Effects of Heavy Metals on Activated Sludge Process

Abstract

The purpose of this study was to evaluate the toxic effects of various heavy metals on activated sludge process. Different concentrations of Cu(II) (0.5, 1.0, 5.0, and 10.0 mg/l), Ni(II) (5.0, 10.0, 25.0 mg/l), and Cr(VI) (1.0, 5.0, 10.0, 25.0, 50,0 mg/l) were maintained in a laboratory-seale completely mixed activated sludge unit, without recycle, treating simulated wastewater. The feed solution contained 650 mg/l protein (corresponding to 1300 mg/l COD) as a source of carbon. Experimental results indicated that the treatment efficiency was not adversely affected by the presence of these heavy metals up to 10.0 mg/l Cu(II), 10.0 mg/l Ni(II) and 50,0 mg/l Cr(II) concentrations. Moreover, some stimulatory effects of these heavy metals on the biokinetic parameters; maximum specific growth rate and half-substrate saturation coefficient were observed.