Optimizing bioethanol production from cassava peels through agitation timing variation in separate hydrolysis and co-fermentation

Abstract

Background: This study assessed the effect of various agitation timings on bioethanol production from cassava peels (CP) using separate hydrolysis and co-fermentation (SHCF) technique. Methods: The milled CP was divided into three groups each of 20 g and subjected to two-stage hydrolysis carried out at 100 oC for 60 min and 50 minutes, respectively. Experimental layouts were Sample 1 (B1) [0 hours i.e., no shaking], Sample 2 (B2) [3 hours shaking with an electric shaker at 200 rev/min-1], and Sample 3 (B3) [6 hours shaking at 200 rev/min-1]. Fermentations were carried out at 30 oC for 72 days. Data were analyzed using descriptive statistics, one–way ANOVA, and New Duncan’s multiple range test at P = 0.05. Results: The TSS and pH readings of the treatment groups before and after fermentation were: B1 – TSS (27.15 ± 0.15, 17.25 ± 0.07 oBx), pH (5.50 ± 0.00, 4.53 ± 0.04); B2 – TSS (27.32 ± 0.08, 14.78 ± 0.12 oBx), pH (5.50 ± 0.00, 4.74 ± 0.06); and B3 – TSS (27.17 ± 0.07, 10.24 ± 0.08 oBx), pH (5.50 ± 0.00, 4.77 ± 0.05) (P < 0.05). The mean fermentation efficiency (FE) and ethanol productivity (EP) were B1 (15.17 ± 0.07%, 0.122 ± 0.001 gL-1h-1), B2 (15.70 ± 0.18%, 0.126 ± 0.002 gL-1h-1), and B3 (18.80 ± 0.14%, 0.151 ± 0.001 gL- 1h-1) (P < 0.05). All treatment groups attained the maximum ethanol yields at 72 hours of fermentation (P < 0.05). Agitation at 200 rev/min-1 for 6 hours gave the optimal FE (%), EP, and ethanol yield. Conclusion: The established condition improved the Bioethanol quality and yield of CP. Thus, optimizing bioethanol production from CP would help enhance sustainable biofuel production without affecting food security.

Keywords

• ethanol
• fermentation
• hydrolysis
• saccharomyces cerevisiae
• sugars