Anaerobic Digestion of Slaughterhouse Solid Waste for the Optimization of Biogas Production

Anaerobic digestion is a feasible technology to stabilize the solid waste generated in slaughterhouses obtaining significant quantities of biogas, considered as a clean and renewable fuel. This is why it is important to optimize the digestion process in order to eliminate organic matter and maximize the production of biogas. In this work, a system was developed for treating slaughterhouse solid waste while maximizing the production of biogas. This system is based on the separation of the acidogenic and the methanogenic phases of anaerobic digestion. The study was conducted in two phases. First, the effect of thermal pretreatment of the substrate and inoculation of the bioreactor with granular sludge were evaluated. In this phase, two variables were analyzed: the pretreatment temperature and whether or not inoculum was added. The results showed that the greatest decrease of total chemical oxygen demand (57%) and the highest biogas production (753 mL) were obtained from the inoculated sample pre-treated at 60 °C. In the second phase of the study, we analyzed the effect of running the anaerobic digestion stages, fermentation and digestion, in two separated steps. We found that the removal of organic matter is the same (56%) but more biogas (0.376 m3/m3 reactor*day) was produced in a two-step process.