Identifying REE impacts on wastewater microorganisms

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Over time, bioreactors treated with REE lost the ability to oxidize ammonia.  DNA sequencing revealed changes in microbial community composition that explain the loss of nitrogen metabolism (less Nitrospira) as well as shifts in other microbial clades.

CMI scientists at Colorado School of Mines conducted this research.

Identification of shifts in microbial community and treatment performance caused by rare earth element addition to model wastewater treatment systems.

Significance and impact:

  • Above certain concentration thresholds, Y and Gd induce significant changes to wastewater-relevant microbial communities
  • These shifts can result in a negative impact to wastewater treatment performance


  • Bench-scale aerobic bioreactors were seeded with activated sludge from a local wastewater treatment facility and maintained under stable dissolved oxygen and pH conditions
  • Bioreactors fed synthetic wastewater spiked with varying concentrations of Gd or Y
  • Nitrification shut down in reactors treated with 50 ppm Gd or Y

Next steps:

  • Literature search into functional roles of differentially abundant microorganisms upon REE treatment
  • Metagenomics to identify genes involved in wastewater treatment that are differentially abundant