Introduction: High volumes of wastewater along with contaminants, such as colloids and dyes are discharged from different industries into the environment. These wastewaters create major problems and serious threats for water resources. Therefore, it is essential to treat such wastewaters and reach the effluent discharge standards. In this regard, chitosan as a coagulant has a comparable performance with other coagulants. Moreover, the addition of chitosan and removal of turbidity probably lead to higher efficiency of nanoparticles in lower dosages which is investigated in the current study. Therefore, the purpose of this study was to investigate the efficiency of chitosan and magnesium oxide (MgO) nanoparticles for the removal of color and turbidity.
 
Materials & Methods: Synthetic wastewater was prepared by mixing specific amounts of bentonite and direct blue 71 dye in distilled water. After the preparation of different concentrations of color and turbidity, the experiments were conducted with different dosages of chitosan and MgO separately and in combination. The influence of variables such as pH, initial concentration of dye and turbidity, MgO and chitosan dosages on removal efficiency was investigated in this study.
 
Fidings: According to the results, the highest rate of color and turbidity removal was obtained at 1.5 mg/L chitosan in combination with 1.5 g/L MgO with the efficiency of 97.5%. In addition, the highest removal efficiency was obtained at pH of 7.
 
Discussion & Conclusions: Due to the need for high doses of MgO in high turbidities, the use of chitosan as a coagulant can be effective in reducing the use of MgO.