Application of a continuous electrodeionization (EDI) unit in the ultra-pure water system

• Main Authors: Lo, Kuang-Chao, 羅光照
• Other Authors: Huang, Chih-Pin
• Format: Others
• Language: zh-TW
• Published: 2018
• Online Access: http://ndltd.ncl.edu.tw/handle/er959z

碩士 === 國立交通大學 === 工學院永續環境科技學程 === 106 === All pure water system is a necessary system in the current industry, including semi-conductor, panel industry, electric related chemical industry and fine-tuned mechanism industry, they all need large quantity of pure water involved, However, the highly pure water comes along with energy consumption and medicine related chemical emission problems that is not only environment unfriendly but also highly being needed to run the system, therefore, how to reduce the quantity of chemicals usage and waste water emission is the purpose of this study. The study is using a continuous electro-deionization (EDI) unit and two-pass RO unit to replace cation tower, anions tower and mixed-bed, taking on the site factory for example, under the conditions of non-affection to the current water quality and quantity set by the system, carrying out water quality analysis and making cross check the water quality between transformation and transformation of the current resin tower unit. That of the major difference of continuous EDI unit with the cation/anions/mixed-bed towers is the regeneration method. Moreover, using the continuous EDI unit does not require to install chemical storage tanks, regeneration pumps, and regeneration tanks, as to the space arrangement concerned, the study revealed after using the continuous EDI unit to replace the traditional resin tower, there will be 65% more space available left, compared to that of conventional resin regeneration system, as far as the space placement concerned, that is much more cost saving. After installing the continuous EDI unit, water quality for resistivity is higher than 8MΩ．cm (at 25℃), anions concentration is less than 1 μg/L, metal ion concentration is less than 1 μg/L. Those changes can achieve the originally designed function of the system as well as have a good cleaning rate on the aspect of boron and silica. As for the operation cost concerned, the management cost of using the cation tower, anions tower and mixed-bed is 5.6 NT dollars /m3, however, using the continuous EDI unit only stands 4.9 dollars/m3, as far as long running operation concerned, using the continuous EDI unit to replace the traditional resin tower unit concerning the installing of all pure water systems, we deeply believe that will be a foreseeable trend in the future.