Effect of Acetaminophen in a Membrane Bioreactor: Changes in Microbial Community Structure and Treatment Efficiency

The effects of varying acetaminophen (APAP) concentrations on organic matter and nutrient removal, as well as microbial communities, were investigated using a lab-scale membrane bioreactor (MBR). After APAP exposure, COD and TOC removal remained high at 95 ± 2.5% and 96 ± 1.5%, respectively, while nitrogen and phosphorus removal decreased to 60 ± 5.3% and 60 ± 3.4%. To clarify the microbial basis of this decline, 16S rRNA gene-based metagenomic analysis was conducted. The relative abundance of Nitrosomonas and Nitrospira, key nitrifying genera, decreased by about 3.2-fold at 50 ppm of APAP. Acinetobacter, a representative PAO (polyphosphate accumulating organisms), also declined by 1.9-fold. These microbial shifts likely contributed to reduced nutrient removal under APAP influence, supporting previous findings that high APAP levels negatively affected microorganisms crucial for biological treatment.