Estudo de campo e acoplamento do Cormix2 ao Delft3D para simulação da descarga de efluentes sanitários no rio Guamá, Belém-PA

Abstract

Rapid population growth in several Brazilian cities has occurred along the banks of their main water bodies and has often not been accompanied by adequate sanitation infrastructure, resulting in the indiscriminate discharge of domestic and industrial effluents and cousing environmental pollution. Due to the increasing need to implement new Wastewater Treatment Plants (WWTPs), the use of computational modeling to investigate efluent dilution in receiving water bodies has become an essential management tool for evaluating such projects. Therefore, the study aimed to implement and evaluate the offline coupling between the near-field model CORMIX2 and the far-field model Delft3D-WAQ to simulated treated effluent from the Mártir WWTP discharged through a multiport diffuser into the Guamá River, in Belém, Pará, Brazil. To support the computational simulations, bathymetric surveys, current profile measurements, and water quality assessments were conducted along the river reach considered to be the area influenced by the influence of the effluent discharge. The plumes simulated with CORMIX2

were georeferenced in Civil 3D according to the hydrodynamic fields generated by Delft3D- FLOW. The coupling results showed that, in well-mixed estuaries characterized by low effluent

discharge rates and ambient thermotolerant coliform concentrations substantially higher than the effluent concentrations at the end of the Regulatory Mixing Zone (RMZ), the far-field

dilution estimates generated by CORMIX2 were consistent with those calculated by Delft3D- WAQ. Under these conditions, CORMIX2 alone was sufficient to estimate concentrations in

both the near and far fields. Furthermore, the designed outfall met the applicable regulatory requirements, at the estimated concentrations at the end of the RMZ remained below the limits established by Brazilian environmental legislation. Negatively buoyant discharges were also found to represent the critical condition for near-field dilution.