Clarification is the removal of colloidal suspended solids from water. Liquid solids separation under low velocity gradients takes place within a clarification system because of the specific gravity difference between the solids and liquid. Efficiency can be increased with suitable coagulants and chemicals.
Filtrations systems use granuler media as filtration medium are applicable for removal of suspended solids 50 -100 mg/l range. Pressure filters use both straining and adsorption technique to reduce turbidity. Adsorption is dependent on the characteristics of filter media and influent water.
Ion exchange system aim is either to soften the water or to remove mineral content. Ion exchange resins are polymers capable of exchanging particular ions within the polymer with ions in the water. Ion exchange materials are insoluble substances containing loosely held ions which are able to be exchanged with other ions.
Ultrafiltration provides macro molecular separation for particles in range 20-1000 Angstrom (up to 0.1 microns). UF membranes have molecular weight cut off values between 1000-10000. Ultrafiltration used to remove suspended solids,colloidal matter,high molecular weight substances,bacteria and viruses.
Reverse osmosis is the finest filtration available. The reverse osmosis membrane acts as a barrier to all dissolved salts, inorganic molecules and organic molecules with a molecular weight greater than 100. Water molecules pass freely through the membrane creating a purified stream. Rejection of dissolved salts typically 95% to 99%.
Electrodeionization uses membranes,ion exchange resins and DC potential to remove ionic contaminants from water. EDI process achieves high quality with conductivity less than 0.1 micro siemens/cm.