PACT® Multimedia Filter is used to reduce the level of suspended solids in incoming feed water. Suspended solids consists of small particles such as slit, clay, grit, organic matter, algae and other micro-organisms. Incoming feed water that is high in suspended solids can cause a high-pressure drop and reduce the effectiveness of downstream filtration equipment such as reverse osmosis membranes and ion exchange beds. A multimedia filter typically consist of three layers of media consisting of anthracite coal, sand and garnet, with a supporting (non filtering) layer of gravel at the bottom.

These are the media of choice because of the differences in size and density. The larger (but lighter) anthracite coal will be top and the heavier (but smaller) garnet will remain at the bottom. The filter media arrangement allows the largest dirt particles to be removed near the top of the media bed with the smaller dirt particles being retained deeper and deeper in the media. This allows the entire bed to act as a filter allowing much longer filter run times between backwash and more efficient particulate removal. A well- operated Multimedia Filter can remove particulates down to 15-20 microns. A Multimedia Filter that uses a coagulant addition (which induces tiny particles to join together to form particles large enough to be filtered) can remove particulates down to 5-10 microns.


  • Less or no chemicals required (coagulants, flocculants, disinfectants, pH adjustment)
  • Lower energy consumption than nano-filtration or reverse osmosis;
  • Constant quality of the treated water in terms of particle and microbial removal. Disinfection through removal of bacteria. To a certain extent, UF allows viruses, phage, colloids and macro molecules to be removed.
  • Process and plant compactness
  • Simple automation