Assessment of Co-digestion From Poultry Litter and Swine Wastewater and Enrichment Inoculum Effect in Biogas Production

Abstract

Abstract Lignocellulosic substrate co-digestion as a pre-treatment step to anaerobic digestion increases the viability of using agro-industry waste for biogas production. This study aimed to assess proportions of co-digestion of swine manure and poultry litter for greater methane production, in addition to analyzing the effect of microbial inoculum enrichment on biodigestion. After co-digestions were prepared, the fractions (solid and liquid) were separated, and the liquid was used in the tests. Methane production potential tests were assessed using the Doehlert experimental design in co-digestions of swine manure and poultry litter at 0%, 10%, 20%, 30% and 40% (m/m). The other variable studied was the amount of inoculum added (ISR) at levels of 2, 1.25 and 0.5. The highest methane production values (286–284 NL kgVS-1) were obtained in co-digestions between 10% and 20% (m/m) of poultry litter, which present total solids compatible with using covered lagoon and CSTR model biodigesters. A 34% increase was obtained in the microbial inoculum enrichment study, when compared to standard inoculum use. The co-digestion phase separation procedure developed in this study increased the feasibility of implementing this technology as an alternative to biogas production in commonly used biodigestion systems.