Potential role of nanobubbles in dynamically modulating the structure and stability of anammox granular sludge within biological nitrogen removal process

Fu, Huimin; Peng, Meng-Wen; Yan, Peng; Wei, Zhen; Fang, Fang; Guo, Jinsong; Chen, You‐Peng

doi:10.1016/j.scitotenv.2021.147110

Cited by 10 publications

(5 citation statements)

References 52 publications

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“…However, an excess of extracellular polymers contributes to the clogging of pores, decreases the porosity of granules, and limits the permeability of granular sludge. 40 Alternatively, this might be explained by the increase in the abundance of Chloroflexi and dead bacteria in the anammox granules under iron-free and 0.1 mM FeNP culture. A greater number of larger pores and higher porosity of anammox granules under 0.1 mM FeNP culture provided more space for the transfer of substances and metabolites and indirectly enhanced the activity of functional bacteria, especially that of anammox bacteria.…”

Section: ■ Results and Discussionmentioning

confidence: 99%

“…More extracellular polymers may strengthen the aggregation capacity and stability of anammox granules. However, an excess of extracellular polymers contributes to the clogging of pores, decreases the porosity of granules, and limits the permeability of granular sludge . Alternatively, this might be explained by the increase in the abundance of Chloroflexi and dead bacteria in the anammox granules under iron-free and 0.1 mM FeNP culture.…”

Section: Resultsmentioning

confidence: 99%

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Deep Insights into the Roles of Iron in the Structure and Function of the Anammox Granular Sludge System

Peng

Yan

et al. 2022

ACS Sustainable Chem. Eng.

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Iron has a substantial effect on the growth and metabolism of anammox bacteria in anammox granular sludge (AnGS). Here, the interaction between ferrous ions, iron nanoparticles (FeNPs), and AnGS was examined to study the mechanism by which iron affects the spatial structure and nitrogen removal function of the AnGS system from a morphological and molecular biology perspective. The supply of 0.03 mM Fe2+ increased the live/dead bacterial ratio and the abundance of anammox bacteria. The ribosome metabolism and protein synthesis of bacteria were also promoted. However, higher microbial activity provided by 0.03 mM Fe2+ decreased the porosity and restricted the mass transfer of the AnGS, while the addition of 0.1 mM FeNPs increased the lysis and death of microorganisms by 12.57%, which led to an increase in the porosity (6.05%) and mass transfer of the AnGS. FeNPs also increased the expression of the enzymes involved in the anammox reaction (hydrazine synthetase and hydrazine dehydrogenase) and iron storage proteins. Thus, the increase in mass transfer and anammox-related enzymes jointly promoted the nitrogen removal of the AnGS. These results provided deep theoretical insights that could be used to aid the efficient and sustainable operation of the AnGS system.

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Section: ■ Results and Discussionmentioning

confidence: 99%

Section: Resultsmentioning

confidence: 99%

Deep Insights into the Roles of Iron in the Structure and Function of the Anammox Granular Sludge System

Peng

Yan

et al. 2022

ACS Sustainable Chem. Eng.

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“…Hence, the cell membrane of both acidogens and methanogens may interact with CuO NPs, and consequently, membrane perturbation was induced. Similarly, Fu et al [40] stated that Ag NPs can penetrate into the structure of the aerobic granular sludge and inhibit the activity of the denitrifying bacteria that were located inside the granules.…”

Section: The Role Of Eps On the Diversity And Abundance Of Microorgan...mentioning

confidence: 97%

The Role of Extracellular Polymeric Substances in the Toxicity Response of Anaerobic Granule Sludge to Different Metal Oxide Nanoparticles

Chang

et al. 2022

IJERPH

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Wastewater treatment plants (WWTP) are regarded as the last barriers for the release of incompletely separated and recycled nanoparticles (NPs) into the environment. Despite the importance and ubiquity of microbial extracellular polymeric substances (EPSs) in the complex wastewater matrix, the interaction between NPs and EPSs of anaerobic microflora involved in wastewater treatment and the resultant impact on the biomass metabolomics are unclear. Thus, the impacts of different metal oxide (TiO2, ZnO, and CuO) NPs on functional bacteria in anaerobic granular sludge (AGS) and the possible toxicity mechanisms were investigated. In particular, the binding quality, enhanced resistance mechanism, and chemical fractional contribution of EPSs from AGS against the nanotoxicity of different NPs was assessed. The results showed that CuO NPs caused the most severe inhibition towards acetoclastic and hydrogenotrophic methanogens, followed by ZnO NPs, whereas TiO2 NPs caused no inhibition to methanogenesis. Excessive EPS production, especially the protein-like substances, was an effective strategy for reducing certain NPs’ toxicity by immobilizing NPs away from AGS cells, whereas the metabolism restriction on inner microorganisms of AGS induced by CuO NPs can deteriorate the protective role of EPS, indicating that the roles of EPS may not be amenable to generalizations. Further investigations with lactate dehydrogenase (LDH) and reactive oxygen species (ROS) assays indicated that there are greatly essential differences between the toxicity mechanisms of metal NPs to AGS, which varied depending on the NPs’ type and dosage. In addition, dynamic changes in the responses of EPS content to different NPs can result in a significant shift in methanogenic and acidogenic microbial communities. Thus, the production and composition of EPSs will be a key factor in determining the fate and potential effect of NPs in the complex biological matrix. In conclusion, this study broadens the understanding of the inhibition mechanisms of metal oxide NPs on the AGS process, and the influence of EPSs on the fate, behavior, and toxicity of NPs.

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“…In the experiments of Zhang et al (2023) it was observed that NBS in both environments under acidic and alkaline conditions were smaller in size and more stable as compared to neutral conditions, showing that pH plays a role in maintaining the stability of the NBS, which may be due to the effect of the accumulation of the surface charge of the NBS by the NaOH and HCl used, besides the further findings showing an rise in the NBS's concentration with surfactants' addition, which may be associated with the surface tension of the solution. According to the studies carried out by Fu et al (2021) and others on NBS in biological denitrification, it was found that when the absolute value of the zeta potential of NBS increased, the number of NBS showed an overall increasing trend. Thus, whether the solution pH is too low or too high, positive/negative ions can encapsulate the NBS surface, thus increasing the absolute value of the NBS's zeta potential, and reducing bubble aggregation through the enhancement of electrostatic repulsive force while this high potential structure will maintain the NBS stability (Fig.…”

Section: Effect Of Ph On the Stability Of Nbsmentioning

confidence: 99%

Current status of research on nanobubbles in particle flotation

Chen,

Cheng

2024

Physicochem. Probl. Miner. Process.

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Froth flotation, as one of the most widely used separation approaches in mineral processing, is commonly used to recover valuable components from minerals. However, maintaining high flotation efficiencies is a serious challenge for conventional froth flotation in the face of decreasing particle size of the minerals to be sorted. To date, there have been plenty of reports on the software of nano-bubbles (NBS) in flotation, and the experimental consequences show that nano-bubbles' introduction has given rise to improvement's different grades in the recovery of varieties of minerals, which highlights the great potential of nano-bubbles for mineral flotation. Nanobubbles have smaller bubble radii and unusually high stability compared to conventional flotation bubbles, and their related behavior in flotation has been a hot research topic. This paper reviews some of the methods of preparing nanobubbles, equipment techniques for characterizing nanobubbles, factors affecting their stability, and some of the popular doctrines. In particular, the reinforcing mechanism of nanobubbles in the particle flotation process is discussed, first, the nanobubbles improve the electrostatic attractiveness with the particles by achieving the charge inversion while the nanobubbles that was adsorbed on the particles' surface will cover a share of the charge, which decreases the electrostatic repulsive force between the particles; and second, the nanobubbles can act as a bridge between the surfaces of the two particles, which advances the agglomeration between the particles. This review aims to be able to further advance the research related to the industrialization of nanobubbles.

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Potential role of nanobubbles in dynamically modulating the structure and stability of anammox granular sludge within biological nitrogen removal process

Cited by 10 publications

References 52 publications

Deep Insights into the Roles of Iron in the Structure and Function of the Anammox Granular Sludge System

Deep Insights into the Roles of Iron in the Structure and Function of the Anammox Granular Sludge System

The Role of Extracellular Polymeric Substances in the Toxicity Response of Anaerobic Granule Sludge to Different Metal Oxide Nanoparticles

Current status of research on nanobubbles in particle flotation

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