What is the correct sequence of processes involved in particle removal, from largest to smallest, in waste water treatment?

From largest to smallest particle, the order is screening, then sedimentation, then flocculation.

Screening comes first, catching the biggest floating and suspended debris.

Sedimentation follows, letting heavier settleable solids sink under gravity.

Flocculation comes last, clumping the finest particles into removable flocs.

This staged approach removes progressively smaller material at each step.

Placing coarse screening first protects later units from clogging and damage.