Fig. 2.

Principal component analysis (PCA) of physicochemical parameters in influent and effluent samples from WWTP A and WWTP B. Points show individual samples (color = WWTP, shape = stage), and the first two components explain 42.69% and 18.23% of the variance. Dashed ellipses indicate 95% confidence intervals for each WWTP, highlighting within-plant variability and the overall separation between influent and effluent.