| 摘要 |
The filter medium comprises smooth surtaced, non-porous granular glass or filter sand of which some has been treated with a caustic solution to impart active hydroxyl groups thereto and thereafter treated with a trialkoxysilane. The average concentration of treated medium corresponds to up to 3 to 3.5 grams trialkoxysilane per litre of granular medium in the case of filter sand and up to 1.5 to 1.8 grams trialkoxysilane per litre of medium in the case of granular glass, the desired average concentration being attained either by treating the medium with a corresponding amount of the trialkoxysilane or by treating with a higher amount and diluting the treated medium with untreated medium. The filter medium is backwashable to refresh its lipophilic properties, and does not readily plug or foul when in use. |
