Gas sparged cross-flow microfiltration of biologically treated wastewater

Abstract

A novel technique was tested for reducing tubular mineral membrane fouling by injecting gas into a cross-flow stream. The injected gas is thought to form complex hydrodynamic conditions inside the microfiltration module, which increase the wall shear stress, preventing the membrane fouling and enhancing the microfiltration mass transfer. The experimental study was carried out with biologically treated wastewater filtered through a tubular inorganic membrane (Carbosep M14). The flux, monotonously increasing with gas velocity, was more than tripled. New dimensionless quantities of shear stress number and resistance number were developed by generalisation of the dimensional analysis already carried out for the steady state flux of classical unsparged cross-flow filtration. A unique formalism allowed then interpreting the experimental results of both classical diphasic filtration and sparged filtration. The main limiting mass transport process was due to the solid content.