Crossflow electrofiltration in pilot scale

Abstract

In crossflow filtration, a filter cake is formed on the membrane in the course of filtration. This cake acts as an additional resistance and significantly decreases the high initial permeate flow rate and thus the efficiency of the process. As particles in suspensions carry an electric charge, it is possible by means of a suitable superposition of the crossflow filtration with an electric field to prevent or reduce cake formation, and to considerably increase the stationary permeate rate. While this process has been successfully demonstrated in laboratory scale there are no reports about scale-up applications. In this paper filtration results with a pilot scale crossflow electrofiltration plant are reported. The presented investigations comprise the microfiltration of mineral and biological slurries with constant and pulsed fields. It was possible to increase the specific permeate rate markedly compared to the value without field; for a mineral slurry the obtained increase rate was more than 10. An estimation of the specific energy input demonstrates the cost-saving potential of this technique.