Related Experiment Video
Updated: Jun 22, 2026
07:31
Agarose-Based Model Ecosystem for Cultivating Methanotrophs in a Methane-Oxygen Counter Gradient
Published on: September 6, 2024
A comprehensive model of simultaneous denitrification and methanogenic fermentation processes
A Evren Tugtas1, U Tezel, Spyros G Pavlostathis
1Department of Environmental Engineering, Bahcesehir University, Istanbul, Turkey.
Biotechnology and Bioengineering
|June 17, 2009
Summary
This study integrates denitrification into the Anaerobic Digestion Model No. 1 (ADM1) to understand its impact on methanogenesis. The enhanced model highlights substrate competition and N-oxide inhibition effects in anaerobic digestion systems.
Area of Science:
- Environmental microbiology
- Biochemical engineering
- Wastewater treatment modeling
Background:
- Anaerobic digestion is a key process for organic waste treatment and biogas production.
- Denitrification, the reduction of nitrate, can influence anaerobic processes but is often not included in standard models.
- Understanding these interactions is crucial for optimizing wastewater treatment and managing nitrogen removal.
Purpose of the Study:
- To incorporate the denitrification process into the International Water Association Anaerobic Digestion Model No. 1 (IWA ADM1).
- To evaluate the effect of denitrification on methanogenic fermentation within anaerobic digestion systems.
- To predict the impact of nitrate reduction on reactor performance under various operational conditions.
Main Methods:
- The denitrification process was mathematically integrated into the existing IWA ADM1 framework.
- The extended model was calibrated and optimized using published experimental data and kinetic parameters from a mesophilic methanogenic culture.
- Simulations were performed for batch, semi-continuous, and continuous flow reactors to assess model predictions.
Main Results:
- The integrated model successfully simulated the influence of denitrification on methanogenesis.
- Model simulations revealed significant substrate competition between denitrifying and non-denitrifying bacteria.
- The impact of N-oxide inhibition on the interplay between fermentation, methanogenesis, and denitrification was elucidated.
Conclusions:
- The extended IWA ADM1 provides a valuable tool for analyzing the coupled processes of anaerobic digestion and denitrification.
- Substrate competition and N-oxide inhibition are critical factors affecting the stability and efficiency of anaerobic systems with nitrate presence.
- This modeling approach aids in predicting and managing operational changes and disturbances in wastewater treatment plants.
Related Concept Videos
01:26Microbes and Methanogenesis
Methanogenesis is a critical microbial process in anaerobic ecosystems responsible for the biological production of methane, a potent greenhouse gas and valuable biofuel. This metabolic pathway is primarily facilitated by methanogenic archaea, which thrive in anoxic environments such as wetlands, sediments, and animal gastrointestinal tracts. The absence of oxygen in these habitats prevents aerobic respiration, thereby favoring alternative biochemical pathways for organic matter degradation.In...
01:30Microbial Wastewater Treatment
Microbial communities in aquatic ecosystems play a key role in the natural breakdown of contaminants introduced through domestic and industrial effluents. Acting as biological catalysts, these microbes change and mineralize a wide range of organic and inorganic pollutants under different redox conditions.In oxygen-rich surface waters, aerobic heterotrophs lead organic matter breakdown, using oxygen as the terminal electron acceptor to efficiently oxidize substrates to carbon dioxide and water.
01:26Microbes and the Nitrogen Cycle
The nitrogen cycle is a complex biogeochemical process critical to maintaining the balance of nitrogenous compounds in ecosystems. This cycle involves multiple microbial-mediated transformations through which nitrogen changes oxidation states, supporting essential ecological functions and contributing to plant and microbial growth.Nitrogen Fixation and AmmonificationNitrogen fixation initiates the cycle by converting inert atmospheric nitrogen (N₂) into bioavailable ammonia (NH₃), a process...
01:15Metabolism of Chemolithotrophs
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. However, because inorganic electron donors...
01:22Inorganic Nitrogen Assimilation
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 nitrate reductase...
01:25Microbial Mats
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...