Tratamento do esgoto sanitário da Universidade Federal de Lavras, em estação piloto, objetivando sua caracterização, remoção de poluentes e cinética

Abstract

With the increasing appeal of water management environmental issues, due to their scarcity in several locations in Brazil, the treatment and reuse of large and small scale effluents are increasingly important. The aim of this research was to analyze the combination of anaerobic sludge blanket and upflow (RAFA), submerged aerated biological filter (FBAS), secondary decanter (DEC) and flooded system (SAC) for the treatment of sanitary sewage at scale pilot of the Federal University of Lavras (UFLA), in addition to obtaining kinetic parameters. The experiment was installed in the UFLA sewage treatment plant and was divided into 5 phases: Phase 1 148 days and TDH 40; Phase 2 87 days and TDH 30; Phase 3 95 days and TDH 20; Phase 4 88 days and TDH 16 and Phase 5 108 days and TDH 12 totaling 526 days in the field. During the monitoring period, tributary and effluent samples were collected from each treatment unit twice a week for physical, chemical and biological analyzes. Analyzing the experiment in two phases, before and after the activation of the second Veterinary elevation, it was verified that the affluent to the treatment system presented statistical difference for pH, total solids and total Kjedahl nitrogen variables, while the electrical conductivity, biological demand and oxygen chemistry besides phosphorus, did not present significant difference. The monitoring averages of the five phases studied have a pH of 8.1; 8.3; 7.5; 7.4 and 7.7 respectively for the input, RAFA, FBAS, DEC and SAC. The mean removal efficiencies of BOD and COD varied between 59 and 83% and 89 and 95%, respectively. Regarding the nutrient removal during the research the bands were 88 and 41% respectively for nitrogen and phosphorus. The kinetic values obtained in the RAFA for the 5 phases were: growth coefficient 0.56 mg mg-1 d-1; endogenous decay 0.13 d-1; maximum rate of microbial growth 0.21 d-1; limiting substrate concentration 1,405 mg L-1 COD. The total tifton 85 grass yield was 238 t ha-1, presenting good nutrient-extracting efficiencies of 20 and 13% respectively for nitrogen and phosphorus. After the 526 days of field experiment, it was possible to observe that the time of the first phase (148 days) was not sufficient for the formation of sludge in RAFA, however, it provided good stability to the system. The overall efficiencies for all analyzed parameters were satisfactory, except for solids. The configuration used in this work presented good performance for the removal of pollutants from the sanitary effluent of the Federal University of Lavras.