The present study aimed to evaluate the use of Upflow Anaerobic Sludge Blanket (UASB), and physical-chemical treatment systems to reduce the organic load (TOC) and total phosphorus for wastewater final disposal by submarine outfall at Santos Bay, Santos-SP. The evaluation was performed using the software UASBWARE to estimate the effluent quality and the software CORMIX to verify the influence of treatment in the near field water quality. These results show that a secondary treatment instead of preliminary treatment together with the improvement of diffuser system has an environmental benefit complying with quality standards of Brazilian legislation in the near field.