Abstract

Energy recovery from co-digestion of complex substrate mixtures: An overview, and case study of biogas production modeling

Author(s): Vincenzo Torretta, Ettore Trulli

Anaerobic digestion processes represent one of the mainstream technologies for indirect energy recovery from waste streams, currently supported in many Countries by governmental incentives to promote renewable sources such as biogas production. The intrinsic variability of supply modes, composition and physical-biological characteristics of the feed mixtures, significantly affect the stability of this type of processes, and may negatively impact on the actual rates of biogas production, affecting the financial feasibility of this type of projects. Composition and pH the generated biogas are important indicators of process performance, and the availability of buffer alkalinity plays an key role in the sustainability methane-generating process steps. In this paper, a theoretical analysis of requirements and applications aimed at addressing critical issues arising during process operation in full-scale plants are reported. The aim of the paper is to support proper assessmentmethods to identify adequate design and operating conditions of co-digestion systems for the treatment of solid/liquid mixtures of biodegradable waste while maximizing biogas recovery. In order to appropriately assess the influence of organic load on the process, a case study was included to represent possible process conditions typical of Mediterranean Countries.