Down flow filters

The membrane separation process is based on the presence of semi permeable membranes. The principle is quite simple: the membrane acts as a very specific filter that will let water flow through, while it catches suspended solids and other substances. Membrane filtration can be divided up between micro and ultra filtration on the one hand and  filtration and Reverse Osmosis (RO or hyper filtration) on the other hand. When membrane filtration is used for the removal of larger particles, micro filtration and ultra filtration are applied. Because of the open character of the membranes the productivity is high while the pressure differences are low. When salts need to be removed from water,  filtration and Reverse Osmosis are applied. filtration and RO membranes do not work according to the principle of pores; separation takes place by diffusion through the membrane. The pressure that is required to perform  filtration and Reverse Osmosis is much higher than the pressure required for micro and ultra filtration, while productivity is much lower.