Quartz sand filter media are the core filtration medium in water supply treatment, produced from natural quartz ore by crushing, water washing, screening and drying. They are supplied as ordinary quartz sand and acid-washed refined quartz sand. Standard: CJ/T 43-2005 Filter Media for Water Treatment.
Acid-washed refined quartz sand is preferred for drinking water projects in waterworks.
2. Physical and Chemical Specifications (typical for waterworks)
Main constituent: SiO₂ ≥ 98% (drinking water grade).
True density: 2.55-2.70 g/cm³.
Bulk density: 1.70-1.75 t/m³.
Mohs hardness 7; wear and compression resistant.
Combined breakage and abrasion rate ≤ 1.5%.
Hydrochloric acid solubility ≤ 3.5%.
Mud content ≤ 1.0%.
Loss on ignition ≤ 0.7%.
Light material content ≤ 0.2%.
Good chemical stability and resistance to acid and alkali; suitable over pH 2-13; the water extract is non-toxic and harmless.
3. Common Grain Sizes and Grading for Waterworks
Filter type
Main grain size
Effective size d₁₀
Uniformity coefficient K₆₀
Conventional rapid filter (single media)
0.5-1.2 mm
0.5-0.8 mm
≤1.7
V-type filter (homogeneous media)
0.8-1.2 mm
0.8-1.2 mm
≤1.6
Dual-media filter (coal-sand)
0.5-0.8 mm
0.5-0.7 mm
≤1.7
Other sizes:
1-2 mm and 2-4 mm are available for bedding layers or industrial pre-treatment.
4. Filtration Principle
This is depth filtration. Water flows downwards through the media bed and, by means of the voids between grains, removes suspended solids, silt, colloids and algae through screening, adsorption, bridging and sedimentation, reducing effluent turbidity. After a period of operation the bed clogs, and air-water backwashing regenerates it to restore filtration capacity.
5. Main Functions
Turbidity removal: the key polishing step after coagulation and sedimentation in conventional water treatment, reducing effluent turbidity to below 1 NTU;
Impurity retention: intercepts fine suspended particles and flocs, reducing the load on downstream disinfection;
Biofilm effect: over long-term operation a thin biofilm forms on the sand surface, providing a degree of biological degradation.
