Tampa’s Drinking Water Treatment
Process
Tampa’s demand for
water averages about 80 million gallons a day. Most of the demand,
pumped from the Hillsborough River reservoir, is treated with a
six-step process prior to being stored in large underground tanks
called clearwells.
Step 1: Rapid Mix
Naturally occurring organic matter found in Florida
streams and rivers gives the Hillsborough River its tea-like color.
A coagulant, ferric sulfate, and sulfuric acid are added to the
water, and they react with the organic matter to form substances
called floc.
Back to
Treatment Process
Step 2: Flocculation
During this step, polymers are added to the water,
which is circulated to allow the floc particles to form larger,
heavier floc solids.
Back to
Treatment Process
Step 3: Sedimentation
After flocculation the water flows into rectangular
settling basins. As the water moves down the length of the basin,
the floc settles to the bottom. Clear, settled water is collected at
the end of the basins. Computerized traveling siphon bridges clean
the bottom of the basins, and floc vacuumed from the bottom is
further treated and removed.
Back to
Treatment Process
Step 4: Stabilization and Disinfection
Clear, settled water is collected at the end of the
settling basins and treated with ozone in a large rectangular ozone
contactor. Ozone is a strong oxidant capable of destroying harmful
bacteria and viruses and inactivating microbial pathogens such as
Giardia and Cryptosporidium. Ozone also destroys taste-
and odor-causing compounds. Lime is added to the water after
ozonation to stabilize the pH of the treated water. Fluoride is
added to provide dental health benefits.
Back to
Treatment Process
Step 5: Filtration
The disinfected water is filtered through mixed bed
filters containing sand and activated carbon coal to remove any
remaining particles. The filters are periodically backwashed to
remove collected particles. An automated, computerized backwash
program removes dirty filters from service and begins a
reversed-flow washing process. Air scouring helps dislodge material
collected in the filter media. Backwash water removes dislodged
material to a thickener tank for reclamation. After settling in the
thickener, the backwash water is recycled to the beginning of the
treatment stream for reprocessing. Solids collected in the thickener
are removed for dewatering and disposal.
Back to
Treatment Process
Step 6: Final Disinfection
After filtration, chlorine and ammonia are added to
the treated water to prepare it for storage. The combination of
ammonia and chlorine produce a disinfectant called monochloramine.
Monochloramine is the final residual disinfectant for the finished
water. It maintains the disinfectant integrity of the water in the
distribution system and inhibits the formation of byproducts that
may form when only chlorine is used. Sodium hydroxide is added to
produce the final desired drinking water pH before storage for later
distribution. High service process pumps send the finished water
from storage.
Back to
Treatment Process
Clearwell Storage
Finished water is stored in large cement underground
tanks called clearwells. High service process pumps send the
finished water from storage to Tampa’s water distribution system to
meet the demand for drinking water.
Back to
Treatment Process
Top of Page
|