Section G

1. Section G Incineration and its hazards

2. Decline in medical waste incinerators in USA G1

3. 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

4. Types of incinerators • Multiple hearth • The rotary kiln • Controlled-air incinerators G3

5. Incinerator standards • Combustion efficiency at least 99% • Temperature • Primary chamber - 800+/-50oC • Secondary chamber - 1000+/- 50oC • Secondary chamber gas residence time at least 1 second, with minimum 3% oxygen in the stack gas G4

6. Incineration emissions/ residues • Acid gases • Heavy metals • Products of incomplete combustion (PICs) • Particulate matter • Dioxins and furans • Ash G5

7. 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

8. 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

9. 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

10. 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

11. 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

12. 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

13. 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

14. Human health effects of dioxin • Cancer • increased cancer mortality • Neo-natal abnormalities • change in Sex Ratio • altered level of thyroid hormone • Skin disorders • porphyria cutanea tarda • chloracne G13

15. 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

16. 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

17. 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

18. 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

19. 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

20. Maintenance schedule G19

21. 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

22. Incinerator bans International • 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

23. Incineration: A burn technology

24. Toxic residues & emissions