Optimization of Sebac Start up Phase of Municipal Solid Waste Anaerobic Digestion

T. Forster-Carneiro, L. A. Fernández, M. Pérez, L. I. Romero and C. J. Álvarez

Abstract
Laboratory studies on dry anaerobic digestion of mixture of organic fraction of municipal solid waste, mainly putrescible fraction selected source (SS–OFMSW), and others organic compounds (garden waste, rice hulls, animal waste and sludge) demonstrated the optimum efficiency at 35 % total solid and thermophilic conditions (55 °C). Five starts up and stable phase strategies of SEBAC system were compared and a protocol of start up phase elaborated. The mixture of animal waste with SS–OFMSW in the reactor disposed in two layers favored the waste biodegradation and this suppose an important modification in the conventional SEBAC system configuration. However, the treatment strategy using 50 % SS–OFMSW, 15 – 35 % rice hulls or 15 – 35 % garden waste solved the operational problems and favored the star up and stable phase of the process. Following the conclusions of all experiments, a protocol of start up and stable phase was elaborated. A system operating the optimized protocol showed a rapid start up in the 2 days, initial stable phase in 20 days and initial dead phase in 100 days. At these conditions the performance of this system were a gas production of 6.5 L d–1 and the mean methane production of 7.35 per unit mass (1 g) VSS in all experiment; or proximally of 50 % CH4 in the stable phase.

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Keywords
anaerobic digestion, SEBAC system, thermophilic, source–sorted of organic fraction, biogas