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Semiconductor Production Wastewater Semiconductor production requires the use of complex organic solvents, and it requires the use of chemically pure water, literally 100 percent deionized water. Semiconductor manufacturing companies must dispose of their excess solvents and their metal-laden wastewaters after use; it is illegal and unacceptable to discharge wastewaters containing any of those solvents or metals entrained. (Incidentally, semiconductor solvents have been turning up in effluent by semiconductor manufacturers in the Silicon Valley and perhaps elsewhere.) Those solvents are allegedly carcinogenic and toxic, and at the very minimum they impose severe liabilities on semiconductor manufacturers. In addition, absolutely ultra-pure water is required in the manufacture of semiconductor chips. Water that contains even the most minuscule quantity of organic compounds or carbonate ions is useless for semiconductor manufacture. Even minute amounts of these ions in rinse water can lead to an entire batch of semiconductors to be discarded, at great expense. Presently, a rather complex "Rube Goldberg" process, including ion exchange, ozone-injection, degassing, and ultraviolet oxidation, is used to reduce the total carbonate content in entering process waters to below 2 ppb. The estimated cost of producing such ultrapure water is $20/1000 gal. This is a particularly large cost given that the water is now a one-time use--the water collects too much organics or metals in the manufacturing process to be recycled. To clean up semiconductor manufacturing water, a two stage process can be implemented. First, an organics mineralization process can easily be implemented to mineralize all of the organics embedded in the wastewater. Thereafter, Reticle Carbon CDI cells can easily be used to remove all of the resulting carbonates and other byproducts of such mineralization as well as all metal or other ions. By using the two stage mineralization-deionization procedure, water flowing from a semiconductor production plant could be purified, recycled, and/or discharged. (It is unlikely it would be discharged if it can be cleaned to the requisite degree.) This could render semiconductor plants zero discharge units, which would greatly decrease their perceived and actual deleterious impact on the environment and would greatly reduce their water acquisition costs and reduce their legal liability exposure. The organics mineralization-Reticle Carbon process can be added onto existing process configuration to allow for direct recycle of any portion of the process water for a very small cost per gallon of recycled water. As microchip manufacturers, particularly domestic microchip manufacturers in high cost North America, are reaching new levels of storage and processing speeds, the quality and purity of process water absolutely must be increased. There is no alternative. Loss of production from a modern semiconductor plant is directly tied to the amount of carbonaceous matter in the entering feedwater. Cleanup of semiconductor process and waste waters represents a HUGE market for Reticle Carbon worldwide. |
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