Debate revived on incineration of non-hazardous waste

Talks on an EC Directive on the incineration of all non-hazardous waste have been revived by the European Commission after a gap of two years. A proposal which would have required expensive treatment of solid residues produced by incinerators has been dropped from a revised draft tabled in May. Debate is now centred on the need for identical emission controls for all types of non-hazardous waste, a proposed limit for nitrogen oxides, and rules for co-incineration of waste in industrial processes. Meanwhile, a study for the Commission will stoke renewed controversy over incineration's role in the waste hierarchy by valuing the damage caused by municipal incinerators emissions at 10-60 ECU per tonne of waste - and possibly much more.

The new Directive will replace the two 1989 Directives on new and existing municipal waste incinerators, and will also apply to all other types of non-hazardous waste. Incineration of hazardous waste is covered by a 1994 Directive.

Discussions on the proposal were put on hold two years ago while an economic evaluation of the Commission's initial draft was carried out by the Energy Technology Support Unit (ETSU) at Harwell in the UK. The proposal has since been redrafted, and the Commission met national officials to discuss the new text in May. A further meeting is due in October, with a formal proposal expected early in 1998.

Many of the key features of the latest draft are modelled on the 1994 Directive on hazardous waste incineration. In particular, the emission limits in the two documents are fairly similar - amounting to a significant tightening of the standards set by the 1989 Directive on new municipal incinerators for particulates, acid gases and metals, and setting new limits for dioxins and nitrogen oxides.

The other 1989 Directive on existing municipal incinerators is now redundant, in that it required all existing plant to be upgraded to new plant standards or shut down by last December. In the UK, this forced the closure of all but five incinerators, although one existing plant has since been upgraded and four new ones are under construction (ENDS Report 262, pp 12-14 ).

The main features of the proposal are summarised below, along with the key differences between the current and earlier drafts and between the proposed regime for non-hazardous waste and the existing rules for hazardous waste incinerators.

  • Scope: The proposal applies to all solid and liquid non-hazardous wastes, apart from the categories of waste excluded from EC waste legislation - such as mineral, agricultural and radioactive wastes - and liquid wastes which cannot give rise to emissions other than, or at a higher concentration than, those arising from gas oil combustion.

    The wide scope of the proposal looks like being one of the most difficult issues in the negotiations. Many Member States have told the Commission that they see no justification for applying the same strict emission controls to all types of non-hazardous waste.

    The Nordic countries in particular are concerned about the implications for plants burning biomass, but the repercussions of a uniform regime are potentially much wider. A specific UK worry is the possible extra cost of burning wastes from cattle slaughtered in response to the BSE crisis (ENDS Report 268, pp 19-23 ).

    The Commission is faced with three options on this point: stick with the present draft but have it radically overhauled by Environment Ministers, exclude some wastes from the Directive, or propose a more relaxed regime for specific categories of waste. Its position should be clearer by October.

  • Integration and prevention: Although the proposal is not being treated by the Commission as a "daughter" of the 1996 Directive on integrated pollution prevention and control, it expressly requires incinerator operators to obtain a permit "according to the rules laid down by" that Directive. Member States are pressing for a clarification of how the two regimes will interact, but in the meantime it is evident that the Commission envisages at least a stronger preventive thrust towards managing the wastes produced by incinerators.

    In particular, the proposal stipulates that permit applications must demonstrate that incinerator residues "cannot be prevented, reduced further in their amount and harmfulness, recovered or reused." It also provides that the "best available techniques" (BAT) should be used to minimise the leachability of incinerator residues.

    Neither of these requirements appears in the 1994 Directive on hazardous waste incineration. Nor does a proposal that permits may not be granted unless applications show that energy recovery will be "maximised".

  • Waste reception: The draft is more specific in this area than the 1994 Directive, requiring the use of BAT for storage and pre-treatment of wastes so as to reduce emissions of dust, volatile substances, odour and noise.

    In addition, it stipulates that before wastes are accepted the mass of "each category" of waste must be determined by the operator. The practicality of this requirement for mixed wastes, especially municipal waste, remains in question.

  • Emission limits: The limits proposed by the Commission are unchanged from the earlier draft.

    The standard of 0.1ng/m3 proposed for dioxins and furans is ten times tighter than the limit currently applied in the UK to non-hazardous waste incinerators regulated under integrated pollution control (IPC).

    Many UK operators would also face extra costs in meeting the proposed emission limits for NOx - 200mg/m3 as a daily average, and 400mg/m3 as a half-hour average to be complied with by 97% of all samples over a year.

    Guidance issued last year by the Environment Agency for municipal incinerators controlled under IPC set a weaker "benchmark release level" of 250-300mg/m3 to be met by 95% of hourly averages (ENDS Report 262, pp 34-35 ), with higher values for sewage sludge incinerators. These could be met without add-on abatement - but the proposed EC limits would almost certainly require the use of selective non-catalytic reduction (SNCR) on sludge and municipal incinerators, pushing NOx emissions below 100mg/m3. Clinical waste incinerators may just be able to meet the proposed EC limit without SNCR.

    Although incinerator operators are objecting to the proposed NOx standard, the UK is thought unlikely to oppose it. The use of SNCR on power stations and incinerators overseas is increasing (ENDS Report 262, p 6 ), leaving the UK open to criticism that it is not applying the "best available techniques not entailing excessive cost".

    Another reason why the proposed NOx standard will be difficult to oppose is that ETSU's study concluded that by far the most significant damage caused by incinerator emissions is through the formation of particulates from nitrate aerosols.

  • Liquid discharges: The Commission's proposals in this area are more specific and potentially more onerous than the controls in place for hazardous waste incinerators.

    Like the 1994 Directive, the new proposal would require liquid discharges from flue gas cleaning to be minimised "as far as possible". The 1994 Directive also stipulated that the mass of heavy metals and dioxins in liquid wastes should be less than that allowed to be emitted to air, and provided that EC discharge limits should be set two years after its entry into force - though this has not in fact been done.

    For non-hazardous waste incinerators, however, the first draft of the Commission's proposal contained limits on mass releases of pollutants, and these have now been buttressed with a second set of concentration limits. Both sets of standards appear to apply to treated rather than raw discharges.

    The proposed limits on mass releases are largely unchanged from the earlier draft. One exception is dioxins and furans, for which the revised limit of 150ng/tonne of waste is now five times less stringent. The earlier proposal for a limit of 50mg/kg for chloride has been dropped, presumably because it would have been inordinately difficult to comply with.

  • Solid residues: One of the most controversial aspects of the Commission's first draft was a set of limits on the constitutents of leachate from solid residues such as bottom ash, fly ash and flue gas treatment residues, as determined by standardised tests.

    The results of two recent UK studies on the leachability of municipal incinerator residues are compared with these proposals in ETSU's report (see table ). They show that the chloride content of both bottom ash and flue gas cleaning residues was way in excess of the proposed limits. Zinc and lead levels in bottom ash were close to or slightly above the standards, but concentrations of both metals in flue gas cleaning residues were substantially above the proposed limits.

    In order to comply with the limits, these wastes would have to be washed to remove the soluble chlorides, and then encapsulated or vitrified to contain the metal contaminants. ETSU's calculations suggest that for municipal incinerators alone this would cost 3.8 billion ECU per year in 2000 across the EC - several times the cost of meeting the emission limits set by the Directive.

    The Commission has relented. It has scrapped the leachate limits and, as noted above, left only a general duty to minimise incinerator residues and reuse and recover them "as far as possible". Disposal is to be limited to residues "for which no possibility of recovery exists". Member States way want to include an economic dimension in this requirement.

    The other provisions of the proposal - on issues such as monitoring of releases, temporary derogations from the standards, and co-incineration of wastes in industrial processes - are closely in line with the 1994 Directive. Nevertheless, co-incineration may provoke lengthy debate because the existing formula has proved difficult to apply, and because the waste industry is lobbying hard for all facilities burning waste to be operated to the same standards.

    No deadline for the proposal's entry into force has yet been put forward by the Commission. But the requirements for upgrading of existing plant are similar to those in the 1994 Directive. An existing incinerator which the operator does not intend to upgrade would be allowed to operate for up to 20,000 hours in the five years after the Directive's entry into force before being shut down, provided the authorities were notified of his intention within six months of entry into force.

    ETSU's study gives some insights into the costs and benefits of the proposal, although its utility in the forthcoming debate will be limited because it covers only municipal waste incinerators.

    ETSU's calculations are based on in-depth studies of the incineration sector in France, Germany and the UK, where the mix of plant is broadly representative of that across the EC.

    ETSU estimates that the cost of meeting the proposed air emission limits across the EC would range between 423 and 491 million ECU per year in 2000, with retrofits of existing plant being the cheaper option.

    In comparing these costs with the potential benefits, ETSU's central estimate of the damage caused by incinerator emissions is 10-60 ECU per tonne of waste incinerated.

    The effects of the new emission limits in reducing this damage were calculated for three hypothetical incinerators in Stuttgart, Birmingham and Paris. The results were then scaled up across the EC.

    For the Stuttgart case, the avoided damage was estimated at 633 million ECU per year - giving a net benefit of 172-240 million ECU per year when set against the emission control cost. But for Birmingham, the avoided damage was much lower at 358 million ECU per year - giving a net disbenefit of 65-133 million ECU. The figures illustrate the importance of incinerator location in relation to centres of population and wind direction.

    However, the damage estimates are, as ETSU acknowledges, subject to considerable uncertainty. In the first place, they are derived from "willingness to pay" techniques for valuing damage to health and the environment whose methodological soundness and use in decision-making remain highly controversial.

    That consideration aside, ETSU had to make very large assumptions in some of its valuation work. For instance, for secondary particulates, which dominate the overall damage estimate, two of a series of assumptions were that there is no threshold for the effects of PM10 on health, and that all chemical species of PM10 are equally damaging on a mass basis. Both may have led to an overestimation of damage.

    Conversely, the central estimate of damage excluded the chronic effects of particulates on mortality because they remain subject to significant uncertainty. When these are included, the total damage attributable to incinerator emissions rises to 60-180 ECU per tonne of waste - well above its central estimate of 10-60 ECU per tonne. Use of the higher figure would have given a considerably larger net benefit from abating emissions.

    Also excluded from the damage estimates were pollution effects on ecosystems and the architectural heritage, and non-carcinogenic effects of heavy metals and dioxins.

    ETSU estimates that the proposed Directive would reduce annual emissions from municipal incinerators around the turn of the century by 27,300 tonnes for NOx, 8,400 tonnes for sulphur dioxide, 1,600 tonnes for particulates, and 521 grams for dioxins. For most of these pollutants, incinerators contribute only a small fraction of emissions from all sources. The report closes by suggesting that "it is possible that larger and more certain welfare benefits could be achieved through expenditure on strengthening emission limits in other sectors."

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