Reverse
Osmosis Plant
With projected population growth in
this Florida west-coast town dictating expansion of its 8 mgd lime
removal treatment process line, the city looked to a deeper aquifer
as its source for the expanded capacity. This new source was more
saline, requiring a different treatment process. The utility chose
reverse osmosis technology as the best fit for their needs.
BSU serves an area of about 50 square
miles, containing approximately 20,000 homes and businesses. Population
was projected to reach 75,000 by 2020, with a water consumption
estimated to reach 15 mgd.
The new plant was designed for a capacity
of 12 mgd, and the phase one portion of the project will provide
6 mgd of that maximum design capacity.
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Entrance
to the utility's office complex, which includes customer service,
administration, and engineering, in addition to both the old and
the new treatment plants.
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Raw water is sampled and tested, with acid being
injected as needed to change pH and solubility. Cartridge filters
remove suspended solids. A transfer station does further testing
and controls the addition of sodium hydroxide, sulfuric acid,
and a scale inhibitor, which modifies the solubility of salts
in the water to protect the RO filter membranes from crystallization.
The good water that comes out of the RO treatment
process goes to a degasifier (odor scrubber) to remove hydrogen
sulfide before sending it to a clear well and on to a storage
tank. The last step before distribution is a static mixer for
the addition of post treatment chemicals, such as chlorine.
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Bad water (the highly saline
reject from the end of the RO treatment process) is sent to a deep
injection well. This involves pumping the bad water down to a depth
of 3200 feet. This puts it in a deep aquifer that is covered by multiple
layers of clay to prevent upward migration of the water. Monitoring
wells are maintained to assure no such upward migration takes place. |
