The potential of biogas production from fruit wastes (Watermelon, Mango and Pawpaw)

The study determined the potential of biogas production from fruit wastes: mango, pawpaw and watermelon and their combinations. Fixed batch type anaerobic digesters were locally fabricated and used for the study. Retention time was for 45 days. The different substrates were prepared into slurry treatments by grinding and mixing with water in the ratio of 1:3, and 1:2 for only watermelon treatment because of its high moisture content. Determination of process pH, temperature and viable anaerobic counts were carried out to monitor how their variations in the anaerobic digesters affected the biogas production process, using pH meter, mercury in glass thermometer and a locally designed anaerobic glove box. Quantification of biogas yield was by liquid displacement. The pH, temperature and anaerobic counts varied over the 45 days retention time. The total volume of biogas produced from each digester at the end of the digestion was 2971 cm³, 1577 cm³, 83 cm³, 5103 cm³, 1630 cm³, 916 cm³, and 4348 cm³, from watermelon (W), mango (M), pawpaw (P), watermelon + melon (WM), pawpaw + water melon (PW), mango and  pawpaw (MP) and mango, watermelon, and pawpaw (MWP), respectively. The excellent biodegradability potential displayed by watermelon waste and to a lesser extent mango waste is of great importance in waste management and the energy transition vision of Nigeria.