3. What is hazardous waste?
• Hazardous Waste is a “waste" which because
of its quantity, concentration, or physical,
chemical, or infectious characteristics may:
Potential hazard to human health or the
environment when improperly treated, stored or
disposed off, or otherwise mismanaged; or
Cause or contribute to an increase in mortality, or
an increase in irreversible or incapacitating illness.
4. • The following list includes
categories often applied to HW:
• Paints and solvents
• Automotive wastes (used motor
oil, antifreeze, etc.)
• Pesticides
(insecticides, herbicides, fungicide
s, etc.)
• Mercury-containing wastes
(thermometers, switches, fluoresc
ent lighting, etc.)
• Electronics
(computers, televisions, cell
phones)
5. Cont..
• Aerosols / Propane cylinders
• Caustics / Cleaning agents
• Refrigerant-containing appliances
• Some specialty Batteries (e.g. lithium, nickel
cadmium, or button cell batteries)
• Ammunition
• Radioactive waste (some home smoke detectors are
classified as radioactive waste because they contain
very small amounts of a
radioactive isotope of americium - see: Disposing of
Smoke Detectors).
6. • If any part of the resulting wastewater or waste
residual which contains the following metals, then
the waste is a Characteristic Hazardous Waste:
• Arsenic - 5 ppm
• Chromium - 5 ppm
• Mercury - 0.2 ppm
• Barium - 100 ppm
• Cyanides - 250 ppm
• Selenium - 1 ppm
• Cadmium - 1 ppm
• Lead - 5 ppm
• Silver - 5 ppm
7. Practical issues with hazardous
waste management
• Physical characteristics
• Unsorted waste- mixed waste of bio degradable and
non- biodegradable
• Low calorific value
• High moisture content
• Presence of hazardous waste
• Lack of awareness
• Unplanned growth and development of cities
• Land availability
14. • Sterilisation/Disinfection Technologies,
– Steam sterilisation, e.g. Autoclaving
– Chemical sterilisation, e.g. with chlorine
– Gas sterilisation, e.g. with ethylene oxide,
formaldehyde
– Dry heat sterilisation, e.g. oil heated screw feed
technology
– Electro-thermal deactivation (ETD),
– Microwave sterilisation,
– Irradiation sterilisation
• Cobalt-60 gamma rays
• Ultra violet
• Electron beam sterilisation
15. 15
Waste Pathway for Incineration
Infectious waste
& Sharps
Pathological
Waste
Chemical
Waste
Incineration
Ash
Flue gas
cleaning
residues
Landfill
Emissions
to Air
Leachate
16. Waste Pathway for Non-Burn Technologies
Infectious waste
& Sharps
Pathological
Waste
Chemical
Waste
Incineration
Cremation or
Burial
Non-Burn
Treatment
Ash or
Body Parts
Waste
Treatment
Residues to
Landfill
Treatment as
Hazardous
Waste
Non-
infectious
waste
Landfill
Cemetery
Leachate
+ Gas
Emissions
17. Advantages of Incineration
• Safe elimination of all infectious organisms in the
waste at temperatures above ~700oC
• Residues are not recognisable
• Very well proven technology
• No pre-shredding required
• No special requirements for packaging of waste
18. Disadvantages of Incineration
• Normally higher investment costs required for incinerator and
flue gas cleaning compared to non-burn technologies
• High cost of monitoring gas emissions and demonstrating
compliance to emission standards.
• Solid and liquid by-products must be handled as potentially
hazardous waste
• Incineration is perceived negatively by many sections of the
community.
• PVC and heavy metals in the waste provide a significant
pollutant load on the gas cleaning system and for heavy metals
on the quality of bottom ash
• Existing health care risk waste incinerators
19. Non-Burn Technologies
• Autoclaving
An autoclave is an instrument used to sterilize equipment and
supplies by subjecting them to high pressure saturated steam at
121 °C for around 15–20 minutes depending on the size of the
load and the contents
FEATURES:
Significant amounts of volatile organic carbon compounds
produced
Contaminated water must be discharged to sewer
Waste and containers must have good steam permeability,
especially if there is no prior shredding
No waste reduction
20. • Microwaving
– Unsuitable for very high quantities of infected metal (e.g.
needles from inoculation campaigns)
– Low sterilisation temperature increases time required for
treatment.
• Electro-thermal Deactivation
– Relatively high investment and operating costs
– Low sterilisation temperature increases time required for
treatment.
21. FEATURES OF NON-BURN
TECHNOLOGIES
– High sterilisation efficiency under appropriate
conditions
– Low temperature of operation 90oC to 160oC
– Volume reduction depending on type of
shredding/compaction equipment that has been installed
– Low risk of air pollution
– Moderate operation costs
– Easier to locate as generally more acceptable to
communities and neighbours than incineration
– Recovery technologies can be used on sterilised waste
