Abstract:The arsenic residue produced by chemical precipitation treatment of arsenic-containing wastewater is usually unstable and easily leads to arsenic leakage, which will cause serious pollution to the environment. In this study, an arsenic removal method with high arsenic removal efficiency and stable solid arsenic residue was adopted. Besides, the effects of initial pH, Fe/As molar ratio and ferric sulfate dropwise addition speed on the removal efficiency of arsenic and iron, crystallinity, morphology and leaching toxicity of scorodite were investigated. The experimental results showed that the increase of initial pH and Fe/As molar ratio was beneficial to improve the arsenic removal efficiency, but it would lead to the decrease of the crystallinity and content of scorodite in residue. High ferric sulfate droplet acceleration rate was beneficial to the reaction efficiency, but not to the purity of scorodite. The precipitation rate of arsenic was 97.24% and the leaching toxicity was 0.75 mg/L under the conditions of initial pH of 1.5, Fe/As molar ratio of 1.5, ferric sulfate droplet acceleration rate of 40 mL/h and drip time of 1.125 h.