It really depends on the goals, and it is very important to properly define them before assuming the cost.
There’s waterwashing, and then there’s waterwashing. Is the target 0% gums? Or is it <1%? <2%?
Is this for a pharma-type operation, with special product requirements? Or just getting it clean enough to distill easily, with minimal “gums/sugars” that would impact distillation?
Generally, gums/sugars impact yield during decarb, and impact yield during distillation, but you don’t need 0%; getting into the <1-2% range virtually eliminates both yield losses and issues with gear pumps and fouled lines. Of course, it is also important to define exactly how you measure that 1-2%.
We’ve found that degumming crude is very critical when it comes to either older biomass, or older crude. Gums form in the presence of moisture and heat; and tend to form in the presence of other gums. While you cannot unwind existing losses to gums, by effectively degumming the material you can eliminate future losses, which happen dramatically faster in the presence of high heat.
This is why some poor quality crude turns into huge chunks of glass-like, asphalt-like crap under heat; its already saturated with amorphous gums in the oil layers (sometimes you’ll see the sticky residue on the bottom of an empty barrel). Our industry often calls them sugars.