The presence of micropollutants in groundwater threatens drinking water resources. Dissolved organic matter (DOM) is an important groundwater component and potentially a key factor to enhance the natural attenuation of micropollutants in groundwater. Micropollutants can be co-metabolized during bioconversion of DOM. In addition, specific DOM can act as a structural analogue, whereby it primes the microbial community to produce enzymes also capable to degrade micropollutants. This research will first investigate the biodegradation of micropollutants, relevant for drinking water safety, in presence of different DOC fractions (incl. humic and fulvic acids) and for different redox environments by mixed microbial cultures indigenous to aquifers. Elucidating co-metabolism and other dependencies between micropollutants biodegradation and DOM represents a novel scientific challenge. We will follow DOM and micropollutants transformations to unravel the underlying mechanisms. Subsequently, using continuous columns mimicking aquifer conditions, DOM dosing will be optimized in order to develop an in situ treatment method.