Microbial diversity of suspended growth and biofilm in integrated fixed-film activated sludge wastewater treatment systems

Integrated fixed-film activated sludge (IFAS) wastewater treatment is a modification of the conventional activated sludge process (CAS), which incorporates free-floating biofilm carrier media into the suspended growth reactors of the activated sludge process. IFAS systems show potential improvements in the removal of trace organic contaminants (TrOCs) from municipal wastewater, as compared to CAS. This differential removal between IFAS and CAS systems is potentially due to the enrichment of TrOC degrading microbes in the biofilm of IFAS wastewater treatment plants; however, micrbial communities in IFAS suspended growth and biofilm are not well characterized. In this study, six full-scale IFAS-WWTPs were surveyed to characterize the bacterial, archaeal, and fungal populations within the activated sludge and biofilm.