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Gewählte Doctoral Thesis:

Dorothea Summer (2020): SYNERGISTIC COMBINATION OF BIOLOGICAL AND CHEMICAL DEGRADATION OF TETRACHLOROETHENE TO IMPROVE GROUNDWATER CLEAN-UP EFFICIENCY.
Doctoral Thesis - Institut für Bodenforschung (IBF), BOKU-Universität für Bodenkultur, pp 75. UB BOKU obvsg FullText

Data Source: ZID Abstracts

Abstract:: The pollutant Perchloroethene (PCE) can mainly be found on urban sites. This calls for innovative in-situ remediation techniques, like the underground application of zero-valent iron (ZVI) or dehalorespiring bacteria. ZVI reductively dechlorinates PCE but also reacts anaerobically with water producing H2. Dehalococcoides spp. completely dechlorinate PCE using electron donors (e.g.: H2). By combining the two processes controllability of the microbial dechlorination can be increased and needed ZVI amounts reduced, decreasing remediation costs. Within study 1 microcosms experiments investigating the influence of nano-sized (nZVI) and micro-sized (mZVI) ZVI particles on two dechlorinating bacterial cultures with different dehalogenation behaviors: • nZVI inhibits and mZVI stimulates anaerobic bacterial PCE dechlorination • mZVI can start ethene production in an otherwise incomplete degrading culture • H2 produced by ZVI can be used by PCE degrading and methanogenic bacteria • slow H2 formation at low levels by mZVI favors the dechlorinating metabolism A lysimeter experiment with the nZVI and the completely dechlorinating bacterial culture was set-up within study 2. Under field-like, but still very controllable conditions an artificial aquifer was built and the effects of nZVI on the biotic dechlorination was observed for over 350 days: • nZVI increased microbial PCE reduction and ethene formation • nZVI reduced accumulation of hazardous metabolites by bacterial degradation • beneficial effects were pronounced in absence of an additional electron donor • H2 from anaerobic corrosion of nZVI was consumed by the bacteria present The different results of study 1 and 2 regarding nZVI may be due to different spatial distances. While they exist in proximity within microcosms, the bacteria can establish themselves at a distance from nZVI, avoiding disruptive particle agglomeration on bacterial cells, while still benefiting from the H2 produced.; Betreuer: Gerzabek Martin; 1. Berater:; 2. Berater: Schöftner Philipp