AD	Anaerobic digestion
ML	Machine learning
COD	Chemical oxygen demand
LR	Linear Regression
SVR-RBF	Support Vector Regression with a Radial Basis Function
RF	Random Forest
DT	Decision Tree
GBR	Gradient Boosting Regression
KNN	K-Nearest Neighbors Regression
GPR	Gaussian Process Regression
MLP	Multilayer Perceptron
R2	Coefficient of determination
MAE	Mean absolute error
MSE	mean squared error
RMSE	Root mean squared error
AIC	Akaike Information Criterion
LORO-CV	Leave-one-reactor-out cross-validation