Characterization and Enhancement of Microbial Biodiversity in Digestate in the Agronomic Field

The possibility of producing biogas and methane from two phases olive pomace was considered using anaerobic digestion and the microbial characteristic of digestate for the agrarian use was analyzed. In the work, the main aim was to obtain biogas, made from at least 50% methane, and a digestate that can be used in the field of agronomy, from the anaerobic digestion of the substrates. The tests were carried out by digesting different mixtures of the two-phase pomace, mulberry leaves and mud civil wastewater (pre-digested) in a batch system and in anaerobic mesophilic conditions (35 °C). The substrates were properly homogenized in order to obtain mixtures of known and uniform composition. The initial and final STi (Total Solids) and initial SVi (Volatile Solids), the concentration of chemical oxygen demand and total phenols were measured and the process yield (m3/t SV) was quantified with standard procedure. The objectives of the study were the analysis of microbial biodiversity developed during fermentation of mixtures based products and the microbial communities corresponding to Eubacteria, Archaea and Fungiwas analyzed. The suitability of the digestate for agronomical use was evaluated by estimating pathogens bacteria that may be present and by index of inhibition of plant organisms model.