UWI is an interdisciplinary DFG graduate school at the TU Berlin and the Leibniz Institute for Freshwater Ecology and Inland Fisheries (IGB), where both, engineers and scientists work together. An improved understanding of processes taking place in  urban water systems will be achieved in this project.

This sub-project, focusses on investigating the influence of various cement-bound building materials on biofilm formation in the sewage system.

This sub-project focusses on characterising and influencing the biofilm on building materials exposed to sewer systems. Cementitious mortars with a very different chemical composition (normal, sulphate resistant and white OPC, cements with slag and fly ash, HAC, geopolymers etc.) as well as doped samples (e.g. manganese, copper) will be exposed to wastewater (at the pilot plant of BWB) and the formed biofilm will be analysed by DNA/RNA sequencing. After exposure, the material will also be characterised by X-ray fluorescence analysis,light and scanning electron microscopy to study the binder degradation.

 Microbial induced concrete corrosion (MICC) is considered as the most important degradation process in the sewage system with enormous potential for damage, which significantly reduces the service life of sewage systems based on cementitious concrete (Grengg et al. 2018; Wu et al. 2020). MICC is based on a complex sequence of biological and chemical reactions. anaerobic sulfate-reducing bacteria (e.g., Desulfovibrio spp. and Desulfomaculum spp.) present in the sediment layer in wastewater, reduce sulfates and sulfur-containing organic compounds to hydrogen sulfide (H₂S).

Since most sewer systems are made of concrete, ensuring durability and longevity is of great importance to authorities and engineers. The development of more sustainable and resistant possible building material compositions play an important role.

In order to gain a deeper understanding of the bacteria involved, and the influence of the building materials on their colonization, the biofilm diversity on different cement-bound materials as well as their corrosion rates and depths are analyzed in this project. For this purpose, a series of cement mortars with different chemical compositions as well as doped samples are placed in a pilot plant of the Berliner Wasserbetriebe (BWB) in Berlin-Neukölln, which is operated with real wastewater. The different mortars are exposed in the gas phase of the pilot plant for long-term studies to investigate the influence of the mortar composition on biofilm formation and its reaction to the mortar.