Quartz Sand Filter Operation and Maintenance Guide

Quartz sand filters are widely used in water treatment systems, particularly at the front end of security filters and reverse osmosis equipment, to remove large particles and solid impurities from raw water. Due to their significant filtration effect, quartz sand filters play a crucial role in industrial water treatment and drinking water purification processes. However, they can only function effectively over the long term with proper operation and regular maintenance. This guide provides a comprehensive overview of the operating steps, startup procedures, maintenance, and daily care required to ensure the filter operates optimally.

Startup Preparation

Before using a quartz sand filter, a thorough inspection and preparation are necessary to ensure proper startup and optimal performance. Follow these steps:

1. Inspect Equipment Components

Valves and Pipelines: Check all valves, pipelines, instruments, and accessories of the filter for damage or leaks.
Coagulant Dosing System: Ensure that the coagulant dosing tank has enough liquid and that the dosing pump is functioning properly.
Electrical System: Verify that electrical equipment, such as the control panel and pump motors, are in good working order.

2. Check Valve Status

Make sure all discharge valves, backwash valves, and other related valves are closed to prevent accidents during startup.
Ensure all valves and pipeline systems are in the correct open or closed position for subsequent operations.

3. Inlet Water and Venting Check

Open the inlet and vent valves and vent the system until the water flows steadily from the vent valve. Then, close the vent valve.
Open the backwash discharge valve in preparation for the next steps.

Equipment Startup and Operation

After the filter is started, follow the preset processes and operational requirements. During operation, closely monitor the equipment's parameters to ensure optimal filtration performance.

1. Start the Equipment

Open Inlet and Outlet Valves: First, open the inlet and outlet valves of the filter, and start the raw water and dosing pumps to begin the filtration process.
Monitor Pressure Differential: Regularly check the inlet and outlet pressure differential. When the differential reaches 0.07–0.1 MPa or the system has filtered the preset amount of water, it indicates the end of the filtration cycle, and backwashing should be prepared.

2. Operation Cycle

During normal operation, the filter will adjust its cycle based on water quality and filtration performance. A large pressure differential may indicate that the filter media is clogged and requires backwashing.

Backwashing

Backwashing is essential for cleaning the filter media and extending its lifespan. By reversing the water flow, impurities captured on the surface of the media are flushed away, restoring the filter's effectiveness. Follow these steps for backwashing.

1. Backwash Preparation

Close Inlet and Outlet Valves: Before starting the backwash, close the inlet and outlet valves.
Open Backwash and Discharge Valves: Open the backwash discharge valve and backwash valve, then start the backwash pump.

2. Backwash Process

The backwash typically lasts 10-15 minutes but can be adjusted based on water quality. During this time, the backwash water should continuously flush the filter media, with the discharged water turbidity controlled below 3 mg/L.
Keep the vent valve closed throughout the backwash process to maintain stable water flow and balanced internal pressure.

Forward Washing and Drainage

After backwashing, forward washing is necessary to ensure the filter media is thoroughly cleaned and the water quality reaches the desired standards. Forward washing removes fine particles from the media, stabilizing water quality and meeting discharge standards.

1. Forward Washing

Open Inlet and Discharge Valves: Open the inlet and forward washing discharge valves to begin forward washing. Continue until the turbidity of the discharged water drops below 1 mg/L.
Continue Forward Washing: The forward washing should last at least 30 minutes, until the water quality stabilizes and the turbidity meets the required level.

2. Drainage

After forward washing, close the inlet and forward washing discharge valves, and open the drainage valve to expel any accumulated water. Drain until the water level reaches about 200 mm above the filter media layer, adjusting as needed based on actual conditions.

Air-Water Scrubbing

Air-water scrubbing is the final cleaning step, using a mixture of air and water to deeply clean the filter media, ensuring no residual impurities remain and improving filtration efficiency.

Scrubbing Procedure

Close Inlet and Outlet Valves: Close the inlet and outlet valves.
Start Air-Water Scrubbing: Open the forward washing discharge valve, air inlet valve, and backwash inlet valve. Set the air input to a strength of 10 seconds per square meter and the water flow to 10 m³/h, continuing for about 10 minutes.

Equipment Maintenance and Care

Regular maintenance is crucial to ensure the quartz sand filter operates smoothly and lasts longer. Proper care not only extends the filter's life but also enhances its water treatment performance.

1. Daily Inspection and Monitoring

Regularly check the operation of the equipment and record operational data. Address any issues, such as large pressure differentials or unusual noise.
Monitor parameters such as inlet pressure, outlet pressure, and discharge turbidity to ensure the system is operating at peak performance.

2. Regular Cleaning

Periodically clean the filter media. Perform backwashing and forward washing based on water quality and operational conditions to maintain the media’s effectiveness.
Inspect and Replace Parts: Regularly check the valves, pumps, and electrical systems. Replace worn or damaged parts, such as seals or pipes.

3. Rust and Corrosion Prevention

When the equipment is not in use, especially in humid or corrosive environments, take steps to prevent rust and corrosion. Use rust inhibitors or protective coatings to safeguard the equipment’s durability.

Conclusion

The quartz sand filter plays a vital role in water treatment. Proper operation and regular maintenance are key to ensuring its efficient, long-term performance. By following the detailed procedures for startup preparation, operation, backwashing, forward washing, air-water scrubbing, and daily maintenance, you can ensure the filter functions optimally, minimizing failures and extending its service life.