Monitoring of bacterial biodiversity in anaerobic membrane bioreactors (AnMBRs) dealing with wastewater containing X-ray contrast media compounds

Iodinated contrast media compounds (ICM) have been identified in wastewater within the last 20 years. In this study, the biodiversity of activated sludge in anaerobic membrane bioreactors dealing with synthetic hospital wastewater with addition of ICM was investigated, using fluorescent in situ hybridization (FISH) and denaturing gradient gel electrophoresis (DGGE). During the adaptation of microorganisms to anaerobic growth conditions and to ICM presence, differences in the content of Alpha- and Betaproteobacteria were noted and bioreactors showed higher biological diversity (H = 2.9), suggesting that ICM were not toxic to the bacteria. The long sludge age had the strongest influence on the composition of activated sludge biocenosis.