Guidance

Incineration activities: pollution inventory reporting

Updated 21 August 2024

Applies to England

• Publication for Northern Ireland
• Publication for Scotland
• Publication for Wales

If you operate an A1 facility, you must submit data to the pollution inventory. The Environment Agency will have sent you a notice explaining this when your environmental permit was issued.

The ‘general guidance’ available in the pollution inventory reporting guidance gives information that applies to all business and industries. It explains what the pollution inventory is and how to report.

This guidance gives information specific to incineration activities. This includes incineration of:

• animal by-products
• clinical waste
• hazardous waste
• municipal waste
• sewage sludge

You may also need to refer to other guidance for these sectors.

What to report

You should report annual mass releases of specified substances to air, water, and land, as well as off-site transfers of waste.

Reporting ‘releases to land’ only applies to pollutants in waste which is disposed of by ‘land treatment’ or ‘deep injection’. If you treat waste in this way, you must report substance-specific releases regardless of the disposal location.

Do you not have to report accidental releases of pollutants onto the soil on the site of your facility (for example spillages). This guidance note applies to air, water, and off-site waste transfer only.

Release estimation techniques (RETs) are described in the ‘general guidance’ available in the pollution inventory reporting guidance. Our recommended RETs for incineration activities are as follows.

First preference

Use continuous emissions monitoring systems (CEMS) data. Calculate the release based on daily CEMs average and daily average flow, integrated over year. You should base this on raw or as measured data without subtraction of confidence intervals.

Second preference

Use periodic monitoring data. Calculate the release based on average of periodic samples and annual flow.

Third preference

Use mass balance or emissions factors. Calculate the release based on mass balance or emission factors.

Fourth preference

Use agreed alternative technique. If you deviate from the above arrangements, you need to agree an appropriate technique with us.

Emissions to air

Incineration installations subject to Chapter IV of the Industrial Emissions Directive (IED) are normally required to be monitored continuously for:

• carbon monoxide (CO)
• hydrogen chloride (HCl)
• hydrogen fluoride (HF)
• nitrogen oxides (NOx)
• sulfur dioxide (SO₂)
• total organic carbon (TOC)
• total particulate matter

Under certain circumstances, continuous monitoring of HCl, HF and SO₂ may not be required, and periodic monitoring can be used instead. The specific requirements for continuous or periodic monitoring are detailed in your EPR permit.

Your permit also specifies frequencies for periodic monitoring of:

• dioxins and furans
• dioxin-like PCBs (polychlorinated biphenyls)
• heavy metals
• poly aromatic hydrocarbons (PAHs)

The monitoring frequencies required by Chapter IV of the industrial emissions directive (IED) are the minimum frequencies for such periodic measurements. Your permit may specify higher frequencies.

Your environmental permit may set additional specific monitoring requirements for your site, depending upon local circumstances. Where selective non-catalytic reduction (SNCR) is in operation, these may include:

• ammonia (NH₃) releases, depending on the reductant used
• nitrous oxide (N₂O)

Relevant pollutants

The most common air emissions from waste incineration activities, and their sources, are:

• ammonia (NH₃) - flue gas where NH₃ is used as a reducing agent for SNCR
• cadmium (Cd) -
  • flue gas in municipal solid waste (MSW) incinerators from batteries, accumulators, paints and plastics
  • hazardous wastes including effluent treatment sludges and drummed waste from metal plating works
• carbon dioxide (CO₂) - flue gas from complete combustion of organic material (between 0.7 and 1.7 tonnes of CO₂ is generated per tonne of MSW combusted)
• carbon monoxide (CO) - flue gas from incomplete combustion of waste (for example, if spontaneously evaporating or rapid-burning substances are present, or when combustion gas mixing with the supplied oxygen is poor)
• dioxins and furans –
  • flue gas from re-combination reaction of carbon, oxygen and chlorine
  • boiler ash, bottom ash, fly ash and sorbents
  • dioxin and furan releases should be reported as I-TEQ and WHO-TEQ equivalents as calculated to fulfil the requirements of your EPR permit
• dioxin-like PCBs –
  • flue gas from most municipal waste streams and some industrial wastes - higher concentrations in some hazardous waste streams
  • bottom ash and air pollution control (APC) residues
• heavy metals and compounds including antimony, arsenic, chromium, copper, lead, and nickel –
  • flue gas as particulate matter usually as metal oxides and chlorides
  • bottom ash, fly ash and sorbent
• hydrogen chloride (HCl) - flue gas from wastes containing chlorinated organic compounds or chlorides
• hydrogen fluoride (HF) –
  • flue gas from fluorinated plastic or fluorinated textiles in MSW
  • fluorinated compounds in hazardous waste incinerators (HWI)
• mercury (Hg) –
  • flue gas from MSW containing batteries, thermometers, dental amalgam, fluorescent tubes or mercury switches
  • HWI from coking plant tars, waste from chlorine alkaline electrolysis, caustic oil sludge from refineries and other chemicals containing mercury
  • bottom ash, fly ash and sorbents
  • sewage sludge incinerator (SSI), mercury from sewage (especially dental amalgam)
• nitrogen oxides (NOx) - flue gas as both thermal and fuel NOx – in MSW incinerators the proportion of thermal NOx is important, with each type of grate having an inherent background NOx level (thermal NOx is often more significant than fuel NOx)
• nitrous oxide (N₂O) –
  • principally from SNCR
  • modern MSW incinerators have low combustion-originated N₂O but, depending on reagent, significant emissions resulting from SNCR
• particulate matter (total, PM10 and PM2.5) –
  • flue gas as fine ash from the incineration process entrained in the gas flow
  • fugitive releases of dust from waste storage areas
  • note that emissions of PM10 and PM2.5 from the stack must be estimated using the method specified in ‘Calculations and resources’, and be reported accordingly – that is, the estimated figure or below reporting threshold (brt) as appropriate)
• poly aromatic hydrocarbons (PAH) –
  • flue gas as products of incomplete combustion
  • bottom ash, fly ash and sorbents
• sulfur oxides (SOx) –
  • flue gas where sulfur is present in the waste stream
  • common sources of sulfur in some waste streams are wastepaper, plasterboard (calcium sulfate), and sewage sludge
• volatile organic carbon (VOC) –
  • flue gas from incineration of organic waste
  • fugitive releases from waste storage areas

Use this list as a guide only and check that there are no other pollutants emitted from your installation. See ‘Calculations and resources’ for a summary of currently used emission source factors.

Emission sources

Point source emissions

For combustion activities taking place within a variety of furnace types at incineration facilities, point source (main stack) emissions are usually the most significant emission source, in terms of annual mass releases.

Fugitive emissions

Fugitive emissions are those that are not released from a point source such as a stack.

Fugitive dust and VOC emissions will be minimised where combustion, flue gas treatment processes, and plant in general (including storage areas) operate at negative pressure.

Some examples of fugitive emissions from incineration activities are losses from:

• loading and unloading transport containers
• storage areas (for example, bays and stockpiles)
• transferring material between vessels (for example, silos and volatile liquids such as substitute liquid fuels (SLF))
• conveyor systems
• pipework and ductwork systems (for example, pumps, valves, flanges)
• abatement equipment by-pass
• accidental failure of containment from plant and equipment
• oil and ammonia storage tanks
• poor building containment and extraction
• use of poorly sealed waste charging systems

You only need to report fugitive emissions that leave the installation to the pollution inventory. You do not need to report contained spills, but you do need to report vapour emissions that may have dispersed.

Any spills may still need to be reported in other ways as part of your permit conditions.

Emission factors

If unit operations remain consistent, representative monitoring data can be used to generate site-specific emission factors. The emission factor will be the ratio of the measured or calculated pollutant emission to the process activity. For example, you might use waste feedstock flow rate.

You should periodically check site-specific emission factors to ensure they are still valid, especially where waste feedstock quality varies throughout the year. Where different waste feedstocks are used, you should separately determine the emission for each waste feedstock, then add the results together.

Emission factors are usually expressed as the mass of a substance emitted per unit of activity, multiplied by the unit mass, volume, distance, or duration of the activity emitting the substance. In some cases, particularly for SO₂, the emission factor is based on waste feedstock analysis data.

For new or modified processes, you can obtain initial emission factors from manufacturer’s data and carry out sampling during commissioning to confirm the assumed values.

Carbon dioxide factors

Check the method shown in our pollution inventory ‘technical guidance and equations’ to estimate carbon dioxide emissions from incinerators.

If the primary purpose of your installation is incineration of hazardous or municipal waste, you are exempt from UK ETS. You might still find the method useful to complete your pollution inventory return.

Waste feedstock analysis and process stream data

Using waste feedstock analysis and process stream data to calculate emissions is similar to using of emission factors. Equations to calculate waste feedstock emissions are given in the ‘technical guidance and equations’ guidance.

For MSW incineration, analysis of fuel is not used for calculation of emissions. Either analysis is not carried out, is too variable, is too unreliable, or cannot be related to emissions.

Normalisation

Take care in all calculations to ensure that the emission concentration and flow rate are compatible. See our ‘technical guidance and equations’ for formulae to convert between normalised and actual emission concentrations.

Emissions to water

Emissions of substances to water can be either direct to controlled waters or indirect, following transfer to off-site effluent treatment plant.

For what constitutes an emission or a transfer, check the ‘general guidance’ available in the pollution inventory reporting guidance.

Relevant pollutants and emission sources

Water discharges from incineration processes arise from several sources, including:

• air abatement equipment (for example, wet scrubbers)
• storm water
• cooling water
• boiler blow-down
• incoming waste handling areas
• ash and other residue handling areas
• accidental emissions of raw materials
• products or waste materials
• firefighting
• on-site effluent treatment

The most common pollutants emitted to water, and their main sources, are:

• dioxins and furans – from scrubber liquor, releases from ash quenching
• ethylene dichloride – from scrubber liquor, releases from ash quenching
• metals – from waste storage, scrubber liquor, releases from ash quenching
• PAHs – from scrubber liquor, releases from ash quenching
• suspended solids – from raw material preparation, storage and handling, scrubber liquor, releases from ash quenching
• TOC – from waste storage, scrubber liquor, releases from ash quenching

Check that there are no other substances emitted from the process, including in association with suspended particulate. See ‘Calculations and resources’ for methodologies used to determine emissions to water.

Discharges of the above substances depend on your ‘in process’ preventative measures (good housekeeping, re-use) and the presence and technical standards of wastewater treatment facilities. At some installations wastewater will pass through an on-site effluent treatment plant prior to discharge into controlled waters.

You should consider all emission sources to water and characterise the flows and emission concentrations from each source.

Off-site waste transfers

Relevant wastes

The most common waste streams from incineration facilities are:

• air pollution control (APC) residues
  • 19 01 07 (commonly combined with fly ash, and then approximately 2.5% by weight of waste input for a modern municipal waste incinerator (MWI))
• bottom ash (approximately 25% by weight and 10% by volume of input for an MWI)
  • 19 01 11 where bottom ash contains hazardous substances
  • 19 01 12 where bottom ash does not contain hazardous substances
• fly ash
  • 19 01 13 where fly ash contains hazardous substances
  • 19 01 14 where fly ash does not contain hazardous substances
  • where fly ash is combined with APC residues, include it in the mass of APC residue
• rejected feedstock wastes
  • chemical or physical incompatibility, for example large objects
• recovered waste fractions
  • for example, for steel and aluminium extracted from ash, use 19 01 02

Calculations and resources

Incineration source factors - releases to air

We have provided lists of the pollutants potentially emitted from various typical incineration processes. Where available, we have also provided a literature reference for further information, and an emissions factor.

Beside each substance name, we have suggested the most suitable method to determine the release quantity:

• M = measurement
• C = calculation
• E = estimation (engineering judgement)

For pollutants not named in these lists, a return of not applicable (‘n/a’) is expected in most cases, to indicate that this pollutant is not knowingly discharged by the site.

Use this list as a guide only and ensure that all pollutants discharged from your site are reported on your return.

Waste combustion

• antimony (Sb) - M – use BS EN 14385 for extractive monitoring
• arsenic (As) – M - use BS EN 14385 for extractive monitoring
• benzene - C - no specific reference literature or source factors recommended
• benzo(a)pyrene - M - refer to BS ISO 11338 for extractive monitoring
• butadiene - C - no specific reference literature or source factors recommended
• cadmium (Cd) – M - use BS EN 14385 for extractive monitoring
• carbon dioxide (CO₂) - C – refer to UK ETS M and R Methodology (2004/156/EC) – although incinerators are not subject to the UK ETS requirements, the UK ETS methodology is considered best practice
• carbon monoxide (CO) - M - refer to CEN, ISO, or MCERTS: continuous and periodic monitoring carried out for all incinerators is covered by Chapter IV IED, or use BS EN14181 for CEMs
• chromium (Cr) – M - use BS EN 14385 for extractive monitoring
• copper (Cu) – M - use BS EN 14385 for extractive monitoring
• dioxins and furans - M – refer to BS EN1948, use periodic monitoring required for Chapter IV IED incinerators
• hydrogen chloride (HCl) - M – refer to MCERTS, use BS EN 14181 for CEMs, and BS EN1911 (or demonstrated equivalent) for periodic monitoring carried out for all incinerators covered by Chapter IV IED
• fluorine and inorganic compounds – M – use BS EN14181 for CEMs and USEPA Method 26A for periodic monitoring – note, not all Chapter IV IED incinerators are required to monitor HF continuously
• lead (Pb) – M - use BS EN 14385 for extractive monitoring
• manganese (Mn) – M - use BS EN 14385 for extractive monitoring
• mercury (Hg) – M - use BS EN 14385 for extractive monitoring
• nickel (Ni) – M - use BS EN 14385 for extractive monitoring
• nitrous oxide (N₂O) – M – extractive monitoring is required for Chapter IV IED (use ASTM D634803, ISO 10849, and VDI2469-1)
• NMVOCs - M – refer to MCERTS or BS EN 12619, use CEM and extractive monitoring
• poly aromatic hydrocarbons (PAH) – M – use BS ISO11338 for extractive monitoring
• poly chlorinated biphenyls (PCBs) – M – use BS EN1948 for dioxin like PCBs extractive monitoring
• total particulate matter (see note at the end of this section) – M – use continuous monitoring carried out for all incinerators covered by Chapter IV IED, BS EN13284-2 for CEMs, and BS EN13284-1 for SRM
• particulate matter: PM10 and PM2.5 – E - to provide a conservative estimate, the same annual mass emission as that calculated for total particulate matter should be used for both pollutants (assume that TPM = PM10 = PM2.5)
• sulfur oxides (SOx) – M - refer to CEN, ISO, or MCERTS, use BS EN14181 or BS 6069 (ISO 7935) for CEMs, and BS EN14791 (SRM); use BS ISO11632 or BS ISO 6069 alternatives for extractive monitoring
• vanadium (V) – M - use BS EN 14385 for extractive monitoring
• zinc (Zn) – M - although not specifically validated for zinc, BS EN 14385 will be applicable in most cases (see Environment Agency Method Implementation Document for metals)

MSW combustion

• methane (CH₄) - C – use 0.0008 kg/t of MSW combusted
• hydrogen chloride (HCl) – C – refer to USEPA AP-42, use 3.2 kg/t of MSW combusted
• NMVOCs - C - use 0.0308 kg/t of MSW combusted
• nitrous oxide (N₂O) – C – refer to IPCC (2000), use 0.03 kg/t of MSW combusted
• sulfur oxides (SOx) – C – use 0.076 kg/t of MSW combusted

SSW combustion

• methane (CH₄) (C) – refer to US EPA AP-42, use 0.39 kg/t of SSW combusted in multiple hearth (controlled)
• hydrogen chloride (HCl) – C – refer to US EPA AP-42, use 0.05 kg/t of SSW combusted on fluidised bed (controlled)
• NMVOCs – C – refer to US EPA AP-42, use 0.84 kg/t of SSW combusted in multiple hearth (uncontrolled)
• nitrous oxide (N₂O) – C – refer to IPCC (2000), use 0.8 kg/t of SSW combusted
• sulfur oxides (SOx) – C - refer to US EPA AP-42, use 2.3 kg/t of SSW combusted in multiple hearth (venturi scrubber), and 0.15 kg/t of SSW combusted in fluidised bed (uncontrolled)

CW combustion

• hydrogen chloride (HCl) – C - refer to US EPA AP-42, use 16.8 Kg/t of CW combusted
• sulfur oxides (SOx) – C - refer to US EPA AP-42, use 1.09 kg/t of CW combusted in controlled air (uncontrolled)

SNCR nitrogen oxide abatement

• ammonia (NH₃) – M – with MCERTS certified equipment continuous or periodic monitoring may be required depending upon BAT assessment

Fugitive VOC releases

• NMVOCs – C -  no specific reference literature or source factors recommended

Note about total particulate matter

Some plants use their particulate CEMS as indicative monitors, in accordance with Environment Agency M20 guidance. In these cases, you can use a conservative estimate of the annual total particulate emissions, based on the normalised annual flow multiplied by the highest single result obtained from periodic monitoring over the last 3 years (or since the start of regular operation if less than 3 years of data are available) excluding commissioning. This applies for each line, in the case of a multi-line plant.

If your plant has undergone maintenance in the last 3 years, you may have agreed a shorter period with the Environment Agency, as this will have reduced particulate emissions (for example, replacement of the bag filters). Periodic monitoring will include all tests for calibration and validation of the CEMS (QAL2) and annual surveillance tests (ASTs) carried out under BS EN 14181, as well as any further periodic monitoring specified in your permit, or agreed in writing with the Environment Agency.

Periodic monitoring in this instance can be an attempted QAL2 or AST, in which case a single result means the average of the samples obtained over the test period under normal operating conditions (normally 15 results for a QAL2 or 5 for an AST). If no QAL2 or AST has been attempted, a single result will be a single sample, or the average of triplicate (or more) samples taken as part of any other single test campaign under normal operating conditions.

Alternatively, as per the M20 guidance, you may instead assume that the plant operates constantly at 30% of the daily ELV (that is, the maximum allowable uncertainty) and multiply this figure by the normalised annual flow.

Releases to controlled waters and transfers in wastewater

For any releases to water from once-through cooling, your data should reflect the pollutant load considering incoming cooling water quality. Where this would result in a negative return (that is, removal of pollutants from incoming waters) you should enter ‘n/a’ on your return, unless you have previously agreed something else with us.

We have listed the main water pollutants that could be discharged from effluent treatment facilities and their analytical methods. In all cases we expect you to measure the release of these pollutants with monthly flow-proportional sampling or continuous monitoring (as specified in your permit). The list is not exhaustive, and other analytical methods may be appropriate.

Analytical methods for water pollutants include:

• arsenic (As) - BS EN ISO 11969
• cadmium (Cd) - BS EN ISO 17294
• chlorides (as total Cl) - sewage and effluents 1981 SCA blue book
• chloroform - BS EN ISO 10301
• chromium (Cr) - BS EN ISO 11885
• copper (Cu) - BS EN ISO 11885
• ethylene dichloride - BS EN ISO 10301
• lead (Pb) - BS EN ISO 11885
• mercury (Hg) - BS EN 13506
• naphthalene - BS ISO 17993
• nickel (Ni) - BS EN ISO 11885
• PAHs (includes benzo(a)pyrene, benzo(b)fluoranthene, benzo(k)fluoranthene, indeno(123-cd)pyrene) - BS ISO 17993 US EPA method 0610
• PCBs – US EPA methods 0680, 1668
• TOC – use continuous monitoring
• tributyl tin - BS ISO 18073
• zinc (Zn) - BS EN ISO 11885

Dioxins and furans

This family of compounds is known chemically as:

• polychlorinated dibenzodioxins (PCDDs)
• polychlorinated dibenzofurans (PCDFs)

Each compound is made up of two benzene rings interconnected by oxygen atoms. Each individual PCDD or PCDF is termed a congener (there are 210 congeners in total).

When reporting dioxin and furan releases, only the mass of PCDD and PCDF with chlorine atoms in the 2, 3, 7 and 8 positions should be included. These are releases of the most environmental concern.

The two ways we want you to report the toxicity of dioxin releases are:

• international toxicity equivalents (I-TEQs)
• World Health Organisation toxicity equivalents (WHO-TEQ)

Each dioxin congener is assigned a toxic equivalency factor (I-TEF for the international scheme and WHO-TEF for the WHO scheme). The 2,3,7,8-TCDD isomer is the most toxic, and is assigned a TEF of 1.0. The remaining 2,3,7,8-positional congeners are then assigned lower relative TEFs.

The toxicity mass of a particular substance relative to 2,3,7,8-TCDD can then be expressed by multiplying the mass of those 2,3,7,8-positional congeners present in the mixture by their respective TEFs. The resulting toxic equivalents are expressed as masses in the same way that the individual congeners are expressed.

You must give the total quantity of dioxins and furans in terms of their I-TEQs and WHO-TEQs.

TEFs for each of the 17 relevant 2,3,7,8-positional congeners of PCDDs and PCDFs are:

• 2,3,7,8-TCDD - WHO-TEF 1 and I-TEF 1
• 1,2,3,7,8-PeCDD - WHO-TEF 1 and I-TEF 0.5
• 1,2,3,4,7,8-HxCDD - WHO-TEF 0.1 and I-TEF 0.1
• 1,2,3,7,8,9-HxCDD - WHO-TEF 0.1 and I-TEF 0.1
• 1,2,3,6,7,8-HxCDD - WHO-TEF 0.1 and I-TEF 0.1
• 1,2,3,4,6,7,8-HpCDD - WHO-TEF 0.01 and I-TEF 0.1
• OCDD - WHO-TEF 0.0003 and I-TEF 0.001
• 2,3,7,8-TCDF - WHO-TEF 0.1 and I-TEF 0.1
• 2,3,4,7,8-PeCDF - WHO-TEF 0.3 and I-TEF 0.5
• 1,2,3,7,8-PeCDF - WHO-TEF 0.03 and I-TEF 0.05
• 1,2,3,4,7,8-HxCDF - WHO-TEF 0.1 and I-TEF 0.1
• 1,2,3,7,8,9-HxCDF - WHO-TEF 0.1 and I-TEF 0.1
• 1,2,3,6,7,8-HxCDF - WHO-TEF 0.1 and I-TEF 0.1
• 2,3,4,6,7,8-HxCDF - WHO-TEF 0.1 and I-TEF 0.1
• 1,2,3,4,6,7,8-HpCDF - WHO-TEF 0.01 and I-TEF 0.01
• 1,2,3,4,7,8,9-HpCDF - WHO-TEF 0.01 and I-TEF 0.01
• OCDF - WHO-TEF 0.0003 and I-TEF 0.001

All other congeners that may be present in a sample do not need to be reported.

Worked example - calculating dioxin and furan releases

If monitoring data representative of annual releases are available, you can get the TEQ of the mixture by summing the individual TEQs as follows:

Step 1: Calculate the TEQ for each congener released. Multiply the concentration (per m³) of each released congener by its TEF. Then multiply by the total volume released in that year (in m³) to provide the TEQ.

Step 2: Calculate the total TEQ released. Add together the TEQs of all the congeners released. Carry out Steps 1 and 2 for both sets of TEFs.