Anaerobic batch digestion of sheep tallow

Anaerobic batch digestion reactors were operated at mesophilic (35°C) and thermophilic (50°C) temperatures with sheep tallow at levels up to 59% of the volatile solids. Tallow was rapidly fermented to long-chain fatty acids (LCFA) and volatile fatty acids (VFA) at 35°C, but was refractory at 50°C. Oleic acid was fermented to palmitic, stearic and acetic acid. Methanogenesis was delayed by characteristic adaptation periods before LCFA and VFA were completely degraded. This demonstrated that wastes with high lipid contents are amenable to stabilization by mesophilic batch digestion.