Estudo de viabilidade do reúso de águas cinzas para fins não potáveis em edifícios residenciais multifamiliares

Abstract

The advancement of urbanization and the challenges of water management, such as the crisis that affected several regions of Brazil between 2020 and 2021, require the urgent adoption of sustainable solutions for water preservation. The construction industry, responsible for high water consumption, must incorporate practices that promote efficiency in using this resource. In this context, the reuse of greywater from activities such as showers, sinks, and laundry emerges as an effective alternative to reduce potable water consumption in multifamily buildings. This study evaluates the technical and economic feasibility of implementing greywater reuse systems in two hypothetical residential buildings in Curitiba, Paraná, considering the collection of greywater from showers and the defined ideal treatment system, which includes the stages of pre-filtration, Compartmentalized Anaerobic Reactor (RAC), Submerged Aerated Biological Filter (FBAS), Secondary Settling Tank (DS), Tertiary Filter (FT), and UV Disinfection. The analysis covers the dimensioning of these treatment stages, estimating the volume of water saved, and comparing installation and maintenance costs with the savings generated in the water tariff. The results indicate that greywater from showers exceeds 46% of the demand for non-potable water in both buildings, reducing the volume consumed by 29.5%. The system implementation generates savings of R$ 11,999.30 in the water tariff for Building A and R$ 5,437.00 for Building B, with a payback period of 0.8 years and 3.5 years, respectively.