisms the growth of these communities is are limited by nutrient availability. Often the substrate provides sufficient amounts of macro nutrients (C, N, O, P, Ca, K), while trace elements in a number of cases have been shown to limit bacterial growth in high rate biogas processes. This limitation set the maximal growth rate of the microorganisms and, thus, often also the maximal loading. Hence, in many cases the organic loading rate (OLR) of a given reactor process can be increased, when trace elements are supplied. It also opens up for the use of substrates earlier regarded as more or less impossible to treat at reasonable OLR. This in its turn creates opportunities for more efficient processes, where less reactor volume is needed per unit of substrate treated. Our research within this field links the efficiency of the process to trace element concentrations and the microflora composition. Another area, which is important for the process efficiency is the rheology of the reactors. This strongly governs the ability to employ good mixing conditions, where microorganisms and substrate are in optimal contact, which is crucial for a fast digestion. We study this area by linking differences of viscosity in biogas process liquids to process conditions, substrate composition, concentration of extra polymeric substances (EPS) and microflora composition. Changes in viscosity has been observed in relation to shifts in substrate composition and this can led to problems with process mixing and foaming and can in the same way as nutrient limitation set a limit for the OLR of biogas processes.

The research group at WES, led by Professor Bo Svensson, has co-workers with background in microbiology, chemistry and molecular biology.