The influence of increased concentration of total solids on the performance of co-digestion process of organic fraction of municipal solid waste (OFMSW) and activated sludges

In co-digestion it is important to consider the effects of the different incoming waste solid content. In fact in this study the effect of changes in the substrate concentration of OFMSW (ORL 1.8-3.6-4.5 KgTVS/m3*d1) on the specific biogas production rates, organic matter degradation and digestion system stability in anaerobic mesophilic digestion processes was evaluated. Reactors tests were executed in continuous conditions, two consecutive hydraulic retention times (HRT) of 20 days for each ORL, controlling the temperature, pH and biogas composition with a biogas analyzer. Organic wastes have furnished the best results in terms of the biogas quantity and quality. The specific biogas production (m3/kg TVS added) for the two reactors was in the range of 0.50-0.73 m3/kg VS added .These value are above those found in literature relating to the processing of organic fraction of municipal solid waste in mesophilic digestion (0.40-0.60 m3/kg VS added).