Performance of the anaerobic lagoons with dividing baffle and facultative of the wwtp of Santa Fe do Sul (São Paulo, Brazil)

Abstract

The main objective of this research was to evaluate the performance of the sewage treatment plant (stp) of Santa Fe do Sul in the different climatic seasons. A bathymetric survey of the anaerobic and facultative lagoons was carried out to determine the sludge accumulation profiles and estimate the hydraulic retention time of the units; Three-stage monitoring of the raw sewage and the ponds’ effluents for 3-months long each was carried out. The average removal of the biochemical oxygen demand (bod) was 78.6 %, lower than the minimum efficiency allowed by the current Brazilian legislation; the amount of fecal coliforms (fc) and the settleable solids volume exceeded the permitted values by the regulation. The stp needs maintenance on the anaerobic lagoon and a post-treatment system to guarantee additional bod, fc and solids removal on the final effluent.