Uso da respirometria para caracterização da atividade metabólica de bactérias heterotróficas.

Abstract

An experimental investigation was carried out with the main objective of evaluating the metabolic capacity of heterotrophic bacteria generated with different substrates (raw and digested sewage), using two pilot-scale activated sludge systems. The metabolic capacity of anaerobic sludge under aerobic conditions, or rather of the facultative bacteria present in the anaerobic reactor, was also evaluated. The metabolic capacity is determined by assessing the kinetic constants: maximum growth rate, decay rate, utilization rate of organic material and half saturation constant. Also the survival in an anaerobic environment of the bacteria generated under aerobic conditions as well as the fraction of organic material oxidized under aerobic conditions were determined. These rates were determined by respirometric methods by which the oxygen uptake rate was measured. The results showed that the metabolism of the sludge generated from raw sewage is different from the one obtained from digested sludge. It was also established that different monosubstrates lead to different growth rates. When the sludges were submitted to an environment without substrate or oxygen it was established that the sludge generated from digested sewage was more resistant than the one generated from raw sewage, maintaining its metabolic capacity for more than 20 days. Insofar as anaerobic sludge is concerned, it was established that in an aerobic environment the oxidative metabolic capacity was comparable to that of aerobic sludge in the presence of oxygen.