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Nitrogen compound cycle

Measure N2O in wastewater processes

Unisense offers a number of sensors which can be used for wastewater research and analysis. including the following processes:

  • Biogenic sulfide corrosion
  • Sludge profiling
  • Nitrification/Denitrification processes
  • Anammox research
  • Biofilm analysis

Nitrous oxide (N2O) is a significant greenhouse gas having an approximately 300-fold stronger effect than CO2. Nitrous oxide is produced during oxidation of NH4 to N2 in wastewater during both nitrification and denitrification processes.
The Unisense N2O microsensor can directly measure levels of dissolved N2O in aqueous environments and is not sensitive to O2.

Nitric Oxide (NO) is an intermediate byproduct of reduction of NO2 to N2 during denitrification. The Unisense NO sensor can directly measure levels of dissolved NO in aqueous environments and is insensitive to O2.
Oxygenation is a key step in wastewater and sludge treatment. Our oxygen sensors can be used in conjunction with all of our sensor to monitor biological processes.

Wastewater tanks

The Unisense NO3- or NO2- sensor is an ideal tool to study the dynamics of nitrification/denitrification in wastewater. The fast response time and the true on-line signal from the sensors provides a unique opportunity to calculate nitrification/denitrification rates with a minimum of time-lag, e.g. within a few minutes. In addition, a very detailed study of the kinetics of the bacterial enzyme systems is possible due to the opportunity of discriminating between NO3- and NO2- concentration. NO3- concentration is calculated by subtracting NO2- from NOx- concentrations.

NOx_Michael_Nielsen The figure above shows NOx-, NO2- and O2 concentrations in activated sludge sourced from a waste water treatment pilot plant. NOx-  and NO2- were measured with the Unisense biosensor and O2 concentrations were measured with a Unisense OX-500 sensor. The activated sludge was periodically aerated.


Biogenic sulfide corrosion

Biogenic sulfide corrosion of concrete vessels and pipes which carry wastewater, is a major industrial problem. Anaerobic conversion of sulfate to sulfide in biofilms, results in a build-up of H2S in the water and the headspace above the water. In the presence of oxygen, sulfide oxidizing bacteria found on concrete surfaces, convert H2S to sulfuric acid which corrodes concrete.
The Unisense sulfide microsensor for dissolved H2S is a Clark-type microsensor, and it is the first reliable microsensor for measuring the products of sulfate reduction.

Related products

N2O Microsensor

Kampschreur, Marlies J. et al (2008), Dynamics of nitric oxide and nitrous oxide emission during full-scale reject water treatment, Water Research, 812 - 826, vol. 42 Read abstract

Zhou, Yan et al (2008), Development of a 2-sludge, 3-stage system for nitrogen and phosphorous removal from nutrient-rich wastewater using granular sludge and biofilms, Water Research, 3207 - 3217, vol. 42 Read abstract

Downing, Leon S. et al (2008), Total nitrogen removal in a hybrid, membrane-aerated activated sludge process, Water Research, 3697 - 3708, vol. 42 Read abstract

Nielsen, Michael et al (2004), Bacterium-Based NO2? Biosensor for Environmental Applications, Applied and Environmental Microbiology, 6551 LP - 6558, vol. 70 Read abstract

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