Effects of heavy metals on denitrification processes in water treatment: A review

Liu, Enqi; Fan, Chunzhen; Zhao, Min; Jiang, Shunfeng; Wang, Zhiquan; Jin, Zhan; Bei, Ke; Zheng, Xiangyong; Wu, Suqing; Qing-yuan, Zeng

doi:10.1016/j.seppur.2022.121793

Cited by 17 publications

(3 citation statements)

References 84 publications

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“…The complete pathway of HNQ acting on effluent DON is shown in Figure . Besides the challenge of low-influent organic carbon source that would limit the nitrogen removal performance of the postdenitrification system, WWTPs may also face the challenge of other unfavorable influent conditions such as toxic heavy metals . Redox mediators have been proven to have the potential to enhance the metal biotransformation processes, and it is important for future research to investigate whether HNQ can maintain its applicability when the presence of toxic heavy metals in the influent.…”

Section: Resultsmentioning

confidence: 99%

“…Besides the challenge of lowinfluent organic carbon source that would limit the nitrogen removal performance of the postdenitrification system, WWTPs may also face the challenge of other unfavorable influent conditions such as toxic heavy metals. 60 Redox mediators have been proven to have the potential to enhance the metal biotransformation processes, 61 and it is important for future research to investigate whether HNQ can maintain its applicability when the presence of toxic heavy metals in the influent. Moreover, in full-scale applications, this HNQ dosing approach is suitable for existing facilities to employ without any extra treatment step, and engineers can easily adjust the dosage of HNQ according to the local effluent TN permits.…”

Section: Implication For Practicementioning

confidence: 99%

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2-Hydroxy-1,4-Naphthoquinone: A Promising Redox Mediator for Minimizing Dissolved Organic Nitrogen and Eutrophication Effects of Wastewater Effluent

Cheng,

You,

et al. 2024

Environ. Sci. Technol.

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Researchers and engineers are committed to finding effective approaches to reduce dissolved organic nitrogen (DON) to meet more stringent effluent total nitrogen limits and minimize effluent eutrophication potential. Here, we provided a promising approach by adding specific doses of 2-hydroxy-1,4-naphthoquinone (HNQ) to postdenitrification bioreactors. This approach of adding a small dosage of 0.03−0.1 mM HNQ effectively reduced the concentrations of DON in the effluent (ANOVA, p < 0.05) by up to 63% reduction of effluent DON with a dosing of 0.1 mM HNQ when compared to the control bioreactors. Notably, an algal bioassay indicated that DON played a dominant role in stimulating phytoplankton growth, thus effluent eutrophication potential in bioreactors using 0.1 mM HNQ dramatically decreased compared to that in control bioreactors. The microbe-DON correlation analysis showed that HNQ dosing modified the microbial community composition to both weaken the production and promote the uptake of labile DON, thus minimizing the effluent DON concentration. The toxic assessment demonstrated the ecological safety of the effluent from the bioreactors using the strategy of HNQ addition. Overall, HNQ is a promising redox mediator to reduce the effluent DON concentration with the purpose of meeting low effluent total nitrogen levels and remarkably minimizing effluent eutrophication effects.

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Section: Resultsmentioning

confidence: 99%

Section: Implication For Practicementioning

confidence: 99%

2-Hydroxy-1,4-Naphthoquinone: A Promising Redox Mediator for Minimizing Dissolved Organic Nitrogen and Eutrophication Effects of Wastewater Effluent

Cheng,

You,

et al. 2024

Environ. Sci. Technol.

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“…Previous studies have shown that some heavy metal ions (e.g., Cd 2+ , Cu 2+ , Ni 2+ , Zn 2+ , Cr 6+ , Fe 2+ , Pb 2+ ) have different inhibitory effects on the metabolic processes of aerobic denitrifying strains [ 35 ]. Their effects vary greatly depending on the type, valence, and concentration [ 36 ]. Calcium channels in bacteria can cause the accumulation of Ca 2+ around cell walls, triggering nucleation and crystallization [ 37 , 38 , 39 , 40 ].…”

Section: Discussionmentioning

confidence: 99%

Effects of Ion Combinations and Their Concentrations on Denitrification Performance and Gene Expressions of an Aerobic Strain Marinobacter Hydrocarbonoclasticus RAD-2

Cai

et al. 2023

Microorganisms

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Salinity is one of the most important factors affecting the nitrogen-removal efficiency of denitrifying bacteria. A series of different ion combinations and salinity gradients were carried out to clarify the effects of ion types and concentrations on nitrogen removal by halophilic aerobic denitrifying bacteria RAD-2. Nitrate concentrations, nitrite concentrations, TAN concentrations, and OD600 were monitored to investigate their effects on denitrification in each group. The results showed that Na+, K+, and Cl- accelerated the denitrification process and improved nitrogen-removal efficiency at moderate additions, while Ca2+ and Mg2+ showed no significant effect. Na+ was effective alone, while K+ or Cl- needed to be combined with at least one of Na+, K+, or Cl- to achieve similar efficiency. The batch tests of salinity confirmed that the addition of a moderate concentration of NaCl/Na2SO4 could effectively improve nitrogen-removal efficiency, while excessive salinity might hinder denitrification metabolism. In the salinity range of 5~40‰, a 5‰ dosage might be the most economical method for strain RAD-2. Real-time PCR experiments on 17 key nitrogen metabolism-related genes revealed that chloride was widely involved in the nitrogen and carbon metabolism of microorganisms by altering cell osmotic pressure and opening ion channel proteins, thereby affecting the efficiency of denitrification. The results of this study may contribute to a better understanding of the different roles of various ions in aerobic denitrification and highlight the importance of salinity control in highly salted wastewater treatment.

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The Joint Anaerobic Denitrification Performance of Klebsiella sp. and Enterobacter hormaechei Using Two Carbon Substrates With and Without the Presence of Heavy Metals

Amoako-Nimako

Chen²,

Fu³

et al. 2022

Water Air Soil Pollut

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Effects of heavy metals on denitrification processes in water treatment: A review

Cited by 17 publications

References 84 publications

2-Hydroxy-1,4-Naphthoquinone: A Promising Redox Mediator for Minimizing Dissolved Organic Nitrogen and Eutrophication Effects of Wastewater Effluent

2-Hydroxy-1,4-Naphthoquinone: A Promising Redox Mediator for Minimizing Dissolved Organic Nitrogen and Eutrophication Effects of Wastewater Effluent

Effects of Ion Combinations and Their Concentrations on Denitrification Performance and Gene Expressions of an Aerobic Strain Marinobacter Hydrocarbonoclasticus RAD-2

The Joint Anaerobic Denitrification Performance of Klebsiella sp. and Enterobacter hormaechei Using Two Carbon Substrates With and Without the Presence of Heavy Metals

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