Desempenho de filtros anaeróbios no tratamento de águas residuárias da lavagem e descascamento dos frutos do cafeeiro

Abstract

Three anaerobic filters with upflow were operationally evaluated for the treatment of wastewater from the coffee cherries processing (ARC). The reactors were made with PVC tube with total volume for 139.5 L. They were operated under environmental temperature varying from 13.8 to 24.4 ºC. The ARC had the pH corrected with whitewash to values up to 7 and the concentration of nutrients to relationship DBO/N/P equal 100/5/1. The volumetric organic load rate and hydraulic retention time varied from 1.49 to 12.99 kg m-3 d-1 and 32.3 to 56.9 h, respectively. The filters were monitored, by collecting both the affluent and effluent samples of the filters, and quantifying the variables: COD, BOD, phenolic compounds, pH, alkalinity and volatile acids. At the end of the evaluated conditions it observed that the great oscillation in the hydraulic and organic load did with that the anaerobic filters used in this work operated in an unstable condition, presenting unbalance between the producers and consumers of volatile acids, with production no satisfactory of alkalinity bicarbonate. However, the affluent and effluent pH values were inside of the range of appropriate values so that it has the anaerobic degradation of the organic material. The filters didn’t support the organic shock load rate, what reduced the efficiency of removal of organic matter drastically and phenolic compounds. Based on the results of performance and conditions operational, it is conclude that the maximum organic load rate to be applied in anaerobic filters for treatment of ARC, it should not exceed 2 kg m-3 d-1 of DQO.