ANÁLISE COMPARATIVA DO TRATAMENTO DE ESGOTO DOMÉSTIMO E CUSTO-BENEFÍCIO DA TECNOLOGIA DE IODO GRANULAR AERÓBICO EM RELAÇÃO AO SISTEMA DE UASB, SEGUIDO DE IODOS ATIVADOS

Abstract

Nowadays, the low rates of the Brazilian population served with domestic sewage treatment systems are being hotly debated. The current number is 45%. One of the causes that compromises the progress of this index is the investment required for the construction and operation of efficient treatment plants about concerning the removal of organic matter and nutrients. In the 1990s, the Dutch company Royal-HaskoningDHV began jointly with the University of Delft the development of aerobic granular technology, which has already been deployed in 17 countries worldwide, such as the United Kingdom, Ireland, the Netherlands, Portugal, and South Africa, with 71 plant projects, 30 of them in operation. In Brazil, the technology was brought by BRK Ambiental in 2016, as an alternative to conventional activated sludge systems. In this study, the advantages of adopting this technology for the treatment of domestic sewage within the Brazilian scenario were evaluated through a comparative study with the UASB system followed by activated sludge. It was used full-scale treatment plants located within the municipality of Rio Claro, in the state of São Paulo. The results showed that after eleven months from the startup period, the plant that adopted the aerobic granular technology, presented 54% of the aerobic granules formed in its reactors with diameters greater than 0.2 mm, which allowed total phosphorus and total nitrogen concentrations in the treated effluent to be 41% and 64,7% lower, respectively, than the concentrations found in the treated effluent of the UASB system followed by activated sludge plant. The comparative economic analysis, which considered unit operating and construction costs of each plant, showed an increase of U$ 4,16 million in the Net Present Value of a 30 years project that adopted the aerobic granular technology, showing that within the Brazilian scenario, aerobic granular technology can find its space for domestic sewage treatment.