Anoxic Microbial Community Robustness Under Variation of Hydraulic Retention Time and Availability of Endogenous Electro
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Anoxic Microbial Community Robustness Under Variation of Hydraulic Retention Time and Availability of Endogenous Electron Donors Dagoberto Y. Okada 1 & Rachel B. Costa 2 & Caroline de Cassia B. Garcia 3 & Eloisa Pozzi 3 & Theo S. O. Souza 4 & Eugênio Foresti 3 Received: 6 February 2020 / Accepted: 23 April 2020/ # Springer Science+Business Media, LLC, part of Springer Nature 2020
Abstract
The ADNMED (Anaerobic Digestion, Nitrification, and Mixotrophic Endogenous Denitrification) system comprises a triple chamber configuration that was shown to provide high-quality effluent regarding carbon, nitrogen, and sulfide. Hydraulic retention time (HRT) was 7 h in the anaerobic and anoxic chambers, and 5 h in the aerobic chamber (stage A). Sewage was directly added to the anoxic chamber to provide extra organic electron donors for denitrification (stage B) to improve the nitrogen removal efficiency (stage A 47 ± 19%). The addition of sewage at a flow rate equivalent to 10% of the feed flow increased nitrogen removal efficiency to 61 ± 12%. Illumina® sequencing revealed a restructuring of the microbial community in the anoxic chamber, according to the availability of the endogenous electron donors for denitrification. At stage A, denitrification was related to the decay of biomass, while the addition of sewage during stage B stimulated the establishment of fermentative bacteria. Keywords Domestic sewage . Endogenous electron donors . Sulfide-driven autotrophic denitrification . Nitrogen removal . Illumina sequencing
Introduction Human population growth overloads the use of hydric resources, demanding the development of cost-effective wastewater treatment. Energy positive wastewater treatment has been pursued Electronic supplementary material The online version of this article (https://doi.org/10.1007/s12010-02003327-5) contains supplementary material, which is available to authorized users.
* Dagoberto Y. Okada [email protected] Eugênio Foresti [email protected] Extended author information available on the last page of the article
Applied Biochemistry and Biotechnology
for the last 20 years [1, 2]. Anaerobic treatment tends to be energy neutral or even energy positive, and the removal of considerable fractions of organic content reduces the aeration costs in the aerobic polishing step, usually placed downstream [3]. However, anaerobic systems are unable to remove nutrients. Conventionally, nitrogen is removed by two biological steps: autotrophic nitrification (under aerobic conditions) and heterotrophic denitrification (under anoxic conditions, using organic electron donors). However, when an anaerobic step precedes the treatment, heterotrophic denitrification is impaired, as most of the organic compounds easily degradable are converted in the anaerobic reactor. In these cases, the addition of an external carbon source may be required, increasing the operation costs. Moreover, sulfide is usually formed under anaerobic conditions, which can be related to unpleasant odors and corrosion, even at low sulfide concentratio
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