VOC Pollution Control And The SED

There are many factors to consider in the control of VOC emissions to air from coating processes with the impact of the Solvent Emissions Directive (SED) on process authorisations. Dr Tony Smith of Envirocare reports.

The purpose of the Solvent Emissions Directive (SED) is to prevent or reduce the effects of emissions of VOC's into the environment by providing measures and procedures to be implemented for specified activities. Much of this runs in parallel with current legislation under the Pollution Prevention and Control Act and the opportunity has been taken by DEFRA to incorporate most of the requirements of the SED into the recently redrafted Process Guidance (PG) Notes 6 series, which are especially relevant to the Part A2 and Part B processes.

These guidance notes usually form the basis of the new authorisations and permits which are required by most of the authorised coating processes either currently or in the next few months, so it is important to understand this guidance.

Interpretation of the Process Guidance Notes
The new guidance notes (6 series) are far more comprehensive and complex than the previous guidance for coating processes (from 1997) and this results from the integration of the requirements of the SED, which has a great deal more definition of installation, activity and process and has the requirement to choose between various compliance schemes.

The initial step is to decide on the organic solvent consumption of the PPC installation and that of any SED activity or activities because it is on this decision that the application of the specific paragraphs will rely.

Essentially two compliance options are available for those processes which fall under the SED:

  • 1. meeting emission BAT limit values in waste gases and fugitive emission limit values;
    or,
  • 2. implementing a solvent reduction scheme (to reduce emissions equal to those that would have been achieved by meeting the emission limit values).

    In addition any operator using a substance having a risk phase in the group R45, R46, R49, R60, R61or halogenated VOC with R40 must either substitute it or control it.

    Existing installations have until end October 2005 or end October 2007 to comply dependant upon compliance route chosen. So for many companies there is now not much time to choose the compliance route and then to meet the timetable.

    Careful choice of route is required, as short term gains (financial or technical) produced from one route may result in a more onerous route at a later stage. If the choice involves going down the abatement route, then the choice of abatement technique could also be fundamental to the company's future existence. The choice of the abatement route, often referred to as 'end-of-pipe' technology, can lead to the replacement of one emission by another (as in incineration) or create another effluent stream (as in scrubber liquor), except where some form of recovery/recycling of the pollutant is practised (solvent recovery).

    Fundamental to all of this choice is measurement; - "if you cannot measure it, you cannot control it". At the minimum you must have a good solvent inventory system, good knowledge of all of your controlled sources of emission and some idea of the areas in which fugitive emissions could arise.

    Which Scheme?
    With this knowledge in hand it is important to have a good grasp of the specific PG note applicable to your installation and the spread of SED activities, indeed there may be more than one. You should then be able to trawl through the whole range of possibilities outlined in Table 1 and Table 2 of the PG note and decide exactly which section and paragraphs apply to your process!! It is a daunting task even for those skilled in the art, and for many it is a complete minefield. Don't necessarily expect a great deal of help from your EHO, they may well be just as bewildered and they have to write your new authorisation/permit!

    All processes/activities will have to comply with the emission limits specified in Table 4 (for non-VOC emissions) and for VOC emissions choose one of the two compliance options; reduction scheme or emission/fugitive limits.

    Emission limits scheme
    Table 5 and SED Box 5 will apply for this choice with the emission limits set dependant upon the exact process, and SED Box 9 will apply for fugitive emissions.

    Reduction scheme
    Choose this scheme to achieve emission reductions to a "target emission" and use Table 6 to determine the target emission value which is based on the total solids content of coatings used multiplied by a factor (which is dependant upon the process). Compliance is achieved if the annual solvent emission determined from the Solvent Management Plan is less than or equal to the target emission. You will need to produce an "emission reduction plan" and Table 6 shows significant improvements are required by October 2007.

    A Solvent Management Plan is required when you adopt either scheme. It is used for the emission limits scheme to assist with the quantification of fugitive emissions initially and for the reduction scheme it is used annually to quantify the actual emissions.

    Monitoring of Emissions
    Emissions of VOC and other substances from specific stacks or as fugitive emissions may require monitoring either as a one off or annually. To ensure the quality of the data produced, it is important that the expertise of environmental consultancies with stack sampling skills are utilised. The recent introduction of MCERTS, the Environment Agency's monitoring certification scheme, has led to an increase in the numbers of companies in the stack sampling field that have undertaken UKAS accreditation to ISO 17025. This is good news for everyone concerned, as it has improved the quality of the data for compliance sampling but also recognises the expertise of the stack sampling engineers and the quality of the operations of the stack sampling companies.

    The PG notes specify appropriate standards to be used as follows:

  • VOC to be determined using either BS EN 13526 or BS EN 13649;
  • Particulate matter using BS ISO 9096 (or low dust equivalent BS EN 13284);
  • Carbon monoxide using ISO 10849; and
  • Oxides of nitrogen using ISO 12039.

    It is important that competent stack sampling engineers are chosen to provide this data using calibrated equipment - get this wrong and your careful choice of option could be ruined by poor data which could be extremely costly.

    In conclusion, there are a number of factors to bear in mind when considering the impact of the SED on your processes. A complete understanding of the processes concerned is extremely important, so that all options can be considered and any changes made can be properly quantified in terms of their influence on emissions to atmosphere. This may be undertaken by the process operator alone, or better, in conjunction with an MCERTS accredited and experienced stack sampling company to provide the accurate data. Following this, if there is a requirement to install or monitor abatement equipment, then the choice of the most appropriate equipment can be made using good quality, relevant data and its efficiency can be determined after installation.

    So now there is nothing more to be SED!!

    For further information and guidance on interpretation of the SED and process guidance notes please contact Dr Tony Smith 01274 738668 or tony@envirocare.org.

    www.envirocare.org


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