Chapter 6.5 Thermal treatment
Notes on this chapter
The material presented in this chapter aims to give an overview of the principles of
thermal treatment methods and some of the associated aspects: energy and materials
recovery, flue gas treatment, disposal of liquid and solid residues.
Waste incineration, the most widely used thermal treatment option, is typically more
strictly regulated than some other waste treatment options. The legal requirements differ
from one country - or association of countries, such as the European Community - to
another. The most important differences concern the requirements over air emissions and
residues.
Slides cover only the main points of the different technologies. They could be easily
expanded with more technical aspects. However some of the technical details eg of
controls, regulation and management, are questions which must be adapted to each local
case.
List of slides
Title slide
Slide 2 Definitions
Slide 3 Application of thermal treatment
Slide 4 Good practice in hazardous waste management combustion
Slide 5 Waste characteristics
Slide 6 Examples of CV
Slide 7 Combustion
Slide 8 Combustion techniques
Slide 9 Operation of the furnace
Slide 10 Energy recovery
Slide 11 By-products of incineration
Slide 12 Solid residues
Slide 13 Flue gases
Slide 14 Dioxins
Slide 15 Example of flue gas cleaning technology
Slide 16 Wastewater from incineration
Slide 17 Measurement
Slide 18 Measurement -an example
Slide 19 Costs
Slide 20 Cement kiln incineration
Slide 21 Requirements for combustion in cement kilns
Slide 22 Fuel blending
Slide 23 Examples of technology 1 Rotary kiln incinerator
Slide 24 Examples of technology 2 Fluidised bed combustion
Slide 25 Pyrolysis
Slide 26 Application of pyrolysis
Slide 27 Gasification
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Slide 28 Key considerations
Slide 29 Summary
Background notes
1 The technology for a number of thermal treatment techniques is well-developed and
proven, and thermal processing of hazardous wastes is in common use around the world.
2 The main technologies are often differentiated from one another by the type of grate
which is used in the process. Some technologies have been specifically developed to deal
with a particular waste stream, while others can handle a broad range of waste types.
3 New thermal techniques are also being developed and refined, including some smaller
scale options which may have value in future for hazardous wastes treatment in
industrialising countries.
4 Typically thermal processes have higher capital costs than most other treatment
methods, not least because of the high costs of gas cleaning systems which may represent
one third of the cost of the facility.
5 The complexity of the technology requires skilled and trained personnel to specify,
construct and operate the facilities.
6 The opportunity to recover materials, heat or energy from the combustion of wastes can
reduce costs. The location of the facility, and its proximity to markets for heat or power,
will dictate the recovery option.
7 There are a number of different industrial processes which use wastes as fuel, some for
their energy content, others for their minerals or for a combination of the two. These
include steel, glass and cement manufacture, but of these, cement kiln use is the most
widely applied.
8 Because of the high levels of lime present in cement kilns, the acid components in the
flue gases are absorbed, making the co-combustion of hazardous wastes an effective way
of treating (ie neutralising) acidic flue gas emissions. Metals are fixed into the cement
product.
9 High operating standards are crucial. Many countries now have stringent regulations
covering the operation and monitoring of thermal treatment facilities, and enforcement of
those regulations is an important part of the hazardous waste management system.
10 Some of the emissions of concern from thermal processes are extremely small, and
their accurate measurement is very difficult. This includes dioxin emissions, which are
often cited as an issue by opponents to incineration. Greenpeace has an international antiincineration campaign, based largely on the dioxin issue. Good combustion control and
gas cleaning measures enable modern plants to meet very strict regulatory limits for
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dioxins as well as other pollutants. In Europe, dioxin emissions from a number of other
industrial processes eg steel production, are believed to be far greater than those from
modern well-managed waste incineration.
11 The benefits of thermal processing include the effectiveness of the process for
reducing hazard from the wastes, the energy recovery opportunities and also the volume
reduction, given the limited availability of permitted landfill space in some countries.
Sources of further information
Batstone, R; Smith, JE & Wilson, DC editors (1989) The safe disposal of hazardous
wastes: The special needs and problems of developing countries World Bank,
Washington, Technical paper No 93 Vol 3 ISBN 0-8213-1144-1 (available as pdf files
from www.worldbank.org/publications/)
Dean, RB & Wilson, DC (Editors) (1990) Adapting hazardous waste management to the
needs of developing countries, Waste Management & Research Vol 8 No 2
Guyer, Howard H (1998) Industrial processes and waste stream management Wiley
ISBN 0-4712-9984-7
LaGrega, MD; Buckingham, PL; Evans, JC & ERM Group (1994) Hazardous Waste
Management McGraw Hill, New York ISBN 0-07-019552-8
Lohwongwatana, B; Soponkanaporn, T & Sophonsridsuk, A Industrial hazardous waste
treatment facilities in Thailand Waste Management & Research Vol 8 No 2
Nash, JM; Cheung, B; Fung, CH; Lei PK, Mak, PW; Rootham, RC; Stokoe, MJ & Tong,
R (1991) Control and treatment of hazardous (chemical) waste in Hong Kong Waste
Management & Research Vol 9 No 3
Ravishankar, R (1990) Opportunities and constraints for cement kiln incineration in
Malaysia, Waste Management & Research Vol 8 No 2
Santoleri, JJ, Theodore, L & Reynolds, J (2000) Introduction to hazardous waste
incineration Wiley ISBN 0-4710-1790-6
Technical guidelines from the Secretariat of the Basel Convention www.basel.int
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