Biohydrogen and methane production via a two-step process using an acid pretreated native microalgae consortium.

Area of Science:

• Biotechnology
• Renewable Energy
• Environmental Science

Background:

• Microalgae are a promising feedstock for biofuel production.
• Sequential processes can enhance biogas yields from microalgae.
• Thermal-acidic hydrolysis is a potential pretreatment method.

Purpose of the Study:

• To evaluate the production of hydrogen and methane from a native microalgae consortium using thermal-acidic hydrolysis.
• To determine the optimal acid concentration for maximizing biogas yields.
• To assess the energy recovery and chemical oxygen demand (COD) removal efficiency.

Main Methods:

• A two-step sequential process involving thermal-acidic hydrolysis of microalgae.
• Testing various acid concentrations to optimize hydrogen and methane production.
• Analysis of hydrogen and methane yields, volatile fatty acid production, and COD solubilization.

Main Results:

• Hydrogen and methane yields reached up to 45mL H₂/gVS and 432mL CH₄/gVS, respectively.
• Lower acid concentrations resulted in higher hydrogen and methane production.
• Significant COD solubilization (up to 30%) and volatile fatty acid generation (up to 10gCOD/L) were observed.
• COD removal ranged from 50-70% with energy recovery up to 15.9 kJ/gVS.

Conclusions:

• Thermal-acidic hydrolysis is a simple and effective pretreatment for sequential hydrogen and methane production from microalgae.
• The process offers substantial COD removal and high energy recovery, indicating its potential for sustainable biofuel generation.