Coordination FOR 5095

Project: Coordination FOR 5095

Supervision: Prof. Dr. Jan Siemens

Person in charge: Dr. Benjamin J. Heyde

Duration: 2021-2024

Summary

The use of wastewater for irrigation in agriculture is an important way to alleviate water shortage and increase food production under the conditions of a growing world population and a changing climate. Infrastructure investments to achieve Sustainable Development Goal 6 "Clean Water and Sanitation" lead to a shift from irrigation with untreated wastewater to irrigation with treated wastewater. This switch leads to a reduction in the input of organic carbon, nutrients and many pollutants. However, the switch can also mobilise pollutants such as antibiotics and disinfectants in the soil that have accumulated there in the past during irrigation with untreated wastewater. We therefore postulate that the implementation of conventional wastewater treatment in established irrigation systems that have used untreated wastewater is associated with hitherto unforeseen risks. These risks result from i) remobilisation of pollutants accumulated in the soil in the past, which ii) lead to pollutant concentrations in soils and plants that cause (co-)selection of antibiotic resistance, where iii) release and concentrations of pollutants as well as selection of antibiotic resistance depend on the soil type. However, a fundamental understanding of the (co)selection processes of resistant bacteria and the transfer of resistance genes under the influence of subinhibitory concentrations of antibiotics and disinfectants and their combinations in soils and plants is still lacking to assess the extent and relevance of these risks. Moreover, colloidal and spatial control factors of these interactions are poorly understood. Little research has also been done on the coupling of the behaviour and effects of antibiotics and disinfectants under subtropical conditions, where elevated temperatures can increase both the selection of resistant bacteria but also the dissipation of organic pollutants to a previously unknown extent. The implementation of wastewater treatment in the world's largest wastewater irrigation system, Mexico City-Valley Mezquital, provides an opportunity to gain the necessary process understanding to assess the above risks. The proposed research group will elucidate the controlling mechanisms of the dynamics of contaminants and multidrug-resistant bacteria during the transition from irrigation with untreated wastewater to irrigation with treated wastewater. Such a research group will also provide a basic process understanding of the interactions between the behaviour of different pollutants and bacteria and the selection and spread of antibiotic resistance in agroecosystems.

Funding: Deutsche Forschungsgemeinschaft