Coordination Funds

• Applicant: Professor Dr. Jan Siemens
• Subject Area: Soil Sciences
• Term: since 2021
• Project identifier: Deutsche Forschungsgemeinschaft (DFG) - Project number 431531292

Wastewater reuse for irrigation is a crucial leverage point for increasing the efficiency of water usage, decreasing water shortages and raising food production under conditions of a growing population and changing climate. Water treatment prior to its use in agriculture is generally advocated for reducing environmental and health risks of wastewater irrigation. Investments in infrastructure for reaching the Sustainable Development Goal 6 “Clean water and Sanitation” cause a shift from irrigation with untreated wastewater to irrigation with treated wastewater. However, while replacing untreated with treated wastewater may reduce the loads of nutrients, carbon and many pollutants that reach irrigated fields, it can mobilize pollutants such as antibiotic agents and disinfectants that wastewater-irrigated soils have accumulated in the past. Therefore, we hypothesize that hitherto unforeseen risks arise from the implementation of wastewater treatment in long-established wastewater irrigation systems, due to i) the release of pollutants that have formerly been accumulated in soils, leading to ii) concentrations that (co-)select for antimicrobial resistance, with iii) release and concentrations of antibiotics as well as selection of antibiotic resistance depending on soil type. Yet, the magnitude and relevance of these emerging risks cannot be predicted because we lack fundamental understanding of (co )selection processes of multiple resistant bacteria and transfer of resistance genes at sub-inhibitory concentrations of antibiotics and disinfectants and their combinations in soils and plants. Moreover, colloidal and spatial controls for these interactions are largely unknown. Also, nothing is known regarding the coupling of fate and effects of antibiotics and disinfectants under subtropical conditions, where high temperatures can promote both, the selection of resistant bacteria harboring transferable resistance plasmids, but also the dissipation of organic pollutants, so far to an unknown degree. The implementation of water treatment in the world´s largest wastewater irrigation system, the Mexico City-Mezquital Valley, offers the unique chance to gain the required process understanding for assessing the above mentioned risks. The proposed Research Unit will thus elucidate the mechanisms controlling the dynamics of pollutants and multiple resistant bacteria in soils during the transition from irrigation with untreated wastewater to irrigation with treated wastewater. This Research Unit will deliver fundamental process understanding regarding the interaction between the fate of different pollutants, bacteria, and the spreading and selection of antibiotic resistance in agroecosystems.

• DFG Programme: Research Units
• Subproject of: FOR 5095: Pollutant – Antibiotic Resistance – Pathogen Interactions in a Changing Wastewater Irrigation System
• International Connection: Mexico
• Cooperation Partner: Professorin Dr. Christina Siebe