Evaluation of the microbial community of upflow anaerobic sludge blanket reactors used for the removal and degradation of linear alkylbenzene sulfonate by pyrosequencing

The microbial communities from two upflow anaerobic sludge blanket (UASB) reactors treating synthetic wastewater supplemented with linear alkylbenzene sulfonate (LAS) (RS) and laundry wastewater (RL) were analyzed by pyrosequencing of 16S rRNA genes. A higher LAS degradation rate was observed in RL (82 ± 9%) than RS (45 ± 16%). A high proportion of the LAS removal rate (55-90%) was observed in the PS region for both reactors, most likely due to the low concentration of co-substrates and oxygen diffusion in this region. A microbiological analysis of samples taken at 112 days of operation from the sludge blanket (SB) and the phase-separator (PS) region of both reactors confirmed these findings. The distinct microbial communities found in each reactor resulting from the different wastewaters used were related to the LAS degradation rates obtained. The microbial community from reactor RL was more capable of degrading LAS, most likely because of the presence of xenobiotics.