Home N2O Monitoring Puts VCS Denmark at the Technological Forefront
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N2O Monitoring Puts VCS Denmark at the Technological Forefront

Energy Production Lead to Increased N2O Emission

Wastewater treatment has previously been a very energy-intensive process, but in recent years the industry has focused on reducing CO2 emissions. VCS Denmark, one of the largest and oldest water and wastewater companies in Denmark, is actively committed to resource optimization. One of the major efforts has been on optimizing its biggest treatment plant – Ejby Mølle Renseanlæg – to produce significantly more energy than it consumes. However, in its efforts to achieve its goal, VCS Denmark encountered a problem: When you reduce energy consumption in the complex microbiological treatment process, you also potentially increase N2O emissions. N2O is a potent, overlooked greenhouse gas which – when emitted – has an eco footprint 273 times that of CO2.

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Measurement Technology Reads N2O Concentration

Increased levels of N2O do not sit well with VCS Denmark’s goal of reducing greenhouse gas emissions and becoming CO2 neutral. The company therefore decided to invest in N2O sensors from Unisense Environment. “We wanted to measure N2O levels in our wastewater treatment tanks, as these data enable us to optimize the operation of our treatment plants and reduce N2O emissions. Unisense Environment had the technology we were looking for – and at a very affordable price,” explains Per Henrik Nielsen, Project Manager at VCS Denmark.

Unisense Environment’s measurement technology integrates with VCS Denmark’s monitoring system, enabling the water company to monitor N2O concentration along with ammonium, nitrate, oxygen, and redox potential.

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N2O measurement – a giant leap forward

N2O concentration and emission data have been scarce. Therefore, the wastewater treatment companies have based their control efforts on guesswork and lab tests from the 1990s. Armed with the new technology, however, VCS Denmark can measure N2O concentration levels with a high degree of accuracy.

“There’s a big difference between lab tests and the real world. So it’s a huge leap forward to be able to perform stable, full-scale, online N2O measurements in an industrial context online 365 days a year using Unisense Environment’s measurement technology,” says Per Henrik Nielsen.

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Deep Background Knowledge and Respect for Practice

The measurement technology was jointly developed by Unisense Environment and VCS Denmark with the help of DHI, and the project was funded by The Foundation for Development of Technology in the Danish Water Sector and Aarhus Water.

The development process has been so smooth that the measurement technology was developed and made implementable in record time. Per Henrik Nielsen believes this has a lot to do with Unisense Environment’s attitude and business approach.

“Unisense Environment possesses extensive theoretical background knowledge and a deep understanding of the biological processes in wastewater treatment. They have also shown a great deal of respect for how things work in practice and understand our operational needs. That’s a rare but highly desirable combination, which we value highly,” he concludes.

Monitor N2O emissions with the N2O Wastewater System

Tech Notes & References

Tech Notes
N2O Sensor
Tech Notes References
N2O sensor matches 91% of measured off-gas emissions

Case Study: Full-scale comparison of N2O emissions determined by liquid sensors and off-gas measurement

Tech Notes References
Direct Effect of Activated Sludge Concentration on N2O Emission and CO2-equivalents at Full-scale

Significant 3-fold increase in IPCC2019 wastewater N2O emission factor supported by Danish studies.

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Tech Notes References
Positioning of the N2O Wastewater Sensor

A case study from Kralingseveer WWTP in the Netherlands explores the influence of sensor placement.

N2O mechanisms
Tech Notes
National N2O Mapping and Reduction of N2O Emission through Advanced Online Control

Based on data from Danish WWTPs through advanced online-control.

Figure 1: Activated Sludge Tank
Tech Notes References
N2O Monitoring Highlights Potential for GHG Emissions Reduction

Learn about the results from N2O monitoring in the activated sludge tanks at Severn Trent’s Spernal sewage treatment plant

Tech Notes
A Tool for Carbon Dosage Control

Monitor the N2O concentration in the liquid and use N2O as a control parameter for carbon dosage in the denitrification process.

N2O Sensor Controls Emissions from Deammonification Processes
Tech Notes References
N2O Sensor Controls Emissions from Deammonification Processes

Learn how the water utility Aquafin controls emissions from deammonification processes using the the N2O Wastewater Sensor

Nitrous Oxide Measurement
Tech Notes
Nitrous Oxide Measurement as Key Step towards Climate-Neutral Wastewater Treatment

Greenhouse gas emissions at wastewater treatment plants are coming into focus as the water industry works to reduce its climate footprint

WWTP-Flensburg_credit-photo-Andreas Große
Identifying N2O at the Flensburg wastewater treatment plant

The investment costs had initially deterred us somewhat. However ...

Tech Notes
Characterizing N2O emissions from WWTPs

A study of three very different WWTPs in Denmark: Bjergmarken (125,000 PE), Holbæk (60,000 PE), and Hvalsø (11,570 PE)

Tech Notes
N2O Emissions from Danish WWTPs – a two year monitoring project

The available data show that the nitrous oxide emission varies in time and between wastewater treatment plants.

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Tech Notes
Nitrous Oxide Emissions from Trickling Filters

Information regarding N2O emissions from trickling filters is limited, partly caused by the difficulties in capturing off-gases.

Tech Notes
IPCC Greenhouse Gas Emission Factors

Significant 3-fold increase in IPCC2019 wastewater N2O emission factor supported by Danish studies.

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N2O Monitoring Puts VCS Denmark at the Technological Forefront

VCS Denmark, one of the largest and oldest water and wastewater companies in Denmark, is actively committed to resource optimization

Frederikshavn Water Utility

Frederikshavn Water Utility contacted Unisense Environment for assistance in determining the actual N2O derived CO2 footprint