Influence of selector technology on heavy metal removal by activated sludge: Secondary effects of selector technology

The purpose of this research is to compare the ability of metal removal between an aerobic selector activated sludge system and a conventional CSTR system. Metal biosorption by sludge harvested from experimental systems was determined by a series of batch experiments. Heavy metals studied in this research were zinc, cadmium and nickel. Results of experimental data revealed that metal biosorption by activated sludge was rapid; about 70% of the soluble metals in solution was removed during the first 30 min. The sorption isotherm showed that at metal equilibrium concentrations greater than 0.05 mg/l, the selector sludge had significantly higher sorption capacity than did the CSTR sludge. Metal biosorption behavior closely followed a Freudlich isotherm model for equilibrium concentrations above 0.05 mg/l. Results of the Freundlich model suggested that the adsorption capacity of sludge from the aerobic selector was significantly higher than that of the CSTR system.