In this study, pretreatment of banana pulp using eggshells in both calcined and un-calcined forms to examine the extent of hydrolysis was conducted. Reactor C O containing banana pulp and inoculum but with no eggshells added was used as the control, while reactors C 1 , C 2 , C 3 , C 4 , and C 5 containing banana pulp and inoculum were spiked with 1, 3, 5, 7, and 9 g of un-calcined eggshells and calcined eggshells, for experiment 1 and 2, respectively. Anaerobic digestion was carried out at

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... philic temperature (35°C) for a period of 20 days. Digester C 3 with 5 g of calcined eggshells gave the largest cumulative biogas yield of 2343 mL with 62% CH 4 , followed by digester C 5 with 9 g of un-calcined eggshells which gave 2032 mL with 51.9% CH 4 . The least biogas yield of 10 mL was obtained in digester C 5 with 9 g of calcined eggshells additive.