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Accueil du site → Doctorat → Mexique → Modelación dinámica de la demanda de oxígeno en una laguna aireada facultativa primaria : exceso de sustrato, limitación de oxígeno y efecto de los episodios de lluvia (región semiárida de México San Luis Potosí, SLP)

Universidad Autónoma del Estado de San Luis Potosí (UASLP) 2016

Modelación dinámica de la demanda de oxígeno en una laguna aireada facultativa primaria : exceso de sustrato, limitación de oxígeno y efecto de los episodios de lluvia (región semiárida de México San Luis Potosí, SLP)

Ábrego Góngora, Carlos Joel

Titre : Modelación dinámica de la demanda de oxígeno en una laguna aireada facultativa primaria : exceso de sustrato, limitación de oxígeno y efecto de los episodios de lluvia (región semiárida de México San Luis Potosí, SLP)

Auteur : Ábrego Góngora, Carlos Joel

Etablissement de soutenance : Universidad Autónoma del Estado de San Luis Potosí (UASLP)

Grade : Doctorado en Ciencias Ambientales 2016

Résumé
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. Also , four dynamic aerated lagoon models based on completely - mixed flow were developed and evaluated in a primary surface - aerat ed facultative lagoon belonging to a municipal 4 - lagoon treatment train in a semiarid region of Mexico (San Luis Potosí, SLP) with episodic heavy rains. The models were calibrated with data from a 2- year period, and validated against a different 5- year per iod at the same lagoon. Regarding the existing models : One of them 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 R MSE 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 ; with some modifications the fit of this model 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 possib le causes of the models’ inadequacy are discussed. Regarding the models developed and evaluated in this research : The first model, a modification of an existing 3- compoment model (BOD or COD, VSS, dissolved oxygen) showed a poor description of the lagoon behavior, especially for VSS. Since modeling oxygen demand variables was the main focus of the study, the 3- component (3C) model was simplified, leaving oxygen demand (either COD or BOD) as the sole state variable (1C model). Since substrate excess and oxy gen deficiency prevail in this primary lagoon, oxygen supply was assumed to be limiting for the degradation dynamics. This new model, although much simpler than the 3C model, provided a similar description of the substrate in effluent. However, the 1C mode l, like the 3C model, tended to overestimate substrate concentrations during seasonal heavy rain episodes. Three modifications to the model (1C2 1C3 and 1C3r) were introduced to account for the observed lower oxygen requirements per unit substrate during r ainy periods. These 1C models provided a clearly better description of COD and BOD behavior (R 2 up to 0.71 in calibration). In summary, a single component, oxygen- transfer- driven model (1C3) accounting for specific behavior during heavy rain episodes was able to give a fair to good description of COD and BOD in the primary lagoon. Additionally, a dynamic version of an existing steady - state thermal model provided a good to excellent estimate of the lagoon temperature : R 2 = 0.918, and root mean square error (R MSE) of 0.84 C. These models are proposed as a novel, simpler approach for modeling non- icing primary lagoons, while accounting for temperature and rainfall - linked flow peaks

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Page publiée le 21 septembre 2017