COMBINED EFFECTS OF CU2-SLUDGE PROCESS( AND ZN2+ ON ACTIVATED)

The aim of this study is to investigate the combined effects of Cu2+ a nd Zn2+ in a synthetic wastewater (WW) on activated sludge process (AS P) over a wide range of mean cell residence times. Experiments were pe rformed in two phases: (i) experiments without heavy metals (HMs), (ii ) experiments with HMs using acclimated microorganisms (MOs). In the f irst phase, biokinetic constants of the synthetic WW inoculated with s eed MOs were determined and a linear relationship between substrate re moval efficiency and mean cell residence time was found. In the second phase, experiments were conducted with acclimated MOs for processing a WW containing 1.5 mg Cu2+/L and 9 mg Zn2+/L. A variable relationship between substrate removal efficiency and mean cell residence time was obtained. The net result of the presence of Cu2+ and Zn2+ in a synthe tic WW was found to be toxic to the MOs in ASP. (C) 1997 Elsevier Scie nce Ltd.