Water hardness is defined as the magnesium and calcium i on content of water. The pH of raw water ranges from 7.7 to 8.5. Another raw water factor is the alkalinity or total calcium carbonate equivalent units. Next the water flows through an inline power mixer where ferric sulfate is added before entering a series of basins. Coagulation Ferric sulfate is used as a base substance in the formation of floc particles.
Ferric sulfate forms a positive trivalent particle with very sticky characteristics.
The water and suspended floc next enter a series of basins. These basins have mixers which provide gentle agitation to aid the formation and buildup of floc particles. This buildup of particles is called flocculation. Flocculation results from both the physical entrapment of impurities on the sticky ferric sulfate surface and also an ionic attraction between the negatively charged turbidity particles and the positive ferric sulfate. The settling basin provides an area for these newly formed floc particles to settle out.