Ultrapure water equipment for silicon wafer cleaning

Ultrapure water equipment pretreatment's multimedia filtration refers to the process where water passes through a bed composed of media such as quartz sand, garnet, or anthracite under gravity or pressure, and particulate contaminants in the water are intercepted by the media, thereby achieving separation from the water. Granular media filtration removes particulate suspensions, impurities, and colloids from water based on the "filtration-clarification" working process. Common filtration types in water treatment include downflow single-media filtration and upflow filtration. To enhance the performance of media filtration, the following methods are typically employed: using layered filtration with multiple media; for downflow filtration, the common arrangement from top to bottom is anthracite, quartz sand, and graded gravel, which increases filtration flow rate and effectively improves filter efficiency. Adding chemical flocculants before the filtration unit allows water and coagulants to repeatedly collide during flow through the sand column gaps, facilitating coagulation and reaction. When the formed flocs reach a certain size, they are trapped in the sand column voids, further adsorbing fine floc particles from the flowing water, clarifying the water quality. After a certain period of operation, based on changes in inlet and outlet pressure differentials, backwashing is performed, or combined water and air mixed backwashing with compressed air can be used to expel flocculated pollutants, thoroughly cleaning the filter media and restoring the filter to normal operation. Ultrapure water generally refers to water with a resistivity of 18 MΩ*cm (25°C).

What are the reasons why mixed-bed ultrapure water equipment fails to operate normally? The EDI module is a critical component of mixed-bed ultrapure water equipment, and its condition directly affects the normal operation of the equipment and its service life. If the EDI module is not cleaned and maintained for a long time or is left idle without protection, organic matter can grow on the membranes and channels, increasing the inlet and outlet pressure differential, leading to decreased water quality, increased voltage, unadjustable current, and rendering it unusable. The use of inappropriate cleaning and disinfecting agents can directly cause damage and breakage of EDI resin, increasing the inlet and outlet pressure differential, resulting in a decline in both water quality and output. During manual operation of the EDI system, applying power under water-deficient conditions can directly burn the membranes, resin, and EDI module hardware, making cleaning ineffective and the module unusable. Lack of a pre-filter before EDI intake. Calcium and magnesium salts in raw water consist of negatively charged ions (anions) and positively charged ions (cations), and reverse osmosis equipment can remove over 99% of these ions.