Multi-Media Filter
Working Principle of Multimedia Filter
Multi-Media Filter is pressure-type depth filtration equipment for water pretreatment. It removes suspended solids, silt and colloids, reduces turbidity and SDI to protect RO/UF membranes.
Its main advantages are high dirt loading capacity, long filtration cycle, automatic backwash and low maintenance cost. It is widely used in raw water purification, pure water production, industrial circulating water and wastewater reuse projects.
The multi‑media filter tank is filled with multi‑layer filter media of different particle sizes and specific gravities, such as quartz sand and anthracite. Raw water flows downward through the filter bed. Through depth‑filtration mechanisms including screening, adsorption, sedimentation and interception, suspended solids, silt, colloids and other contaminants are trapped inside the filter media. This reduces effluent turbidity and SDI value, providing pretreatment protection for downstream RO and UF membrane systems.
As filtration proceeds, accumulated contaminants increase pressure differential across the filter. When the preset pressure difference or running time is reached, air‑water backwash is triggered. Backwash water flows upward to fluidize the filter bed, while compressed air agitates the media. Trapped pollutants are stripped off and discharged with wastewater. The filter media re‑stratifies, and the unit is ready for another filtration cycle.
Advantages
Application Fields
- ✓Pretreatment for RO / UF membrane systems to reduce SDI and protect membranes
- ✓Removal of suspended solids and turbidity for surface water & groundwater
- ✓Industrial process water, boiler water, cooling water, wastewater reuse, food & beverage, power industry
Frequently Asked Questions
What is a multi-media filter tank?
It is pressure depth filtration equipment for water pretreatment, filled with multi-layer filter media (anthracite, quartz sand, manganese sand etc.) to remove suspended solids, silt and colloids.
What is its working principle?
Raw water flows downwards through layered filter media. Impurities are trapped via screening, adsorption and interception. When pressure difference rises to the set value, air-water backwash starts to clean and regenerate the filter bed.
What are the main advantages?
High dirt holding capacity, long filtration cycle, automatic air-water backwash, low operation cost, corrosion-resistant tank, manual or automatic control optional. Filter media can be customized for different raw water quality.
What is it used for?
Mainly as pretreatment for RO / UF membrane systems to reduce SDI and protect membranes. Widely applied in surface & groundwater treatment, industrial process water, boiler water, cooling water, wastewater reuse, food & beverage and power industry.
How to maintain the multi-media filter tank?
Regularly check pressure differential and backwash status. Inspect filter media loss and replenish media if needed. Check valves and piping for leakage periodically.
What’s the difference between multi-media filter and quartz sand filter?
Multi-media filter uses multiple types of filter material with different densities for graded filtration, holding more dirt and longer running cycle. Single quartz sand filter only uses quartz sand media with lower dirt loading capacity.
Send Your Requirements
- Raw water source — Surface water / Groundwater / Wastewater reuse, etc
- Raw water flow rate: m³/h (design capacity) —
- Raw water quality: Turbidity, SDI, TSS —
- Operating working pressure: Bar / MPa —
- Design temperature: ℃ —
- Tank material — Carbon steel with epoxy coating / FRP / Stainless steel 304 / SS316L
- Control type — Manual valve / Automatic pneumatic valve (auto backwash)
- Filter media requirement — Anthracite + quartz sand / add manganese sand (for iron removal)
- Voltage & power supply: V, Hz, Phase —
- Installation condition — Indoor / Outdoor
- Other special requirements — Size limitation, paint standard, certificate (ISO, CE）
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