Characteristics of residual metals from phosphorus removal in sewage treatment plants around Paldang lake, Korea

AbstractThe abundant use of chemicals to remove phosphorus in water could pose a problem to the safety of drinking water. In this study, we investigated the amount of residual aluminum and iron remaining in river. Paldang lake consists of two major tributaries (North Han River and South Han River) and one minor tributary (Gyung-an Stream). As a result of a total inspection on 45 phosphorus removal treatment plants in Paldang watershed of Han River, it was found that 39 treatment plants used aluminum-related coagulants while six treatment plants used iron salts. We investigated aluminum and iron concentrations in influent and effluent from six representative phosphorus removal treatment plants (A–F) in three tributaries and found that iron concentrations in A and C and aluminum concentrations in B and D exceeded drinking water standards. The background concentrations of aluminum and iron not affected by treatment plants nearby were 0.04–0.20 and 0.09–0.11 mg/L, respectively. In sediments, the background co...