Desempenho ambiental e energético do tratamento de esgotos sanitários por meio da associação do processo anaeróbio e wetlands construídos

Abstract

The negative environmental impacts associated with wastewater treatment affect the quality of environmental compartments and should be discussed by decision-makers, as the entire production chain associated with this activity must be considered, and not only compliance with treated effluent discharge standards recommended in environmental legislation. In this context, the Life Cycle Assessment (LCA) is a widely used tool to assess the environmental impacts of wastewater treatment plants (WWTP) in the world. Considering that in developing countries, such as Brazil, there is a lack of LCA studies applied to wastewater treatment, this thesis analyzed the applicability of LCA for evaluating the potential environmental impacts of the sewage treatment process. The technological arrangement that associates the UASB reactor and constructed wetlands, including the construction and operation phases and the potential for recovering resources from this technological arrangement in small municipalities with a population of fewer than 5,000 inhabitants were considered. A detailed Life Cycle Inventory (LCI) was prepared including the collection network, preliminary treatment, solid-phase treatment process, sludge disposal, and the quality of the final treated effluent, in full scale, also evaluating the applicability of the technique from the choices made in the preparation of the ICV using the databases available in the SimaPro® software. The results indicated that the impacts associated with the construction phase of the WWTP should not be neglected. Also noteworthy is the great potential impact of the WWTP studied for the increase in global warming, due to methane emissions from the UASB reactor to the atmosphere. The results of the analysis of the choice of database processes showed the differences in the contribution of the impact potential according to the process coming from the database used, available in the software. For the evaluation of the proposed scenario, the results showed significant environmental gains with the recovery of resources, highlighting the potential of biogas recovery as a quick transition solution to combat the climate crisis. In addition to pointing to the potential for the recovery of resources in municipalities with a population of fewer than 5,000 inhabitants, made invisible by the government, as an alternative to achieving the goals of universal sanitation with environmental, social, and economic gains. Finally, it was concluded that the study contributed to the inclusion of the environmental aspect in the discussion of the sustainability of sewage treatment systems in Brazil and developing countries.