Glycerol Treatment

Glycerol Treatment

During the biodiesel production process, glycerol is produced as a major by-product. This glycerol, however, isn’t in its purest form and contains residues of catalysts, alcohol, and other contaminants. Proper treatment and purification can turn this by-product into a valuable commodity, used in various industries. Let’s explore the glycerol treatment process.

Why Glycerol Treatment is Important

  • Economic Value: Purified glycerol has numerous applications in the pharmaceutical, cosmetic, food, and other industries, offering an additional revenue stream for biodiesel producers.
  • Environmental Consideration: Proper treatment prevents environmental pollution and promotes resource optimization.
  • Safety: Some residues in crude glycerol, like methanol, can be hazardous.

Steps in Glycerol Treatment

1. Methanol Recovery

Crude glycerol contains unreacted methanol, which can be recovered and reused.

Process: The glycerol is heated, allowing methanol to evaporate. This vapor is then condensed and collected for reuse or sale.

2. Neutralization

Residual catalysts (like sodium or potassium hydroxide) make the glycerol alkaline. Neutralization brings its pH to a neutral level.

Process: Acids, often sulfuric acid or phosphoric acid, are added to the glycerol to neutralize the alkalinity.

3. Filtration

Remove solid impurities and catalyst residues.

Process: The neutralized glycerol is passed through filters or centrifuges to remove suspended solids.

4. Distillation

This step is used to purify glycerol to a higher grade.

Process: Glycerol is heated, allowing impurities with lower boiling points to evaporate. The remaining glycerol, now in a more refined state, is collected.

5. Bleaching

To improve the color and remove any remaining colored impurities.

Process: The glycerol is passed through activated carbon or bleaching earth, which binds to the colored contaminants.

6. Deodorization:

Remove any undesirable odors.

Process: Glycerol is heated under vacuum, allowing volatile compounds causing odors to be stripped away.

7. Equipment Used in Glycerol Treatment

  • Evaporators: For methanol recovery.
  • Neutralization Tanks: Vessels where acids are added for pH adjustment.
  • Filtration Units or Centrifuges: For removing solid impurities.
  • Distillation Columns: For the purification of glycerol.
  • Bleaching Tanks: Vessels equipped with agitators where bleaching agents are added.

8. Considerations for Efficient Glycerol Treatment

  • Quality Control: Regularly test glycerol at different stages to ensure desired purity levels are achieved.
  • Safety: Handle chemicals, especially acids, with care, and ensure the workplace is well-ventilated.
  • Optimization: Recovered methanol and refined glycerol can significantly offset biodiesel production costs.


Glycerol treatment isn’t just about managing a by-product; it’s about optimizing resources, reducing waste, and tapping into a potential revenue stream. Properly treated glycerol stands as a testament to the comprehensive approach of biodiesel production, where every component, primary or secondary, has value.