PiCO2buddies - Detoxifying diclofenac-contaminated water by symbiosing green microalgae and bacterial cellulose-producing microorganisms

• Applicant: Dr. Manuel Ibañez, Ph.D.
• Subject Area: Biological Process Engineering
• Term: since 2025
• Project identifier: Deutsche Forschungsgemeinschaft (DFG) - Project number 554890432

Diclofenac (DFC) is an anti-inflammatory human medicine. DFC toxicity in water has become a significant concern all over the world, including Germany. DFC adversely affects aquatic organisms and when accumulates inside fish, plants, and animals. The European Water Framework Directive set the current environmental quality standard for DFC in surface waters at 0.05 μg/L in Europe. In 2017, a report indicated that DFC contamination had been observed in several water sources in Germany, with concentrations up to 25 times higher than the permitted value in 21 of the 24 existing monitoring stations. DFC enters the environment via landfill leachate and municipal and industrial discharges due to water reclamation processes of varying efficiency that were not meant to target this specific substance. There is no consensus about the most suitable water-treatment technology to target DFC and similar pollutants. Six months ago, the applicant presented a proposal and won seed money to design and test a proof of concept for a biofilm reactor (BR) containing a consortium of two microorganisms capable of reducing the amount of DFC present in synthetic wastewater. The latter is the case of P. salinarum, a microalga naturally able to break down DFC, and K. sucrofermentans, a gram-negative aerobic bacterium able to produce Bacterial Cellulose (BC) and form a compatible biofilm. The preliminary results of the applicant suggest that the alga alone can remove up to 85% of DFC when fresh cells are placed in contact with an initial concentration of DFC equal to 10 mg/L in a new medium suitable for the growth of the bacteria designed to maximize the gas-liquid exchange while considering all the necessary nutrients to establish the symbiosis. This forms the platform for the present research within the Walther-Benjamin program, wherein the applicant seeks to study how to push the permeability of DFC from the bulk liquid into the biofilm and design strategies for influencing the partition of target components into the biomaterial. The results of this work will lead to establishing model-based strategies for the design of high active biomass concentration biomaterials and, subsequently, processes that approach market viability and lay the groundwork for novel concepts beyond wastewater treatment, like biofilm reactors for the production of bulk chemicals.

• DFG Programme: WBP Position