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Journal ArticleDOI

The long-term effects of hexavalent chromium on anaerobic ammonium oxidation process: Performance inhibition, hexavalent chromium reduction and unexpected nitrite oxidation.

TL;DR: The results showed Anammox performance was not affected at low Cr(VI) concentration, but was severely inhibited at 0.8 mg L-1, and microbial community showed no enrichment of Cr( VI) reducing bacteria and other nitrogen transformation-related bacteria.
About: This article is published in Bioresource Technology.The article was published on 2019-07-01. It has received 53 citations till now. The article focuses on the topics: Anammox & Hexavalent chromium.
Citations
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Journal ArticleDOI
TL;DR: For quantitative evaluation of the Anammox granules flotation in upflow reactors, an integrated mathematical model was formulated based on the principles that the limitation of substrate diffusion would result in bacterial starvation, lysis and subsequently aiding the formation of cavitation in the inner zone of granules.

74 citations

Journal ArticleDOI
TL;DR: In this paper, a review of the bacterial responses against chromium toxicity and scope for their application in bioremediation is discussed, and the differences and similarities between Gram negative and positive bacteria against chromIUM are also highlighted.

70 citations

Journal ArticleDOI
TL;DR: Anaerobic ammonium oxidation (anammox) is a promising biological nitrogen removal process, due to its advantages of high efficiency and low cost as discussed by the authors. However, problems remain in the application, such a...
Abstract: Anaerobic ammonium oxidation (anammox) is a promising biological nitrogen removal process, due to its advantages of high efficiency and low cost. However, problems remain in the application, such a...

51 citations


Additional excerpts

  • ...…2018), antibiotics (Fernandez, MosqueraCorral, Campos, & Mendez, 2009; Meng, Sheng, & Meng, 2019; Zhang et al., 2015), or heavy metal (Yang et al., 2013; Yu et al., 2019; Zhang, Chen, et al., 2018); and salinity (Chen, Ma, Ji, Ni, & Jin, 2014; Liu, Yamamoto, Nishiyama, Fujii, & Furukawa, 2009)....

    [...]

Journal ArticleDOI
TL;DR: The findings suggested that anammox could be inhibited by metals and antibiotics, but it has the potential to remove nitrogen from wastewaters containing both of them within the concentration threshold.

47 citations


Additional excerpts

  • ..., 2013), Hg, As, Cr (Yu et al., 2016; Yu et al., 2019), Ag (Bi et al....

    [...]

Journal ArticleDOI
Xuewen Wang1, Zuqiang Cao1, Biao Du1, Yang Zhang1, Rongbin Zhang1 
TL;DR: Zhang et al. as discussed by the authors developed a facile strategy for constructing ZnO sheets with defective zeolite imidazolate frameworks-8 (ZIF-8) to form visible-light-driven Zif-8@ZnO composite for efficient photoreduction of hexavalent chromium Cr(VI).
Abstract: Hexavalent chromium Cr(VI) is a well-known heavy metal widely existing in wastewater due to various anthropogenic activities. Cr(VI) ions are not biodegradable and tend to be toxic both in flora and fauna. Therefore, effective removal of Cr(VI) has become a very important procedure for treating Cr(VI)-containing wastewater. Here, we developed a facile strategy for constructing ZnO sheets with defective zeolite imidazolate frameworks-8 (ZIF-8) to form visible-light-driven ZIF-8@ZnO composite for efficient photoreduction of Cr(VI). It is widely accepted that both neat ZnO and ZIF-8 show no visible-light photocatalytic activity. However, our study demonstrates that a wide visible-light absorption band is observed in defective ZIF-8@ZnO after introducing self-defects in ZIF-8. Moreover, this strategy of visible-light Zn-based composite photocatalysts can also be used to design other photocatalytic materials for heavy metal treatment.

39 citations

References
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Journal ArticleDOI
TL;DR: It is suggested that the SBR could be used for the enrichment and quantitative study of a large number of slowly growing microorganisms that are currently out of reach for microbiological research.
Abstract: Currently available microbiological techniques are not designed to deal with very slowly growing microorganisms. The enrichment and study of such organisms demands a novel experimental approach. In the present investigation, the sequencing batch reactor (SBR) was applied and optimized for the enrichment and quantitative study of a very slowly growing microbial community which oxidizes ammonium anaerobically. The SBR was shown to be a powerful experimental set-up with the following strong points: (1) efficient biomass retention, (2) a homogeneous distribution of substrates, products and biomass aggregates over the reactor, (3) reliable operation for more than 1 year, and (4) stable conditions under substrate-limiting conditions. Together, these points made possible for the first time the determination of several important physiological parameters such as the biomass yield (0.066 ± 0.01 C-mol/mol ammonium), the maximum specific ammonium consumption rate (45 ± 5 nmol/mg protein/min) and the maximum specific growth rate (0.0027 · h−1, doubling time 11 days). In addition, the persisting stable and strongly selective conditions of the SBR led to a high degree of enrichment (74% of the desired microorganism). This study has demonstrated that the SBR is a powerful tool compared to other techniques used in the past. We suggest that the SBR could be used for the enrichment and quantitative study of a large number of slowly growing microorganisms that are currently out of reach for microbiological research.

2,022 citations

Journal ArticleDOI
TL;DR: The physiology of anaerobic ammonium oxidizing (anammox) aggregates grown in a sequencing batch reactor was investigated quantitatively and the anammox process was completely inhibited by nitrite concentrations higher than 0.1 g of nitrogen per liter.
Abstract: The physiology of anaerobic ammonium oxidizing (anammox) aggregates grown in a sequencing batch reactor was investigated quantitatively. The physiological pH and temperature ranges were 6.7 to 8.3 and 20 to 43°C, respectively. The affinity constants for the substrates ammonium and nitrite were each less than 0.1 mg of nitrogen per liter. The anammox process was completely inhibited by nitrite concentrations higher than 0.1 g of nitrogen per liter. Addition of trace amounts of either of the anammox intermediates (1.4 mg of nitrogen per liter of hydrazine or 0.7 mg of nitrogen per liter of hydroxylamine) restored activity completely.

1,274 citations

Journal ArticleDOI
07 May 2010-Science
TL;DR: This work explores process innovations that can speed up the anammox process and use all organic matter as much as possible for energy generation.
Abstract: Organic matter must be removed from sewage to protect the quality of the water bodies that it is discharged to. Most current sewage treatment plants are aimed at removing organic matter only. They are energy-inefficient, whereas potentially the organic matter could be regarded as a source of energy. However, organic carbon is not the only pollutant in sewage: Fixed nitrogen such as ammonium (NH4+) and nitrate (NO3−) must be removed to avoid toxic algal blooms in the environment. Conventional wastewater treatment systems for nitrogen removal require a lot of energy to create aerobic conditions for bacterial nitrification, and also use organic carbon to help remove nitrate by bacterial denitrification (see the figure). An alternative approach is the use of anoxic ammonium-oxidizing (anammox) bacteria, which require less energy ( 1 ) but grow relatively slowly. We explore process innovations that can speed up the anammox process and use all organic matter as much as possible for energy generation.

968 citations

Journal ArticleDOI
03 Nov 2011-Nature
TL;DR: It is shown that N2H4 is produced from the anammox substrates ammonium and nitrite and that nitric oxide is the direct precursor of N2 H4, which presents a new biochemical reaction forging an N–N bond and fills a lacuna in understanding of the biochemical synthesis of the N2 in the atmosphere.
Abstract: Two distinct microbial processes, denitrification and anaerobic ammonium oxidation (anammox), are responsible for the release of fixed nitrogen as dinitrogen gas (N(2)) to the atmosphere. Denitrification has been studied for over 100 years and its intermediates and enzymes are well known. Even though anammox is a key biogeochemical process of equal importance, its molecular mechanism is unknown, but it was proposed to proceed through hydrazine (N(2)H(4)). Here we show that N(2)H(4) is produced from the anammox substrates ammonium and nitrite and that nitric oxide (NO) is the direct precursor of N(2)H(4). We resolved the genes and proteins central to anammox metabolism and purified the key enzymes that catalyse N(2)H(4) synthesis and its oxidation to N(2). These results present a new biochemical reaction forging an N-N bond and fill a lacuna in our understanding of the biochemical synthesis of the N(2) in the atmosphere. Furthermore, they reinforce the role of nitric oxide in the evolution of the nitrogen cycle.

694 citations

Journal ArticleDOI
TL;DR: Multihaem c‐Cyts play critical roles in S. oneidensis MR‐1‐ and G.’sulfurreducens‐mediated dissimilatory reduction of solid metal (hydr)oxides by facilitating ET across the bacterial cell envelope.
Abstract: Dissimilatory reduction of metal (e.g. Fe, Mn) (hydr)oxides represents a challenge for microorganisms, as their cell envelopes are impermeable to metal (hydr)oxides that are poorly soluble in water. To overcome this physical barrier, the Gram-negative bacteria Shewanella oneidensis MR-1 and Geobacter sulfurreducens have developed electron transfer (ET) strategies that require multihaem c-type cytochromes (c-Cyts). In S. oneidensis MR-1, multihaem c-Cyts CymA and MtrA are believed to transfer electrons from the inner membrane quinone/quinol pool through the periplasm to the outer membrane. The type II secretion system of S. oneidensis MR-1 has been implicated in the reduction of metal (hydr)oxides, most likely by translocating decahaem c-Cyts MtrC and OmcA across outer membrane to the surface of bacterial cells where they form a protein complex. The extracellular MtrC and OmcA can directly reduce solid metal (hydr)oxides. Likewise, outer membrane multihaem c-Cyts OmcE and OmcS of G. sulfurreducens are suggested to transfer electrons from outer membrane to type IV pili that are hypothesized to relay the electrons to solid metal (hydr)oxides. Thus, multihaem c-Cyts play critical roles in S. oneidensis MR-1- and G. sulfurreducens-mediated dissimilatory reduction of solid metal (hydr)oxides by facilitating ET across the bacterial cell envelope.

594 citations