Influence of organic matter from waste water on the permeability of membranes

Abstract

The progress in the development of membranes for the treatment of aqueous solutions in the last years has attracted much interest in this technology. In order to find out the application limits, for example by ultrafiltration and reverse osmosis for waste water, research was carried out into the influence of organic matter, expressed as chemical oxygen demand (COD), on the permeability of the membrane on a pilot-scale. Different waste waters (pig and cattle slurry, milkhouse waste water and vegetable wash water) with different concentrations of organic matter were treated by ultrafiltration, and the permeates were treated partly by reverse osmosis. These tests as well as experiments for ultrafiltration with anaerobically treated mixtures of pig slurry and potato wash water showed that the permeability of membranes is determined by the concentration of organic matter of waste water and is independent of the kind of waste water. By ultrafiltration of different waste waters with an anorganic silicon-carbide membrane with a nominal pore diameter of 0.05 μm for example, the permeability decreased from 158 l/m 2 ∗ h to 26 l/m 2 ∗ h when the COD-concentration increased from 0.63 g/l to 42.8 g/l, respectively.