Autotrophic denitrification by nitrate-dependent Fe(II) oxidation in a continuous up-flow biofilter
Jun Zhou1, Hongyu Wang2, Kai Yang3
1School of Civil Engineering, Wuhan University, Wuhan, 430072, China.
Bioprocess and Biosystems Engineering
|December 10, 2015
Summary
This study demonstrates effective nitrate removal using a continuous-upflow biofilter with sponge iron and Microbacterium sp. W5. The biofilter achieved up to 90% nitrogen removal efficiency, optimizing conditions for anaerobic nitrate reduction.
Area of Science:
- Environmental Microbiology
- Water Treatment Engineering
- Bioremediation
Background:
- Nitrate contamination in water poses environmental and health risks.
- Anaerobic bioreactors are explored for efficient nitrate removal.
- Sponge iron biofilters offer a promising medium for microbial denitrification.
Purpose of the Study:
- To evaluate the efficacy of a continuous-upflow biofilter packed with sponge iron for anaerobic nitrate removal.
- To investigate the role of Microbacterium sp. W5 in nitrate reduction and Fe(II) oxidation.
- To optimize operational parameters for maximum nitrogen removal efficiency.
Main Methods:
- Construction and operation of a continuous-upflow biofilter using sponge iron.
- Inoculation with Microbacterium sp. W5, a nitrate-reducing and Fe(II)-oxidizing bacterium.
- Analysis of influent and effluent for nitrate, nitrite, and Fe(II) concentrations.
- Investigation of Fe(II)EDTA as an anti-encrustation agent.
- Characterization of biofilms using X-ray fluorescence spectroscopy.
Main Results:
- Optimal conditions for nitrate removal were observed at 30 mg/L NO3(-)-N and 800 mg/L Fe(2+).
- Nitrite in the influent inhibited nitrate removal, and aqueous Fe(2+) caused biofilter encrustation.
- Fe(II)EDTA addition prevented cell encrustation, achieving a maximum nitrogen removal efficiency of approximately 90% at 1100 mg/L Fe(II)EDTA.
- Nitrate reduction followed first-order reaction kinetics.
Conclusions:
- The continuous-upflow sponge iron biofilter inoculated with Microbacterium sp. W5 is effective for anaerobic nitrate removal.
- Fe(II)EDTA is crucial for mitigating encrustation and enhancing biofilter performance.
- The study provides insights into optimizing bioreactor design and operation for water remediation.
Related Concept Videos
01:15Metabolism of Chemolithotrophs
1.2K
Chemolithotrophs are microorganisms that obtain energy by oxidizing inorganic molecules such as hydrogen gas (H₂), ammonia (NH₃), reduced sulfur compounds (H₂S, S²⁻), and ferrous iron (Fe²⁺). Unlike heterotrophic organisms that rely on organic carbon, chemolithotrophs transfer electrons from these inorganic donors to the electron transport chain (ETC), generating a proton motive force (PMF) that drives ATP synthesis through oxidative phosphorylation.
1.2K
01:20Overview of Nitrogen Metabolism
12.5K
Nitrogen is a very important element for life because it is a major constituent of proteins and nucleic acids. It is a macronutrient, and in nature, it is recycled from organic compounds and stored in the form of ammonia, ammonium ions, nitrate, nitrite, or nitrogen gas by many metabolic processes. Many of these metabolic processes are carried out only by prokaryotes.
The largest pool of nitrogen available in the terrestrial ecosystem is gaseous nitrogen (N2) from the air, but this...
The largest pool of nitrogen available in the terrestrial ecosystem is gaseous nitrogen (N2) from the air, but this...
12.5K
01:22Inorganic Nitrogen Assimilation
799
Nitrogen is an essential element in biological systems, forming a crucial component of proteins, nucleic acids, and other cellular constituents. Many bacteria and archaea acquire nitrogen in the form of nitrate (NO₃⁻) or ammonia (NH₃), which are then assimilated into biomolecules through specific enzymatic pathways.Assimilatory Nitrate ReductionWhen nitrate enters the cell, it undergoes a two-step reduction process known as assimilatory nitrate reduction. Initially, the enzyme...
799
01:28Microbial Nutrition
1.9K
Organisms exhibit remarkable metabolic diversity, categorized based on how they acquire energy and carbon. These strategies enable survival in various ecological niches and are essential for maintaining energy flow and nutrient cycling within ecosystems.Energy and Carbon SourcesOrganisms are classified as phototrophs or chemotrophs based on energy acquisition. Phototrophs use light as their energy source, while chemotrophs rely on oxidizing chemical compounds. Further differentiation arises...
1.9K
01:25Microbial Mats
40
Microbial communities forming biofilms and mats represent complex, spatially structured ecosystems where metabolic processes are stratified according to light, oxygen, and nutrient gradients. Biofilms are initial colonization stages, only a few millimeters thick, while mature microbial mats can reach centimeter-scale thickness and display intricate vertical organization. Their structural and functional heterogeneity allows microorganisms to occupy distinct ecological niches within a few...
40
01:24Microbes and Other Elemental Cycles
61
Microbial activity plays a pivotal role in the biogeochemical cycling of iron and manganese, especially at the redox gradients characteristic of stratified aquatic environments. These cycles are driven by microbial transformations between oxidized and reduced forms of the metals, allowing organisms to exploit them for metabolic energy and structural purposes.Iron Cycling Across Redox GradientsIn neutral, oxygen-rich surface waters, iron is predominantly found in its oxidized, insoluble ferric...
61