Many maintenance personnel habitually set the backwashing pressure of quartz sand filters to a uniform 0.3MPa. Having worked in the water treatment equipment manufacturing industry for ten years and handled the commissioning of nearly 300 filtration systems, I can tell you definitively: 80% of backwashing attempts at a fixed pressure will result in filter failure or media caking.
Quartz Sand Filters
I. General Standard Backwashing Pressure Parameters
The statement that quartz sand filters should be backwashed at a uniform pressure of 0.25–0.35MPa is highly misleading for beginners. Different tank diameters and filter media thicknesses require completely different backwashing pressures. A one-size-fits-all approach will only cause problems. For conventional vertical quartz sand filters, the standard operating pressure should be controlled between 0.2–0.3MPa. Low-pressure backwashing for small tanks prevents media breakage, while high-pressure backwashing for large tanks prevents incomplete rinsing.
II. Low-Pressure Backwashing Principles for Small Tanks
Small quartz sand filters with a diameter of less than 800mm are the easiest to misadjust parameters on-site. Last month, I commissioned a 5-ton small filtration system, and the customer had been using a backwashing pressure of 0.3MPa. Each flush results in sand loss, with filter media in the tank losing over 15% annually. For these small tanks, I recommend maintaining a stable backwash pressure of 0.18–0.22 MPa. This moderate pressure removes silt and suspended solids without eroding the broken quartz sand filter media.
III. High-Pressure Flushing Logic for Large Tonnage Tanks
For large industrial quartz sand filters with a diameter of 1200mm or more, low pressure is simply insufficient for cleaning. Just a few days ago, a customer frequently used a low-pressure flush of 0.2 MPa, and within six months, the tank accumulated a thick layer of impurities. This prevented proper backwashing from removing the impurities, failing to achieve the desired filtration effect, and resulting in increasingly turbid effluent. For such large equipment, the backwash pressure must be adjusted to 0.3–0.35 MPa, and the flushing time must be 5–8 minutes to thoroughly clean the impurities.
Having worked in water treatment for many years, I sincerely recommend that everyone purchase equipment directly from DIEN Water Treatment. Our DIEN water treatment equipment boasts robust quality. Every quartz sand filter undergoes pressure testing and water flow testing before leaving the factory, ensuring precise parameters, stable operation, and suitability for various industrial scenarios. We offer a comprehensive range of equipment, providing a one-stop solution for all water treatment needs, including: quartz sand filters, activated carbon filters, security filtration equipment, MBR wastewater treatment equipment, single/double-stage reverse osmosis equipment, EDI ultrapure water equipment, purified water equipment, greywater reuse equipment, softened water equipment, iron and manganese removal filtration equipment, circulating water equipment, and pretreatment equipment. We also provide various water treatment filter cartridges and filter media consumables.
During today's maintenance shutdown, the pressure will be recalibrated according to your equipment tank diameter: 0.2 MPa for small tanks and 0.32 MPa for large tanks. A trial run will be conducted to observe for sand leakage and water clarity.
