The production of biodiesel involves multiple steps, one of the most crucial being the washing phase. This process eliminates any remaining contaminants after transesterification. Agitators play a pivotal role in ensuring the washing step is thorough and effective.

Role of Agitators in Biodiesel Washing

  • Enhanced Mixing: Agitators facilitate the thorough mixing of biodiesel with water or other washing agents, ensuring all contaminants come into contact with the washing medium.
  • Preventing Settling: In the washing stage, without proper agitation, heavier particles or contaminants might settle at the bottom. Agitators keep them suspended for effective removal.
  • Uniformity: Agitators ensure uniform distribution of washing agents throughout the biodiesel, leading to consistent product quality.

Design Features Tailored for Biodiesel Washing

  • Corrosion Resistance: Biodiesel and its contaminants can be corrosive. Hence, agitators used should be made of materials like stainless steel which resist corrosion.
  • Variable Speeds: Depending on the viscosity of the biodiesel and the stage of washing, variable speed agitators allow for greater flexibility and control.
  • Efficient Impellers: The design of the impeller can influence the mixing efficiency. Propeller and turbine impellers are commonly used for biodiesel washing.
  • Shaft Seals: To prevent leakage or contamination during the washing process.

Challenges & Considerations

  • Emulsion Formation: Over-agitation can lead to the formation of stable emulsions between water and biodiesel, which are hard to break. This complicates the separation process.
  • Energy Consumption: Effective agitation requires energy. Finding the balance between thorough washing and energy efficiency is crucial.
  • Maintenance: Agitators must be maintained regularly to ensure they function optimally. Wear and tear, especially in seals, should be routinely checked.

Types of Washing and the Role of Agitators

  • Water Washing: Agitators help in the dispersion of water droplets throughout the biodiesel, allowing the contaminants to bind with water.
  • Dry Washing: Though termed “dry”, this method often uses viscous compounds like magnesol. Agitators ensure that these compounds are evenly distributed, optimizing contaminant absorption.


In biodiesel production, the washing phase is pivotal in determining the final fuel quality. Agitators, with their capacity to ensure even mixing, play an indispensable role in this stage. Selecting the right agitator, optimizing its speed, and regular maintenance can significantly enhance the washing efficiency and, by extension, the quality of biodiesel produced.