Exploration and application of emergency treatment methods for thallium pollution in rivers

In recent years, thallium pollution incidents have occurred frequently, and the development of a practical and efficient emergency method for thallium removal has become an urgent need to improve eco-environment risk prevention and ensure drinking water safety. Taking an abnormal incidence of thallium concentration in a river as an example, the effectiveness and feasibility of four methods, including direct coagulation, oxidation+coagulation, oxidation+adsorption and sulfide precipitation, in the emergency treatment of thallium pollution were compared and analyzed. The results showed that the sulfide precipitation method could reduce the thallium concentration from about 5 times above the standard to less than 0.1 μg/L, meeting the limit requirement of thallium in the surface water source of centralized domestic drinking water in Environmental Quality Standards for Surface Water (GB 3838-2002). Maintaining pH in the river in the range of 8-9 through adding sodium hydroxide could effectively reduce the production of H₂S. This method was successfully applied to the emergency treatment of the abnormal thallium concentration incident and achieved good effects.