Drinking water purification process
Around the world, household drinking water purification systems, including a reverse osmosis step, are commonly used for improving water for drinking and cooking.
Such systems typically include a number of steps:
• a sediment filter to trap particles, including rust and calcium carbonate
• optionally, a second sediment filter with smaller pores
• an activated carbon filter to trap organic chemicals and chlorine, which will attack and degrade thin film composite membrane reverse osmosis membranes
• a reverse osmosis filter, which is a thin film composite membrane
• optionally, a second carbon filter to capture those chemicals not removed by the reverse osmosis membrane
• optionally an ultraviolet lamp for sterilizing any microbes that may escape filtering by the reverse osmosis membrane
• latest developments in the sphere include nano materials and membranes
In some systems, the carbon prefilter is omitted, and cellulose triacetate membrane is used. The cellulose triacetate membrane is prone to rotting unless protected by chlorinated water, while the thin film composite membrane is prone to breaking down under the influence of chlorine. In cellulose triacetate membrane systems, a carbon postfilter is needed to remove chlorine from the final product, water.
