Removal of Inorganic Contaminants from Simulated Stormwater by Three Sorbents in Columns Under Intermittent Runoff Condition

Abstract

Combined removal of inorganic contaminants from a synthetic stormwater was investigated by their sorption on hydrous ferric oxide (HFO) (5%), HFO + Ca(OH)2(6%), and HFO + Ca(OH)2 + MnO2 (7%) in columns containing 93–95% anthracite, conducted under seven intermittent runoffs, each of 8 h duration with a 40 h (drying) period between them. At the initial period when Ca(OH)2 produced elevated pHs, the HFO column removed less metals but more Se than the HFO + Ca(OH)2 columns. With increased time when the pH effect of Ca(OH)2 became insignificant, the MnO2 in the column increased the removal of all contaminants. The removal efficiencies (%) at the flow rate of 0.75 m/h for Cd, Cu, Ni, Zn by the HFO + Ca(OH)2 + MnO2 column were 88–100%, and Se by the HFO column were 92–94% for the 1st and 3rd runs. The corresponding values for the 5th and 7th runs were 51–88% and 82–88%, respectively.