To cause (a liquid) to change into a curdlike or semisolid state, not by evaporation but by some kind of chemical reaction; to curdle.
ETYM Latin coagulatio.
1. The change from a liquid to a thickened, curdlike, insoluble state, not by evaporation, but by some kind of chemical reaction.
2. The substance or body formed by coagulation.
The clumping together of very fine particles into larger particles caused by the use of chemicals (coagulants). The chemicals neutralize the electrical charges of the fine particles and cause destabilization of the particles. This clumping together makes it easier to separate the solids from the water by settling, skimming, draining, or filtering.