COMPREHENSIVE FATE MODEL FOR METALS IN MUNICIPAL WASTE-WATER TREATMENT

A model was developed for predicting the fate of metals in municipal wastewater treatment. The model, which incorporates metal solubility and sorption onto solids, was calibrated with experimental data obtained by a titration technique. The calibrated model was evaluated using dynamic data collected in a separate study from three Ontario wastewater-treatment plants (WWTPs). A goodness-of-fit test was employed to determine if the model predictions were statistically different from the observed effluent concentrations. Predictions of copper and zinc effluent concentrations at two WWTPs were found to lie within the confidence limits defined by the variability of field replicates. Lack of fit of some model predictions was attributed to biasing of the data at low concentrations and lack of model calibration. The configuration of the model was concluded to be correct since the behavior of metals with significantly different physical properties were well predicted. It is concluded that the most accurate model predictions can be made if the model is calibrated at the specific WWTP.