Effect of the Oxidative Phosphorylation Uncoupler <i>Para</i>-Nitrophenol on the Activated Sludge Community Structure and Performance of a Submerged Membrane Bioreactor
In this work, the metabolic uncoupler <i>para</i>-nitrophenol (pNP) was applied to suppress excess sludge production and to investigate its effects on the system’s performance and activated sludge community structure. The COD removal efficiency decreased from 99.0% to 89.5% prior to and...
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| Main Authors: | , , , |
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| Format: | article |
| Language: | EN |
| Published: |
MDPI AG
2021
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| Subjects: | |
| Online Access: | https://doaj.org/article/a7ffeb90a7cc409694d13e78e4726483 |
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| Summary: | In this work, the metabolic uncoupler <i>para</i>-nitrophenol (pNP) was applied to suppress excess sludge production and to investigate its effects on the system’s performance and activated sludge community structure. The COD removal efficiency decreased from 99.0% to 89.5% prior to and after pNP addition, respectively. Application of pNP transiently reduced NH<sub>4</sub><sup>+</sup>-N, NO<sub>3</sub><sup>−</sup>-N and NO<sub>2</sub><sup>−</sup>-N removal efficiencies, suggesting partial inhibition of both nitrifying and denitrifying activity. However, no changes in the relative abundance of the nitrifying bacteria occurred. Phosphorus removal efficiency was sharply reduced after pNP addition, as the consequence of hydrolysis of stored cell reserves. <i>Tetrasphaera</i>, a key polyphosphate accumulating organism, was also affected by the addition of pNP, a fact that highly influenced system’s ability to remove phosphorus. A drastic drop in Soluble Microbial Products (SMP) and Extracellular Polymeric Substances (EPS) was also detected shortly after the introduction of the uncoupler. On the other hand, MBR’s physicochemical parameters were restored to initial values a week after the addition of pNP. Moreover, remarkable changes in beta-diversity were noted after pNP addition. An increase of <i>Bacteroidetes</i>, <i>Gammaproteobacteria</i> and <i>Firmicutes</i> over <i>Actinobacteria</i> and <i>Alphaproteobacteria</i> was also observed after pNP addition. |
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