South Water Treatment Plant

South Water Treatment Plant (SWTP)

The SWTP has a permitted capacity of 6.0 mgd of potable water. To produce 6.0 mgd of raw water, the plant needs between 8 to 8.2 mgd of raw water from the 18 brackish water wells on Marco Island. Brackish water is rough filtered to remove sand and treated with a scale inhibitor and sulfuric acid to reduce the pH.  The raw water then goes through six (6) polishing filters to remove very fine materials and is then pumped to a high pressure pump and sent to one (or all) of the six (6) dual stage reverse osmosis membrane trains. The reject water is pumped to the City's treatment facilities located on Elkcam Circle for injection into the City's deep injection  wells (3,200 ft). The permeate from the membranes is treated with sodium hypochlorite and ammonia to form chloramines and then contacted with air in one of two (2) degasifiers to remove hydrogen sulfide. The water is then sent to the storage tanks and the off-gas from the degasifiers goes to a scrubber to remove the hydrogen sulfide from the air before it is vented into the atmosphere.