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Annals of Dangerous Electronic Waste: Attempts to Detox LCD Manufacturing Waste With SWO.

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NNadir Donating Member (1000+ posts) Send PM | Profile | Ignore Tue Sep-22-09 06:46 PM
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Annals of Dangerous Electronic Waste: Attempts to Detox LCD Manufacturing Waste With SWO.
One of the great ironies of the destruction of a large swathe of the groundwater in San Jose, California at the end of the last century, was that the semi-conductor industry was welcomed enthusiastically by most people since it was considered by almost everyone to be a "green" industry.

The result was the designation of many sites like the South San Jose Fairchild Semiconductor site as superfund sites because the groundwater had become toxic and unsafe for human consumption or any other use. Since the late 1980's, for instance as part of a "clean up" the Fairchild Semiconductor Corporation has been continuously pumping ground water out of the ground - using dangerous fossil fuels, largely as the energy source for the energy to do this, predictably dumping the dangerous fossil fuel waste in that great dump, Earth's atmosphere) and trying to remove the organochlorine compounds from the water. (One strategy for doing this is to aerate the water, and thus dump the organochlorine compounds in that wonderful waste dump, again, Earth's atmosphere.)

Of course, since then, electronic waste, both in terms of disposed products, and the side products of manufacture, have represented huge toxic risks, mostly to poor people in the third world, since we are now way to "green" here in the West to have any part of the manufacturing of all that stuff we consume.

For instance, in another thread, one by a dumb fundie anti-nuke complaining about so called "nuclear waste," - the so called "nuclear waste" having been stored for many decades in this country without harming anyone - I pointed out how our "green" solar industry dumps its waste (predictably)in China: Solar Energy Firms Leave Waste Behind in China and um, continuously harms people.

But in fact, the solar industry, which is known widely (at least in the scientific literature if not in pop literature to have a toxicity problem, is too trivial to be a major electronic waste risk. It very may well might do so, and will do if...

If...

It will only become obvious if we end up - and I doubt this will happen having listened to decades of solar soothsaying - if solar PV ever begins to produce one or two exajoules out of the 500 exajoules consumed by humanity

But it's probably not comparable to the other electronic waste problems observed around the world, not because solar is so good, but because everything else is so bad.

Anyway...

In connection with other work I'm doing related to the properties of various metals under relatively extreme conditions, I came across a paper in the scientific journal Journal of Supercritical Fluids relating to electronic waste from the electronic consumer industry, specifically LCD.

The paper is entitled "Supercritical water oxidation of wastewater from LCD manufacturing
process: kinetic and formation of chromium oxide nanoparticles."

The lead author is Bambang Veriansyah. (I happen to be an atheist, but if I am wrong, and the Hindus are right, and there is such a thing as reincarnation, in my next life I want to come back as someone named Bambang. Dr. Verisansyah is, by the word, a fine scientist working in the field of supercritical fluids, which are fluids at temperatures and pressures high enough to eliminate the distinction between liquid and gas states.)

The abstract of the paper is here: The Journal of Supercritical Fluids Volume 34, Issue 1, May 2005, Pages 51-61

I will offer some excerpts of the paper below, but I wish to note that one of the big problems of electronic waste, including the waste that all the world's solar cells will become, is that they are diffuse sources of toxic metals, making them ultimately the same sort of thing that great miracle of distributed energy, the car, is, a point source pollutant generator.

Now a few words from Bambang Veriansyah:

Liquid crystal display (LCD) serves as the user interface in wide range application include notebook computers, desktop monitors, cell phones, consumer electronics, and business, industrial, and transportation categories. LCDs have greatly increased in number, type, and applications. International Data Corporation (IDC) forecast the LCD market to grow fast every year <1>. Therefore, the potential for high market penetration and an increased LCD material volume is significant. Concern over the environment impact associated with the LCD manufacturing has emerged in recent years. These concerns have been driven in part because LCD manufacturing plants generate several million tons of wastewater annually. It contains a wide variety of organic pollutants and heavy metal chromium.


That's um, several million TONS of water.

...Conventional treatment methods as coagulation or membrane separation have major disadvantages since they generate a concentrated stream that is more harmful than the Generally, it is a waste too dilute to be incinerated, and due to its toxicity, it is difficult to treat biologically...


Wait a minute...cleaning up the waste makes a toxic waste stream?

Um...um...um...where have I heard this sort of thing before? Oh yeah, I know, the toxic coal industry, which generates a toxic waste stream when it tries to scrub mercury instead of using the traditional method of dumping over ever square centimeter of earth's landmass.

(Let's have a round of the "Sequester Talk Game.")

So what's in that water?

Recently, Fang et al. studied the behavior of heavy metals during combustion of industrial organic wastes in supercritical water in the temperature 450 or 525 ◦C and 30.6MPa and found that 97.6% of the Cd, 87.3% of the Cr, and 100% of the Pb were changed from soluble to insoluble substance. They also reported that main solid products identified were CdO, CdCO3, CrO2
HCrO2, PbCrO4, PbCO3, and PbOx <12>. Toxic hexavalent chromium species were effectively removed by precipitation of chromate salts <13>. Smith et al. also have recovered more than 35 wt.% of metals from simulated high-level liquid waste with hydrothermal crystallization <14>. However, there are no references in the literature about kinetic reaction rate and recovery of chromium from SCWO of LCD wastes, even though these industrial wastes are quite important due to their large volume and high toxicity. Thus, in this study we Fig. 1. Schematic diagram of the continuous-flow reactor system for SCWO experiment. Table 1 Property of LCD wastewater in its concentrated form describe experiments designed to identify kinetic reaction rate and formation of chromium oxide nanoparticle during the SCWO of LCD wastes


This chromium waste, by the way is multivalent, including the extremely carcinogenic Cr (VI) species. But who cares. I want to watch, um, American Idol, especially since the American Idol is consumption followed by consuming.

Specifically I wish to point out that lead and cadmium, are not major constituents of LCD waste, but the latter metal, cadmium, is a major factor in solar PV waste. All three metals, lead, cadmium, and chromium are features of other consumer electronics waste, notably computer chips and monitors.

It turns out - and anyone who understands supercritical water may realize this - that one can, in fact, remove chromium from LCD waste in this manner, as a transiently insoluble Cr(VI) species, although the method is energy intensive, since it involves high temperatures and pressures.

For practical purposes the solvation properties of supercritical water and normal water are almost reversed, many metal salts are entirely insoluble in supercritical water, including table salt, NaCl.

Most of the energy consumed on this planet for purposes of heat, such as might be involved in the producting of supercritical water, involves the dumping of dangerous fossil fuel waste, so effectively this is trading dirty water for dirty air.

I love irony.
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jpak Donating Member (1000+ posts) Send PM | Profile | Ignore Tue Sep-22-09 07:03 PM
Response to Original message
1. I heard there are 750,000 metric tons of highly toxic corrosive depleted uranium hexafluoride
hanging around US uranium enrichment plants in corroding casks.

Is that true????

Yup

:evilgrin:
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Name removed Donating Member (0 posts) Send PM | Profile | Ignore Tue Sep-22-09 08:39 PM
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Name removed Donating Member (0 posts) Send PM | Profile | Ignore Wed Sep-23-09 05:17 AM
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AlecBGreen Donating Member (1000+ posts) Send PM | Profile | Ignore Tue Sep-22-09 08:03 PM
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2. supercritical water
Edited on Tue Sep-22-09 08:04 PM by AlecBGreen
isnt that water that has been heated far above its normal boiling point by keeping it under pressure?

if i read correctly, it will cause any dissolved solids to COME OUT of solution. pretty cool!

edit - me no spel so gud
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NNadir Donating Member (1000+ posts) Send PM | Profile | Ignore Tue Sep-22-09 08:49 PM
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4. Yes. Supercritical water is water at temperatures greater than 373 C and pessures greater
than 22.1 MPa.

It has remarkable properties and is the subject on an enormous amount of research.

Regrettably the most common supercritical water use right now is in coal fired power plants.
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kristopher Donating Member (1000+ posts) Send PM | Profile | Ignore Tue Sep-22-09 11:29 PM
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5. When I read these posts indirectly comparing the environmental consequences of
..solar to nuclear, I'm driven to lend perspective to the level of impact with of analogies such as an agitated Idi Amin railing against petty tyrants in the home...
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kristopher Donating Member (1000+ posts) Send PM | Profile | Ignore Wed Sep-23-09 12:50 AM
Response to Reply #5
6. Or my favorite...
A nuclear beheading compared to a solar hangnail...
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Name removed Donating Member (0 posts) Send PM | Profile | Ignore Wed Sep-23-09 01:33 AM
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Name removed Donating Member (0 posts) Send PM | Profile | Ignore Wed Sep-23-09 07:22 AM
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Name removed Donating Member (0 posts) Send PM | Profile | Ignore Wed Sep-23-09 11:26 AM
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HamdenRice Donating Member (1000+ posts) Send PM | Profile | Ignore Wed Sep-23-09 01:03 PM
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11. "You have become, basically, the crazy uncle of the environmental/energy forum. "
:rofl: :rofl: :rofl: :rofl: :rofl:

:rofl: :rofl: :rofl: :rofl: :rofl:

:rofl: :rofl: :rofl: :rofl: :rofl:

:rofl: :rofl: :rofl: :rofl: :rofl:

:rofl: :rofl: :rofl: :rofl: :rofl:

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