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Yetiş, Ülkü
There is little information in the literature to describe the effects of heavy metals on activated sludge kinetics. The purpose of this study is to evaluate the toxic effect of nickel on activated sludge. Different concentrations of Ni(II) (5.0, 10.0 and 25.0 mg l−1) were maintained in a laboratory-scale completely mixed activated-sludge unit, without recycle, treating, simulated wastewater. The feed solution contained 650 mg l−1 protein (corresponding to 1300 mg l−1 COD) as a source of carbon. Experimental results indicated that the treatment efficiency was not adversely affected by the presence of nickel up to a concentration of 10.0 mg l−1. However, a concentration of 25.0 mg l−1 Ni(II) caused serious upsets in the system, while 5.0 mg l−1 Ni(II) in feed solution had some stimulatory effects. The maximum specific growth rate, μm, of the culture also doubled when the nickel concentration was 5.0 mg l−1 and better floc formation was noticed at this nickel concentration.