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Science

Desalination Plant Begins Operation in Tampa 45

Posted by Hemos from the you-gotta-start-me-up dept.
ambisinistral writes "The Tampa Tribune reports that the first commercial desalination plant in the U.S. is set to begin operations today. By March the plant is expected to be operating at full capacity, producing 25 million gallons of fresh water a day (10% of the water currently provided to the area from well fields). There are ecological concerns about returning highly saline water from the plant back into Tampa Bay. Proponents of desalination claim the natural tide cycle will effectively flush the bay of the saline rich discharge, while opponents of the plant feel the ecology of the bay will be badly damaged. Both sides plan on strict monitoring of the situation."
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Desalination Plant Begins Operation in Tampa More

Desalination Plant Begins Operation in Tampa

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  • Sounds like a great opportunity... (Score:3, Funny)

    by HotNeedleOfInquiry ( 598897 ) on Monday January 06, 2003 @01:34PM (#5026246)
    To raise vast quantities of sea monkeys in Tampa Bay.

  • Obligatory 'Top Secret' reference (Score:4, Funny)

    by Anonymous Coward on Monday January 06, 2003 @01:46PM (#5026335)
    Dr. Flammond:
    "A year ago, I was close to perfecting the first magnetic desalinization process. So revolutionary, it was capable of removing the salt of over 500 million gallons of sea water a day. Do you realize what that could mean to the starving nations of the earth."

    Nick:
    "Wow, they would have enough salt to last them forever."

    Top Secret! [imdb.com]

  • It's about time (Score:5, Insightful)

    by dschuetz ( 10924 ) <davidNO@SPAMdasnet.org> on Monday January 06, 2003 @01:51PM (#5026378)
    We in the US take water for granted. It's basically free -- cheaper than all other utilities, our water bill is about $15 a month, tops.

    Not only do we take it for granted, we tend to take it at the expense of the environment or others downstream. The Colorado River, for example, is only a trickle of a dried-up stream where it used to dump into the ocean, and many Mexican communities have been lost, all because people keep moving to LA and, well, needing water.

    We need to be much more aware of how we use water in this country, and most importantly, start looking for alternative sources whenever local demands start to affect the ecology or overall flow levels of major rivers.

    Desalinization is a great step -- but the next big step would be builidng the huge pipelines (or canals, which'd be much cheaper) to bring water from the coasts to interior cities (though, since most of the population, and thus, most of the worst of the water problems, are near the coast, this isn't as bad as it might be). (yes, I'm ignoring cyclical dust-bowl problems or interior water-starved cities like San Antonio).

    Of course, if this current effort flops, then it'll be much tougher to get other cities interested in the program.

    It'd be, obviously, preferable of they could use some kind of distillation system, rather than permeable membranes, to arrive at "pure" water with disposable solids (that might themselves be mineable for things like table salt or other chemicals). On the other hand, it might be possible to pipe the very salty "leftover" water back into the ocean, but through a wide-ranging diffusion network over several hundred square miles.

    At any rate, I really hope this works!

    • Re:It's about time (Score:2, Insightful)

      by Smidge204 ( 605297 )
      ...and many Mexican communities have been lost, all because people keep moving to LA... ...Like Mexicans ;)

      Not to understate the importance of desalinization, of course!

      The main problem here is energy. It takes a lot of energy to desalinate/purify water, which is not always practical to deliver when you want to supply towns or cities.

      A simple, smallish solar-powered distillation system, using heat from the sun to evaporate water, may be enough to supply one person's daily requirements. No moving parts, either. Cheap to build, easy to maintain, zero cost of operation. I think these types of systems would be better suited for those remote areas.
      =Smidge=

      • Re:It's about time (Score:4, Informative)

        by Smidge204 ( 605297 ) on Monday January 06, 2003 @02:37PM (#5026662) Journal
        I decided, as an afterthought, to run a quick calculation based on my last comment :)

        I've been told that the average person required about 2 liters of water (64-70 ounces) daily, as a healthy requirement. That's about 2kg worth.
        (More if you're a large guy, and/or do a lot of strenuous activity)

        Water has a latent heat of vap. of about 2300 joules per gram. So evaporating 2000 grams of water (Assuming it's already at boiling temp) would require 4.5 million joules.

        A very conservative estimate of solary energy would be 90 watts per square foot.

        Assuming you would want to distill at least a day's supply of water every day (10 hours), you would need about 1.5 sq. feet of collection area.

        A collector the size of a peice of plywood (32 sq. foot), under these operating assumptions, could provide over 40 liters of fresh water daily!

        This does not include cooling the vapor back into drinkable liquid. You could use the feedwater for that, which will help preheat the feedwater and improve output.

        =Smidge=

        • Re:It's about time (Score:3, Informative)

          by TheSHAD0W ( 258774 )
          Yeah, at 100% efficiency... I think you'd be hard-pressed to reach 10% efficiency. That would still be useful, with a 4' x 8' collector producing 4 liters of fresh water per day...

          But then, you'd also need to take into account that there aren't a lot of places in the US where you can get consistently sunny skies, clear for ten hours per day. A run of cloudy weather for a couple of weeks would devastate your system unless you had a sizeable reserve tank.

          Further, solar evaporators need a surprising amount of maintenance. The surfaces need to be kept clean or the efficiency drops, and they have to be flushed periodically to keep bacteria from growing in the fresh water outlets.

          To sum up -- it's do-able, but not quite as easy as building one and then getting free water forever.
          • We're not extracting work out of it, remember. This isn't bound by cycle efficiencies. If all you're doing is heating stuff up, solar energy can be upwards of 80% efficient easily. I compensated a bit by using 90 watts/sq.ft. instead of a 'real' value, which for northern Mexico would be more around 120 or so.

            But yes, the overall math was ambitious (especially neglecting the cooling part), but not entirely off-base. Total output is going to be limited by how fast you can condense the vapor.
            =Smidge=


        • Your last point is the key to how very efficient distillation systems work.

          You put the heat into the water to make the vapor.
          Then you take the heat back out of the vapor to get pure water.

          Using the heat from step 2 in step 1 is how you get high efficiency.

          Since the two temperatures need only be on either side of the dew point, you can run the system at any average temperature you like. Instead of heating the water to make vapor, you can cool the vapor to make water.

          One scheme pumped cold water from low ocean depths to chill air below the dew point. Pumping water is cheap compared to raising the temperature.

          As for worrying about high salinity, that need not be a problem. You need only remove enough water that the salinity changes by one or two percent (i.e. from 0.0035 to 0.0036). The seawater can be continuously pumped through the system, with only a small amount of water removed at any one time.

        • I've been told that the average person required about 2 liters of water (64-70 ounces) daily, as a healthy requirement. That's about 2kg worth.

          Drinking water is probably the *smallest* proportion of the average person's daily water usage. Think about how much water gets used washing yourself, your clothes, using the toilet, etc.

      • home solar distiller (Score:4, Interesting)

        by zogger ( 617870 ) on Monday January 06, 2003 @02:46PM (#5026733) Homepage Journal
        --we use solar PV here, and have three battery banks. Needing a lot of distilled water every month, we got a commercial solar distiller, which is mounted down by the panel arrays. It's roughly a 3 foot by 5 foot box with a glass top that is sealed to the sides. It worked pretty good for around a year,2-3 gallons a day output, then it stopped working, the glass developed some recurring film that stops the drips from falling into the collection tray. We tried adjusting the angle, etc, opened it up, cleaned the glass several times-nada. It evaporates water great,that part works as advertised, then the water that collects on the glass just sits there until the weight of the droplet causes it to fall right back into the pool of water, instead of sliding down the incline. So we switched to an electric distiller for now, next summer I'm going to make a hot water heater out of the thing and design and build my own distiller. The glass cleaning deal really stumped us, we tried vinegar, windex, you name it, that glass is spotless clean, but within a day or two it gets dirty enough to stop working-just unacceptable. There's probably some sort of application chemical like rain-x or something to use but it's a hassle to keep doing that, it should "just work" for at least a month without having to open it up for additional cleaning. I imagine on a bigger scale it would actually work better as you could have extremely steep sides for the collection efforts.

        There's a neat deal that was invented, it uses rotating sails to collect moisture from the air, some places in south america are using it now. this was covered on slashdot before earlier this summer, here's a generic link to a page of links about fog collection [sculptors.com]. cool stuff.
        • You've probably got minute calcium deposits on the surface, making it less smooth. You might want to try using a buffing tool. Think about how shiny your car could be, too!

          If buffing won't do it, then yes, there may be some coating the factory applied before it sent you the unit, and you might be able to apply more. Remember, it worked for a year before it gummed up on you.
          • ---hmm, didn't think of buffing it, thanks for the tip! It's a pain to get to the inside glass, it's permanently glued down with caulk, have to cut it off then re apply the caulk each time-another lame design feature. The good thing is I didn't buy it, the folks I work for did. If I don't make a solar water heater out of the box, I might try building a door for the glass on a hinge with some sort of permanent gasket, then try some more cleaning techniques, including the buffing. We washed it carefully before, used paper towels, crumpled newspaper, and lint free cloth, truly annoying to not have it "work" again after those efforts. Seems like the vinegar should have removed the calcium/mineral deposits though, but it obviously didn't. It's a perfectly good theory, actually evaporates the water quickly once the sun starts hitting it, just the collection part is dismal. Anyway, it's winter now, wouldn't work all that good when it's so cold out, next spring I'l mess with it again. I *might* try exhausting the moisture laden air and just using a huge coil of hose as the cooling mechanism leading to the collection container, then not worry about collecting it inside the box. Tipping it slightly so that a normal thermosiphon effect would come into play would probably work, ie, "heat doth rise".

            Had to refill one bank of batts yesterday, it wasn't too bad, 24 T-105 Trojan 6 volters took around 6 gallons to top them off to the correct levels. I had a large food grade plastic drum I was trying to fill up before winter with the solar distilled water, that was "the plan" anyway, too bad I have to waste juice now to make the water. Oh well...
            • Not to butt in on something I know nothing about, but couldn't rig some sort of inverted plastic cone (like a mini-traffic cone) inside the collector that minimized the amount of "re-drippage" and funneled the water to "finished" area.

              Basically the vapor would have no problem rising through the narrow part of the cone, but most of the drips would be "off target" and go where they belong.

              Also, I don't know if filtering the water in someway might help with the residual buildup on the glass or not, but it too may be worth looking in to.

              • --it's a very shallow box, so it would require hundreds of smaller cones then some sort of feed delivery system from the apex drip point of each cone. The steep angles would help of course, just no way to do it practically with the existing rig. A rippled glass might work better then a flat pane, but the cost for such a pane would be high I would wager. Deep single cones, put over holes in the ground, are an emergency solar distiller that work. I have made those, just loose plastic larger than the hole diameter, drop a marble in the center and it will fall until the plastic sheet is tight to make a "cone". You place a collection can down in the bottom. It's "enough" with a three foot across hole and putting a lot of torn off vegetation in the hole tomake around a quart a day in hot weather. What we are after is a daily steady supply of some gallons. Most likely I will first try the ultra buffing/polishing, and if that doesn't work go to a very large narrow diameter coil of hose where the moisture laden hot air, pumped by it's own heat outside the box, has enough surface area in the coil for cooling and condensation.

                the filtration would be neat if it was possible cheaply, reverse osmosis would do it, but that is some specialised expensive equipment that takes electricity. The deal with having the distilled is you want as pure as water for "topping off" as possible, as any minerals introduced in the storage batteries will stick to the lead plates, reducing their effectiveness. That's one of the quickest ways to ruin any lead acid battery, using normal tap water in them, or hard well water. Now filtered rainwater works about as good as distilled, as rain is just distilled water condensed around a dust or soot particle, but there again, getting the mud out is the problem. I could dedicate one high end water filter to it, but as I only have two, daily use for one and one carefully packed away as reserve, I'd rather just do distilled.

                Solar "stuff" is a lot of fun to play with, as well as practical-WHEN it works! hahaha! I will say the PV's are just a joy, day after day, nice clean power.
                • Okay one more thought. What about a series of nylon threads inclined at a steep angle so that the thread would channel the drips and condensation to the collection area?

                  • --a synthetic thread that didn't absorb water might work like that, but the problem would be you'd need so many of them attached (glued?) to the upper glass collection plate that they would block the sunlight infra rad heat from hitting the water to be distilled in the bottom of the solar collection box. You want as much "open" space as possible so the heat gets transferred to the water so it will evaporate. Catch 22 then. When the distiller is operating, as the water heats up from the hot sun hitting it, first you get a 'fog" on the inside of the glass, just like on your windshield in cold weather. Next you can see the individual droplets getting bigger and bigger, until the weight of the single drops overcomes the surface tension/adhesion on the glass, and the slight angle of the glass allows the drops to "break free" and flow downhill until they come up against a stop and then drip straight down into the collection trough, which is itself at a sight angle to where it exits the box into a short collection tube going to whatever container you have. That's the simple design and it worked well until that dang "too sticky" problem started getting bad. It worked really, really well the first year too, automatic, low tech, lotsa distilled water from some pretty hard well water.

                    Thanks for the input, yourself and the other poster, helps to have different ideas thrown at problems sometimes, I got some more to think about now. One would be a variation on the threads idea, not for the delivery but for the propogation of liquid water into "humidity", something that would keep the same size box I have but increase the surface area of the water so it evaporated faster at a lower temp. A mass "wicking" action on the bottom of the box itself, some sort of fibrous spongy mat perhaps. Hmmmm and hmmmmm Between that and an external coil condenser it could up the output without having to deal with the "sticky glass" syndrome. hmmmm
    • builidng the huge pipelines (or canals, which'd be much cheaper) to bring water from the coasts to interior cities

      You'd be suprised at what "cheaper" means, though. For example, the canal from the San Francisco Bay Delta (up in the Bay Area) to L.A. loses about 80% of the water it draws off the bay in evaporation before it even makes it down there. Canals may seem cheaper, but in the long run they waste much (in this case, the majority) of the water you worked so hard to obtain.

    • We in the US take water for granted. It's basically free -- cheaper than all other utilities, our water bill is about $15 a month, tops.
      I can tell you that there are an increasing [waterissweet.org] number [saveamericaswater.com] of places [savemiwater.org] where [redding.com] it isn't being taken for granted. Water is worth quite a bit to a few international companies that want to come in and take it all, basically for free, and then sell it for $2+ a bottle.

      And America is just the tip of the aquifer [google.com].

  • Why dump it??? (Score:1, Redundant)

    by eggstasy ( 458692 )
    Why the heck are they dumping it? Why not sell the salt? Around here, salt is generally obtained in much the same way it has been obtained for thousands of years, by letting sea water evaporate. The only reason I can come up with for them not to sell the salt is that said water is heavily polluted and maybe it would be hard to clean??
    • Or because the retail packaged value of salt is 25 cents a pound, which puts the bulk value at only several cents a pound.

    • Re:Why dump it??? (Score:3, Informative)

      by John Hasler ( 414242 )
      > Why the heck are they dumping it? Why not sell
      > the salt?

      They aren't producing salt. They are producing water that is somewhat saltier than seawater. To produce salt they would need to remove almost as much water as they would starting with plain seawater, and they would produce far more salt than the local market could consume.

  • California (Score:3, Interesting)

    by macdaddy357 ( 582412 ) <macdaddy357@hotmail.com> on Monday January 06, 2003 @02:06PM (#5026458)
    Since the feds have strictly curtailed California's [yahoo.com] ability to take water from the Colorado River, California needs to build desalination plants like this one, and to do it quickly! Too bad they will take 10 or 20 years debating it.

    • Re:California (Score:3, Informative)

      by dozer ( 30790 )
      Sounds like it might be time for Santa Barbara to turn on the desalinization plant it built in 1991...

      http://ci.santa-barbara.ca.us/departments/public_w orks/water_resources/bffaq.html [santa-barbara.ca.us]
      • You mean turn it back on -- they ran it briefly in late 92 or early 93, for about 2 weeks, IIRC. I was living in SB at the time; the general consensus, at least according to the Independent, was that the plant's output still tasted a bit like seawater, suggesting that their process needs a bit of fine-tuning.

        Not to say that it wasn't better than SB's water supply at the time; SB had really awful water, very high in sulfur and manganese.
    • But this is a commercial effort, is it not? If so, why can't a few companies create plants to do the same thing, and sell the water to the public, or else to the government and then the public?

  • Desalination since 1928 (Score:4, Informative)

    by espee ( 64799 ) on Monday January 06, 2003 @02:09PM (#5026476)
    On Curacao, an island in the Caribbean Sea, we desalinate our drinking water since 1928 [kaenv.com]. We call it the 'World's Best Water' (and probably most expensive as well! my past month's waterbill was approx. US$ 120.-).
    But what the brine does with our coral reef? I dunno, but ppl who are interested in finding out might get some answers from the ppl of NACRI [nacri.org], the Netherlands Antilles Coral Reef Initiative.

  • 2 Sides to Every Story (Score:5, Funny)

    by ConeFish ( 216294 ) on Monday January 06, 2003 @02:27PM (#5026573) Homepage

    I believe that both the proponents of the project, as well as the ecology-defenders, have valid points.

    But, just remember to take everything with a grain of salt...

  • dilute the salty water

    Use water that is going into the bay anyway like form wast water treatment to dilute the salty water. This might be difficult if the wast water plant is far from the desalination plant. This of course makes one wonder if it would not be better to treat the wast water back to a potable form. Though I suspect there is a social factor in why people don't like this idea.

  • Salt will damage.... (Score:4, Insightful)

    by jsimon12 ( 207119 ) on Monday January 06, 2003 @02:53PM (#5026796) Homepage
    While most vertebrates have mechanisms to rid themselves of excess salt most invertebrates (sessile or otherwise) do NOT have such mechanisms and depend on their environment to maintain a constant salt concentration. (Note: I have been building salt water aquariums for decades). Suffice to say increasing the salt content even slightly will more them likely not effect fish and up, but will at best stress most invertebrates making them susceptible to disease and at worst kill off large numbers of them and most certainly damage any coral. In turn this could damage food supplies, breeding areas etc for other animals not effected by the increase in salt.
  • You might decide that this is looney because Lyndon LaRouche is associated with it.

    You have to understand first that LaRouche is NOT a Libertarian - he is a Democrat. That in itself, explains much.

    Anyhow ...

    Outline of NAWAPA [schillerinstitute.org]

    "The North American Water and Power Alliance--NAWAPA--is the most comprehensive of a series of plans developed during the 1950s and 1960s to capture and redistribute fresh water in Alaska and Canada. NAWAPA would deliver large quantities of water to water-poor areas of Canada, the lower forty-eight states of the United States of America, and Mexico."

    and the map of the project [schillerinstitute.org].

  • Crap (Score:3, Interesting)

    by Ratbert42 ( 452340 ) on Monday January 06, 2003 @04:01PM (#5027323)
    There are ecological concerns about returning highly saline water from the plant back into Tampa Bay.

    As opposed to the crap [pqarchiver.com] they dump into the bay every time it rains hard?

    • As opposed to the crap [pqarchiver.com] they dump into the bay every time it rains hard?

      I thought that was just a problem with the morons running the government in Milwaukee [greatlakesdirectory.org]

  • Usage of water (Score:3, Insightful)

    by dl248 ( 67452 ) on Monday January 06, 2003 @04:09PM (#5027380) Homepage
    There is going to be a water shortage in the future, and I believe that there is a very easy way to deal with it, however it will require a change in thinking, and an investment in infrastructure:

    I don't know how many of you drink the tap water in your community, but here in Canada I know of few people that don't. But we also water our lawns with it, bathe in it, wash dishes with it, wash our cars with it, water our plants with it, etc. etc. etc.

    Do you see a pattern here? We use drinkable/potable water for a huge number of things that don't require the water to be drinkable. We spend huge amounts of money to treat our water to then pour it onto our lawns and cars? This makes no sense. What we need is a dual system of delivery: the taps in your kitchen provide drinking water, but the faucet in your laundry room or on the exterior of your house provide non-drinking water for general use.

    We could then forgo a huge number of costly, time-consuming treatments for water that is simply not meant for consumption. Previously non-viable sources of water suddenly become available for use in the "secondary" system of water.

    You surely don't care if the water that is cleaning your clothing is chlorinated and fluorinated, do you?
    • i went to Arizona to visit the grand canyon over the summer, and it was the first time i was exposed to the desert. i'm from pennsylvania and used to lots of trees and streams. i was shocked to learn that due to the extreme height of the area (around 7000 ft above sea level) there are 3 wells in the town near the canyon. all the toilet and wash water is recycled. there are huge basins connected to all of the gutters on buildings. it was pretty impressive. unfortunately, the tap water in philadelphia is thoroughly disgusting so i use a brita filter.

  • Corpus Christi bay... (Score:3, Interesting)

    by Vrallis ( 33290 ) on Monday January 06, 2003 @04:31PM (#5027599) Homepage
    I used to work for a research institute that monitored tidal conditions along the Texas coast. One thing we did was monitor salinity and dissolved oxygen levels in the Corpus Christi and Nueces bays. It wasn't from desal plants, but from the Nueces river being dammed in, limiting it's flow into the bays. This caused salinity to rise, and dissolved oxygen to decrease, putting the local wildlife in danger. They used our measurements to schedule releases--times when they would open the dams and dump X amount of fresh water into the bay in order to correct the levels. As far as I know, it worked just like it was supposed to.

    I haven't looked up any maps of the area, but surely there are similar factors at play.

  • Santa Barbara (Score:3, Interesting)

    by tbmaddux ( 145207 ) on Monday January 06, 2003 @04:52PM (#5027818) Homepage Journal
    During the drought of the early 1990's, the City and County of Santa Barbara voted in both a connection to the California Water Project as well as building themselves a desalination plant [santa-barbara.ca.us] (cost of $34 million).

    Proponents hyped both as solutions to the crisis, even though the CWP never delivers to full capacity when it is most needed (during a drought), is much more expensive than was originally stated, and the desalination plant was never used yet must still be maintained yearly.

    In fact, the largest proponents of the addition of state water and the desal. plant were developers, who saw a way around the county's long-standing moratorium on new water hookups (the county essentially running Mulholland's famous "whoever brings the water brings the people" in reverse to keep development at bay).

    In general, Marc Reisner's "Cadillac Desert" is a good review for those interested in the politics of water in the West. The issues faced by the semi-arid West are starting to appear elsewhere in the U.S. as our population grows, and we would do well to learn the lessons of the past.

  • case studies (Score:2, Interesting)

    by zozzi ( 576178 )
    In the island of Malta, obtaining sufficient water for industries and households was a significant problem and thus they were forced to experiment with any way they could to obtain enough water to meet their needs. To this end, several reverse osmosis plants were built and the problem has been solved to a large extent. The problem is that the plants consume a hefty 15% of all the electricity generated by the two power stations! Most of the electricity is required to generate enough water pressure and a lot of this energy was being wasted because the highly saline water being pumped out kept corroding the turbines. Thankfully however, technology has improved and now they recover a good part of that electricity again because the turbines are now made of a ceramic material.


  • There was a desalination plant off the coast of Freeport, Texas for about a decade during the '60s and '70s.

    I think it was a pilot project, so the article can still claim "first commercial desalination plant" in the USA.

  • I find it odd that they refer to this is the first. I could easily be wrong. But I thought Cape Coral, FL (a 2.5 hr south of tampa, 1.5 hr when I am driving) had a large reverse osmosis desalination plant. The second link even refers to how this is the more power efficient method. I'm pretty sure this place was in operation, since I remember several years back there was talk of taking a field trip from my high school to see it. We also mentioned how it differed from the system of wells that we used (in Fort Myers, the town across the river from Cape Coral)

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