Abstract: | The effect of shock-loading of zinc, copper and cadmium ions on the removal of total organic carbon (TOC) and phosphate in an anaerobic-aerobic activated sludge process was investigated. TOC removal was not sensitive to shock-loading of Zn2+ and Cd2+ ions, and complete removal was achieved even at 20 mg Zn2+/l and 20 mg Cd2+/l. However, with over 1 mg Cu2+/1 TOC removal efficiency decreased. PO
inf4
sup3-
removal, in contrast, was extremely sensitive to these metal ions, with the threshold being 1 mg Zn2+/l and 1 mg Cd2+/l. Higher concentrations adversely affected PO
inf4
sup3-
removal. Copper again proved detrimental; no PO
inf4
sup3-
removal was achieved even at 1 mg Cu/l. These results highlight the sensitivity of the removal efficiencies of TOC and PO
inf4
sup3-
to shock loadings of these heavy metals.Y.P. Ting is with the Department of Chemical Engineering, National University of Singapore, Kent Ridge, 0511, Singapore; H. Imai and S. Kinoshita are with the Department of Chemical Process Engineering, Hokkaido University, Sapporo 060, Japan. |