Follow the Liter: Tampa Bay’s Foray into Desalination

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Follow the Liter:
Tampa Bay’s Foray into Desalination

By Shawn Reynolds




“Water, water, every where, nor any drop to drink,” laments Samuel Taylor Coleridge in The Rime of the Ancient Mariner. “More than ninety-seven percent of the water on Earth is saltwater” (Swichtenberg, 2003). Sadly, this enormous resource is not potable. If ingested, our cells urgently endeavor to equalize our system. They release fresh water to dilute the salts, which subsequently forces the body into a state of dehydration. Cells then transport the salt to the kidneys. The salt overcomes the kidneys, the kidneys shut down, and then we die. With fresh water stores dwindling worldwide, the Earth’s vast oceans seem our most likely targets. We need only figure out a viable means of harnessing them. How then might we derive fresh water from the sea? The solution is desalination. But what is desalination?
The obvious definition is the removal of salts from a solution or compound. A more focused explanation, for the sake of this essay, pertains to the removal of salts from the world’s most abundant resource - seawater. There are two commercial techniques for seawater desalination: the membrane process and the thermal process. The first utilizes various forms of osmosis; the second relies on an assortment of phase-change processes, such as distillation (Hamdan, Zarei, Chianelli, & Gardner, 2008).
Reverse osmosis (RO) forces seawater through a semipermeable membrane. This permits fresh water to pass through and traps the salts on one side. Thermal procedures separate fresh water from saltwater through the evaporation of water out of a solution. One then collects the distillate for consumption, irrigation, and other uses. (Hamdan, Zarei, Chianelli, & Gardner, 2008).


A Brief History of Reverse Osmosis
Since the early 1900s, scientists sought the utilization of a membrane with which to divide salt from seawater. They base this concept on the “osmotic nature” of cell walls, which asserts, “certain semipermeable membranes, such as animal and plant cell walls, allow water to pass through, creating an equilibrium between a highly concentrated solution on one side of the membrane and a diluted concentration on the other.” Scientists postulate that sufficient pressure against the proper membrane will reverse this process, thus leaving a higher concentration of dissolved solids on one side (Graber 2006).
In the 1960s, industrial researchers realize that membranes they have created might well be suited for desalination (Graber 2006). In order to do such, these units remove very minute particles - in the Angstrom range - with a molecular weight in excess of two hundred (Hafez, Khedr, & Gadallah, 2007). By the 1970s, developers put these membranes to use in the first desalination plants of this kind (Graber 2006).
Originally, the high costs associated with the massive amounts of energy necessary for desalination processes were a huge factor in the consideration of a plant. As technology progresses, advancements greatly reduce the amount of energy essential to the process. In fact, over the last three decades, the requisite energy for desalination decreases by nearly seventy-five percent (Graber, 2006). The years between 1994 and 2004 witness the total volume of worldwide seawater desalination increase from 17.3 to 35.6 million cubic meters per day. Current desalination efforts generate one percent of the world’s drinking water (Yermiyahu, Tal, Ben-Gal, Bar-Tal, Tarchitzky, & Lahav, 2007).
In late 2005, Israel opens the world’s largest RO desalination facility. This plant churns out one hundred million cubic meters of fresh water per year. An ideal example of the advances in technology, this is the first time any desalination facility has produced potable water for less than fifty-five cents per cubic meter (Yermiyahu et al, 2007). Juan Maria Galtes, director of special projects for Inima, a Spanish corporation that specializes in desalination, emphasizes, “We are very close to the minimum energy for desalination. There’s a point where it’s impossible to go any further” (Graber, 2006).
New Technologies
There are a couple technologies on the horizon worthy of mention. In one example, the University of Florida’s John Klausner pushes saltwater through a heat source into a diffusion tower where it mists down into an upward surge of warm air and evaporates. It then blows into a condenser that extracts the fresh water (Jennings, 2005).
In another, Yale University’s Menachem Elimelech has a new approach he calls forward osmosis desalination. Where reverse osmosis uses high pressure to force seawater through a semipermeable membrane and this pressure fights the predisposition of the fresh water to dilute the salt. Forward osmosis has fresh water act as the higher concentrate through the addition of NH3 and CO2. Water now flows from the saltwater solution to the higher-concentrate “draw solution.” Elimelech then heats the draw solution to evaporate NH3 and CO2 to obtain fresh water – no pressure necessary. The only obstacle in the way is the development of a membrane that will consistently remove ninety-nine percent of the salts. Elimelech’s current membrane removes only about ninety-five percent (Patel-Predd, 2006).


Why desalination?
According to the United Nations, one third of the world’s population exists in areas lacking ample fresh water. Projections suggest this number will increase to sixty percent by the year 2025 (Patel-Predd, 2006). The decade between 1993 and 2003 ushers in drastic reductions in the costs of maintaining and operating a desalination plant. In 2003, the United States Desalination Coalition looks to Congress for legislation that will provide incentives and grant money for the evolution and improvement of desalination treatment facilities. (Swichtenberg, 2003).
Florida feels the pain. Not since 1895 has the Sunshine State suffered such a drought (Arrandale, 2007). The preponderance of evidence suggests the time is at hand to devise drought-proof water sources. The Tampa Bay region has been relying on groundwater from the Florida Aquifer for too many years. The demand on the dozen well fields, in 2001, was two hundred and forty-seven million gallons-per-day. Nature has been able to meet these demands sufficiently until recent indicators of stress surfaced (Brown, 2001). Florida typically receives between fifty-two and fifty-four inches of rainfall per year. The period between 1988 and 1994 saw precipitation dip to the thirties and forties. Swift population elevations compound the strain on regional stores. This six-year drought forces many outside entities to take notice, among them, developers, agricultural interests, the Florida Department of Environmental Protection, and the Southwest Florida Water Management District (SFWMD) (Wright, 2002). Tampa Bay Water (TBW), the supplier of fresh water for 2.4 million residents, with the help of Hillsborough, Pinellas, and Pasco counties and the cities of Tampa, St. Petersburg, and New Port Richey, is desperate for an answer (“Tampa Bay seawater,” 2008; Arrandale, 2007; Wright, 2002). TBW executive director Jerry Maxwell suggests there are “four D’s” that control the region’s water strategy: “drought, drainage, development, and drawdown.” Though nearly impossible for TBW to control the first three, “We can,” Maxwell offers, “attack the drawdown” (Wright, 2002). The consortium recognizes two necessary solutions: first, increase the capacity to maintain pace with the demand; second, lower the region’s dependence on ground sources. TBW immediately lowers the permitted groundwater pumping capacity from one hundred and ninety-two to one hundred and fifty-eight million gallons-per-day. That figure drops to one hundred and twenty-one million gallons-per-day by 2003 and to ninety million gallons-per-day by 2008 (Brown, 2001). “We had to do something,” Maxwell asserts, “We had over-permitted the system. We were extracting more groundwater than we could replenish” (Wright, 2002). Through this new “Master Water Plan,” TBW devises various methods to meet existing water demands while preserving groundwater stores. First, and most significant, the region will cull supplies from surface water sources - the Hillsborough River, the Alafia River, and the Tampa Bypass Canal. As a precautionary measure, TBW monitors flows at each location to insure they sustain downstream estuaries without harm (Brown, 2001). A sixty-six million gallon-per-day surface water plant comes online in September of 2002 for the processing of this surface water (Wright, 2002).
Back in October of 1996, the forerunner to TBW, the West Coast Regional Water Supply Authority, set in motion a visionary plan for Tampa Bay’s future. Requests went out for proposals for the construction of a desalination plant (“Tampa Bay seawater,” 2008). The employment of such a facility eases the stress on groundwater stores as well as to area rivers (“Applause,” 2007). “Without the plant’s twenty-five million gallons a day,” says Maxwell, “Tampa Bay Water will be hard-pressed to meet wellfield withdrawal reductions in 2008 required by Swiftmud” (Johnson, 2006a). In August of that same year, contractors begin work on an eleven hundred acre reservoir capable of storing fifteen billion gallons of water. This basin connects to the desalination plant via seventy miles of large transmission pipelines (Wright, 2002).
So why, then, is desalination necessary? In Tampa Bay’s case, at least, there exist few other options. With the rate of growth as it is and the current strain on groundwater sources, action is essential.
Desalination Around the World
More than 15,000 desalination plants - most in the Middle East - operate worldwide today (Graber 2006). Until quite recently, the process was rife with inefficiency, prohibitive costs, and frequent breakdowns. Initial facilities employed a distillation system. This setup is cost prohibitive for most environments given the need to generate an enormous amount of heat to enable vast quantities of seawater to boil. (Jennings, 2005). The first such facility churned out fresh water in Saudi Arabia in 1938 (Arrandale, 2007). In the 1950s and 1960s, the first significant desalination facilities came to life in desert regions primarily in the Middle East. Though these locales are devoid of water, most do possess access to substantial quantities of fuel for heating the water (Graber 2006). As of October 2003, twenty-seven desalination plants exist in Saudi Arabia that supply the country with twelve million cubic meters of fresh water daily; this is seventy percent of the nation’s drinking water. The United Arab Republic manufactures five and a half million cubic meters and Kuwait approximately three million (Ayres, 2003).
 
In 1964, on the island of Lanzarote in the Canary Islands, Spain asserts itself as the first European country to build and operate a desalination plant. Since then, Spain has become a force in the industry. The country currently produces enough water daily for eight million people and is now the fourth-largest user of this technology behind Saudi Arabia, the United Arab Emirates, and Kuwait (Graber, 2006).
Carboneras, Spain hosts Europe’s most massive seawater desalination plant. A major player in desalination, Spain’s nearly forty years in the field dominate in both construction and operation. Spanish companies now comprise the bulk of the competition “on the international market for the design, engineering, construction, and operation of new desalination plants around the world” (Graber, 2006). Spain’s own Priseda is jointly responsible for the remediation and operation of Tampa Bay’s desalination facility (Graber, 2006).
Fresh Water for Tampa
The increased efficiency of desalination and dire groundwater situation affecting the Tampa Bay region presses authorities to seek ways to augment available clean water sources. As mentioned earlier, TBW, Florida’s largest wholesale water supplier, took steps in 1996 to construct what would become the largest desalination plant in the United States. The project receives full approval from TBW in July of 1999 (Economist, 1999). Originally quoted at one hundred and ten million dollars, the plant is the product of four years of planning and eighteen months of construction (Swichtenberg, 2003). Infrastructure project management corporation, Poseidon Resources and large engineering firm, Stone & Webster Engineering Corporation, are charged with the joint construction of America’s largest desalination plant. Stone & Webster actually defers responsibility to their subsidiary, S&W Water LLC (Beebe, 2000). “S&W Water’s development team,” says Tampa Bay Water’s project manager, Don Lindeman, “will design, build, own and operate the desalinization facility and Tampa Bay Water will have the option to purchase it at a later date. Basically, we are taking the technical risks and transferring them to the developer and away from Tampa Bay Water” (Beebe, 2000).
S&W Water’s Best and Final Offer cites a twenty-five million gallons-per-day wholesale cost of one dollar and seventy-one cents per one thousand gallons for the first year of operation (Beebe, 2000). The plant is to operate under a thirty-year contract at an average cost of two dollars and eight cents per one thousand gallons. This price nearly matches that of treated wastewater. The outlay is mere pennies more than that of water the region culls from wells. Moreover, it lacks the deleterious effects to the environment associated with the unbridled pumping of the water table (Economist, 1999).
Developers employ various methods to defray costs. The desalination plant is adjacent to Tampa Electric Company’s (TECO) existing Big Bend Power Station. This relationship provides low-priced electricity and reduces the disposal costs. The power station draws and emits 1.4 billion gallons of water per day for cooling purposes. The concentrated brine discharge from the desalination plant easily dilutes into the power facilities warm discharge then flows out into the tepid waters of Tampa Bay. Local bay waters are less salty than the neighboring Gulf of Mexico; this lessens the effects of hypersaline effluent. These conditions make possible the use of reverse osmosis instead of the more expensive distillation process employed in earlier seawater desalination plants (Economist, 1999).
The SWFWMD has committed to funding up to ninety percent of the plant’s eligible costs. This might lower the cost of desalinated water by sixty cents per thousand gallons, thus making this a very economical water solution for the region (Beebe, 2000).
The desalinated water will travel through adjacent filter basins and fourteen miles of forty-two-inch-diameter pipeline to regional facilities. There it is blended with other water sources and sent to consumers (Beebe, 2000).
In the year 2000, the first of many calamities befalls the desalination plant at Big Bend. Engineering firm Stone & Webster goes bankrupt (Landers, 2004). Poseidon Resources Corporation opts for replacement company, Covanta Water, to “design, build, and operate” the plant for the original thirty-year terms (Design-Build, 2001). Construction on the plant begins in August of 2001. Sadly, the next predicament looms just around the corner.
Covanta and Poseidon are unable to access stable financing (Landers, 2004). In December of 2001, with construction already underway, TBW moves one hundred and ten million dollars to private activity bonds for the finance of the plant and assumes Poseidon’s interest in the project (Landers, 2004; Design-Build, 2001).
After four months of clear skies, the next wrinkle develops in the saga.
On April 1, 2002, Covanta Energy, Covanta’s parent company, files for bankruptcy protection (“Company News,” 2002; Landers, 2004). Undaunted, Covanta proceeds with the first performance test in May 2002. Problems abound. Cartridge filters designed to last three months necessitate change after five days. Membrane filters in the reverse osmosis phase foul much sooner than expected. Tampa Bay Water project manager Ken Hurd laments, “There are about ten thousand cartridges in the plant. At ten dollars a cartridge, changing them every five days gets pretty expensive” (Wright, 2003a). The original date for full production of January 2003 comes and goes (Landers, 2004). Months pass as teams try desperately to remedy the filtration issues. Finally, on March 16, 2003, the first three million gallons of water gush from the plant with the expectation of twenty-five per day by mid-April (Swichtenberg, 2003).
The only thing constant is change, and change the plans did. In April, a split pipeline forces yet another shut down (Landers, 2004). One month later, in May, Covanta undergoes another critical fourteen-day acceptance trial. Although they meet the agreed upon flow levels, TBW produces a list of thirty-one paucities in the system. Most concerns surround flaws in the facility’s pretreatment process. Per TBW’s estimations, cartridge filters positioned after the dual sand filtration system and before the reverse osmosis membranes are still fouling too rapidly (Landers, 2004). Covanta, beset with such consistency problems, agrees to an extension to resolve the list of deficiencies by September 30, 2003. Numerous attempts at mechanical adjustments offer little hope. The membranes and cartridges continue to disappoint. On September 30, 2003, Covanta fails yet another fourteen-day acceptance test (Landers, 2004; Wright, 2003a).
Workers isolate the problems. The agglomeration of sand in the filters allows raw water to bypass the system. This causes “biological-bacterial” membrane fouling which drops production to sixteen million gallons-per-day (Wright, 2003a). Covanta employs a chemical wash to sanitize the membranes. This would inundate the sewage treatment facility with one hundred gallons of contaminated water per minute. TBW says no. The permit does not allow for that amount of discharge in that small a period. Tempers flare. Teeth gnash. Kent Burton of Covanta’s Washington D.C. branch argues that TBW only procured permits for ten gallons per minute. Kent Hurd responds that the acquisition of the permit was based on sequential cleaning of the membranes, not concurrent (Wright, 2003a).
Meanwhile, millions of gallons of “spent solution” Covanta uses in the cleaning of the RO membranes accumulate. In excess of one hundred tankers, each filled to its twenty-thousand gallon capacity, sit on the project site. The ultimate disposal costs Covanta almost one million dollars and ties them up for three months. This distraction, Covanta argues, contributes to the failure of their evaluation on September 30 (Landers, 2004). The argument is irrelevant. Covanta already owes the equivalent of nearly five hundred thousand dollars in damages; TBW must receive three hundred and six million gallons of water at no charge. Covanta must also successfully complete another round of analyses by November 18, 2003, lest they shoulder one and a half million dollars in fines (Wright, 2003a).
Covanta, as a stipulation of the agreement with TBW, needs to execute a battery of tests including the production of seven days of drinking water at 28.75 million gallons-per-day and seven days at twenty five million gallons-per-day. On October 1, 2003, Covanta again fails to meet the fourteen-day performance test deadline; TBW issues a default notice (Wright, 2003a). Covanta now has forty-eight days to right the ship, lest TBW terminate the agreement (Landers, 2004). Unbeknownst to TBW, Covanta has an angle.
On October 29, 2003, Covanta Tampa Construction Inc. files for Chapter Eleven bankruptcy. This filing temporarily averts the termination of the contract with TBW (“Contractor,” 2003). Covanta seeks this stay of execution given the attached operation and management (O&M) contract it will lose valued between three hundred and three hundred and sixty million dollars over thirty years (Wright, 2003b). The very next day, TBW’s general manager, issues a press release in which he asserts Covanta’s action as a “betrayal of the public trust that simply delays fixing and operating the plant (Landers, 2004).
Again, fingers wag in both directions. Covanta claims TBW procured insufficient discharge permits. Covanta wants compensation for time and expenses associated with the disposal of the solution. TBW maintains that the project design is Covanta’s responsibility and that Covanta should conform to any associated permit stipulations. TBW cites failures in the silt density test that indicate consistent underperformance (Landers, 2004). TBW plans a request to the court to lift the stay so it might find a provisional operator to get the plant up and running. Three suitors loom: Ionics Inc., U.S. Filter Inc., and American Water Works Co. (“Contractor,” 2003).
 
In November, 2003, a judge forces Covanta and TBW to procure a third party to hash out their dispute (Wright, 2003b). The meeting is set for January 22 and 23, 2004 (Wright, 2004).
In December 2003, Hydranautics Inc, the manufacturer of the plant’s RO membranes, issues a letter to TBW that asserts the facility is operating outside design specifications and that, consequently, their warranty is void. Covanta executive vice president, Scott Whitney, maintains, per the engineers at Hydranautics, they are “operating the membranes within the design parameters of the scope book appended to the contract.” TBW asks Covanta to cease activities at the plant and to produce the preceding thirty days of data for each of the seven RO membrane trains (Wright, 2004).
In January of 2004, mediation sessions take place. The board of directors for TBW endorses a settlement that pays Covanta Tampa Construction 4.4 million dollars. In exchange, Covanta agrees to forego any claims and ditch plans to retain the O&M contract (“Tampa Bay settles,” 2004).
With a new focus on pretreatment, the bidding begins for Covanta’s replacement. Ionics Inc. drops out of the race, which leaves American Water Services/Pridesa (AW-Pridesa), a joint venture between New Jersey’s American Water Services and Spain’s Pridesa S.A., and former USFilter, Veolia Water North America (Veolia) (Wright, A.G., 2004). TBW opens competition between AW-Pridesa and Veolia for a long-term contract to mend and operate the desalination plant. With tests to begin in June, TBW charges the teams with running two “pilot plants” each through the summer of 2004. The teams make use of different methods in the fix. AW-Pridesa employs a “precoated, diatomaceous earth filter and Hydranautics’ submerged, HydraSub filtration membrane” (“Pilot plants,” 2004). Veolia swaps out stage two’s dual-sand filters with an ultrafiltration submerged membrane from Zenon. Veolia also places “USFilter’s Actiflo ballasted clarification process” prior to the dual sand filters” (“Pilot plants,” 2004). Ron Maness, Veolila’s North America desalination director argues no matter who wins, “Somebody needs to get in there and fix that plant. The road to the future of desal in the U.S. leads through Tampa” (Wright, A.G., 2004).
Prior to its dismissal, Covanta’s estimate to bring the plant online came in around fourteen million dollars. On August 5, 2004, TBW publishes both new teams’ cost projections. AW-Pridesa suggests a figure of twenty eight million dollars, Veolia’s is fifty million (Wright, A.G., 2004). In August, TBW selects a victor. Based on price, technological expertise, and, well, price, on November 15, 2004 TBW goes public with AW-Pridesa as the caretaker of this project (Wright, A.G., 2004). As far as TBW is concerned, Pridesa’s experience in the desalination industry, through the design and build of fifty plus desalination plants worldwide, speaks for itself (Landers, 2005).
Upon the completion of detailed negotiations, TBW and AW-Pridesa agree on a figure of twenty-nine million dollars. AW-Pridesa opts to swap out Hydranautics RO membranes for Dow membranes at a cost of around six million dollars. AW-Pridesa’s American desalination manager, Kent Turner, maintains, “It’s not a reflection on Hydranautics. Pridesa uses both in plants we’ve built in Spain. Our technical folks say that the Dow units work better in this particular plant” (Wright, A.G., 2004). If AW-Pridesa succeeds in the production of volume requirements, this corroboration carries with it an eighteen-year O&M deal, the first year of which is worth 5.3 million dollars. “We’re very excited and optimistic,” Hurd affirms, “about having a qualified contractor join our team” (Wright, A.G., 2004).
As far as modifications are concerned, the RO membrane swap is just the beginning. Additional alterations to the pretreatment phase, Herd avers, are “the most significant part of the fix. [They] will involve installing so-called precoat filtration to augment the existing sand filters, helping to extend the life of the facility’s valuable RO membranes (Landers, 2005). Proper pretreatment is crucial to the efficient and productive operation of such an endeavor. It is imperative that the facility cleans the water “to the highest level possible before it reaches the reverse osmosis membranes, the most important, expensive, and delicate part of the entire operation. The purer the water, the longer the membranes last and the more effective they remain” (Graber, 2006).
The contractor also seeks to convert the two-stage sand filtration system to a single-stage system (Wright, A.G., 2004). “Another key step,” Hurd offers, “involves converting the plant’s existing two-stage sand filtration system into a single-stage system, thereby doubling the number of first-stage sand filters. In this way, individual filters can operate at lower feed rates and achieve greater filtration efficiency” (Landers, 2005). This configuration will employ additional pipes and improved control of the distribution of seawater over the entire span of the cartridges (Wright, A.G., 2004).
Augmentations are also set for the facility’s intakes. AW-Pridesa adds variable frequency drives to sustain water temperature and stabilize water chemistry. Additional screening and chemical feed systems keep the lines free of debris and the accumulation of biological organisms such as the Asian green mussel (Landers, 2005). On the topic of mussels, Tampa Bay plays host to cargo ships from all over the world. Their cavernous ballasts contain water and organisms from faraway places. The vital capacity of one ship’s ballasts might reach ten million gallons. Inhaled at one port and exhaled in another, foreign waters teem with invasive species plant and animal alike. A study in 1996 projects the influx of unfamiliar water into Tampa Bay at one gallon per minute. The Asian green mussel of Indo-Pacific waters is one such hitchhiker (Parker, 2006). Unintentional stowaways, Asian green mussels arrive in Tampa in 1999 (Wilson, Coledan, Erwin, & Gourley, 2004). The introduction of this species proves a hardy foe. Per engineers, initial fouling in the pretreatment stage was the result of intake water temperature variations and “biofouling from Asian green mussels, bacteria, and algae” (Wright, A.G., 2004).
AW-Pridesa has until October of 2006 to bring the plant around. The addition of the firm puts the total cost of the plant at one hundred and forty million dollars (“Tampa Bay moves,” 2004). TBW releases a rate estimate of two dollars and fifty-four cents per one thousand gallons based on this new partnership. While a bit higher than the initial one dollar and seventy-one cents per one thousand gallons, the figure is still the lowest in the world for a facility of this magnitude prior to the opening of Israel’s plant in late 2005 (Landers, 2005).
In mid-2005, AW-Pridesa contracts engineering firm Hatch Mott MacDonald (HMM) to help with the design-build modifications and thus takes a huge step towards making the plant a reality. HMM is responsible for any structural, architectural, electrical, mechanical, and site-related designs of proposed amendments (Ehrenman, 2005).
HMM and AW-Pridesa have nearly two and a half million people pulling for them. “Unless the plan works as designed,” says Jerry Maxwell, “the Southwest Florida Water Management District will not pay eighty five million dollars it pledged to defray construction costs in return for reduced pumping at wellfields. That money would reduce what residents pay for their water bills” (Johnson, 2006b).
In what seems to be a rare helping of good news, on April 4, 2007, TBW announces that the problems at the desalination plant at Apollo Beach are but a memory (Scott, 2007). In November 2007, the plant completes its two-week acceptance test, meeting the requisite twenty-five million gallons per day for seven days as well as the maximum capacity of twenty-eight and three quarter million gallons per day for seven days (“Troubled,” 2007). With the success of this test comes a reward: AW-Pridesa collects the final three million dollar payment of its twenty-nine million dollar contract (Van Sickler, 2007).
Though the plant was offline for a few months, in the just under ten months of 2007 it did run, the facility produced three billion gallons of water. “What this means,” says Pinellas County Commissioner Susan Latvala, “is we have a large supply of water that’s drought proof” (Van Sickler, 2007). American Water’s Kent Turner gushes, “Way back in 2004, I promised you a world-class facility. We’ve done that” (Van Sickler, 2007).
 
At one-hundred and fifty eight million dollars, the project is forty million dollars over budget. On the plus side, it is now an example on which other potential endeavors might model themselves. “We’ve already had folks from coastal areas in California, Texas, and other parts of Florida look at the plant” (“Drought-proof,” 2008). Current cost estimates rest at three dollars and thirty-eight cents per one thousand gallons, nearly twice the original estimates in 1999. Once Swiftmud puts forward its endowment, the rate drops to three dollars and four cents per thousand gallons (Green, 2008a).
In early February 2008, TBW’s general manager Jerry Maxwell retires. He submits a letter to the people of Tampa Bay via the Tampa Tribune. In his address, Maxwell cites the many obstacles overcome on this journey. “When I came to Tampa Bay Water’s predecessor in 1995, the region was in the midst of the ‘water wars.’ Local governments were at odds with each other and regulators over water supply. Population growth had outpaced the development of new water supplies and increasing demands on the region’s groundwater supply strained the environment…We now have a diverse, interconnected supply of water. Groundwater pumping has been reduced more than twenty-nine percent since 2000” (Maxwell, 2008).
Hot on the heels of Maxwell’s grand farewell, more bad news arrives. In the past four months, the plant violates the sewer dump permit three times (Salinero, 2008). Hillsborough County officials cite cleaning fluids the facility employs on the RO membranes as the cause. While the amount does not exceed the daily allotment, it does surpass the gallons per minute agreement. Representatives of the desal plant emphasize that these violations occurred during the repair process and that they are attributed to operator error and a defective flow meter. They vow to automate the system and replace the necessary items (Pittman, 2008). Assuming that no news is good news, Tampa Bay residents should hope this is the last they hear of the desalination plant until AW-Pridesa’s contract expires in eighteen years.
Effluent and the Environment
When the topic of desalination arrives, disquiet surfaces surrounding associated energy consumption and disposed waste. The general scientific opinion espouses that the latter of the two is not of much concern. “Despite extensive research,” Technology Review’s Cynthia Graber asserts, “there has not been a documented case of serious deleterious effect resulting from the disposal of brine” (2006). “Many people think,” offers Corrado Sommariva, president of the European Desalination Society and divisional director of Mott Macdonald, “that desalination has sort of bad impact on the environment. This is exactly the contrary” (Graber, 2006). Though most evidence points to this, long-term applications are the true test.
It takes one and a half to two and a half cubic meters of seawater to produce one cubic meter of fresh. The primary effluent is a super saline, negatively buoyant stream known as concentrate, brine stream, or brine-blowdown. The total dissolved solids (TDS) in this expulsion are one hundred and fifty to two hundred and fifty percent higher than the seawater into which they flow (Jirke, 2008; Alameddine & El-Fadel, 2007; Voutchkov, 2007).
Numerous methods exist through which the concentrate may be disposed. First, one can dispose of the brine directly into a wastewater plant. Second, one may do so through deep-well injection, which must be well below existing drinking water sources. Third, a facility can employ a submarine ocean outfall, a pipe that emits the concentrate directly into the sea. Alternatively, as in Tampa Bay’s model, the plant may coexist with an existing power facility and blend the brine into vast quantities of cooling water before flushing them into an adjoining waterway (Hamdan, Zarei, Chianelli, & Gardner, 2008).
“As large desalination plants are located by the shoreline, it is commonly accepted that the brine waste stream being discharged into the sea will ultimately be dispersed” (Al-Barwani & Purnama, 2007). The term “ultimately” is so vague.
There are several dilemmas associated with disposal. One issue with the dumping of concentrate directly into a body of water is the oscillatory nature of coastal currents. These currents carry expelled brine plumes back and forth, saturating the coastal area around the outfall with a very high concentration of salt up to twenty-five kilometers downstream (Purnama & Al-Barwani, 2006). “Within two tidal periods after being discharged, the plume may have returned to the outfall three times before eventually leaving. If brine waste stream is continuously discharged at a constant rate, then the coastal water which is close to the outfall at the time of flow reversal, where the flow speed drops to zero and there is no dispersion, will be carrying an undesirably high salinity” (Al-Barwani & Purnama, 2008). This aggravates existing issues with saltwater intrusion into the aquifer. (Purnama & Al-Barwani, 2006). The mixing of brine plumes is also sensitive to seabed depth. Shallow water creates an environment of higher salinity. We attribute this to currents that are much weaker in contrast with those in deeper waters. Moreover, the depth itself allows for a greater vertical area in which to disperse the stream (Al-Barwani & Purnama, 2007).
A 2007 Arabian Gulf study on brine discharge modeling offers three outfall position strategies: surface discharge via a channel within the inter-tidal zone of the bay (as in Tampa), single-port submerged, and multi-port diffuser. Results signify that the surface discharge example “fails to achieve the required dilution rates within a mixing zone of three hundred meters under [typical] conditions…The low dilution rates are due to the dynamic attachment of the plume to the downstream bank resulting in the formation of a zone in which the effluent undergoes recirculation” (Alameddine & El-Fadel, 2007). Since this bay in the Arabian Gulf is shallow, the brine plume affixes itself to the bottom, inhibits current, and thus reduces the likelihood of dilution. The single-port submerged option shows significant elevations in dilution rates, but also fails to meet established standards within the three hundred meter mixing zone. The most successful option is the multi-port diffuser. This choice attains the required dilution rates and, subsequently, minimizes the possibility for environmental harm (Alameddine & El-Fadel, 2007). One then can deduce that great care is essential in the design of an outfall. It must provide for the most rapid mixing possible. These structures should also avoid lagoons, with inter-tidal areas there is limited circulation and weak flushing. Another consideration in the design of an outfall is the gradual slope of the seabed. The pipe has to be of significant length if it is to reach the USEPA mandated depth of ten meters (Alameddine & El-Fadel, 2007).
Comprised of the one thousand foot sector that surrounds the outfall, the point from which the effluent spews into the sea is the zone of initial dilution (ZID). In this zone, salinity must achieve a level that local marine life can safely tolerate. There is one example in which discharged brine has affected local organisms. Between one and two hundred meters from the Dhkelia RO plant in Cyprus, researchers note the influence of the plant on littoral flora and fauna (Alameddine & El-Fadel, 2007). “Brine usually contains corrosion products, halogenated organic compounds, and a combination of anti-scaling/fouling/foaming/corrosion additives” (Alameddine & El-Fadel, 2007). The addition of these contaminants to the environment threatens to degrade its physical, chemical, and biological attributes. Just how much degradation occurs depends on the total volume of brine released, the character of the brine, the pre-discharge dilution rate, and the aspects of the receiving body of water. The location of the outfall also greatly affects environmental impact (Alameddine & El-Fadel, 2007).
The Arabian Gulf shares similarities with Tampa Bay. It is closed and shallow. Alameddine and El-Fadel’s study of outfall designs suggests, “the restricted hydraulic circulatory currents hinder the mixing and dilution processes and may result in the recirculation of the discharged pollutants. This situation is especially exacerbated at the plant site due to the shallowness of its area within the bay and characterized with more limited circulation patterns…” (2007).
As is the case in Tampa Bay, many desal plants are now built in conjunction with a coastal power plant. This negates the need for the permitting and building of separate ocean intake and outfall pipes. Additionally, this configuration takes advantage of the massive amounts of a power facility’s cooling water output. The higher temperature water passes through the membrane much easier, requiring less energy than if the facility draws water directly from the sea. Prior to discharge, the facility mixes the brine stream with the massive cooling water release of the power plant, thus lower the salinity of the main output (Pittman, 2008; Voutchkov, 2007).


The facility in Tampa Bay dilutes the brine with up to 1.4 billion gallons of cooling water before it releases the runoff into the bay. Studies show no measurable salinity variance in Tampa Bay as a result of the desal plant (“Drought-proof, 2008).
In addition to keeping costs low, the joint Big Bend location allows the brine discharge to mix with the warm effluent of the power plant, and thus thins out the concentration prior to reintroducing it to the bay (Landers, 2004). This blended discharge “is environmentally safe, as indicated by chronic and acute whole effluent toxicity testing of a blend of demonstration plant concentrate and power plant cooling water in a ratio corresponding to full-scale, worst-case discharge conditions” (Voutchkov, 2005).
“In the rest of the world,” Maxwell declares, “they don’t have as high or as strict of standards as it relates to the environment as we do here in the U.S., so working in a real natural, sensitive ecosystem meant that we had a very high bar to clear in terms of environmental stewardship” (“Nation’s first,” 2008). The plant’s permit allows for the release of sulfuric acid and other cleaning agents. Former member of Save Our Bays, Air and Canals (SOBAC), Jeanette Doyle, points out, “It’s unconscionable to have this desal effluent enter the Bay’s waters without monitoring” (Salinero, 2007a). In late 2007, Hillsborough County places monitoring stations near Apollo Beach to observe if significant impacts exist as a result of discharge from the plant. The county Environmental Protection Commission examines overall water quality, while TBW looks at that directly discharged from the plant, which they must report to state and local officials (Green, 2008; Salinero, 2007a). SOBAC’s Dominick Gebbia expresses concerns over low dissolved oxygen levels near TECO’s big Bend power plant and suggests it will be years before we can detect any environmental effects (Green, 2008b; Salinero, 2007a).
In February of 2008, researchers begin the installation of three monitors for the observance of temperature, salinity, and oxygen – one at TECO’s Big Bend discharge canal, one at the intake, and one just north of Apollo Beach (Green, 2008b).
Determining salinity tolerance
One method through which to reveal the effects on marine species is the testing of various species’ limits. The maximum concentration of total dissolved solids (TDS) marine life in the ZID can tolerate is the salinity tolerance threshold. The “whole effluent toxicity” (WET) test exposes marine organisms to a wide range of salinities in order to assess survival rates. The WET test establishes the maximum concentration aquatic flora and fauna can endure without perishing. The salinity tolerance test assesses whether certain species can survive the hyper-saline environment amid the ZID and on its fringe (Voutchkov, 2007).
Recent salinity tolerance test results from the site of Carlsbad’s future desal plant are promising. Estimates place the initial brine stream at sixty-eight parts per million, which is about twice the salinity of the ocean from which it is derived. They then blend the stream with a sample representative of that from the cooling water outfall to simulate conditions between thirty-five and forty parts per million. After five and a half months of tests, there were no deaths. More encouraging, all organisms remain healthy, with no discoloration or irregularities (Voutchkov, 2007).
The Fish Test
An additional method to monitor the effects of a desal plant on the environment is the aquarium test. Scientists select various indigenous organisms for study, many of which are of some economic or recreational fishing significance. They fill the aquarium with a sample of water representative of that leaving the plant’s discharge lines mixed with that of the surrounding area. In one such analysis based on a plant in Encina, California, “the marine species have adapted seamlessly and, after more than nine months of continuous exposure to the elevated salinity concentration, are healthy and tolerate the new discharge conditions” (Voutchkov, 2005).
Conclusion
Environmentalists may see the propagation of this technology as bittersweet. As mentioned, many desalination plants work in tandem with a power generator or wastewater facility. Japan currently builds desalination centers in conjunction with nuclear power plants, which also require large quantities of water for cooling (Ayres, 2003). There will come a time when environmentalists will have to choose a side. Is nuclear energy cleaner than other methods? Opinions vary. Has nuclear technology met the safety concerns of the public? It depends on whom you ask. The addition of infinite, affordable water to a community in need will weigh heavily on the minds of both positions. The dearth of alternative energy and clean water solutions coupled with a global population increase forces a long, hard look at these systems. Plans exist to derive freshwater from saltwater employing no fossil fuels or nuclear energy. Scientists look to solar and wind power for answers. These methods, however, are not without issue. The intermittent nature of solar and wind power, coupled with the imminent disposal of batteries required for energy storage after five to ten years is a huge drawback (Graber, 2006). I argue that nuclear power and desalination is the future. I believe nuclear power to be a viable, safe solution to sustain growing populations. If a population’s power and fresh water needs can be met through the construction of a joint facility that emits only steam, brine, and the occasional radioactive concrete block, is that not more responsible than burning fossil fuels and tapping depleted groundwater stores? The answer seems obvious to me.
 
Not bad but I have to say it's been a long time since I've read a paper written with that citation. As a historian if I'm not beseeched by endnotes or footnotes I feel like I'm lost in a psychological abstract. That's a true nightmare for me. :eek:
 
I thought Wikipedia wasn't often allowed as a creditable source due to the way the information can be added. You may want to cite the source Wikipedia used.
 
A: props on the clever title

2: hippies who bitch about nuclear energy piss me off. it's safe, reliable, extremely fucking efficient and the damn FRENCH of all people use it for three quarters of their energy production. it would pretty much end our dependence on foreign oil, cut our immediate CO2 contribution in half and there is no reason the goddamn frogs should be ahead of us in anything for christ's sake