Fig. 13
![Fig. 13](http://media.springernature.com/full/springer-static/image/art%3A10.1186%2Fs13750-020-00211-x/MediaObjects/13750_2020_211_Fig13_HTML.png)
PO4–P removal as a function of pH and Mg to PO4 ratio. The additive GAM model is presented on the left, and the thin plate model on the right
PO4–P removal as a function of pH and Mg to PO4 ratio. The additive GAM model is presented on the left, and the thin plate model on the right