how the plant works (continued)
post-treatment, blending and delivery
After the RO process, chemicals are added to stabilize the desalinated seawater. The high-quality water is delivered to Tampa Bay Water’s regional facilities site where it is blended with treated drinking water from other supply sources before being delivered to Tampa Bay Water’s members.
concentrate return
At full capacity, the RO process leaves about 19 mgd of twice-as-salty seawater behind which is returned to Big Bend’s cooling water stream and blended with up to 1.4 billion gallons of cooling water, achieving a blending ratio of up to 70-to-1. At this point before entering and mixing with any bay water, the salinity is already only 1.0 to 1.5 percent higher, on average, than water from Tampa Bay. This slight increase falls within Tampa Bay’s normal, seasonal fluctuations in salinity.
The cooling water mixture moves through a discharge canal, blending with more seawater, diluting the discharge even further. By the time the discharged water reaches Tampa Bay, its salinity is nearly the same as the Bay’s. And, the large volume of water that naturally flows in and out of Tampa Bay near Big Bend provides more dilution, preventing any long-term build-up of salinity in the bay.