Second-generation ethanol production from elephant grass at high total solids

Area of Science:

• Biomass Conversion
• Biofuel Production
• Enzymatic Hydrolysis

Background:

• Pennisetum purpureum (elephant grass) is a potential lignocellulosic feedstock for biofuel production.
• Efficient enzymatic hydrolysis of biomass is crucial for cost-effective ethanol generation.
• High solid loading presents challenges in biomass hydrolysis due to mixing and mass transfer limitations.

Purpose of the Study:

• To evaluate the enzymatic hydrolysis of elephant grass at high solid loadings (4-20% w/v).
• To investigate the effect of simultaneous ball milling treatment in a rotating hydrolysis reactor (RHR).
• To assess the subsequent fermentation of released sugars into ethanol using Saccharomyces cerevisiae.

Main Methods:

• Enzymatic hydrolysis of untreated elephant grass biomass at varying solid concentrations (4-20% w/v).
• Simultaneous ball milling and hydrolysis within a rotating hydrolysis reactor (RHR).
• Fermentation of hydrolysates using Saccharomyces cerevisiae to produce ethanol.

Main Results:

• The highest glucose yield achieved was 20.17% using 4% (w/v) untreated biomass.
• The greatest ethanol yield was 22.61% from sugars derived from 4% (w/v) biomass.
• Hydrolysis in the RHR resulted in approximately double the ethanol production compared to a static reactor (SR).
• Highest glucose (12.47 g/L) and ethanol (6.1 g/L) concentrations were obtained at 20% and 16% (w/v) solids, respectively.

Conclusions:

• Simultaneous milling and enzymatic hydrolysis in an RHR is an effective strategy for enhancing glucose and ethanol yields from elephant grass.
• The RHR system demonstrates improved efficiency over static reactors for biomass hydrolysis and biofuel production.
• This approach shows potential for the sustainable and efficient production of bioethanol from lignocellulosic materials like elephant grass.