Substrate Characterization in the Anaerobic Digestion Process

Anaerobic digestion, for the production of biogas and digestate, can be a powerful technology to obtain a gaseous fuel used for combined heat and power generation and for transportation (if upgraded to biomethane) and simultaneously obtain also a fertilizer. Anaerobic digestion is a biochemical process in which wet biomass is converted into gas by bacteria. To optimize the process at both research and industry level, it is necessary to characterize in detail the substrate before and during the process. Analytical methods applied to anaerobic digestion start from substrate characterization (which can be done through proximate and ultimate analysis and calorimetry, but also through the analysis of COD, alkalinity, pH, FFA, and other inhibitors); then also the microbial community has to be monitored during the process, and gas analysis has to be performed to determine the heating value and also the contaminants inside it (e.g., siloxanes). All these measurements have to be carefully standardized and are discussed in this chapter to provide information to researchers and operators in the field of anaerobic digestion.