Experimental evaluation and data-driven modeling of a household anaerobic digester for waste-to-biogas conversion

The paper describes the outcomes of a ten-months experimental campaign and a hybrid model aimed at characterizing a micro-biogas plant behavior under realistic operational conditions. Both the experimental data and the results of the simulation were used to estimate the plant's performance and the effect of equipping it with a thermal insulation system and a heating system to increase its internal temperature. The results of the monitoring showed that the digesters produced an average of 170 l/d of biogas with an average methane content of 53% and a conversion efficiency of 84 kg of methane per ton of organic matter; moreover, it was observed that biogas production increased by 1.2 l/h or each additional 1 °C internal temperature. The results of the simulations showed that, in the base scenarios, the digester can produce an average of 0.98 kWh/d in the Mediterranean island of Lampedusa and of 0.32 kWh/d in the alpine village of Tarvisio. Thermal insulation alone showed a negative effect on digester temperatures and energy production. Solar base heating showed some benefits, while the best results were achieved through the combination of the two measures (+14.6% average internal temperature and +33.7% energy generation in Lampedusa, +22.9% and +69.0% in Tarvisio).