Simultaneous nitrification-denitrification (SND) using a thermoplastic gel as support: pollutants removal and microbial community in a pilot-scale biofilm membrane bioreactor.

In this study, experiments were carried out to treat sanitary wastewater in a biofilm membrane bioreactor using a thermoplastic gel as a support to assist the nitrification-denitrification process. For this purpose, the system was operated in two different dissolved oxygen concentrations (2.3 ± 0.2 and 0.9 ± 0.3 mg O/L for Phases I and II, respectively) and the removal of organic compounds and nitrogen, as well as the microbial community in suspended biomass and biofilm were evaluated. The MB-MBR system was able to withstand raw wastewater variations and maintaining a low permeate COD concentration (18 mg/L) even at low DO concentrations. On the other hand, it was found that oxygen concentration significantly influenced the process of nitrogen conversion. In Phase I the average removal of total nitrogen was 18 ± 8%, while in Phase II it increased to 66 ± 11%. The denitrification rate was two times higher (7.8 mg -N/h) at low dissolved oxygen, with a significant contribution of the biofilm (41%). Additionally, the high-throughput 16S rDNA sequencing showed that the oxygen concentration was determinant for arrangement patterns of the samples and not the sampling site (suspended biomass and support material). , , , , , , , , and, were the main genera regarding the nitrogen cycle.