Potential Biogas Production Generated by Mono- and Co-digestion of Food Waste and Fruit Waste (Durian Shell, Dragon Fruit and Pineapple Peel) in Different Mixture Ratio under Anaerobic Condition

This work investigated the potential of generating biogas from mono-digestion of various substrates such as food and fruit waste (e.g., durian shell, dragon fruit peel and pineapple peel) and co-digestion in different combinations of a co-substrate as food waste as well as different types of fruit waste (durian shell, dragon fruit peel and pineapple peel). The mixture of food waste and fruit waste ratio varied as follows: 75:25, 50:50 and 25:75, which was based on weight. The batch experiments were carried out using 125 ml anaerobic digesters and were incubated for 50 days. For a mono-substrate, food waste produced the highest amount of methane gas (60.63 ± 1.02 ml/gvs) followed by durian shell (34.93 ± 1.30 ml/gvs), pineapple peel (31.70 ± 1.60 ml/gvs), and dragon fruit peel (30.12 ± 1.20 ml/gvs), respectively. The highest amount of methane gas came from food waste mixed with durian shell (FW75:D25), and it was on a higher level than food waste mixed with dragon fruit peel (FW75:DF25) and pineapple peel (FW75:P25). The highest methane gas production of co-digestion which was observed at the proportion of food waste and durian shell was 75:25 and produced higher content of methane gas than the highest methane gas production of mono-digestion (food waste) according to the high organic compound and optimum pH value in the system. The results showed that the co-digestion of durian shell and food waste improved methane production and reduced the startup time compared with their mono-digestion. On the other hand, pineapple peel was not suitable for co-digestion with food waste due to a decreasing pH value in the system.