Which one is better, bentonite slurry and polymeric slurry?

For the construction of diaphragm walls, bentonite slurry is commonly used to form a filter cake on walls of trenches to support earth pressure. The use of bentonite solely is based on its thixotrophic gel viscosity to provide support.

Though the cost of polymer is generally more expensive than bentonite, the use of polymer is increasing because polymer is generally infinitely re-usable and very small amount of polymer is normally required for construction works. The disposal cost of bentonite is quite high while the disposal of polymer can be readily conducted by adding agglomerator.

This question is taken from book named – A Self Learning Manual – Mastering Different Fields of Civil Engineering Works (VC-Q-A-Method) by Vincent T. H. CHU.