| 摘要 |
A filtration medium comprises a first grade of glass particles and a material suitable to form a water permeable retention layer. Preferably, the filtration medium comprises at least two grades of glass particles. The first grade is preferably distributed substantially over the range of 0.75mm to 1.7mm. The second grade is preferably substantially in the range of 1.7mm to 3mm. In a further aspect, a filter is described having a water permeable retention layer supporting a filtration medium substantially comprising the first grade of particles. The retention layer may comprise the second grade of glass. |
