Influence of complex feed mixture on performance of anaerobic co-digestion

Anaerobic digestion represents one of the main processes for the treatment of waste for energy purposes, recently supported also by the national economical incentives for the production of biogas in the promotion of renewable sources. The variability of the supply modalities, the composition and physical and biological state of feed mixtures, significantly affect the stability of the process and may reflect negatively on the rate of biogas production. The pH and composition of biogas are important indicators of current processes and the availability of alkalinity plays an important role for the maintenance of the phases that promote methane. This paper describes a theoretical and applicative study aimed to analyze the critical issues that may arise during the development of the process in full-scale plants. The aim of the research is designed to support assessment methods appropriate to define design data and optimal operating conditions of centralized co-digestion systems for treating mixtures of biodegradable waste both solid and liquid. In order to focalize the applicative aspects related to the influence of organic loads, the study was supported also by modeling simulation to represent predefined scenarios typical of Mediterranean areas.