Continuous mercury monitoring offers major advantages over periodic sampling 

The latest WI BATC document highlights the importance of continuous mercury monitoring

For many of us, it felt like time got all mixed up during the pandemic. “How can it be 2023 already? It was just 2019!” We understand how you feel, so consider this a reminder to review the mercury monitoring solution for your WtE plant. You probably remember, but the latest changes to the WI BATC document came in December 2019. This document describes the abatement techniques and associated emission levels (BAT-AELs) for waste-to-energy plants.

The most notable change is the requirement to monitor mercury emissions. The new WI BATC document sets levels as 5-20 µg/Nm3 (daily average) or 1-10 µg/Nm3 (long-term sampling). The new monitoring regulations require continuous mercury monitoring, with a few exceptions.

Importantly for you, it set a four-year transition period, after which all facilities in its scope need to be in compliance. If you’re doing the math at home, four years from 2019 is 2023.

That’s this year. Yes, really.

If you’ve been doing periodic measurements up to this point, you need to look into switching to continuous measurement, because there’s a good chance that the old method of periodic measurements won’t cut it anymore. Long-term sampling or periodic measurements can only be accepted as an exception if „low and stable“ mercury content can be proven by the operator.

The difficult question of “low and stable”

Many countries in the EU, such as Finland, are adopting the view that heterogeneous waste streams (like municipal waste) inherently vary in their mercury content and cannot be considered stable. This means that most WtE facilities using these types of waste streams need to implement continuous mercury monitoring.

The UK has adopted a different approach. It has been determined that six consecutive periodic mercury measurement results with a mercury content of less than 10 µg/Nm3 proves “low and stable emissions.” This enables the use of periodic measurements or long-term sampling instead of continuous mercury monitoring in these cases. If the limit is then exceeded later, the facility must identify the reasons and improve the process within a fixed time frame. If the facility fails to return below emission limits (demonstrated by additional periodic measurements), continuous mercury monitoring needs to be implemented.

It might be tempting to try and conform to the requirements using periodic measurements, but test results indicate that that might be challenging. Heterogeneous waste streams are prone to having varying mercury content which will then often directly translate into large variation in the flue gas mercury content.

The below data is taken from a typical WtE facility burning heterogeneous waste streams, measured with a continuous mercury monitoring system for one week. The data shows a high degree of variation in the cleaned flue gas mercury content both between different days as well as within a single day of operation.

For instance, if the periodic measurement is done on day six in the morning or during the day, the measurement is likely to pass. However, if the same measurement is done in the evening it would likely fail. Any measurements done on day three are also likely to exceed the ELV and cause issues. Looking at each day, there are times where the test would pass and times where it would fail. You’re already taking chances with one measurement, and you have to pass six in a row.

Why give yourself another headache over your plant’s mercury emissions? Simplify your life and implement continuous monitoring. By measuring the mercury content continuously, it’s also possible to identify the situations in which the content rises and therefore do continuous improvement to reduce the emissions. This will have a positive impact on the emissions as well as public’s perception on the WtE operations. It can only help your plant improve when mercury is monitored 8600 hours per year instead of 16 hours per year as with periodic measurements.

Gasmet can help implement a mercury monitoring solution that fits your needs

With over 20 years of experience in mercury monitoring, We at Gasmet have a system that will fit your needs. The benchmarks in continuous mercury monitoring are our CMM and CMM AutoQAL systems. They have the lowest certified measuring range (0-5 µg/m3, certified by TÜV and MCERTS) for compatibility with current regulations. This is lower than the lowest concentration of the new WI BREF requirements, ensuring a future-proof solution. You can sleep well at night knowing that our system is always monitoring your plant’s mercury emissions.


Mercury Emission Monitoring – CMM & CMM AutoQAL

Continuous Mercury Monitoring systems CMM AutoQAL and CMM are the perfect solutions for monitoring mercury continuously from hot, wet and corrosive gas streams.

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