The combination of ferric chloride and latex is what's called coagulation flocculation treatment. The coagulant, in this case the ferric chloride, neutralizes

The combination of ferric chloride and latex is what's called coagulation flocculation treatment. The coagulant, in this case the ferric chloride, neutralizes the charges on suspended particles in a liquid, causing them to clump together into larger aggregates (flocs) that can then be more easily separated from the liquid through sedimentation or filtration. The latex in this case is the flocculant, assist in binding together the microflocs formed by coagulation into larger, more stable aggregates known as flocs. Flocculants often work by bridging the particles through long chains of polymers, effectively linking the microflocs into larger clusters. After the coagulation and flocculation process, the water usually enters a large settling basin where the flocs gradually settle to the bottom, resulting in clarified water.