Landelijke organisatie

Effect of different types of dissolved organic matter and redox conditions on micropollutant biodegradation by aquifer microbial community

25 oktober 2021

Eline Anvik

Groundwater, the largest body of freshwater in the European Union (EU), supplies drinking water to about 75% of its residents. Nevertheless, micropollutants, such as pesticides, pharmaceuticals and industrial substances, are detected in European groundwater above the concentration limits set by the EU (0.1 μg/L for individual pesticides and 0.5 μg/L for total pesticides). Removal of micropollutants at the source of contamination is difficult given its diffuse and diverse nature. Micropollutants can enter the water cycle either from point sources, as wastewater treatment plants (WWTPs), or diffuse sources, such as landfills and agricultural fields treated with pesticide or manure. To ensure safe drinking water, drinking water production relies on energy-intensive adsorption or advanced oxidation technologies.

Biodegradation, the major process for natural attenuation of xenobiotics in the environment, could be a cost-effective and sustainable solution. However, groundwater is often oligotrophic and many aquifers are anaerobic, which limits in situ microbial activity and thus micropollutant biodegradation. Recent studies have shown that amendment with dissolved organic matter (DOM) can enhance biodegradation. Therefore, a DOM-based in situ bioremediation technology could be developed to remove micropollutants in groundwater (Figure 1). However, little is known about the mechanism by which DOM supports micropollutants biodegradation.

The aim of this study is to understand how DOM amendment can be used to enhance in situ micropollutant biodegradation in groundwater. Therefore, we investigated the biodegradation of micropollutants frequently found in groundwater by an aquifer microbial culture under two redox conditions, i.e. aerobic and nitrate reducing. The effect of DOM sources with different biodegradability, such as acetate, dextran and humic substances, on micropollutant degradation was evaluated. By monitoring micropollutant transformation, DOM and electron acceptor consumption, as well as microbial community composition and the presence of functional genes for micropollutant degradation, we aim at understanding how different DOM types can enhance micropollutant biodegradation. This is thus a first step towards developing an in situ micropollutant bioremediation technology.

Source: Branco, R. H. R. 2021. Effect of different types of dissolved organic matter and redox conditions on micropollutant biodegradation by aquifer microbial community. Quality assurance, Biodegradation and tools for its assessment. Risk & Resilience. AIWW 2021.