One of the environmental consequences of industrial estates is the creation of environmental pollution, including the production of industrial wastewater. In this research, the main objective is to investigate the effect of coagulants and nano-coagulants in different concentrations to reduce the BOD of industrial wastewater using the Taguchi statistical method. Two chemicals, ferric chloride and aluminum sulphate, and two nanoparticles of iron oxide and alumina, were used as coagulants in the wastewater flocculation process at Beshel industrial complex. A L16 orthogonal array with the four factors of control at four levels each and two interactions was employed for optimization of coagulants and nano-coagulants concentration to reduce biological oxygen demands (BOD) in industrial wastewater. The optimal conditions were obtained concentration of ferric chloride 0.8 g/l, concentration of iron oxide nanoparticles 3 g/l, concentration of aluminum sulphate 1 g/l and concentration of alumina nanoparticles 1.5 g/l to achieve the highest percentage of BOD reduction.