Joint project

Funder: German Research Foundation

Period: 2021-2025

URI: https://gepris.dfg.de/gepris/projekt/462480103

Detailed description: 
Using wastewater for irrigation in agriculture is a critical opportunity to increase water use efficiency, alleviate water scarcity and increase food production. Treatment of wastewater prior to agricultural use is generally recommended to reduce environmental and health risks. Switching from irrigation with untreated to irrigation with treated wastewater leads to a reduction in the input of organic carbon, nutrients and many pollutants. However, switching to treated wastewater irrigation may also mobilize pollutants that have historically accumulated in the soil 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 previously unforeseen risks. These risks arise from the remobilization of pollutants that have accumulated in the soil in the past, which leads to pollutant concentrations in soils and plants that cause (co-)selection of antibiotic resistance and ii) through a subsequent increased selection and spread of resistant bacteria and resistance genes. However, in order to assess the extent and relevance of these risks, a fundamental understanding of the (co-)selection processes of resistant bacteria and the transfer of resistance genes under the influence of sub-inhibitory concentrations of antibiotic active ingredients and disinfectants and their combinations in soils and plants is missing. Furthermore, spatial and sorptive control factors of these interactions are poorly understood. The coupling of the behavior and effects of antibiotics and disinfectants under subtropical conditions, under which elevated temperatures can increase both the selection of resistant bacteria and the dissipation of organic pollutants to a previously unknown extent, has also hardly been investigated. The implementation of wastewater treatment in the world's largest wastewater irrigation system, Mexico City-Valle Mezquital, offers the opportunity to gain the necessary process understanding to assess the risks mentioned above. The proposed research group will elucidate the controlling mechanisms of pollutant and multidrug-resistant bacteria dynamics during the transition from irrigation with untreated wastewater to irrigation with treated wastewater. Such a research group will also provide a fundamental process understanding of the interactions between the behavior of different pollutants and bacteria as well as the selection and spread of antibiotic resistance in agroecosystems.