The results showthat the coagulant dose and dye concentration significantly affectthe color removal performance of O. basilicum and the dye con-centration is the most significant parameter. However, pH (withinthe selected range) is not a significant factor in the color removalefficiency of the natural coagulant. The parameters also have nointeractive effects on the response. This means that the modifica-tion of one of the factors does not affect the other factors insidethe working region. Negative coefficient values of the individualfactors, A, B and C, indicate that the factors negatively affect the