Avaliação operacional de uma estação de tratamento de esgotos em uma universidade pública

Abstract

The human activities constantly degrade the environment, polluting the soil, the water and the air, therefore actions in the area of sanitation are of great importance to ensure an adequate environment for life. In the Brazilian context, the law No. 11,445 / 2007 establishes the national guidelines for the basic sanitation services and for the National Policy of Sanitation. The implementation of a sewage system, along with its treatment, is part of this national policy and contributes to the environmental pollution control. At the Federal University of Sergipe (UFS), São Cristóvão campus, there is a Wastewater Treatment Plant (WWTP) that, like any WWTP, requires the treatment process to be systematically monitored so that it occurs efficiently. Thus, the purpose of this research was to evaluate the operation activities of the university’s WWTP at São Cristóvão campus, analyzing whether it affects the performance of the treatment stages and fails to comply with environmental legislation. Routine visits to the treatment station were then made, with the purpose of obtaining photographic records and collecting samples to evaluate the physical-chemical performance of the biological units (UASB and oxidation ditch). In order to identify the problems, regarding the Institution, questionnaires were applied to the operators and to the administration of the wastewater treatment plant. At the end of the research, it was verified that the project flow and the raw sewage organic load were overestimated, resulting in the oversize of the treatment station. It was also verified that the COD removal efficiency in the UASB (2,6%) and in the oxidation ditch (2,2%) are much lower than the project had proposed. Nevertheless, the effluent’s BOD meets the Conama Resolution No. 430 standard, mainly due to the low concentration of organic matter in the station affluent. Moreover, it was observed that the tertiary treatment is not occurring properly either, making it necessary the implementation of a routine so that the disinfection of the effluent happens efficiently. Thus, it would be possible to return to the original philosophy of the project to reuse the treated effluent as a source of irrigation for the green areas of the campus. In order for the ETE to function properly, it is suggested: some structural changes at the treatment units, the elaboration of an operation manual detailing all the treatment plant’s activities, the implementation of systematics sampling collection and laboratory analysis, the equipment’s preventive maintenance and the creation of a shift-based work schedule for the operators. It is, therefore, concluded that there are major difficulties for a public educational institution to operate a sewage treatment plant adequately.