Figure 1.

Experimental design of the study. Two MBBRs R1 (spiked) and R2 (unspiked control) were continuously supplied with wastewater. The wastewater supplied to R1 was spiked with a mix of five micropollutants in monthly increasing concentrations; from 0.1 mg L⁻¹ to 10 mg L⁻¹ (held for two months). Whereas R2 acted as the control receiving the wastewater unspiked. Each month carriers from R1 and R2 were sampled for 1) Total RNA analysis and 2) inoculation in batch cultures. The batch cultures were conducted in serum bottles in triplicate, which contained a mix of micropollutants at 10 mg L⁻¹ of each. The yellow bottles represent the treatments inoculated with biofilm carriers housing active microbiomes, and the pink bottles represent the treatment where biofilm carriers were sterilized (controls). *T₀ batch microcosms were created using carriers taken from the pre-treatment reactors immediately prior to all the carriers being distributed evenly between the two reactors R1 and R2.