Waste Incineration and the Environment

By R.E. Hester, R. M. Harrison

The Royal Society of Chemistry

Copyright © 1994 The Royal Society of Chemistry
All rights reserved.
ISBN: 978-0-85404-205-0

Contents

Incineration as a Waste Management Option J. Petts, 1,
Pollutants from Incineration: An Overview P. T. Williams, 27,
Recovering Energy from Waste: Emissions and Their Control G. W Rae, 53,
Organic Micropollutant Emissions from Waste Incineration G. H. Eduljee, 71,
Pilot-scale Research on the Fate of Trace Metals in Incineration G.J. Carroll, 95,
The US Approach to Incinerator Regulation E. M. Steverson, 113,
Environmental Assessment and Incineration D.O. Harrop, 137,
Subject Index, 155,

CHAPTER 1

Incineration as a Waste Management Option

J. PETTS

1 Introduction

Role of Incineration

For thousands of years the value of burning wastes has been recognized, both to reduce the quantity of surplus materials generated by households, trades, and agricultural practices, and to provide fuel for heating or cooking. Recognition of the potential environmental problems generated by burning wastes also has a long history. In the United Kingdom (UK) the existence of city controls on the burning of rubbish in open dumps can be traced back to the 13th century.

The industrial revolution and accompanying urban population explosion of the 18th and 19th centuries transformed the nature and volume of wastes arisings and the potential health problems of improper disposal practices. Mass-burning of wastes in enclosed and controlled conditions became an important waste management option. The first municipal solid waste (MSW) incinerator in England was commissioned at Nottingham in 1874, and by 1912 there were some 300 incinerators in the UK, 76 generating power from waste. Similar early developments took place in other countries, including Sweden, Germany, and the USA. Provision of industrial and hazardous waste incineration capacity was primarily by the major chemical companies requiring in-house facilities; for example, in the US, Dow Chemical installed the first rotary kiln in 1948. The development of large-scale commercial, or merchant, sector hazardous waste incineration capacity has primarily been post-1960s.

The specific benefits of incineration include:

(i) A reduction in the volume and weight of waste especially of bulky solids with a high combustible content. Reduction achieved can be up to 90% of volume and 75% of weight of materials going to final landfill.

(ii) Destruction of some wastes and detoxification of others to render them more suitable for final disposal, e.g. combustible carcinogens, pathologically contaminated materials, toxic organic compounds, or biologically active materials that could affect sewage treatment works.

(iii) Destruction of the organic component of biodegradable waste which when landfilled directly generates landfill gas (LFG ). Estimates suggest that LFG may account for over 40% of the UK ‘s total methane emissions to atmosphere.

(iv) The recover y of energy from organic wastes with sufficient calorific value.

(v) Replacement of fossil1uel for energy generation with consequent beneficial impacts in terms of the ‘greenhouse’ effect.

The range of wastes incinerated has expanded in many industrialized countries accompanied by development of specialized and dedicated facilities, including mobile plant. Incineration development has been influenced by: (i) concerns over direct landfill of certain materials, e.g. clinical wastes, (ii) legislative controls curtailing other disposal routes, e.g. for sewage sludge, (iii) identification of new environmental problems requiring remediation, e.g. contaminated soils, (iv) identification of problem wastes for which incineration represents the only commercially available method of disposal, e.g. polychlorinated biphenyls (PCBs), and (v) recognition of energy generation potential from wastes having the potential for adverse environmental impact if inappropriately disposed, e.g. scrap tyres. The extent of uptake of incineration in different countries has been influenced by the availability of other disposal options, in particular landfill, and the degree of central government market intervention in, and financial support of, capital investment and operation costs.

Issues and Concerns

Despite the versatility of incineration as a waste treatment method, opposition, particularly to commercial or merchant sector facilities, has developed to such an extent over the last two decades that in many countries proposals for new plant have faced long delays and often refusal, existing plant have closed, and even national waste management programmes have had to be delayed or modified following protest (for example, that of Spain and also Australia’s proposals for handling hazardous wastes). The 1970s saw a rapid growth in the concern over incineration as a public health risk, particularly with the identification of chlorinated dibenzo-p-dioxins (PCDDs) and dibenzofurans (PCDFs ) in MSW incinerator emissions, which coincided with the release of 2,3,7,8-TCDD (tetrachlorodibenzo-p-dioxin) and subsequent environmental contamination in a chemical accident at Seveso in Italy.

Public perceptions of health risks are underpinned by the reaction of specific communities against existing and proposed facilities in their local area, including concerns about management and control capabilities, and the management of wastes generally. The balance of arguments for and against incineration forms the basis of national policy development. A justification of incineration as the Best Practicable Environmental Option (BPEO) for managing different waste streams has to be set in the context of reducing the pollution potential of wastes generated and achieving the BPEO by identifying the optimum balance in terms of emissions and discharges at a reasonable cost. In 1993, the UK’s Royal Commission on Environmental Pollution (RCEP) published a report on the incineration of wastes, which urged the UK Government to give a higher priority to developing a national waste management strategy based upon the BPEO and commending incineration as having a more important place within such a strategy.

In order to place discussion of the role of waste incineration as the BPEO in some context it is appropriate to first consider the ‘current’ (i.e. 1993) situation with regard to its use. The potential for incineration is then considered in terms of: (i) policy development; (ii) the economics of incineration; (iii) environmental impact and risk assessment; (iv) technology development; and (v) public acceptance.

2 Use of Incineration

The UK

Table 1 presents approximate annual UK arisings for each of the main incinerable waste streams. As in many countries, the data are estimates being based upon variable arisings data collected by the local authorities at the disposal point rather than at source and in a variety of recorded formats. Figures for arisings of ‘special’ wastes as defined are subject to annual fluctuations, apparently partly caused by isolated disposals of contaminated soils and similar materials, but have not witnessed a significant growth compared to MSW. The UK imports hazardous wastes for treatment. Figures for the period 1991/2 show that approximately 47 000 tonnes were imported into England and Wales, of which 31% were incinerated. The UK’s importance in this context has been influenced by the availability of capacity for the handling of PCBs.

In 1991 there were some 230 licences for incineration facilities, 47 of these held by the public sector (i.e. primarily the local authorities) the rest by t he private sector. Less than 30 MSW incinerators were operating in 1993, five of which were recovering energy. Incineration provides for only 7% of MSW arisings. Installed capacity has shown a recent decline with existing plants not able to meet new emission standards set by Her Majesty’s Inspectorate of Pollution (HMIP) under Part 1 of the Environmental Protection Act, 1990. The plants most likely to survive are those able to recover energy and new proposals reflect recognition of the changing economics of incineration (see Section 4). MSW incinerators are generally based on agitating grates with excess air.

In 1993 there were four merchant sector chemical waste incinerators operating with a notional installed capacity of 138 000 tonnes of which 80 000 tonnes were available through rotary kiln systems. In addition, two or three in-house chemical company incinerators could accept third party wastes. In 1992, permission was granted for another 30 000 tonnes hazardous waste incinerator on Teesside, north-east England (not yet built). Approximately 3% of total ‘special’ wastes arisings are incinerated by the merchant sector. The majority of some 60 small chemical waste facilities within industrial companies provide for specific in-house process streams mostly utilizing liquid injection systems.

Sewage sludge has traditionally been disposed to the North Sea, used for land-spreading, or landfilled. With the ban on the former route to become effective by 1998 (under the EC Urban Waste Water Treatment Directive 91/271/EEC), incineration has become an attractive alternative option and the amount of sludge incinerated has already risen from about 45 000 tonnes in 1980 to 77 000 tonnes in 1991. A recent survey estimates that incineration could rise from the current 7% of arisings to about 19% by 2006. New plant are utilizing fluidized bed systems.

In addition to the licensed facilities, some 700–800 small incinerators for clinical waste may be operating, mostly within hospitals. As with MSW incinerators, the majority of these plant cannot meet new emission standards and are having to close. Clinical waste incineration is proving a major attraction to the private sector using ashing rotary kiln systems.

A number of small plants offer specialized services, including recent investments in plant for handling poultry litter (in Suffolk) and scrap tyres (in Wolverhampton, Midlands). Only 5% of scrap tyres are incinerated in the UK, although the new plant at Wolverhampton could handle 25% of total UK arisings. Incineration of wastes at sea has now ceased in response to resolutions of the London Dumping Convention meeting of November 1990.

Other Countries

Table 2 presents comparative data on the use of incineration in other countries. The data are from a number of different sources which may have used different definitions so they should be interpreted as indicative rather than actual. Nevertheless, some revealing differences are apparent, most particularly in the percentages of MSW incinerated, and in this context the very low usage in the UK.

The countries with over 50% of MSW incinerated reflect a shortage of landfill capacity (particularly Japan) and demands for cheap energy generation for district heating (particularly Sweden). They also reflect countries with more structured and centralized waste management planning. In many such countries generation of electricity is a local authority function. While agitating grates are popular for MSW incineration in most European countries, in the US rotary kiln systems are also used, and in Sweden and Japan fluidized bed systems contribute small proportions of total capacity.

Data on hazardous wastes disposal and treatment are very difficult to collate, because of differing definitions in different countries, commercial confidentiality, and the varying proportions of incinerable industrial wastes in different countries. It is estimated that only 5–8% of hazardous wastes are incinerated in the OECD/Europe with some countries (e.g. Ireland, Spain, Greece) having no merchant capacity, others having under-capacity. In-house handling of hazardous wastes which are not accounted for in national arisings figures also complicate any attempt to make comparisons between different countries. In the US, more than 90% of incinerated hazardous wastes are handled at the same facility that generated them. In France, some 16% of hazardous wastes are incinerated by the merchant sector and some 14% in-house. A component of hazardous wastes arisings is accounted for by contaminated soils, for which centralized soil treatment facilities, including rotary kiln incinerators, are provided in the Netherlands and Denmark and mobile plant are in use for remediation of contaminated sites in the US.

3 Policy Development

Waste Management Policy

A hierarchy of waste options providing a framework for waste management forms the basis of both European Community (EC) and national policy, i.e.:

(i) waste reduction at source — first priority;

(ii) waste recycling and reuse;

(iii) recovery of raw materials and/or the energy content of the wastes;

(iv) treatment — physical, chemical, biological, thermal — to convert wastes to a form that permits ultimate disposal; and

(v) disposal of the residues from treatment and of other unavoidable wastes — last option. Even at this point of final disposal the objective should be to continue to utilize the inherent characteristics of the waste to optimize reduction of its pollution potential and to extract the latent by -products (i.e. utilization of landfill gas).

It should be noted that in the UK a national policy on waste management has only gained any degree of transparency and structure since the publication of the Government’s White Paper on the Environment in 1990. The UK’s traditionally decentralized and free-market approach to environmental policy and strategy development with a heavy reliance upon a private-sector based waste disposal industry (virtually 100% for hazardous wastes) has meant that both the ability and willingness to adopt, and invest in, options higher in the waste management hierarchy have been reliant almost entirely upon perceived economic benefits (such as lower liabilities and market advantage). This contrasts with the type of regime seen in the Netherlands, Denmark, and certain of the German Lander where waste disposal is controlled centrally and projections of waste arisings, required disposal and treatment capacity, and provision of facilities in terms of number and regional allocation has been planned and encouraged by central authorities. In Denmark hazardous waste is directed to a single, multi-functional, treatment facility (Kommunekemi). It should be noted that reliance upon a single facility places considerable pressure upon operation to high standards, as non-availability for any reason would significantly interrupt achievement of policy objectives.

A move to more explicit policy encouragement of the options higher in the waste hierarchy is now apparent in the UK. Waste is regarded as a renewable resource and incineration with energy recovery alongside materials recovery are stated preferred options. Strategic, regulatory, action is providing some opportunity for a more structured and formal framework for consideration of the BPEO for wastes. Long-term planning is provided for in the form of: (i) waste recycling plans which have to be com piled by the Waste Collection Authorities (Section 49 of the Environmental Protection Act, 1990); (ii) waste local plans (or combined waste and minerals plans) now required to be produced by the local planning authorities under the Planning and Compensation Act, 1991; and (iii) the waste disposal plans which have to be produced by the waste regulation authorities (Section 50 of the Environmental Protection Act, 1990, replacing requirements in the Control of Pollution Act, 1974). If adequately coordinated, these plans should provide for a framework within which regional BPEOs can be formulated for various waste streams, together with a strategic reasoning that underpins the final choice of options and identification of appropriate sites. The UK Government has announced proposals for the formation of a national environmental protection agency (although this is unlikely to be formed before 1996). Such a move away from the local authority domination of waste regulation would provide the opportunity for a national strategic waste disposal plan to provide for optimum implementation of the waste management hierarchy at the national level.

The ‘proximity principle’, adopted both within the EC and US, requires that wastes should be handled at the nearest suitable facility to the point of arisings and complements legislative action at the EC level to minimize the transfrontier shipment of wastes to lower cost facilities. The principle raises a number of questions about the level at which appropriate facilities should be provided for particular waste streams, for example, regionally for MSW or nationally for hazardous wastes. Linked to the requirement for long-term waste disposal planning, effective implementation of the proximity principle requires good data on waste arisings, integrated planning across a number of authorities, application of BPEO principles to the identification of required options, and the willingness of local authorities to identify potential sites for facilities in the face of often strong local political pressure against.

The Environmental Protection Act, 1990, through: (i) a new emphasis on integrated pollution prevention and control; (ii) increased penalties for infringements; (iii) fees and charges for authorization of processes; (iv) introduction of a legal ‘duty of care’ in relation to waste management; and (v) public registers of information relating to authorizations and licences, underpins the waste management hierarchy. The resultant recognition of potential liabilities, combined with rising merchant sector disposal prices at the beginning of the 1990s, and external pressures brought about by the greater public accountability of industry in terms of environmental performance, is already having an effect upon waste producers encouraging a re-examination of processes and consideration of in-house handling of wastes currently going to landfill. This will have an effect on the amount and type of waste available for off-site disposal, for example, increased recycling is likely to generate a greater proportion of residues in the form of sludges, which could be difficult to treat. An increase in the amount of waste classed as hazardous under Directive 91/689/EEC, together with EC strategy to control such wastes, is likely to lead to greater use of incineration. Larger companies are likely to consider expansion of, or investment in, in-house treatment including incineration, although capital outlays may be significant.

(Continues…)Excerpted from Waste Incineration and the Environment by R.E. Hester, R. M. Harrison. Copyright © 1994 The Royal Society of Chemistry. Excerpted by permission of The Royal Society of Chemistry.
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