highly significantp = 0.0001
According to the model fit statistics, the quadratic model is suggested to be highly significant among linear, 2-factor interactions (2FI), and quadratic models for turbidity ( p = 0.0001), COD ( p = 0.0004) removal, and residual Al ( p = 0.0274) implying high correlation coefficient (R 2 ) values, 0.9831, 0.9838, and 0.9775, respectively.