1. n. 
The process of removing colloidal materials from water. A chemical coagulant (for example, alum) or a chemical flocculant (for example, polymer) or both are added to the water. Colloidal particles attach to each other and to the additives and clumps grow to sufficient size that they can be separated from the water by gravity settling, centrifuging, hydrocycloning or filtration. Clarification is a final step in a closed mud system when a clear effluent is needed.