The Two-Stage Anaerobic Digestion System Using Solar Heat Energy

Abstract

Garbage is a major problem in Thailand and the quantity is increasing every year. The way to help reduce waste is to convert it into alternative energy such as biogas. This research aims to study biogas production from municipal waste using a two-stage anaerobic digester system heated by solar energy. Two experiments were performed, the first to find the relationship between the amount of biogas and the amount of food waste fed into the system with volume of 0.5 kg, 1 kg, 1.5 kg and 2 kg per day. And a second experiment to compare the results of fermentation in parabolic dome and in greenhouses. The results of the experiment showed that, when the system was fed 0.5, 1, 1.5 and 2 kg of food waste per day, the average total biogas content were 1.340, 1.592, 1.801 and 1.927 liters per day, respectively. And when the system has been implemented until the 30-day period, the results show that the feeding amount of food waste 0.5, 1, 1.5 and 2 kg per day. It can produce the highest accumulated biogas at 20.41, 23.57, 26.34 and 28.33 liters respectively. Another study was conducted to compare the effect of fermentation in parabolic domes and in greenhouses. The results of the experiment showed that the average daily biogas content of fermentation in the greenhouse and parabolic domes was 1.59 and 1.72 liters, respectively, and the accumulated biogas content in the houses and in the parabolic domes was 23.57 and 25.58 liters, respectively. It can be seen that the experiments in the parabolic dome yielded higher biogas content than in greenhouses. In the parabolic dome, average daily biogas content was 8.17% higher than in the greenhouse experiment, and the average accumulated biogas content throughout the experiment was 8.52% higher than in the greenhouse experiment.