... sites in China were the major incidents of arsenic contamination in groundwater. Between 2000 and 2005, arsenic- related groundwater problems have emerged in different Asian countries, including ... (Table 2). In AIRUs (I~IV), in spite of having adequate iron concentrations of 3.4~6.9 mg/L in the influent water to enable adsorption and co-precipitation of arsenic, the effluent arsenic concentrations ... (Choprapawon and Rodcline, 1992). The people of this district use water, which drains from the highly-contaminated areas of the Suan Jun and Ronna Mountains having 0.1% arsenopyrite. Mobility of arsenic...