Multimedia Pressure Filtration

Multimedia Pressure Filtration

A multi-media filter is employed to reduce the level of suspended solids in process water. Suspended solids can consist of particles such as silt, clay, grit, organic matter. The filtration degree of a multi-media filter depends heavily on the filter media and flow (velocity) through the filter.

A typical multi media filter setup contains three layers of filling. Those are anthracite, sand and gravel.
• The anthracite traps the coarse dirt particles to prevent the formation of a layer cake on top of the filter bed.
• The smaller particles get trapped in the sand layer. With a low fluid velocity particles will adhere to the sand with a cohesive bonding.
• The gravel acts as a support structure and distributes the water evenly to the plastic strainers underneath.

1. High rate of filtration is possible in the range of 15 -18 m3/m2.h
2. The pressure at the filter outlet is normally in the range of 4-6 kg/cm2.No downstream pumping is required to transport the water to long distances.
3. Single filter can remove particulates, control odour and remove colour

Full customization of filtration system is possible. IEC can offer fully automated systems will state of the art transmitters for monitoring pressure drop. The backwash action can be initiated with pneumatic/ electrically actuated valves. The system can be controlled with a relay interface or a PLC. Feedback for the key process conditions such as DP, backwash pump and blower status can be monitored remotely from the central control room.

Over time the pressure drop over the filter rises while the flow remains the same, due to the adhered suspended solids. Eventually the filter media needs to be cleaned, a process called backwashing.

A backwash should be performed when the differential pressure exceeds 0,1-0,2 bar over the differential pressure of a clean filter. In a backwash a reverse flow of water is ensured along with air-scouring. With a setup of valves the flow direction over the filter reverses. At a velocity of 35m/h (depending on the type of media) the filter bed expands. The backwash occurs for a pre-determined fixed time period.

As source for backwashing the filter the filtered water of another (media) filter or raw water which normally enters the filter at the top. With the use of raw-water a small amount of raw water entering the system downstream should be taken into account.

• Pre-filtration of disinfection equipment
• Preparation for micro and ultrafiltration
• Swimming pool filtration
• Groundwater purification
• Separation processes in which flocculants are used
• Water treatment plants

Process Info

  • Multimedia Pressure Filtration
  • Water Filtration