Membrane Technology: Microfiltration, Ultrafiltration, and Reverse Osmosis

Ultrafiltration is employed as a tertiary treatment to remove low concentration suspended solids, dissolved organics and dissolved inorganics to achieve water quality limits. Membrane technology is not applicable to a wide range of raw industrial wastes or removal of large waste quantities. It is generally used as a polishing step to remove specific waste water components such as suspended solids, dissolved organics and dissolved inorganics to achieve water quality limits, produce reusable water, or to recover product from specific wastes. However, in waste treatment contaminant removal and conversion to an environmentally inactive form is the primary objective; the concentrated reject volume produced must be small relative to the initial waste volume. The primary driving force in a membrane system is pressure, with increasing flux resulting from increasing pressure. Initially, the gel resistance is negligible and the flux is proportional to the applied pressure difference.