was employed with a local linear regression matrix and normal kernel settings. 40, The bandwidth, which is the window width of the kernel and thus determines the degree of smoothing, was set differently depending on the characteristics of each sensor signal. In particular, for orthophosphate and TSS, the offsets (or shifts) of the sensor data were further corrected based on daily on-site laboratory measurement data. To adjust the incorrect baseline of the online monitoring data, the interpolated difference between the on-site laboratory analysis data and the original sensor signals was added to the smoothed sensor data.