Toxic Effects of Metals on Microbial Activity in the Activated Sludge Process

F. Carta-Escobar, P. Álvarez-Mateos, F. Romero-Guzmán and J. Pereda Marín

Abstract
The toxic effects of the metals cadmium, zinc and copper on microbial activity in the activated sludge process, are reported. The dissolved metals were added to the process in synthetic wastewater with a COD of 520 mg L–1. Metal toxicity was determined by the reduction in activity levels of variables such as the specific oxygen uptake rate and mass fraction of active cells present in the reactor. The results have permitted establishment of the following toxicity sequence: Cd > Cu > Zn.

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Keywords
anoxic/aerobic systems, aerobic biological treatment, Batch reactor, bio-mineralization, dairy industry, nitrification