Clean groundwater is an essential source of drinking water. However, its quality is threatened by contamination with organic micropollutants (OMPs) arising from our use of pharmaceuticals, household chemicals, and pesticides. This presentation introduces the challenges of OMPs in drinking water aquifers, and elucidates proper conditions for engineering OMP biodegradation in oligotrophic, anaerobic groundwater.
Overcoming the oligotrophic conditions in drinking water aquifers is key to OMP biodegradation. Particularly important is dissolved organic carbon (DOC), as DOC dictates microbial activity and OMP biodegradation. Research suggests that the OMP-degrading community utilises DOC as an occasional substrate to sustain growth, while incidentally degrading OMPs. Our results show that groundwater DOC does not sustain OMP biodegradation. We explored if dosing natural DOC can stimulate OMP biodegradation.
In column experiments, we showed that dosing DOC supports OMP biodegradation. This DOC was used as a substrate for metabolic activity and biomass growth. The experiments simulated a variety of conditions typical for groundwater, namely the presence of different terminal electron acceptors and low flow conditions. Most biodegradation was observed coupled to nitrate as terminal electron acceptor, indicating that nitrate-reducing conditions were most favorable.
Furthermore, we explored the capacity of natural groundwater microorganisms to biodegrade OMPs. In batch experiments using natural groundwater containing indigenous microbial communities, we showed that groundwater microorganisms have the capacity to biodegrade OMPs. However, these microorganisms are not active under natural groundwater conditions. Stimulation with easily biodegradable DOC and incubation under aerobic conditions was required to support OMP biodegradation.
This research provides two key insights. First, these results provide insight into the fate and transformation of OMPs in natural groundwater conditions, which support drinking water companies in protecting their aquifers. Secondly, the results on stimulating OMP biodegradation by dosing DOC is a first proof-of-principle for an in situ OMP remediation technology.
