Hybrid pathway of bio-ethanol production employing empty fruit bunches co-gasified with charcoal and mixed culture fermentation: Optimization using response surface methodology

Abstract

The research focuses on the synthesis of syngas from lignocellulosic biomass via co-gasification, employing response surface methodology. In addition, the study aims to optimize syngas fermentation efficiency for bioethanol production, utilizing two species of microorganisms – Saccharomyces cerevisiae and Clostridium butyricum – within an integrated biorefinery framework. The raw syngas was generated through the co-gasification of empty fruit bunches and charcoal mixtures (75:25). The optimal ratio of these components was determined via central composite design. The individual performances of S. cerevisiae and C. butyricum, as well as their co-fermentation, were thoroughly investigated, considering parameters such as colony forming units (CFU), pH, total organic carbon (TOC), and syngas flow rate. Morphological features of microorganisms during syngas fermentation were characterized using field emission scanning electron microscopy analysis. The results indicated that the highest bioethanol concentration, reaching 31.20 mmol, was achieved through co-fermentation as opposed to single-inoculum fermentation. Furthermore, a significant increase (3.08%) in bioethanol productivity was observed when the syngas flow rate was elevated from 50 to 1000 mL/min. Therefore, microbial co-fermentation emerges as a promising strategy to enhance bioethanol production from syngas derived from lignocellulosic biomass. Highlights Parametric optimization for co-gasification using response surface methodology Syngas was co-fermented using Saccharomyces cerevisiae and Clostridium butyricum Effects of syngas (CFU, pH, and TOC) were investigated during co-fermentation Bioethanol production increased 3.08% when syngas flowrate increased from (50 to 1000 mL/min)