Opsis blog

Historically, mercury (Hg) has found its use in many products such as thermometers, batteries, and fluorescent lamps. However, mercury is extremely toxic, and it has in modern days been banned from use in most applications.

By example, the Minamata Convention on Mercury from 2013 has been designed to prevent releases of mercury and mercury compounds in order to protect human health and the environment. It is signed and ratified by well above 100 countries around the world.

Nevertheless, mercury continues to be released also nowadays. Major anthropogenic sources are coal-fired power plants due to the natural occurrence of mercury in coal, and waste incineration facilities. In the latter case, the mercury emissions owe to old mercury-containing products ending up in the waste being burnt.

Reducing Mercury Emissions

Emissions of mercury from combustion facilities can be reduced by appropriate flue gas cleaning equipment. To drive the installation and use of such equipment, legislation can dictate emission limits. A recent example of this is found within the European Union, where the Industrial Emissions Directive (the “IED”) was supplemented by a new set of Associated Emission Levels for Waste Incineration in December 2019. These are referred to as the “BAT-AELs” of the “WI-BATC”, where BAT stands for best available techniques and BATC for BAT conclusions.

One of the new BAT-AELs states that the total mercury emissions expressed as a daily average of a normalized gaseous mercury concentration in the flue gas is possible to keep below 5 µg/m³ and in all cases must be kept below 20 µg/m³. The mercury concentration must be monitored continuously unless the waste can be proven to contain a low and stable level of mercury content. Such proof can be hard to obtain, notably in cases of mixed-waste or hazardous-waste incineration.

Practical Challenges

What then remains is to make sure that the flue gas cleaning equipment is installed and working, and then monitor the remaining mercury emissions continuously. This must all be up and running at applicable facilities within the EU not later than by end of 2023, when the new BAT-AELs become in full force and effect on national level. It’s therefore high time to act now, if not before.

When it comes to the monitoring part, the word “total” in total mercury must be observed. The mercury BAT AEL applies not only to atomic (metallic) mercury in the flue gas but to all gaseous substances containing mercury, such as mercury chloride (HgCl₂) and methylmercury (CH₃Hg⁺). Accordingly, a gas monitor of total mercury is needed, preferably with a proven reliability and a low total cost of ownership.

OPSIS Mercury Monitoring

Here is where OPSIS offers the best solution on the market: the OPSIS System 400Hg. It is based on differential optical absorption spectroscopy, DOAS, which works excellent for atomic mercury (Hg⁰), where also extremely low levels can be detected. This is extended to apply also to total mercury (THg) by introducing a durable catalytic converter which transforms all THg to Hg⁰. The OPSIS System 400Hg has been thoroughly tested and verified in harsh industrial environments over the past years, with excellent results. It is now being rolled out to customers both within the European Union and elsewhere in the world.

Please contact OPSIS or its representative for more information on the OPSIS System 400Hg.