Ozonation - Ozone
is the primary disinfectant of the water coming into the plant. Ozone-rich
air is bubbled up through the water in a series of ozone contact
chambers. In addition to being a highly effective disinfectant, the
ozonation process also destroys compounds which cause unpleasant tastes
and odors in the water.
- After ozonation, the water moves on through a flash mixer where chemicals
called coagulants are added. These coagulants react with particles in the
water, causing them to clump together. The water then goes to the flocculation
basins, which use the hydraulic energy of the water for mixing to create "floc" particles which are large and heavy enough to settle to the
Sedimentation - The water
then moves onto a double decked sedimentation basin where the heavier floc
particles settle to the bottom, while the clearer water moves on to be
filtered. A vacuum system removes the settled solids and deposits them
in a solids holding basin.
Filter Press - The material
removed in the sedimentation and filtration process contains a significant
amount of water. In order to separate the water from the solids so that
it can be recycled, the material is sent to a gravity thickener and then
to a filter press where the remaining water is squeezed out. The compacted
solids are then transported to a landfill for disposal.
Filtration - Following sedimentation,
the clarified water is filtered through layers of anthracite coal and sand.
The process removes any remaining particles that did not previously settle
out. This "polishing" provides a high level of clarity. As the water leaves
the plant, it receives a small dose of chlorine to keep it fresh and clean
as it travels through the distribution system to customers. The pH of the
water is adjusted for corrosion control and fluoride is added to benefit
the community's dental health.