The characteristic and treatment of wastewater in tin and galvanized plating industries were investigated in this study. This study showed that such wastewater contains heavy metals like chromium, iron, and tin having concentrations of 1176.47, 130, and 11 mg/L, respectively. The results also indicated that by adding sodium bisulfate and a coagulant aid such as ferric chloride and lime, coagulation and flocculation is the effective method for the treatment of the Wastewater. The results indicated that:
Sodium bisulfate with the optimum concentrations of 50 and 3120 mg/L can remove about 99% of chromium from chromic acid and sodium dichromate wastewater.
Ferric chloride with the optimum concentration of 5 mg/L can remove 90.86%, 98.28%, and 99.73% of the heavy metals such as chromium, iron, and tin from this wastewater.
Lime with an optimum concentration of 2.5 mg/L can reduce the ferric chloride to 3 mg/L, and can remove 97.11% of the heavy metals such as iron, chromium, and tin from the wastewater.The results also show that ferric chloride with the highest effectiveness for the removal of heavy metals and the lowest sludge production is the best coagulant for this wastewater and that lime together with ferric chloride is very effective in the removal of heavy metals.