One problem of membrane filtration is the blocking of the membrane surface by the substance to be separated. The functionalized membrane modules developed use an electrical effect that reduces this buildup. This allows the time to membrane cleaning to be extended and the flow rate through the membrane to be increased.
The shortage of drinking water is becoming more and more acute due to the increasing demand for water with a decreasing availability of pure water sources. Filter membranes for water treatment show a strong limitation: The deposition of the substances to be separated on the membrane surface, also called fouling, leads to a continuous reduction of the water flow through the membrane during continuous operation. The developed dielectrophoresis membrane modules (DEP modules) help to significantly reduce membrane fouling. For this purpose, polymeric membrane surfaces are equipped with electrodes via a screen-printing process and then provided with a thin protective layer of titanium oxide by means of an innovative process. By applying a low alternating voltage, the electrodes generate a strong electric field over the membrane surface, which prevents suspended solids from being deposited by electrokinetic forces during filtration.
In laboratory tests under ideal conditions, the service life - the time it takes for the permeate flow through the module to drop to one-third of its initial value - was extended fivefold. In a pilot plant with a throughput of approx. 1 m3 per day, a 50% higher permeability (flow rate as a function of the applied pressure difference) was achieved in a municipal wastewater treatment plant compared to regular modules. The developed process technology can later be used for compact, portable filter systems, e.g. for crisis situations, as well as for decentralized or stationary systems due to the low energy requirements.
