Stabilization of swine wastes by anaerobic digestion.

The purpose of this study was to evaluate the efficiency of the anaerobic digestion to reduce the organic load of swine waste. Anaerobic digestion is a biological means of decomposition of manure in an oxygen-free environment, and has the advantage of producing a fuel gas (methane) and an odor-free residue rich in nutrients, which can be used as fertilizer. The experiments were carried out in laboratory scale batch digester, at temperature controlled at 35 +/- 2 degrees C, without agitation. The digester was fed with 5% and 15% manure slurry. Results showed an average reduction of TCOD of 58% and DCOD of 85%. The methane content of biogas varied from 55 to 65% and stabilized sludge presented characteristics for use in agriculture.