Improving anaerobic digestion of corn straw by using solid-state urea pretreatment

Area of Science:

• Biotechnology
• Environmental Science
• Biochemical Engineering

Background:

• Cellulosic materials present structural and high carbon/nitrogen (C/N) ratio challenges for anaerobic digestion (AD).
• Efficient pretreatment methods are crucial for enhancing the anaerobic digestion of lignocellulosic substrates.

Purpose of the Study:

• To develop and evaluate a solid-state urea pretreatment for corn straw to improve anaerobic digestion (AD).
• To simultaneously adjust the C/N ratio and enhance methane production from corn straw.

Main Methods:

• Solid-state urea pretreatment of corn straw.
• Analysis of lignin reduction and C/N ratio adjustment.
• Scanning electron microscopy (SEM) to observe structural changes.
• Measurement of cumulative methane yields and digestate nutrient content.

Main Results:

• Solid-state urea pretreatment achieved 7.06% lignin reduction with an optimal C/N ratio of 15.
• SEM confirmed structural disruption, facilitating corn straw hydrolysis.
• Methane yields increased by up to 23.91% (250.03 mL/g VS) compared to untreated corn straw.
• Digestate from pretreated groups showed 9.62% higher nutrient content.

Conclusions:

• Solid-state urea pretreatment effectively disrupts corn straw's dense structure and optimizes the C/N ratio for AD.
• This method enhances methane production and improves the fertilizer value of the digestate.
• Solid-state urea pretreatment is a promising approach for the anaerobic digestion of cellulosic substrates.