Advantages of Separated Silage for Bioenergy Applications without Material Washing

Abstract

In order to guarantee the sufficient efficiency using biomass for the anaerobic digestion (AD) process, lower mineral solid fuels production, saving same time most of fertilizing elements the silage mechanical separation process can be applied. Press liquids (PL) from separation in fact shows tendency to higher biogas yield per dry-matter (DM) on AD process and press cake (PC) gives comparable biogas yields with silage. The separation includes as pretreatment positive impact to biomethane yields on AD process. The period of fermentation of PL from silage is shorter than the duration of the cycle of fermentation process when silage is used as untreated substrate for AD. Based on these trends it is possible to reduce the volume of the reactor, reducing investment costs and to simplify the technology as the substrates can be easier injected in the reactor with a lower need of maintenance. The separation of the solid-liquid phases of the silage enables to produce solid fuels from press cake (PC), or can be used in fluidized bed boiler houses because of high enough dry DM content in range of 43–49%. Solid biofuels, as the result of separation process have less ashes and elements which can cause problems in furnace chemistry and physical performance. Separation of silage enables number of advantages as faster AD process, feedstock specific methane yield per DM, possibility to produce higher quality solid biofuels and save most of nutrients in PL (digestate) as fertilizers on case of using PC as solid fuels. Feedstock mashing with water or hydro-thermal conditioning is not used.