Desalination Part 3 of 4: Getting Better All the Time

by: infiniteseo Total views: 38 Word Count: 766
View PDF | Print View

Related Discussions Online:

Formula One kinetic energy recovery rigs debut
Posted by alexhammer via The Register

China Energy Recovery Board Member, Roger Ballentine, to Appear on ... - MarketWatch
Posted by wonojo via malaysia - Google News

New lows: S&P 500 806.18, SSO 21.97, TNA 24.0
Posted by mitchelltsai via Twitter

Being Discussed on FriendFeed

Open Question: If you gained weight on a short tapering dose of Prednisone, will it come off with diet and exercise?
I'm 48 years old. I had sinus surgery a few weeks ago and the doctor put me on a short tapering dose of Prednisone afterward. I've taken it before in a different manner (as a 5 day Medrol Dose pack). But this time he had me take three 10mg tablets all at once first thing in the morning. When I began tapering, I got terrible withdrawal symptoms (sweats, dizziness, lethargy, weakness). When I finally got off it totally(about 12 days later), I had an increased appetite and I've probably gained 5 to 8 lbs (I'm afraid to get on the scale, but I have a roll of fat on my back that was not there before and my belly is much bigger too). I'm 5'3" and before the surgery I weighed about 137 lbs (which is slightly overweight for me). I'm starting to get active again, which is hard because I have back problems. I'm scared that this new weight will not come off. I have been trying to eat less and eat better foods, but I don't want to do a calorie restriction diet for a few more weeks, until my body heals totally. I still don't have all my previous energy because the surgery and recovery took so much out of me (I was in a lot of pain for many days). If you've been on Prednisone, can you please tell me -- does the weight come off with diet and exercise after you are off of it? I really hope I'm not stuck with this extra roll of fat and a fatter face. I really hate it!!! read more...

Open Question: can anyone tell me in which packs these cards come in i want the name of the deck or booster pack these cards?
elemental hero neos elemental hero flame wingman elemental hero clayman elemental hero sparkam elemental hero clay guardman elemental hero neo bubbleman elemental hero necroshade elemental hero thunder giant elemental hero mudballman elemental hero rampart blaster elemental hero tempest elemental hero wildedge elemental hero shining flare wingman elemental hero steam healer elemental hero sailorman elemental hero wild wingman elemental hero elixier elemental hero necroid shaman winged kuriboh lvl m10 hero kid neo spacian flare scarab neo spacian aqua dolphin neo spacian air hummingbird neo spacian ground mole neo spacian glowmoss neo spacian black phanter feather shot burst return burst impact spark blaster bubble blaster bubble illusion bubble shuffle clay wrap mud max cyclene boomerang wild half skyscraper trandserent wings heated heart emergency call righteous justice oversoul hero flash de-fusion fusion gate fusion recovery metamorphosis mirage of nightmare emergency provision coragous charge spical hurricane pot of greed hero heart kuriboh summoning flute miracle fusion infiltration spy hero battle fusion fusion sage contact neo space fake hero skyscraper 2-hero city climax hour elemental sword metamorphosis neos energy instant fusion power charger hero signal hero barrier hero ring hero spirit a hero emerges clay charge feather wind edge hammer negate attack staunch defender super junior confrontation cross heart dimensional tunnel mirror gate mirror force insurance miracle kids solemn judgement invincible hero hero's rule 1: five freedoms soul union elemental burst final fusion hero ring disgraceful charity kids guard hero call i also forgot to pit some pther card her they are dark magician blue eyes white dragon (x3) read eyes b. dragon also forgot to put HERO FLASH plz tell me in which booster pack or deck this card comes in its ELEMENTAL HERO NEOS this is my favorite card of all i want it cuz its one of the coolest elemental heroes ever!!!!!!!!!!!!!!!!!!!!!!!! read more...

Continued from Desalination Part 2: No Salt, Please..........

In the late 1970s John Cadotte of America’s Midwest Research Institute and the FilmTec Corporation created a much-improved membrane by using a special cross-linking reaction between two chemicals atop a porous backing material. His composite membrane consisted of a very thin layer of polyamide, to perform the separation, and a sturdy support beneath it. Thanks to the membrane’s improved water flux, and its ability to tolerate pH and temperature variations, it went on to dominate the industry. At around the same time, the first reverse-osmosis plants for seawater began to appear. These early plants needed a lot of energy. The first big municipal seawater plant, which began operating in Jeddah, Saudi Arabia, in 1980, required more than 8 kilowatt hours (kWh) to produce one cubic metre of drinking water.

The energy consumption of such plants has since fallen dramatically, thanks in large part to energy-recovery devices. High-pressure pumps force seawater against a membrane, which is typically arranged in a spiral inside a tube, to increase the surface area exposed to the incoming water and optimise the flux through the membrane. About half of the water emerges as freshwater on the other side. The remaining liquid, which contains the leftover salts, shoots out of the system at high pressure. If that high-pressure waste stream is run through a turbine or rotor, energy can be recovered and used to pressurise the incoming seawater.

The energy-recovery devices in the 1980s were only about 75% efficient, but newer ones can recover about 96% of the energy from the waste stream. As a result, the energy use for reverse-osmosis seawater desalination has fallen. The Perth plant, which uses technology from Energy Recovery, a firm based in California, consumes only 3.7kWh to produce one cubic metre of drinking water, according to Gary Crisp, who helped to oversee the plant’s design for the Water Corporation, a local utility. Thermal plants suck up nearly as much electricity, but also need large amounts of steam. “A thermal plant only is practical if you can build it in such a way that it can take advantage of very low-cost or waste heat,” says Tom Pankratz, a water consultant based in Texas, who is also a board member of the International Desalination Association.

Economies of scale, better membranes and improved energy-recovery have helped to bring down the cost of reverse-osmosis seawater-desalination. Although the cost of desalination plants and their water depends on where they are, as well as the local costs of capital and operations, prices decreased from roughly $1.50 a cubic metre in the early 1990s to around 50 cents in 2003, says Mr Pankratz. As a result, reverse osmosis is preferred for most modern seawater-desalination (though rising energy and commodity prices mean the cost per cubic metre has now risen to around 75 cents). Experts reckon that further gains in energy efficiency, and hence cost reductions, will be increasingly difficult, however. According to a recent report on desalination from America’s National Research Council, energy use is unlikely to be reduced by much more than 15% below today’s levels—though that would still be worthwhile, it concludes.
Sometimes, using desalination within water management may be the only way to ensure supply.

To achieve these reductions, researchers want to find better membranes that allow water to pass through more easily and are less likely to get clogged up. Eric Hoek and his colleagues from UCLA, for example, have developed a membrane embedded with tiny particles containing narrow flow channels, producing a significant increase in water flux. The membrane’s smooth surface is also expected to make it harder for bacteria to latch onto. Depending on a plant’s design, the new membranes could reduce total energy consumption by as much as 20%, reckons Dr Hoek. The technology is being commercialised by NanoH2O, a company on UCLA’s campus.

Meanwhile, the possibility of making membranes out of carbon nanotubes, which consist of sheets of carbon atoms rolled up into tubes, has also garnered attention. A study published in the journal Science in 2006 demonstrated unexpectedly high water-flow rates. But insiders think it will be a decade before the idea is ready for commercialisation.

As desalination becomes more widespread, its environmental impacts, including the design of intake and discharge structures, are coming under increased scrutiny. Some of the damage can be mitigated fairly easily. Reducing the intake velocity enables most fish species and other mobile marine life to swim away from the intake system, though small animals, such as plankton or fish larvae, may still get caught in the intake screens or sucked into the plant.

About the Author

Cherish Hill publishes articles for Desalination Company ERI - Energy Recovery Inc., the company behind the PX Pressure Exchanger which promotes energy recovery and is used for seawater desalination.