Situation: | The goal of the KeraRes project is to develop a new membrane process for resource-efficient water treatment. A ceramic nanofiltration membrane (NF) is produced by post-modification with polyelectrolytes, which is intended to enable the safe treatment of even difficult-to-treat water resources (e.g. river water, wastewater, rainwater) in a single treatment step. Particles (e.g. microplastics), bacteria and viruses as well as dissolved water constituents (organic matter, salts) are to be retained. Conventional NF membrane systems are fundamentally subject to the problem of fouling (particles, organics, precipitates, biofilm), i.e. the membranes become clogged with increasing operating time due to the formation of a covering layer of organic and inorganic particles. Backwashing is not possible with conventional NF wound membrane modules and only part of the covering layer can be removed again by membrane cleaning (cleaning-in-place). The energy requirement therefore increases over the operating time up to the point at which the membrane modules have to be replaced. The KeraRes membrane process aims to solve this problem by regenerating the LbL coating: the old LbL layer is dissolved by increasing the pH and then reapplied. |
| Methodology: | The KeraRes project is focussing on the development of an innovative water treatment technology. To this end, functional polyelectrolyte layers are applied to ceramic membranes using the layer-by-layer (LbL) process. The coated membranes are intended to efficiently remove polyvalent ions such as hardness formers, as well as organic molecules, including persistent compounds such as PFAS. The backwashability and regenerability of the NF separation layer enable a one-step process that makes pre-treatment of the water by microfiltration superfluous. Energy efficiency can be further increased through better control of fouling. The sub-project of the DVGW Research Centre TUHH primarily involves the characterisation of the LbL-coated membranes. In order to record and optimise the properties of the coating, the coated membrane surface is examined for its structure and charge properties. The filtration behaviour (separation properties and permeate flux) is recorded in laboratory tests with various waters, including the fouling and backwashing behaviour and energy requirements. This characterisation enables conclusions to be drawn for further adjustments to the coating. The filtration tests with model waters and test waters provide comprehensive data for module development and the evaluation of the filtration process. |
