Hazardous Material Ch 19
(Pre 11th. Edition)
Introduction
Better living through Chemistry has its costs. Example Pesticides, Gas leaks, abandoned
storage sites, Love Canal, Bhopal, Vac and Lekkekerk.
Land, air and water are at risk (accidental or purposely). The potential health effects
range from minor short-term headaches to serious birth defects.
Definitions
Differ from country to country.
The EPA – Hazardous substance “that which can cause harm to humans and the
environment.
RCRA – (Resource Conservation and Recovery Act 1976) that which causes death and or
irreversible serious illness, or poses a potential hazard to health or the environment.
Hazardous material is characterized by
1. Ignitability – fire hazard
2. Corrosiveness – container hazard.
3. Reactivity – explosiveness, spontaneous
4. Toxicity – capable of releasing toxicants.
Toxic refers to a narrow group of substances that are poisonous and cause death or
serious injury.
Hazardous are all dangerous materials, including toxic ones.
are subject to all regulations.
Hazardous Wastes
Sources - Regardless of whether it is raw material, an ingredient or waste. In Developed
countries, the Chemical industry produces most of the hazardous wastes in the
manufacture of soap, rubber, paints, fertilizer, pesticides, and cosmetics.
ID of hazardous / toxic wastes. Most countries draw up a list of substances for which
there is scientific evidence and their effects.
Most times, it is only after a problem has been recognized, that substances are classified
as toxic. Example DDT or Asbestos.
UN estimates was 300 – 500 M MTons of Haz waste generated /year
Issues
Evaluations: New substances are evaluated by tests on animals.
Threshold levels – point of no effect. The level for humans is set even lower. This varies
from country to country.
Regulations- one must consider dosage – time, synergism, persistence and exposure
limits.
Dosage: (Toxicity) Nearly all substances are toxic in high dosages
One massive dose (Acute) –easily recognized quick response.
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Small doses over a long time period (chronic) – effects are not seen for long time.
Example Lead or alcohol
Synergism: The effect of mixing chemicals. Alone a chemical may be harmless,
radioactive gas from uranium, but add tobacco smoke – lung cancer results.
Persistent and non-persistent pollutants : Regulations are influenced by persistence. Most
pollutants (>30,000) are persistent.
DDT
PCBs – Polychlorinated Bi-phenols are very stable, unaffected by heat, acid,
bases or oxidation. Used in transformers. It interferes with reproduction, and the nervous
system. Causes liver aliments, and skin lésions.
Non-persistent pollutants are biodégradable. Can react with other chemicals. Normally
serves as food for decomposers. Called soft biocides because they break down quickly in
sunlight or in the presence of oxygen or water. Example: Organophosphates.
Long-term effects are negligible. Acute dosages are critical.
Diaznon has been pulled off the market as of 2001.
Environmental Problems
Caused by hazardous wastes. Contaminates the environment, particularly the GW from
Leaking pipes (Fugitive emissions – leaked gas), storage, improper incineration and
landfills. It is often uneconomical to restore aquifers, besides it may not be technically
feasible.
Solid and liquid waste are more easily treated and can be released without harm.
1. Health Risks
Every year > 1000 new chemicals are concocted and already > 70,000 are in use. If used
as labels suggest, they are not hazardous.
2. Hazardous Waste Dumps
Prior to 1976 (RCRA), there were no regulations. Waste was buried or placed in landfills
on flood plains, wetlands, etc. The result was GW and surface waters contaminated.
In US, >25,000 uncontrolled sites will cost > $6.0 B to clean up. Most countries in
Europe have the same problem.
In 1980, CERCLA (Comprehensive Environmental Response Compensation and
Liability Act) set up the SUPERFUND to:
Develop a program to set priorities for clean up.
Make responsible parties pay
($1.6 B trust fund) To ID and Clean up sites.
Do scientific research.
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Estimate that it would take 50 years to clean up at a cost of $50. B. To date > $25 B
spent.
Many parties who did the polluting are now out of business. Others find it cheaper to
fight legally than to pay for cleanup.
Gov’t collected $20 B.
Toxic chemical releases in 2001 – approx. 6.2 B lbs released in the US (From mining,
chemicals, power generation and manufacturing Industries report)
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Managing Hazardous Wastes
EPA reports that in 1993, production of wastes was 235 MMtonnes, a decrease from
1991. 70% has been recycled , burned or treated.
The best way to deal with the problem was “not to produce it”.
Requires strong controls in Production, Storage,Transport and Disposal.
1. Pollution Prevention requires operational changes in
Better house keeping
Employee training
2. Waste Minimization which can be accomplished by:
Changing procedures or source material,
Using waste in another process
Cleaning solvents used in the process
Evaporation / concentration.
3. Recycling Waste.
Waste is used as fuel or as ash in concrete.
4. Waste Treatment
1. Treat so as to reduce their hazardous nature. Biodegradable can be subjected to
microorganisms.
2. Incineration can destroy 99% (presently 2% in the US).
3. Air stripping removes volatiles by passing air through waste.
4. Carbon absorption. Carbon combines chemically with the waste or acts as a sieve
catching particles.
5. Precipitation – special materials are added to the waste to cause large particles
(flocks) to precipitate. In modern incinerators, there are fabric filters called “Bag
houses”.
6. Neutralize by reacting with other non-hazardous material.
5. Land Disposal, a last resort.
1. Deep well injection into porous zones or salt domes.
2. Discharge treated substances into streams.
3. Placement in ponds/pits.
4. Put into specially lined dumps and covered over.
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5. Storage in salt domes.
6. Use sanitary landfills
7. Immobilization by turning into solid form.
6. Hazardous Waste Management Choices
Disposal two most common methods are Incineration and land disposal, which ever is
most economical for place and time.
Int’l Trade in Hazardous Waste
Many old sites are being closed and no new ones are opening due to politics and the high
cost of land and construction.
The result is:
1. Export to undeveloped countries (often mislabeled). Eg. From Taiwan to
Cambodia.
2. Creation of the Basel Convention 1989. It forbids hazardous waste exports to
undeveloped countries. From northern countries to those in the southern
hemisphere. It is now involved with management of and reduction of hazardous
waste generation.
Hazardous Waste Program Evolution
Purpose is to store, transport, treat and dispose hazardous waste in an environmentally
sound method.
Programs evolve through stages, starting with:
1. ID and enact legislation, which takes a number of years.
2. Set up agency
3. Set rules and regulations
4. Develop treatment and disposal capacity.
5. Create a compliance and enforcement program.
No two countries follow precisely the same path to the end point, which may be due to:
Geography
Demographics
Industrial profile
Politics and culture.
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Chapter 18
Hazardous Substances and wastes
Introduction :
Chemicals – Better Living
Definitions -EPA
RCRA
Characteristics (CITE) of Hazardous material
Hazardous Waste
Sources
Identification
Evaluations
Issues
Regulations consideration (DFTCE)
Toxicity
Synergism
Persistence
Environmental Problems
Source
Health Risks
Dumps Location
Superfund
Managing Hazardous Waste
Production
Methods
Pollution Prevention
Waste minimization
Recycling
Treatment
Land Disposal sites - Choices
Incineration
Choices
International Trade in Hazardous Waste
Hazardous Waste Program Evolution.
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