Análise comparativa dos custos operacionais de 44 estações de tratamento de esgoto na região sudeste do Brasil.

Abstract

Less than 50% of domestic sewage generated in Brazil are treated before their disposal in the environment, causing environmental hazard in the long term. The low rate of wastewater treatment can be explained by the high costs involved in the construction and operation of treatment plants, which are often carried out without proper planning, making sewage treatment economically unfeasible for municipalities and utilities. In this sense, 44 WWTPs from the Southeast region of Brazil were analyzed, aided by statistical tests, and compared. The treatment processes and the population equivalent of the station were analyzed, in order to supply data for future feasibility studies. The operational costs were analyzed, also, by the idleness of the stations and by the seasonality of flows. It was verified that costs per cubic meter of treated sewage presented a large variation from one WWTP to another, with great influence of the flow treated in the operational costs, and the Lagoons group had the lowest median of operational costs (median R$ 0.40/m³). The overall median of operational costs for all stations was R$ 0.96/m³, and the highest operating cost was R$ 4.67/m³, for WWTP 04, with a population equivalent of less than 5,000 inhabitants and whose treatment is performed by UASB reactor. The lowest operating cost was R$ 0.13/m³, for the WWTP 43, with a population equivalent of over 50,000 inhabitants and a treatment process by UASB reactors followed by trickling filters.