Cápsulas de café expresso como material suporte em reator anaeróbio de leito fixo e escoamento ascendente

Abstract

The present work aimed to evaluate the use of expresso coffee capsules as support material in upflow anaerobic fixed bed reactors, in the treatment of sanitary sewage. Capsules made of aluminum and plastic were collected with expresso machine users. Three reactors (R1, R2 and R3) were constructed in tubes of blue PVC with 30 cm height and 150 mm diameter. R1 was filled with 170 aluminum capsules smashed by hand; R2 filled with 40 plastic capsules smashed by hand and 40 plastic discs, that composes the capsules; and R3 filled with 40 plastic capsules and 40 discs. The inlet sewage was coming from the pre-treatment of the wastewater treatment plant of the Federal University of Lavras (ETE-UFLA). It was stored in a 200 L tank and distributed at the reactors bottom by a level reservoir, in order to maintain the height of wastewater in the reactors. The capsules were characterized by specific mass and porosity in the reactors, as were visualized by optic microscope. To evaluate the reactors performances, were analyzed: temperature, pH, COD, TS, TVS, TSS, nitrogen and phosphorus. The biomass grown in the reactors were quantified by the volatile solids and analyzed by scanning electronic microscope and epifluorescence microscope. The statistics tests were run in Statistica 10. Changes in the organic loading rates implied in twooperational phases, one at a OLR of 2.1 kg COD m -3 d -1 and other at 4.0 kg COD m -3 d -1 . The average temperature during the monitoring time was 18.0 °C. In spite of the operating conditions variations, the reactors had a good performance, presenting COD efficiency removals up to 80% in both phases. The nutrients removal were also high, with values of nitrogen removal of 30% in R1, 26% in R2 e 30% in R3 and of phosphorus 54%, 55% e 54%, respectively. Thecapsules characteristics were similar to other materials used as support, and the low roughness justified the use of smashed capsules in R1 and R2, since these reactors presented great quantity of adhered volatile solids and a diversity of microorganisms. Therefore, it is possible to utilize coffee capsules as support material in anaerobic reactors, providing good biomass adhesion and high pollutants removal efficiencies.