In Germany, over 2,300 pharmaceutical substances are sold in human medicine, with annual consumption exceeding 30,000 tons. These drugs and their residues reach wastewater treatment plants (WWTPs) through excretions, where they are not fully eliminated, leading to contamination of surface and groundwater. The unpredictable effects of substances like diclofenac, antiepileptics, and Xray contrast agents are concerning. Hormonal drugs disrupt fish populations, while antibiotic residues contribute to resistance. The climate crisis increases pressure on ecosystems and trace substance concentrations. Ensuring clean water, a key industrial factor, alongside ecological benefits and compliance with regulations, requires effective solutions.

In 2024, the EU Council decided to introduce a fourth treatment stage for municipal WWTPs. Existing facilities primarily use activated carbon or ozone for trace substance elimination, but the high energy demand for ozone production and the fossil sources of activated carbon raise sustainability concerns. The DeDrug-Bio project aims to establish a stable, self-regenerating filter for cost-effective, lowemission selective degradation of pharmaceuticals. Inspired by marine biological filters—sea sponges (Porifera)—which provide a habitat for microorganisms and have a filtration capacity of up to 20 m³ of water per day per kilogram of body weight, we aim to create a habitat and immobilize selected microorganisms capable of degrading pharmaceutical residues. 

The substrate material will be functionalized using laser and plasma technology to create a stable habitat for microorganisms that form effective biofilms and resist erosion. Selective degradation of trace substances is expected to enhance retention rates and treatment efficiency in WWTPs. Research goals include selecting specific microorganisms (Fraunhofer IFAM), developing surfaces for immobilization (SITEC), and upgrading existing membrane filters to biohybrid filters. A demonstration unit will be built to test the concept at a WWTP (hanseWasser Bremen GmbH). The interdisciplinary consortium includes filter manufacturer Martin Systems GmbH and the Baden-Württemberg Trace Substance Competence Centre for advisory support and material assistance.

The project initially focuses on selecting organisms for drug degradation, creating filter habitats, and choosing a representative trace substance for a biohybrid filter, with diclofenac as a significant challenge due to its persistence and high concentrations. Some WWTPs have inlet concentrations of about 2.8 µg/L and outlet concentrations exceeding 2 µg/L. Ecotoxicological damage is noted at 0.4 µg/L, while the EU is discussing a limit of 0.04 µg/L.