Fig. 1: Dual-axis time-series plot of ciprofloxacin concentration and biofilm TCCs.

The ciprofloxacin (CIP) concentration in the bulk water of BWDRs A, B, and C is connected by solid lines, and its axis is found on the left. The biofilm TCCs in each BWDR, including the control (D) that was not exposed to ciprofloxacin, are connected by dashed lines and its axis is found on the right on the base-10 log scale. After 12 days, the ciprofloxacin was completely removed from the bulk water of BWDRs A, B, and C. Each point represents the mean (n = 3 independent samples), and the error bars indicate the standard deviation. Lines connecting mean values represent the rates of change.