Efeito de antibióticos utilizados em suinocultura sobre a digestão anaeróbia de efluentes / Effect of antibiotics utilized in swine culture on the anaerobic digestion of effluents

AUTOR(ES)
DATA DE PUBLICAÇÃO

2007

RESUMO

The anaerobic systems for wastewater treatment are viable for several reasons, such as low cost and energy use of the biogas generated. However, the anaerobic digestion process is not yet completely understood, mainly due to the lack of knowledge about the toxicity of the anaerobic microbiota present in the sludge with respect to several compounds. In the case of effluents originated from swine manure, antibiotics, widely used both for therapeutic and prophylactic purposes and as growth promoters, are the major compounds that may inhibit these microorganisms. This study aimed to evaluate the effect of some antibiotics normally used in swine culture, on the microbiota responsible for the process of anaerobic digestion of effluents. The experiment was divided into three stages. In the first stage, the possibility of using a synthetic medium as a substitute for the natural swine manure effluent was evaluated in order to prevent the effect of antibiotics likely present as well as to prevent variations normally observed in this type of effluent. The two media were compared as to their behavior and stability under up flow anaerobic sludge blanket reactor (UASB) treatment by applying two levels of biological loads for each medium (0.2 and 0.4 kg COD.kg SVT-1.d-1). The results showed that the reactors containing synthetic medium presented a behavior similar to that of those containing natural effluent both in organic matter removal efficiency and system stability, pointing to the possibility of their use as models in experiments evaluating swine manure effluent treatment systems. In the second stage, the individual effect of antibiotics on anaerobic digestion in the synthetic medium was evaluated. Thus, five antibiotics, amoxicillin, enrofloxacin, gentamicin, oxytetracycline and tylosin, were used at four concentrations each. It was verified that at concentrations normally found in swine manure effluents, only amoxicillin and tilosine had an inhibitory effect. In the third and last stage, the combined effect of these antibiotics was evaluated, by testing all the possible combinations using the five antibiotics. It was observed that the combination of all the antibiotics and the several combinations of these compounds associated four by four and three by three had an inhibitory effect on anaerobic digestion. For the two by two combination, only the amoxicillin and gentamicin association failed to present an inhibitory effect.

ASSUNTO(S)

ciencia de alimentos suinocultura effluent anaerobic digestion swine antibiotics efluente antibióticos digestão anaeróbia

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