Disposal of biodegradable waste has become a stringent waste management and environmental issue. As a result, anaerobic digestion has become one of the best alternative technology to treat the organic fraction of municipal solid wastes and can be an important source of bioenergy. This study focuses on the evaluation of biogas and methane yields from the digestion and co-digestion of mixtures of waste untreated sludge and the organic fraction of municipal solid wastes. These are compared with the results obtained from the digestion and codigestion of mixtures containing waste active sludge and the organic fraction of municipal solid wastes. The two types of substrates were used to perform biomethanation potential tests, in mesophilic conditions (35°C) at lab scale. It was observed a maximum biogas yield for 100% of untreated sewage sludge, corresponding to 0.644 Nm 3 /kg VS and 0.499 Nm 3 /kg VS of biogas and methane production respectively. The study also demonstrates the possibility of increasing biogas production up to 36% and methane content up to 94% using waste untreated sludge substrate in both digestion and codigestion, compared to waste active sludge substrate.

The increasing global demand for biofuels for energy security and to reduce the effects of climate change has created an opportunity to explore new sources of biomass, of which, microalgae is the most promising one. The Laboratory of the Biomass Research Centre (CRB, University of Perugia) is equipped with a photobioreactor that is used to cultivate microalgae under batch conditions. Tests were carried out a temperature of 22 °C and a Photosynthetic Photon Flux Density of 140 µE·m−2·s−1. Cultures were characterized in terms of biomass produced and lipid fraction distribution. The novelty of this paper is the measure of the fuel properties of Selenastrum capricornutum, a new strain for biodiesel production. In particular, after the microalgae have been collected and oil has been extracted, this has been transesterified using a methanol/NaOH solution. The resulting biodiesel has been analyzed with a high-resolution gas chromatograph to determine the concentration of the different methylesters.