Evaluating biochemical methane production from brewer's spent yeast

Area of Science:

• Biotechnology
• Renewable Energy
• Environmental Science

Background:

• Brewer's spent yeast (SY) is a byproduct of brewing, presenting a potential substrate for bioenergy production.
• Anaerobic digestion is a key process for converting organic waste into biogas, primarily methane.
• Optimizing the treatment of SY is crucial for maximizing bioenergy yields.

Purpose of the Study:

• To evaluate the biochemical methane potential (BMP) of brewer's spent yeast (SY) under different dilution conditions.
• To determine the kinetic parameters governing methane production from SY using Gompertz and first-order hydrolysis models.
• To identify optimal conditions for efficient methane capture and bioenergy generation from SY.

Main Methods:

• Biochemical methane potential (BMP) assays were conducted using three SY samples (SY1, SY2, SY3) and various dilutions of SY1 (75%, 50%, 25%).
• Kinetic analysis was performed using the Gompertz equation and the first-order hydrolysis model to assess degradation rates and lag phases.
• Methane production rates, lag phase duration, and total COD (TCOD) conversion were measured and analyzed.

Main Results:

• SY1 exhibited slow degradability with long lag phases (10.72–19.7 days) and low methane production rates (14.59–4.63 mL/day).
• SY2 at 25% dilution demonstrated significantly improved performance, yielding a 17% TCOD conversion to methane and a lag phase under 1 day.
• The average estimated hydrolysis constant for SY was 0.0141 (±0.003) day⁻¹, with SY2 25% being the most suitable for rapid methane generation.
• Methane yield and biogas composition varied depending on the SY source and dilution, highlighting the benefits of co-digestion or dilution.

Conclusions:

• Dilution or co-digestion of brewer's spent yeast is advantageous for enhancing methane production.
• SY2 at 25% dilution is a promising substrate for efficient and rapid biogas generation.
• Understanding the source-specific characteristics of SY is critical for optimizing anaerobic digestion processes for bioenergy capture.