Evaluation of Three Dynamic Models for Aerated Facultative Lagoons

Abstract

In this research, three existing dynamic mathematical models for aerated lagoons were applied to an aerated facultative lagoon (AFL) plant for municipal wastewater treatment. The models’ ability to describe the behavior of the primary lagoon was evaluated, and the advantages and limitations of the three models were compared. For this purpose, 7-year operational data from the municipal WWTP were collected and processed; other necessary data—like dynamic temperature values— were estimated. A 2-year period was used for model calibration, while the remaining 5 years served as validation period. One of the models showed poor calibration fit values in the effluent concentration description (R 2 of 0.242 and RMSE of 16.8 mg/L); however, with some modifications the adjust was enhanced (R 2 of 0.409 and RMSE of 14.0 mg/L); a second model displayed a poor to moderate adjust (0.489 and 13.0 mg/L, respectively), and the third model achieved a moderate fit (0.528 and 11.9 mg/L), though it provided an overestimation of effluent concentration, especially in periods of heavy and frequent rain; this model with some adaptations the adjust was enhanced (R 2 of 0.575 and RMSE of 11.4 mg/L). The validation fits are even lower, illustrating the inability of these models to properly describe the AFL behavior. The possible causes of the models’ inadequacy are discussed. Finally, it is established that in terms of AFL behavior description more research and model development are needed.