treatment facilities

South Water Treatment Plant / Reverse Osmosis (RO) Facility

Operation
  • High pressure water is forced through thin, semi-permeable RO membranes, leaving unwanted contaminants behind.
  • RO treatment units recover about 75% of the water that is forced through and the other 25% washes away contaminants such as salt and calcium (hardness).
  • Waste flow (similar to sea water) from RO units, is disposed of through an ocean out-fall located 300 yards from the shoreline.
  • RO process removes virtually all impurities from the water but after removal, water has no taste; is very corrosive; and has a low pH due to feeding acid into the water before treatment.
  • The finished water is stabilized by blending raw water from the Surficial Well field back into the R/O product water. Chemicals additives are also added into the finished water i.e., chlorine for disinfection, caustic soda for alkalinity and polyphosphates for corrosion control.
 
Reverse Osmosis System Design
  • 2 raw water wells (1 +1 backup)
  • Draw artesian water from the Floridan Aquifer to supply the raw water demand.
  • Wells are approximately 1,300 feet deep
  • Each well supplies 1,400 gallons per minute (gpm) or 2 million gallons per day.
 
Floridan Aquifer used because:
  • Completely isolated from the shallow aquifer and
  • Will reduce draw from the Surficial Aquifer by approximately 50% on a yearly basis & almost entirely during the dry winter months.
  • Waste flow from treatment process is concentrated well water.
  • All contaminants from water end up in the waste flow, commonly called concentrate or brine.
  • Concentrate water has salt strength of about 75% that of sea water.
  • The water flows from the reverse osmosis plant into the degasifiers.
  • The degasifier removes the hydrogen sulfide (rotten egg gas) and excess carbon dioxide from the water.
  • Hydrogen sulfide is in the raw water is a dissolved form and passes through the membranes.
  • Carbon dioxide is a product of the treatment process and causes the water to be corrosive and adds an additional chemical demand on the water.
  • The unwanted gasses are removed by having the water cascade down through a loose media inside the scrubber and forcing air up through the water. The air containing the hydrogen sulfide is removed in odor scrubbing equipment. The odor scrubbers utilize recirculation slurry to neutralize odors. The odor is then bound up in the water solution that is discharged to the sewer system.

North Water Treatment Plant

Operation
  • 7 raw water wells ( 2 used for backup)
  • Draw from the Surficial aquifer to supply raw water demand
  • Permitted plant capacity is 3.61 million gallons per day
  • Total high service pumping capacity is 4,400 gpm at 100 ft TDH.
 
Process Overview

Raw water is pumped to an above ground chemical injection assembly where chlorine, ammonia and corrosion inhibitor chemicals are added. The chemicals are mixed in two (2) static mixers that are located downstream from the chemical injection assemblies and the water is then diverted into the two (2) 500,000 gallon potable water storage tanks. The high service pumping systems consist of 3 – 60 hp pumps and 2 – 20 hp pumps. One 60 hp pump has been equipped with a variable frequency drive unit used for distribution system pressure control. The finished water is continuously monitored for chlorine, pH and system pressure. Adjustments to these parameters are controlled automatically using SCADA and PLC control systems. If the controlled operating parameters go out of range an auto-dialer phone system will notify the water plant operations department immediately.

Nanofiltration Facility

Completed in early 2012, the Nanofiltration Facility at the North Water Treatment Plant on Osprey Street, was a major construction step for SMRU, the last piece of equipment needed to complete the northern water quality improvement plan.  Nanofiltration is a special filter processing technology very much like reverse osmosis with its series of filters which remove the hardness, color and various minerals from the water and enhance the water quality to your tap. 

Prior to the nanofiltration system coming on-line, raw water from 7 surficial or shallow wells was treated through chlorination and the addition of ammonia and a corrosion inhibitor.  Following this chemical injection, the water flowed through a static mixer and into the twin, 500,000 gallon storage tanks, prior to customer distribution by high service pumps.

The new nano system is a “side-stream” operation, meaning that it takes a portion of the flow from the wells just upstream of the existing chemical addition, provides membrane treatment and then blends the membrane permeate with the raw water, just upstream of the chemical addition station, prior to flowing to the ground storage tanks, ready for distribution.  The finished water in the ground water storage tanks is a 50/50 blend of the membrane permeate plus the chemically dosed raw water, to arrive at finished water on an equal par with that leaving the South Plant.

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