Semiconductor applications ultrapure water

Potential applications for CA-CDI technology include the purification of boiler water for fossil and nuclear power plants, volume reduction of liquid radioactive waste, treatment of agricultural wastewater containing pesticides and other toxic compounds, creation of ultrapure water for semiconductor processing, treatment of wastewater from electroplating operations, desalination of seawater, and removal of salt from water for agricultural irrigation. 

The pharmaceutical industry lead the way in adoption of CEDI for the production of ultrapure water. Since the early 1990 s, the power industry has been employing CEDI as a polisher for RO effluent for steam generation. Other industries currently using CEDI include general industry for boiler make-up or high-purity process applications, including semiconductor manufacture. Commercially-available industrial CEDI modules range in size from less than 1 gpm to 80 gpm. 

A number of commercial applications of MCs have been already successfully realized. A bubble-free membrane-based carbonation line, using Liqui-Cel equipment, is in operation by Pepsi in West Virginia since 1993. MCs are also used in beer production the CO2 removal stage is followed by nondispersive nitrogenation to obtain a dense foam head. Another important field of application of MC is the production of ultrapure water for semiconductor manufacturing. 

Most of applications arc in the purification of water, mainly the desalination of brackish and especially seawater to produce potable water (10-13). The amount of salt present in brackish water is between 1000-5000 ppm, whereas in seawater the salt concentration is about 35,000 ppm. Another important application is in the production of ultrapure water for the semiconductor industry. 

In some cases, soft water can be used for most applications and pure or ultrapure water used for the final rinse. In a cleaning operation, surfaces should never be allowed to dry before a final rinse in ultrapure water. It is interesting to note that in semiconductor processing the ultrapure water costs as much as the chemicals that are removed with the water. 

The present ED industry has experienced a steady growth rate of about 15% since 15 years (Srikanth, 2004). The most important industrial ED application is still the production of potable water from brackish water. However, other applications either in the semiconductor industry for the production of ultrapure, that is, completely deionized water without the chemical regenerations of IERs or in the food industry (i.e., whey demineralization, tartaric stabilization of wine, fruit juice deacidification, and molasses desalting) are gaining increasing importance with large-scale industrial installations. 

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