Investigation of Arsenic Removal from Drinking Water Using Alum Coagulant

Increasing urbanization and industrialization of cities has led to an increase in pollutants and the production of many toxic elements. One of these pollutants is arsenic, which is known as one of the most toxic and dangerous elements in drinking water. The aim of this study is to investigate the method of minimizing the amount of this toxic substance by coagulation and flocculation in drinking water. In order to determine the optimal conditions for arsenic removal by coagulation and flocculation methods, in the first stage, the optimal pH is determined by Jar test as 6. Then by selecting alum as coagulant, lime as coagulant and the optimal pH, the optimal amount of chemical material is obtained as 7.5 mg/lit. Determining the optimal places in the current situation can be the novelty of this paper. At the end, the residual concentration of arsenic is determined by atomic hydride absorption spectroscopy. According to the concentration of arsenic in the incoming water sample which is equal to 91 micrograms per liter, the Jar test is performed in two stages with alum coagulants. Based on the optimal pH obtained in different concentrations of coagulants and also a constant concentration of coagulants, the arsenic removal efficiency in the best case in alum coagulants reached 88.46%, which is equal to 10 micrograms per liter, which according to the WHO, is an acceptable result. The result of this study indicates that the coagulation and flocculation method with alum coagulant and a constant amount of lime as a coagulant has a high efficiency in arsenic removal.