Presentation is loading. Please wait.

Presentation is loading. Please wait.

Section G Incineration Section G Incineration and its hazards.

Similar presentations

Presentation on theme: "Section G Incineration Section G Incineration and its hazards."— Presentation transcript:


2 Section G Incineration Section G Incineration and its hazards

3 Section G Incineration Decline in medical waste incinerators in USA G1

4 Section G Incineration Incineration: problems Is a burn technology Claim: burns waste/simple hydrocarbons to CO 2 and H 2 O Converts a biological problem into a chemical problem Toxic residues and emissions G2

5 Section G Incineration Types of incinerators Multiple hearth The rotary kiln Controlled-air incinerators G3

6 Section G Incineration Incinerator standards Combustion efficiency at least 99% Temperature o Primary chamber - 800+/-50 o C o Secondary chamber - 1000+/- 50 o C Secondary chamber gas residence time at least 1 second, with minimum 3% oxygen in the stack gas G4

7 Section G Incineration Incineration emissions/ residues Acid gases Heavy metals Products of incomplete combustion (PICs) Particulate matter Dioxins and furans Ash G5

8 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

9 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

10 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

11 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

12 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

13 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

14 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

15 Section G Incineration Human health effects of dioxin Cancer o increased cancer mortality Neo-natal abnormalities o change in Sex Ratio o altered level of thyroid hormone Skin disorders o porphyria cutanea tarda o chloracne G13

16 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

17 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

18 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

19 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

20 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

21 Section G Incineration Maintenance schedule Activity frequency Incinerator component DailyOxygen monitor, thermocouples, under- fire air ports, limit switches, door seals, ash pit/internal drop out sump WeeklyBlower intakes, burner flame rods (gas- fired units), swing latches and hinges Bi-weeklyFuel trains and burners, control panels MonthlyExternal surface of incinerator and stack, Refractory, Internal ram faces; upper/secondary combustion chamber; burner pilots Semi- annually Hot external surfaces, Ambient external surfaces G19

22 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

23 Section G Incineration 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

24 Section G Incineration Incineration: A burn technology

25 Section G Incineration Toxic residues & emissions

Download ppt "Section G Incineration Section G Incineration and its hazards."

Similar presentations

Ads by Google