Statistical approach for assessing the suitability of substrates for a biogas plant

Abstract

In this paper, we focused on the statistical evaluation of inputs to a biogas plant processing a mixture of kitchen waste and agricultural crops to ensure stable biogas production. The aim of the research was to identify the components of the input substrates that will ensure the maximum yield of CH4 and the substrates that increase the production of H2S. By a suitable combination of substrates, it is possible to optimize the production of biogas from the biogas plant. We analyzed a sample of 858 measurements, which were carried out in a selected biogas station for a period of 2.5 years. We were interested in differences in production of CH4, O2, and H2S outputs depending on the composition of inputs. From 17 inputs, 125 substrates were formed. The significance of the influence of individual substrates as categorical variables with the achieved numerical values was assessed by means of ANOVA analysis. Selected substrates were sorted based on CH4 and H2S production using graphical methods (bubble graphs) into four quadrants defining the desired and undesired values of the output variables. We identified a total of 20 suitable and 11 unsuitable substrates to produce quality biogas. Sorghum silage substrate was defined as a substrate that significantly increases the proportion of H2S in biogas.