Abstract Livestock farming and manure management contribute substantially to greenhouse gas (GHG) emissions in agriculture. Anaerobic digestion (AD) of manure is a promising strategy for mitigating these emissions. This study aimed to assess the biomethane potential (BMP) of various types of pig slurry, investigate factors that influence biomethane production, analyze degradation kinetics, and propose AD process optimization approaches. Thus, substrate analysis, BMP tests in batch assays, kinetic modeling, and principal component analysis (PCA) were conducted. In order to further quantify the effects of different substrate qualities in full-scale operation, biomethane production was simulated under steady-state conditions. Results indicated that piglet slurry had the highest volatile solids (VS)–specific BMP (203 ± 72 L kg−1 VS), followed by mixed slurry (202 ± 132 L kg−1 VS), fattening pig slurry (117 ± 56 L kg−1 VS), and sow slurry (86 ± 17 L kg−1 VS). The PCA revealed different substrate types and significant roles for VS, crude fat, volatile fatty acids concentration, and the carbon/nitrogen ratio in achieving high BMPs. First-order two-step kinetic modeling identified hydrolysis as the rate-limiting step, showing a determinant of rate-limiting step of < 0 for each sample. The simulation of continuous operation revealed notable differences in daily biomethane production (36.7–42.7 L day−1) between the different slurries at the same hydraulic retention time and BMP. This research underscores the variability in pig slurry characteristics, exemplified by a total solids range of 1.4–12.1%, and provides crucial insights for optimizing AD processes in livestock waste management.
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