| 摘要 |
PURPOSE:To enable to save the consumption of water while inhibiting the contamination of a working environment, by letting water containing noxious metal discharged from a working site flow into a delay water reservoir tank, removing the noxious metal existent in outflow water by ion exchange, and then circulating the treated water to said working part. CONSTITUTION:In cutting a GaAs wafer, for instance, by a dicing saw 1, water containing fine powdery chips of a GaAs compound discharged from the saw 1 is let flow into a delay water reservoir tank 2. In the tank 2, As as a noxious metal is converted into an oxide and dissolved in water within a predetermined delay time before the water having flowed in through an inflow opening 21 flows out through an outflow opening 22. Hence, the outflow water contains As ion only. During the passage of said water through an ion-exchange means 3, As ion is removed by ion-exchange adsorption. Hence, the water from which As ion has been substantially removed flows into a water reservoir tank 4. This water is resent to the saw 1 for reuse.
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