Estrutura e dinâmica da comunidade bacteriana presente em reatores de oxidação biológica de sulfeto

Abstract

This study developed two reactors with the aim of promoting the biological oxidation of dissolved sulfide present in UASB reactor effluent in order to predict the structure and dynamic behavior of the bacterial community of over time. The performance of the reactors was monitored over 500 days and filled with different packed materials: polypropylene rings and polyurethane foam. The reactors were operated in three different operating conditions, represented by the hydraulic retention times of 24, 12 and 6 hours, respectively. The physical and chemical parameters sulfide, sulfate, thiosulfide, elemental sulfur, pH and redox potential were monitored. The microbiological analyzes were PCR-DGGE and optical microscopy. The results showed higher sulfide removal efficiency (about 90%) in both reactors when operated at HRT of 12 hours than that observed at HRT of 24 hours. The PCR-DGGE technique revealed that the bacterial community was extremely diverse and very dynamic varying over time within the same reactor and at the same operational phase, and between the reactors. The reduction in HRT from 24h to 12h changed the bacterial community structure and in some cases reduced the diversity. Phototrophic purple and green bacteria involved in the oxidation of sulfide related to Chromatiaceae, Chlorobiaceae were detected in both reactors. The results of microscopic examination showed the predominance of purple bacterial colonies with morphology similar to Chromatiaceae- like cells in all operational phases of both reactors. The sulfur mass balance and the Shannon index showed that reactor 1 (R1) at HRT of 6 hours, filled with polypropylene rings, was the best operating condition for biological removal of sulfide. This work showed that the configuration of the reactor together with a stabilized biomass can be used to remove sulfide from the effluent of anaerobic reactors treating sewage.