Bioproduction of volatile fatty acid from the fermentation of waste activated sludge for in situ denitritation

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Waste activated sludge (WAS) fermentation integrated with denitritation (the reduction of nitrite to dinitrogen gas) at different pHs was investigated in batch-mode reactors over a 24-day period. The results showed that in comparison with controlled pHs, the volatile fatty acid (VFA) bioproduction for in situ denitritation was significantly improved at uncontrolled pH. VFA fermented from WAS was quickly consumed by denitritation at uncontrolled pH, which accelerated sludge degradation. On the other hand, sludge digestion was benefited from the alkalinity produced from denitritation, while methanogenesis was prohibited by alkalinity and nitrite. The integrated sludge fermentation and denitritation can be cost-effectively applied to wastewater treatment plants, so that organic substrates (e.g., VFAs) are produced for denitritation via simultaneous sludge fermentation, which enables WAS reutilization and enhances nitrogen removal efficiency without the need of external carbon sources.

Section snippets

Sources of seeding sludge and WAS

Two types of seeding sludge were used in this study, with one from an anaerobic sludge fermentor (termed as F) and the other from a reactor of sludge fermentation integrated with denitritation (termed as FD). WAS (substrate sludge) was obtained from a pilot-scale SBR (working volume: 7 m3) treating municipal wastewater (Beijing, China). The sludge was concentrated by settling at 4°C for 24 h. In the WAS, the predominant bacterial phylum was Proteobacteria that accounted for 50.1%, which was

Bioproduction of VFA for in situ denitritation at uncontrolled pH

Previous studies found that VFA accumulation at uncontrolled pH was lower than that at controlled pHs, and the VFA concentration under alkaline conditions was higher than that under acid or neutral conditions 13, 18. The lower temperature of the anaerobic fermentation was associated with high pH values required to reach a maximum VFA production, and the optimum pH at room temperature was 10.0 (19). These studies only focused on sludge fermentation, and the criteria was established based on VFA

Acknowledgments

This work was financially supported by National high Technology Research and Development Program (863 Program) of China (2012AA063406) and the project of scientific research base and scientific innovation platform of Beijing Municipal Education Commission.

References (22)

  • Y. Pan et al.

    Effect of pH on N(2)O reduction and accumulation during denitrification by methanol utilizing denitrifiers

    Water Res.

    (2012)

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