Insights into the removal of gaseous oxytetracycline by combined ozone and membrane biofilm reactor

Gaseous emerging organic compounds (GEOCs) may harm human health and ecological environment. High temperature composting of livestock manure may produce oxytetracycline (OTC) waste gas. Here, we investigated treatment OTC in waste gas by combined ozone and membrane biofilm reactor (MBfR) with desulphurizing bacteria. The performance, the microbial community, gene function and the mechanism for OTC removal in the ozone-MBfR were evaluated. The ozone-MBfR system could achieve more degradation of OTC completely than MBfR. Desulfovibrio, Lentimicrobium, Aminivibrio, Thioalkalispira, Erysipelothrix, Mangroviflexus, Azoarcus, Thauera, Geobacter, Paracoccus, and Dethiosulfatibacter were the dominant genera. Pseudomonas, Escherichia, Bacteroides, Salmonella, Paracoccus, Stappia were contribution to OTC degradation. With the addition of ozone, the community diversity increased; some genera, such as Tenericutes- uncultured, and Desulfovibrio, increased in abundance, whereas others, such as Thauera, and Petrimonas, decreased. Ozone destroyed the enol structure in OTC molecular structure and produces biodegradable products, ozone oxidation was combined with biodegradation, to achieve thoroughly degrade OTC in waste gas. The novel hybrid ozone-MBfR is a cost-effective and robust alternative to GEOCs treatment.

Simultaneous Partial Nitrification and Denitrification Maintained in Membrane Bioreactor for Nitrogen Removal and Hydrogen Autotrophic Denitrification for Further Treatment

Low C/N wastewater results from a wide range of factors that significantly harm the environment. They include insufficient carbon sources, low denitrification efficiency, and NH4+-N concentrations in low C/N wastewater that are too high to be treated. In this research, the membrane biofilm reactor and hydrogen-based membrane biofilm reactor (MBR-MBfR) were optimized and regulated under different operating parameters: the simulated domestic sewage with low C/N was domesticated and the domestic sewage was then denitrified. The results of the MBR-MBfR experiments indicated that a C/N ratio of two was suitable for NH4+-N, NO2−-N, NO3−-N, and chemical oxygen demand (COD) removal in partial nitrification-denitrification (PN-D) and hydrogen autotrophic denitrification for further treatment. The steady state for domestic wastewater was reached when the MBR-MBfR in the experimental conditions of HRT = 15 h, SRT = 20 d, 0.04 Mpa for H2 pressure in MBfR, 0.4–0.8 mg/L DO in MBR, MLSS = 2500 mg/L(MBR) and 2800 mg/L(MBfR), and effluent concentrations of NH4+-N, NO3−-N, and NO2−-N were 4.3 ± 0.5, 1.95 ± 0.04, and 2.05 ± 0.15 mg/L, respectively. High-throughput sequencing results revealed the following: (1) The genus Nitrosomonas as the ammonia oxidizing bacteria (AOB) and Denitratisoma as potential denitrifiers were simultaneously enriched in the MBR; (2) at the genus level, Meiothermus,Lentimicrobium, Thauera,Hydrogenophaga, and Desulfotomaculum played a dominant role in leading to NO3−-N and NO2−-N removal in the MBfR.