Pre-treatment - Multimedia Filtration
Mit Water manufactures multimedia filtration (MMF) systems for pre-treatment removal of suspended solids and turbidity from water. MMF is one of the most widely used pre-treatment technologies for protecting downstream RO membranes, ion exchange systems and other sensitive equipment from fouling by particulate matter.
Working Principle
Water passes downward through a pressure vessel containing multiple layers of filtration media: anthracite (top, large and light), sand (middle) and garnet or ilmenite (bottom, fine and heavy). This graded configuration allows coarse particles to be removed in the upper anthracite layer while finer particles penetrate deeper, using the full bed depth. The bed is periodically backwashed to remove accumulated solids and re-classify media layers.
System Features
Our MMF systems include FRP or carbon steel pressure vessels, graded filter media, support gravel, automatic backwash valves, and a PLC control panel. Inlet coagulant dosing enhances filtration performance. Silt density index (SDI) monitoring downstream confirms RO feed water quality.
Multimedia filtration is essential pre-treatment for a wide range of water sources:
- RO and NF pre-treatment
- Surface water (river, lake, reservoir) treatment
- Cooling tower side-stream and make-up water filtration
- Industrial process water from variable-quality sources
- Wastewater tertiary treatment before membrane processes
- Seawater desalination pre-treatment
- Bore water and groundwater turbidity removal
Technical Parameters
| Flow Rate | 1 to 150 m3/h per vessel |
| Filtration Velocity | 10 to 20 m/h |
| Inlet Turbidity | Up to 50 NTU (with coagulation) |
| Outlet Turbidity | Below 1 NTU |
| Media Layers | Anthracite, sand, garnet |
| Vessel Material | FRP or epoxy-lined carbon steel |
| SDI15 (after MMF) | Below 5 (suitable for RO feed) |
| Backwash Rate | 35 to 50 m/h, bed expansion 20-30% |