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