Sea World’s salt water reveals an unlikely alliance between chlorine and bromine.   

Sea World, San Diego, uses salt water, and plenty of it.

           They don’t manufacture their salt water; it’s pumped out of Mission Bay at a rate of 100,000 gallons a day. Every day. That’s how much make-up the 7,000,000 gallon main system requires, a replacement equivalent of the entire system’s contents every ten weeks. 

            And they need it.  Shamu’s not shy, he (she?) lets breakfast go before lunch time, and dinner go all night.  These popular, playful mammals release thousands of pounds of processed food waste into the water at a rate that tops the organic load of the busiest, nastiest big-city pool you could ever imagine.  The operators use ozone, chlorine bleach, on-site hypochlorite generation, alum flocculation… and automation at every turn.  All this, orchestrated marvelously if not mysteriously by the Sea World’s skilled and experienced staff, to effectively treat the combined 38,000 gpm flow that turns the whole place over in just three hours! 

  
AMAZING FILTERS AND AMAZING PUMPS

            A recent consulting and training tour of Sea World revealed top-quality, state-of-the-art equipment and systems of immense proportions, grand examples of the planning and engineering arts. The photos below are only a hint of the behind-features technology engaged there 365 days a year.  “We were impressed” is the understatement of the season. 

            And there are features of this marvelous park that transcend great design, top-flite maintenance, and un-interrupted performance... If one is invited “behind the scenes” to inspect or just marvel at the equipment, she or he finds the backside flank of the fence as beautifully maintained as the touristy side of things.  Now we don’t just mean clean floors, freedom from clutter, slick paint and polish, and designed-in safety, we mean
landscaped as impeccably as the park’s attractions which lure visitors from all over the world.  C’mon, flowering shrubs surrounding filter fields, mowed grass or swept concrete dividing equipment buildings, decorative trees throughout as if the landscape architect subbed as a system operator?  Yep.  Is this exaggeration?  No, it’s kinda’ bragging.  Once someone’s worked with this group a day or two, he begins to be treated sort of like a member of the team.  And the pride rubs off. 

            Anyway, back to the water-chemistry stuff -- so unique to one who’s had to return to the world of everyday pools.  Probably the most interesting challenge, besides the immensity of it all, is the immediately obvious massive and unavoidable amines from the constant introduction of ammonia and complex organics. You’d think that, since the animals live full time in those tanks, superchlorination of the inevitable, dominating ammonia compounds simply can’t be safely performed.  Yes, the operators are between a rock and hard place, (and a false killer whale,) with what might seem like an un-solvable paradox.  But these guys, by isolation of animals, localized treatment, and techniques abbreviated below, manage to make it all work...

            Someone said that maintaining life support for aquatic mammals requires a cross between swimming-pool and wastewater-treatment technology. Every possible oxidizing influence needs to be brought to bear on the problem. Beautifully clear water, which is for the most part irritation free, is maintained at this park by much more than judicious chlorine use. The primary supplement is ozone. Massive treatment with ozone has been used at the park for years -- long before it became popular in swimming pools. Huge corona-discharge ozone generators, one system alone creating 68 pounds per day, are computer operated and monitored. They feed into contact and dissipation towers, in line, which are designed to maximize absorption, oxidation, then destruction of ozone. That should certainly help oxidize organics and minimize ammonia compounds. But there’s more.

            Sea water has a “secret ingredient” in it. Along with over 30,000 ppm salt and a few hundred ppm of almost everything else soluble on earth, it contains at least 60 ppm sodium bromide!  This means that any oxidizer added to sea water goes right to work making HOBr out of the bromide, just as it does in ozone-activated bromide swimming pools. Some or all of the oxidizer is consumed in this beneficial process.  In the case of ozone, virtually all is safely gone before the water returns to the tanks -- yet ozone has had time to do what it does best: oxidize organics.

            How about chlorine?  It is both fed as bleach and generated on site by a large brine electrolysis machine. According to dosage ratios and resident times involved, an unspecified mix of HOCl and HOBr initially develops, apparently presenting the best oxidizing and disinfecting characteristics of each.  With the help of the ozone and the incredible three-hour turnover, chloramines are virtually non-existent. Until the NaBr conversion to HOBr reaches some kind of completion or equilibrium, almost all of the sanitizer produced (and residual measured) is active bromine, giving chloramine and it’s unpleasant characteristics little opportunity to develop. Bromamines are surely developed in the body of the vessel at any point of ammonia introduction but remain, for the most part, both more useful and less offensive than the ammonia compounds of chlorine. Ozone will oxidize much of the bromamine on the trip through the circulation-loop contact tower, keeping it in check.

            So, when park operators measure the DPD residual in their mammal tanks, the color developed in the sample is created by total bromine, not free chlorine.  Actually, they don’t really care what causes the pink color -- they just know that the small target residuals, along with the ozone they’re applying almost constantly and other techniques developed over a lot of years of experience, gives them and their happy, healthy marine animals the results they want -- clear and non-offensive water.

            If you’re in San Diego, don’t miss Sea World. The show’s beyond great.  And you’ll leave with a healthy respect for the guys and gals behind the scenes that make it all work!  

                                  ~  kw