Dosing of cationic polyacrylamide or inorganic coagulants into digested or thickened sludge ahead of dewatering machines. Uniform distribution maximises cake dryness.
Coefficient of Variation (CoV) ≤0.05 at dewatering machine inlet. Sludge is non-Newtonian (yield stress): minimum pipe velocity must exceed yield stress for flow. VN open geometry preferred above 4% DS (helical elements can blind with fibre/grit). Polymer injection at low velocity to avoid shear degradation.
Preferred MOC: Rubber-lined carbon steel or UHMWPE for cationic Polyacrylamide (PAM) (stainless fouling). FRP for chemical sludge. 316SS injection quill.
VN open LPD vane geometry for DS >4% sludge (helical elements blind with fibre/grit). Rubber-lined or UHMWPE interior for cationic PAM. Injection nozzle at centreline in sludge flow. Polymer shear rate (s⁻¹) must not exceed maximum specified by supplier.