Redox sensitivity and long-term persistence of organic trace pollutants in groundwater - wastewater-bound compounds

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The increasing pollution of the aquatic environment with numerous organic micropollutants such as pharmaceutical residues is a problem of alarming global dimensions. Preliminary studies have shown that it is necessary to correlate the behaviour and degradation (and likewise persistence) of organic micropollutants in groundwater with the prevailing transient hydraulic and hydrochemical (in particular redox) conditions in the field in order to identify the key parameters controlling their elimination. The proposed research will investigate the behaviour of wastewater- bound organic micropollutants in groundwater with a particular focus on their redoxdependent biodegradation and long-term persistence. A “redox screening”, where anoxic groundwater contaminated with wastewater residues will be incubated under anoxic or oxic conditions, will first be done to identify redox-sensitive compounds. It will be accompanied by field investigations on contaminated groundwater downstream of former sewage irrigation fields, which will be analysed for organic micropollutants and dated with the tritium/helium method. The results will deliver information on the long-term persistence of the micropollutants under the given hydrochemical conditions. More detailed column studies under variable redox conditions will be conducted mimicking field conditions. Finally, reactive transport modelling will be carried out to confirm developed conceptual models and to derive degradation rate constants in relation to the redox regime.