Fresh banana pseudo-stems as a tropical lignocellulosic feedstock for methane production

Abstract

Background: The banana pseudo-stem is a low-lignin-content lignocellulosic biomass that can be used for methane production. In recent years, anaerobic digestion (AD) of dried banana stems for methane production has attracted considerable attention. However, there is limited information regarding methane production from the fresh banana pseudo-stem. The direct usability of fresh banana stems as a resource for renewable energy production through AD is a called upon prerequisite for an improved waste management system culminating in a sustainable as well as socioeconomic development of local banana-producing communities. Methods: In this study, three series of experiments were performed simultaneously to investigate the methane production from fresh banana pseudo-stems for the first time. The tests included size reduction, enzyme addition, and co-digestion of banana stems with cow manure. Results: The achieved methane yields were 287, 340, to 347 mL g−1 volatile solids for the banana stem with particle sizes of 5, 10, and 20 mm, respectively. The highest yield was obtained at the particle size of 20 mm, showing a 21 % increase compared to the particle size of 5 mm. However, the particle size of 5 mm showed a high initial rate of hydrolysis evident by the highest hydrolysis rate constant of 0.152 d−1 as compared to 0.110 d−1 for the 20-mm particle size. The addition of enzyme and co-digestion improved the rate of hydrolysis evident by a high rate constant as compared to the control though there was no improvement in the ultimate methane production. Conclusions: This study demonstrates the usability of the fresh banana stem for efficient and high methane production after simply applying a minimal size reduction. The implementation of such a study will benefit society especially rural banana-producing areas both toward renewable energy generation and sustainable waste management. These could lead to job creation and an improved standard of living.