RESUMO
Denitrifying capability of glycogen accumulating organisms (GAOs) has received great attention in environmental science and microbial ecology. Combining this ability with granule processes would be an interesting attempt. Here, a laboratory-scale sequencing batch reactor (SBR) was operated to enrich GAOs and enable sludge granulation. The results showed that the GAO granules were cultivated successfully and the granules had denitrifying capability. The batch experiments demonstrated that all NO3(-)-N could be removed or reduced, some amount of NO2(-)-N were accumulated in the reactor, and N2 was the main gaseous product. SEM analysis suggested that the granules were tightly packed with a large amount of tetrad-forming organisms (TFOs); filamentous bacteria served as the supporting structures for the granules. The microbial community structure of GAO granules was differed substantially from the inoculant conventional activated sludge. Most of the bacteria in the seed sludge grouped with members of Proteobacterium. FISH analysis confirmed that GAOs were the predominant members in the granules and were distributed evenly throughout the granular space. In contrast, PAOs were severely inhibited. Overall, cultivation of the GAO granules and utilizing their denitrifying capability can provide us with a new approach of nitrogen removal and saving more energy.
Assuntos
Bactérias/metabolismo , Glicogênio/metabolismo , Esgotos/química , Biomassa , Reatores Biológicos , Carbono/química , Carbono/metabolismo , Eletroforese em Gel de Gradiente Desnaturante , Desnitrificação , Hibridização in Situ Fluorescente , Microscopia Eletrônica de Varredura , Nitrogênio/química , Nitrogênio/metabolismo , Fósforo/química , Fósforo/metabolismo , Proteobactérias/genética , Proteobactérias/metabolismo , Esgotos/microbiologiaRESUMO
Objective To investigate whether ?OH radical species present in the acid oxidation-potential water (AOW). Methods Electron paramagnetic resonance spectroscopy (EPR) coupled with the spin trapping technique was used for determination of ?OH radicals. Results A seven-line spectrum characteristic of 5, 5-dimethyl-2-pyrrolidone-N-oxyl (DMPOX) was formed at first, at 60 min the spin adducted DMPO-OH with four-line spectrum characteristic and at 120 min, no spectrum was observed. Conclusion ?OH can be detected in AOW at 60 min and it may come from the interaction of active substance in the AOW.
