Dewatering Based on Sludge Rheology

How efficient ​is using ​sludge rheology ​(deformation ​and sludge flow)​ to calculate ​the ​dose of ​polyelectrolytes ​for sludge ​dewatering? ​ Theoretically, ​this makes ​sense but I ​have my doubts ​regarding ​actual plant ​conditions. ​since there are ​so many ​parameters that ​affect this ​method. ​ How do I make ​the best ​approximation ​for these ​calculations?​