Chemical Processing of Switchgrass (Panicum virgatum) and Grass Mixtures in Terms of Biogas Yield in Poland

Decomposition of waste biomass as a result of thermal, biological and chemical processing allows for the acquisition of energy and its carriers. Switchgrass (Panicum virgatum) and grass mixtures are a universal biological substrate for energy purposes. The digestibility of organic substrates in the fermentation process limits the presence of raw fiber. The aim of the work was to indicate the effectiveness of the method, which consists in pretreatment with the sodium hydroxide of the plant material. Processing conditions for low sodium concentrations (3.5 and 2% m/m) were determined. The study used the methodology of testing productivity of biogas in accordance with DIN 38414 p.8. Fresh vegetable substrate, slurry and inoculum were used to produce test mixtures. The results of the research have been developed statistically. Shapes of obtained characteristics of biogas productivity showed the correct course of the methane process. The total biogas productivity of switchgrass as a result of processing with sodium hydroxide gave better effect than with similarly processed grass mixtures. Cumulative biogas productivity of switchgrass mixtures as a result of chemical processing increased by about 10% v/v. Cumulative biogas productivity of grass mixtures, as a result of chemical processing, increased by approximately 17.5% v/v.