In this paper, the effect of various inorganic anions, NO3-, HCO3-, SO42-, Cl-, and H2PO4-, in the removal of C.I. Acid Red 17 (AR17), as a model dye pollutant, was investigated in the presence of TiO2 nanoparticles immobilized on a glass plate and optimized using the Taguchi method. Sixteen experiments were required to study the effects of anions in different concentrations. It was found that the nature and concentration of inorganic anions significantly affected the removal rate of AR17 in the presence of immobilized TiO2. The results indicated that high concentrations of NO3- and HCO3- especially in combined mode can improve the AR17 removal rate in the presence of supported TiO2. For the first time, we reported 22 firms increase in the AR17 removal rate in the presence of immobilized TiO2 with combined inorganic anions. Among the mentioned anions, NO3- ions had the most contribution in increasing the removal rate and H2PO4- ions had the highest role in decreasing it. Results indicated that this method can be a useful, promising, and cost-effective method for increasing removal rate of organic pollutants in the fixed-bed system.