Mercury monitoring in waste-to-energy plants – why periodic measurements just won’t cut it
GASMET Why do mercury emissions
need to be monitored? Mercury is a long-term pollutant that is extremely harmful to both humans and animals and has been recognized as a key pollutant of concern.
Governments worldwide have become more environmentally conscious. In Europe, the Industrial Emissions Directive (IED) that sets out the requirements for emissions on processes such as waste incineration and power plants was released in 2010. As a result, a new best available techniques reference document for waste incineration (WI BREF) document was issued in December 2019.
Within the WI BREF document, for larger facilities incinerating more than 3 tonnes/hour of non-hazardous waste or 10 tonnes/ day of hazardous waste, the mercury emission limit has been set between 5 µg/m3 December 2023.
and 20 µg/m3 and will be enforced by
IED is also currently under review. It is expected the mercury gas emission limits, among others, will continue to decline rapidly with the updated legislation. While many of the EU member states have chosen to use the higher end of the emission limit ranges in environmental permitting nationally, at the European Commission level they want to start using values close to the low end of the range as default. This sets tough requirements for all mercury monitoring systems.
2
For many years prior to the IED being implemented, waste incinerator operators had already been required to monitor mercury on a periodic basis (typically 6 monthly or every 3 months for new plants) using the standard reference method EN 13211.
Following the IED and subsequent WI BREF document, the default requirement for measurement of mercury emissions was changed from periodic measurement to continuous emission monitoring. However, if the waste being incinerated can be proven to have a low and stable mercury content, then continuous emission monitoring of mercury may be replaced by long term sampling or periodic sampling of mercury emissions. How this is adopted will differ from country to country.
Variation in mercury emissions
As many waste incineration plants are burning heterogeneous waste streams with randomly varying mercury content, then mercury emissions will also be randomly varying.
Figure 1 shows fl ue gas mercury content during one day from an actual European waste incinerator with emissions measured using a continuous mercury monitoring system. As can be seen, the mercury content stays relatively low for most of the day but experiences occasional high peaks. These peaks are attributed to starting the incineration process on new waste batches.
Page 1 |
Page 2 |
Page 3 |
Page 4 |
Page 5 |
Page 6 |
Page 7 |
Page 8 |
Page 9 |
Page 10 |
Page 11 |
Page 12 |
Page 13 |
Page 14 |
Page 15 |
Page 16 |
Page 17 |
Page 18 |
Page 19 |
Page 20 |
Page 21 |
Page 22 |
Page 23 |
Page 24 |
Page 25 |
Page 26 |
Page 27 |
Page 28 |
Page 29 |
Page 30 |
Page 31 |
Page 32 |
Page 33 |
Page 34 |
Page 35 |
Page 36 |
Page 37 |
Page 38 |
Page 39 |
Page 40 |
Page 41 |
Page 42 |
Page 43 |
Page 44 |
Page 45 |
Page 46 |
Page 47 |
Page 48 |
Page 49 |
Page 50 |
Page 51 |
Page 52
