Tratamento de lodo de reator UASB em leitos plantados com Cyperus papyrus

Abstract

When seeking the use of sewage sludge generated in treatment plants, it is necessary for this material to undergo processes that reduce the content of biodegradable organic matter, the concentration of pathogenic microorganisms, and the moisture content, in order to obtain a product that does not pose a risk to human health and is primarily dry, facilitating transportation and handling. The objective of this study was to evaluate the treatment of sludge from UASB reactors in Planted Drying Beds (PDB) systems, characterizing the physicochemical and microbiological parameters of this sludge after treatment. Three vertical flow PDB planted with Cyperus papyrus were constructed and subsequently monitored for 6 months. The loadings applied were approximately 6, 7, and 8 kgTS/m²week, corresponding to 255, 304, and 363 kgTS/m²year for Leach Bed 01, Leach Bed 02, and Leach Bed 03, respectively. The results demonstrated the effectiveness of CWs in reducing the sludge volume, showing a 79% reduction in the loaded sludge, with total solids content ≥ 65% and volatile solids/total solids ratios below 0.39 (VS/TS ≤ 0.39) for all three leach beds at the end of the resting period. After three months of resting, the biosolid also presented low pathogen concentration (E. coli < 4.00E-1 MPN/gST). Leach Bed 01, Leach Bed 02, and Leach Bed 03 presented nitrogen dry mass contents of 11.8%, 13%, and 12.7%; phosphorus contents of 0.05%, 0.03%, and 0.13%; and potassium contents of 0.5%, 0.63%, and 0.36%, respectively. The metals analyzed showed values well below the limit established by CONAMA Resolution No. 498/20, where for Cd, for example, the obtained value was 96% below the established limit. According to CONAMA Resolution No. 498 of 2020, the parameters obtained from the generated biosolids allow their classification as Class A.