An integrated approach for efficient biomethane production from solid bio-wastes in a compact system.

Area of Science:

• Biotechnology
• Environmental Science
• Chemical Engineering

Background:

• Solid bio-wastes are abundant global resources with potential for bioenergy production.
• Anaerobic digestion (AD) is a sustainable method for converting solid bio-wastes to methane (SW2M).
• Hydrolysis of recalcitrant organic solids is a rate-limiting step in conventional AD processes.

Purpose of the Study:

• To develop and assess a complete bioprocess for efficient SW2M from recalcitrant organic residues.
• To enhance the hydrolysis efficiency for improved methane yield.
• To evaluate the performance of different bioreactor designs in the proposed SW2M scheme.

Main Methods:

• Enzymatic pre-hydrolysis and solubilization of organic residues (brewers' spent grain and pig manure).
• Anaerobic digestion of hydrolysates using expanded granular sludge bed (EGSB), continuously stirred tank reactor (CSTR), and sequencing batch reactor (SBR) designs.
• Measurement of organic loading rates (OLRs) and methane conversion efficiency.

Main Results:

• A complete SW2M scheme was successfully implemented.
• EGSB reactors achieved high OLRs (19-21 kgCOD·m⁻³·day⁻¹), 5-7 times higher than conventional methods.
• Approximately 56% and 45% of the organic matter in brewers' spent grain and pig manure, respectively, was converted to methane.

Conclusions:

• Complex organic solids can be efficiently hydrolyzed into biodegradable components for AD.
• The proposed approach offers an efficient, small-footprint, and fast conversion method for industrial-scale organic residue treatment.
• This study demonstrates a viable pathway for enhanced methane production from challenging solid bio-wastes.