Abstract: Ceramisite filter material for biological aerated filer was prepared with natural clay and diatomite as the main materials. The effect of the roasting temperature on the properties of filter material such as pore size distribution, specific surface area and open porosity rate was investigated. The results of SEM shape analysis, pore size analysis by mercury intrusion and other tests show that when the roasting temperature is 950~1 050 ℃, the specific surface area of the filter material is 7.76~5.49 m²/g; the pore size, 0.003~10 μm; the open porosity,73.88%~71.44%; and the volume weight 0.77~0.84 m³/g, better than those of imported ceramisite filter material. It can be concluded that rough-surfaced ceramisite material with good physical and chemical stability can be produced for biological aerated filter.

Key words: Ceramisite filter material, Roasting temperature, Pore size distribution, Specific surface area