Efficient Sand Filter for Water Treatment

1. Working Principle

Sand filters operate using a physical filtration process where water flows through a bed of fine sand or other granular media. As water passes through the filter bed, suspended particles, dirt, and impurities are trapped within the sand layers. Clean water then exits through the outlet. The filtration can be maintained through periodic backwashing, which reverses the water flow to remove accumulated contaminants.

2. Material Composition of Key Components

• Filter Tank: Carbon steel with anti-corrosion epoxy coating or stainless steel (SS304/SS316)

• Filter Media: Quartz sand, garnet, or anthracite

• Internal Pipework: UPVC, stainless steel, or galvanized steel

• Control Valve: Brass, cast iron, or stainless steel

• Nozzles/Underdrain System: ABS plastic or stainless steel

• Pressure Gauge & Accessories: Stainless steel with corrosion-resistant elements

3. Applications

Sand filters are widely used in various industries, including:

• Municipal water treatment

• Irrigation and agriculture

• Industrial process water pre-treatment

• Cooling tower filtration

• Swimming pool and aquatics systems

• Wastewater polishing systems

4. Key Parameters to Confirm When Selecting

• Inlet water quality (turbidity, particle size)

• Required flow rate and filtration capacity

• Filtration precision (typically 20–100 microns)

• Tank size and filter bed depth

• Operating pressure and temperature range

• Type of filter media required

5. Advantages

• Simple operation and low maintenance

• Durable and long service life

• High filtration efficiency for suspended solids

• Suitable for large flow rates

• Can be used in series or parallel for scalable solutions

• Backwash capability for media cleaning without dismantling

6. Maintenance and Operation

• Monitor pressure differential to determine backwash intervals

• Perform backwash regularly based on load conditions

• Check and replace media every 2–3 years depending on usage

• Inspect valves, gauges, and seals for wear

• Ensure proper start-up and shut-down procedures

FAQ

1. How often should I backwash the sand filter?

• Typically when the pressure difference exceeds 0.1–0.2 MPa or once per day for high-load systems.

2. Can sand filters remove bacteria?

• No, sand filters mainly remove suspended solids. Disinfection is needed for bacterial removal.

3. What type of sand is used in the filter?

• Washed quartz sand or multi-media layers like anthracite and garnet are commonly used.

4. How long does the sand last before replacement?

• Usually 2–3 years, depending on water quality and maintenance frequency.

5. Can I use a sand filter for seawater or corrosive fluids?

• Yes, if the filter tank and components are made of corrosion-resistant materials like SS316.

6. Do I need a pump to operate the sand filter?

• Yes, pressure is required to drive water through the media bed.

7. Is it suitable for high-flow applications?

• Yes, sand filters are commonly used in large-scale water treatment systems.

8. Can it be used as a pre-treatment for RO systems?

• Absolutely, sand filters are effective in reducing TSS before membrane filtration.