Comparative Evaluation and Process Performance Analysis of Bioethanol Production from Carica papaya and Citrullus lanatus Peels

Abstract

This paper comparatively assessed the potential of Carica papaya and Citrullus lanatus peels as inexpensive fruit-waste syrups for renewable energy production, evaluating their bioethanol production potential and process performance. A comparative experimental design was used, with peel samples collected in the Ozoro area of Delta State, Nigeria. The peels were dried, washed, powdered, and placed under dilute- acid hydrolysis with 250 mL of 1% H2SO4 /50g of dry substrate. The hydrolysates were adjusted to pH 5.0, 2g of Saccharomyces cerevisiae were inoculated, fermented for 7 days in darkness, and distilled at 78-82 °C to obtain ethanol. Comparative analysis was conducted on ethanol yield, ethanol volume, pH, density, sugar content, and ethanol mass, whilst advanced analysis used ratios of efficiency, density deviation, and composite feedstock performance. The findings revealed that watermelon peels were superior to pawpaw peels in total ethanol productivity, with ethanol yields of 26.0% and 9.0%, ethanol volumes of 13.0 mL and 4.5 mL, and ethanol masses of 11.7 g and 3.6 g, respectively. The pawpaw peels, however, contained more sugar (4.2% compared to 3.6%) and denser ethanol than the standard ethanol. The results suggest that high ethanol performance was determined by actual bioconversion efficiency rather than by sugar content alone. The research finds that Citrullus lanatus peels are more promising as a substrate for bioethanol production under the conditions tested. The consequence of this is that it adds value to waste, harnessing renewable energy and promoting environmental management for sustainability.