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Section G
Incineration
Section GIncineration and its
hazards
Section G
Incineration
Decline in medical waste incinerators in USA
6,2005,000
2,373
1150
2,000
4,000
6,000
8,000
1988 1994 1997 2003
Year
No
. of
Me
dic
al W
as
te
Inc
ine
rato
rs
G1
Section G
Incineration
Incineration: problems
Is a burn technology Claim: burns waste/simple
hydrocarbons to CO2 and H2O Converts a biological problem into a
chemical problem Toxic residues and emissions
G2
Section G
Incineration
Types of incinerators
Multiple hearth The rotary kiln Controlled-air incinerators
G3
Section G
Incineration
Incinerator standards
Combustion efficiency at least 99% Temperature
o Primary chamber - 800+/-50oCo Secondary chamber - 1000+/- 50oC
Secondary chamber gas residence time at least 1 second, with minimum 3% oxygen in the stack gas
G4
Section G
Incineration
Incineration emissions/ residues
Acid gases Heavy metals Products of incomplete combustion
(PICs) Particulate matter Dioxins and furans Ash
G5
Section G
Incineration
Particulate matter
Minute particles in solid or condensable form.
Range in size from 500µ to less than 0.1µ in diameter.
They can adsorb heavy metals, dioxins, etc. and lodge in human lungs and can cause chronic health effects
G6
Section G
Incineration
Acid gases
Combustion of waste can produce NOx, SOx, HCL, HF
Contribute to acid rains Metal corrosion Irritate eyes, nose, throat Cause damage to respiratory system
G7
Section G
Incineration
Heavy metals
Lead is neuro toxicant Cadmium is respiratory and nephro
toxicant, carcinogenic in animals Mercury is neuro and nephro toxicant,
causes nervous disorders, birth defects
G8
Section G
Incineration
Products of incomplete combustion
Organic chemicals not present in original waste
Form by molecular level recombination, substitution, fragmentation
A review of studies indicates release of around 217 different organic chemicals
More toxic and more difficult to destroy than parent compounds
G9
Section G
Incineration
Dioxins: where do they come from?
Are an unintentional by product of waste incineration, as well as certain chemical and manufacturing processes;
Are toxic at very low levels of exposure
Are persistent in the environment Bio-accumulate Have a half-life of approximately 7
years in humans, 100 years in sub-surface soil and over 50 years in water bodies and sediments
G10
Section G
Incineration
Dioxins and furans
Dioxins refer to a group of polychlorinated dibenzo dioxins that are extremely toxic at very low concentrations:
The most toxic is 2,3,7,8-tetrachloro-dibenzo dioxin (2,3,7,8-TCDD)
Furans are a group of toxic compounds similar to dioxins and formed at the same time
G11
Section G
Incineration
Medical waste incineration and dioxins
Medical waste incinerators are a major source of dioxins in the global environment
Burning of chlorine-containing material such as chlorinated plastics result in dioxins
Dioxins are formed after combustion, during the cooling of the exhaust gases
Polyvinyl chloride (PVC) is a major source of chlorine in medical waste
G12
Section G
Incineration
Human health effects of dioxin
Cancero increased cancer mortality
Neo-natal abnormalitieso change in Sex Ratioo altered level of thyroid hormone
Skin disorderso porphyria cutanea tardao chloracne
G13
Section G
Incineration
Human health effects of dioxin
Immune system Changes/suppression in immune
system
Endocrine (hormone) system effects Low levels of testosterone Increase in glucose tolerance Decreased estrogen and estrogen-
receptor levels after foetal exposure
G14
Section G
Incineration
Ash Incinerator ash is hazardous waste Needs to be disposed in secured
landfills
Problems are: Contamination with heavy metals
(lead, cadmium and mercury) Loaded with dioxins and furans Pollution control equipment increase
toxicity of ash
G15
Section G
Incineration
Air pollution control devices
Primary emission control devices can be any of these types:
Electrostatic precipitators to control particulate emissions
Fabric filter bag houses to control fine particulate
Scrubbers to control gaseous emissions
G16
Section G
Incineration
Pollution control equipment
Very expensive, make incinerators unaffordable
They reduce but do not eliminate emissions
Conditions favouring reduction of one pollutant may favour release of another
Control devices merely shift the toxic material from one medium (exhaust gas) to another (filter cakes, scrubber wastewater, ESP ash)
Disposal of toxic laden material or waste water still a problem
G17
Section G
Incineration
Operational problems Excessive stack emissions Black smoke, white smoke Leakage of smoke from primary
chamber Excessive auxiliary fuel usage Incomplete burnout: poor ash quality Primary burner malfunction Insufficient under-fire air (controlled-
air units) Waste charging Poor temperature control Short retention time in the secondary
chamber Too much air Upset or transient conditions G18
Section G
Incineration
Maintenance scheduleActivity frequency
Incinerator component
Daily Oxygen monitor, thermocouples, under-fire air ports, limit switches, door seals, ash pit/internal drop out sump
Weekly Blower intakes, burner flame rods (gas-fired units), swing latches and hinges
Bi-weekly Fuel trains and burners, control panels
Monthly External surface of incinerator and stack, Refractory, Internal ram faces; upper/secondary combustion chamber; burner pilots
Semi-annually
Hot external surfaces, Ambient external surfaces G19
Section G
Incineration
Economic cost: a major hurdle
Capital and operating costs Pollution control devices (eg.
scrubbers) Stack testing Continuous monitoring Operator training and qualification Cost of maintenance and repair Public image concerns
G20
Section G
Incineration
Incinerator bansInternational 1996: Protocol to the London
Convention banned incineration at sea globally
1996: Bamako Convention banned incineration at sea, on territorial or internal waters in Africa
1992: OSPAR Convention banned incineration at sea in the northeast Atlantic
Jurisdictions in 15 countries have passed partial bans on incineration. Philippines has a complete ban
India Complete ban on incineration of PVC in
all types of incinerators. Discourages on-site incineration
G21
Section G
Incineration
Incineration: A burn technology
Section G
Incineration
Toxic residues & emissions