Total Sago Effluent Concentrate (TSEC) for Bioethanol Production via Fed-Batch Simultaneous Saccharification and Fermentation (SSF)

Abstract

Sago processing waste stream, commonly called sago effluent, consists of a mixture of wet solid biomass and liquid hydrolysate. This industrial byproduct is rich in carbohydrates, particularly lignocellulosic materials, making it a promising feedstock for bioethanol production. In this study, sago effluent was subjected to physical pretreatment involving mechanical pulverisation and centrifugation to obtain a dense starch-rich wet biomass, termed total sago effluent concentrate (TSEC). The TSEC was subsequently used as a substrate for bioethanol production via fed-batch Simultaneous Saccharification and Fermentation (SSF), catalysed by amylolytic enzymes (α-amylase and glucoamylase) and Saccharomyces cerevisiae. SSF experiments were conducted in both non-buffered and citrate-buffered media, with buffer concentrations of 0, 25, 50 and 100 mM. Maximum ethanol production was achieved in the non-buffered medium, with a concentration of 23.44 ± 4.16 g/L and a theoretical ethanol yield (TEY) of 62.94 ± 11.18%. No statistically significant differences were observed in ethanol production across the different buffered conditions. The highest ethanol concentration among the buffered systems was recorded at 23.22 ± 2.44 g/L (62.33 ± 6.57% TEY) in the 25 mM citrate buffer. This was followed by 20.67 ± 2.85 g/L (55.33 ± 4.80% TEY) in the 50 mM buffer and 20.61 ± 1.79 g/L (55.33 ± 4.82% TEY) in the 100 mM buffer. Overall, the findings demonstrate that TSEC is an effective and viable feedstock for bioethanol production using the fed-batch SSF process, with optimal performance observed in a non-buffered fermentation system.