There are currently four commonly accepted categories of membrane filtration systems, defined by the size of material it can remove from liquid. From the smallest to largest pore size, these are Reverse Osmosis (RO), Nanofiltration (NF), Ultrafiltration (UF), and Microfiltration (MF).

Semi-Permeable Membrane
Semi-permeable membrane refers to a membrane that selectively allows certain species to pass through it while retaining others. In actuality, many species will pass through the membrane, but at significantly different rates. In RO, the solvent (water) passes through the membrane at a much faster rate than the dissolved solids (salts). The net effect is that a solute-solvent separation occurs, with pure water being the product. (In some cases, dewatering is desired to concentrate the salts).

What is Osmosis?

Osmosis is a natural process involving the fluid flow of across a semi-permeable membrane barrier. Consider a tank of pure water with a semi-permeable membrane dividing it into two sides. Pure water in contact with both sides of an ideal semi-permeable membrane at equal pressure and temperature has no net flow across the membrane because the chemical potential is equal on both sides. If a soluble salt is added on one side, the chemical potential of this salt solution is reduced. Osmotic flow from the pure water side across the membrane to the salt solution side will occur until the equilibrium of chemical potential is restored. In scientific terms, the two sides of the tank have a difference in their “chemical potentials,” and the solution equalizes, by osmosis, its chemical potential throughout the system. Equilibrium occurs when the hydrostatic pressure differential resulting from the volume changes on both sides is equal to the osmotic pressure. The osmotic pressure is a solution property proportional to the salt concentration and independent of the membrane.

Water World Int’l  line of ultrafiltration, nanofiltration, and reverse osmosis membrane filtration systems for municipal and industrial applications.

Water World Int’l  also offers  EDI electrodeionization system for the continuous and chemical free process of removing ionized and ionizable species from feed water.

                    Please Contact for The For the membranes of Following Brands

1.Filmtec USA

2. Torray Japan

3.Osmonics

4.KOSH

5.Hydrunatics

ESPA Low Energy/High Flow Tap & Brackish Water Thin Film Membranes