The settling process in water purification plants is aided by the addition of

The right answer is coagulents.

Coagulation-flocculation is a physicochemical treatment process for the purification of water, used for the treatment of potabilization or the treatment of waste water.

Its principle is based on the difficulty of certain particles to decant naturally: colloids.

Coagulation, by adding metal salts (usually iron or aluminum), eliminates intercolloid repulsions: the metal cations (Al3 + and Fe3 +) bind to the colloids and neutralize them. Colloidal particles can now meet.

the wires in the toaster turning red and the toast crisping and turning brown