Self-Cleaning Backwash Filter

Backwash Filter – Hands-Free Surface Water Polishing

A backwash filter eliminates manual cartridge changes by reversing flow to clean its own medium. Raw water enters a stainless or FRP vessel filled with sand, mesh or fiber bundles; solids accumulate on the surface until a preset ΔP (0.2-0.3 bar) or time interval triggers an automatic backwash cycle. In 30-90 s a portion of filtered water (1-3 % of throughput) is directed upward, fluidizing the bed or lifting the screen, flushing trapped solids to drain. Models range from single-column 1″ units (1 m³ h⁻¹) to multi-cell systems handling 1 000 m³ h⁻¹ with uninterrupted outlet flow. Options include air-scour assistance, brush or suction scanners for precise screen cleaning, and PLC control for variable-rate operation. Common uses are intake screens, cooling-tower side-stream, RO pre-treatment and tertiary sewage filtration. By maintaining a clean filter face continuously, the backwash filter sustains 15-40 m h⁻¹ hydraulic loading, cuts energy use 20 % versus fixed beds, and guarantees >95 % uptime with minimal operator attendance.