10 ways to improve your bio-based chemical plant – Alfa Laval

5. Cut costs with counter-current diafiltration

Continuous diafiltration is a common way of removing impurities such as salts, solvents and small molecules from the product solution. The process traditionally requires large amounts of water to wash out the unwanted substances. The added water increases the total production costs, both in the diafiltration stage and further downstream when the water has to be removed again.

Reusing wash water

Alfa Laval has developed a new design for continuous diafiltration that dramatically reduces water usage. Instead of adding fresh water in each diafiltration step, the permeate water is reused in previous steps. Fresh water is only added in the last step, and the permeate from the last step is reused as wash water in the second-to-last step, etc.

This unique design leads to large savings in water consumption. With Alfa Laval’s continuous, counter-current diafiltration system you can save up to two thirds of the water consumed in a conventional system.

Major savings

Adding water in a diafiltration stage dilutes the product. This water has to be removed further downstream, for example through evaporation or reverse osmosis, adding to the investment and operating costs.

The big reduction in the amount of added water means Alfa Laval’s counter-current diafiltration systems minimize costs in both the purification and concentration stages of your plant.