- WASTE DUMPING
- MUNICIPAL WASTES
STRATEGIES TO CONTROL ENVIRONMENTAL DAMAGE
- CONCEPTS : WASTE HIERARCHY & POLLUTER PAYS PRINCIPLE
- METHODS OF WASTE MANAGEMENT : LANDFILL
AVOIDANCE & REDUCTION
- WHAT IS GREEN CHEMISTRY ?
- GREEN CHEMISTRY IN DAY-TO-DAY LIFE
The act or process of polluting or the state of
being polluted, especially the contamination of
soil, water, or the atmosphere by the discharge
of harmful substances.
Soil pollution or soil contamination is
caused by the presence of xenobiotic(human
made) chemicals or other alterations in the
natural soil environment.
WASTE DUMPING :
Industrial solid wastes and sludge are the
major sources of soil pollution
Industrial emissions such as fly ash from
thermal power plants can contaminate the
Particles of industrial emissions from the tall
chimney comes down to the surface of the
earth, sooner or later
Nuclear testing laboratories and the increased
number of radioactive nuclear reactions can
contaminate the soil
Radioactive materials are thriving in the soil
for long periods of time, since they often have
a long half-life. Strontium-90, for example,
has a half life of 28 years, and half-life of
cesium-137 is 30 years
MUNICIPAL WASTES :
Municipal waste includes household waste,
kitchen waste, medical waste, waste from
livestock, poultry slaughterhouse waste,
metals, glass and ceramic waste, etc.
Non-biodegradable materials used to
transport, polythene bags, waste plastic
sheeting, PET bottles, etc., remain in soil for
Hospital waste contains organic matter,
chemicals, metal pins, plastic and glass
bottles, which could also contaminate.
Dumping of sewage waste and organic waste
from hospitals pollute the environment with
a wide range of pathogens that will seriously
affect human health.
MUNICIPAL WASTES :
Modern mining projects leave behind disrupted
communities, damaged landscapes, and polluted water.
Mining also affects ground and surface waters, the
aquatic life, vegetation, soils, animals, and the human
Acid mine drainage can cause damage to streams which
in return can kill aquatic life.
The vast variety of toxic chemicals released by mining
activities can harm animals and aquatic life as well as
Mining gas and petroleum also pollutes the land.
Petroleum extraction and manufacturing contaminates
the soil with bitumen, gasoline, kerosene and mining
Opencast mining, which is a process where the surface
of the earth is dug open to bring out the underground
mineral deposits, destroys the topsoil and contaminates
the area with toxic metals and chemicals.
Many of the chemicals used in pesticides are
persistent soil contaminants, which adversely
affect soil conservation
The use of pesticides decreases the
general biodiversity in the soil.
The insecticides DDT, methyl parathion and
especially pentachlorophenol have been shown to
interfere with legume-rhizobium chemical
signaling. Reduction of this symbiotic chemical
signaling results in reduced nitrogen fixation and
thus reduced crop yields.
Animals may be poisoned by pesticide residues that
remain on food after spraying, for example when
wild animals enter sprayed fields or nearby areas
shortly after spraying
Widespread application of pesticides can eliminate
food sources that certain types of animals need,
causing the animals to relocate, change their diet,
or starve. Poisoning from pesticides can travel up
the food chain and bioacculmulate
Construction uses up forestland. More
constructions means increase in demand for
raw materials like timber. This leads to the
exploitation and destruction of forests. There
is more demand for water. Reservoirs are
built leading to the loss of land and valuable
STRATEGIES TO CONTROL
ENVIRONMENTAL DAMAGE :
The public is becoming increasingly aware that the
natural environment is fragile. The news media
have reported on many instances of environmental
changes affecting animal life, often as a result of
pollutants from human activities. Recent reports
have focused on –
Deaths and population declines of birds and fish
because of the large oil spills
Deaths of porpoises and whales along the coasts
as a result of pollutants and disease;
Fish contaminated with polychlorinated biphenyls
Contamination of rivers and lakes by dioxin and
other pollutants that may cause cancer and
These events may be omens that other forms of
life, including people, could become threatened
if environmental conditions continue to worsen.
But how much worse must conditions be before
wildlife and human life are in danger? Or are
they in danger already? Clearly, better methods
are needed to predict the probability of future
environmental and health problems based on
present evidence. Such information could guide
environmental regulators and decision makers in
taking actions in time to minimize damage to the
environment and human health.
And an important strategy to control such
environmental damage is :
WASTE MANAGEMENT :
Waste management is the collection, transport, processing or
disposal, managing and monitoring of waste materials. The term
usually relates to materials produced by human activity, and is
generally undertaken to reduce their effect on health,
the environment or aesthetics. Waste management is a distinct
practice from resource recovery which focuses on delaying the
rate of consumption of natural resources. The management of
wastes treats all materials as a single class whether solid,
liquid, gaseous or radioactive substances, and tried to reduce the
harmful environmental impacts of each through different
The two major concepts which are widely used for waste
management are :
Polluter Pays Principle
Waste Hierarchy :
The waste hierarchy refers to the "3 Rs“ reduce,
reuse and recycle, which classify waste
management strategies according to their
desirability in terms of waste minimization. The
waste hierarchy remains the cornerstone of most
waste minimization strategies. The aim of waste
hierarchy is to extract the maximum practical
benefits from products and to generate the
minimum amount of waste.
Polluter Pays Principle :
The Polluter Pays Principle is a principle where the
polluting party pays for the impact caused to the
environment. With respect to waste management,
this generally refers to the requirement for a waste
generator to pay for appropriate disposal of the
Methods Of Waste Management :
Disposing of waste in a landfill involves burying the waste, and this remains a common
practice in most countries. Landfills are often established in abandoned or
unused quarries, mining voids or borrow pits. A properly designed and well-managed
landfill can be a hygienic and relatively inexpensive method of disposing of waste
materials. Older, poorly designed or poorly managed landfills can create a number of
adverse environmental impacts such as wind-blown litter, attraction of vermin, and
generation of liquid leachate.
Design characteristics of a modern landfill include methods to contain leachate such as
clay or plastic lining material. Deposited waste is normally compacted to increase its
density and stability, and covered to prevent attracting vermin. Many landfills also have
landfill gas extraction systems installed to extract the landfill gas. Gas is pumped out of
the landfill using perforated pipes and flared off or burnt in a gas engine to generate
Incineration is a disposal method in which solid organic wastes are subjected to
combustion so as to convert them into residue and gaseous products. This method is useful for
disposal of residue of both solid waste management and solid residue from waste water
management. This process reduces the volumes of solid waste to 20 to 30 percent of the
original volume. Incineration is also described as "thermal treatment". Incinerators convert
waste materials into heat, gas, steam and ash.
Incineration is carried out both on a small scale by individuals and on a large scale by
industry. It is recognized as a practical method of disposing of certain hazardous
waste materials (such as biological medical waste). Incineration is a controversial method of
waste disposal, due to issues such as emission of gaseous pollutants like dioxins, furans and
Incineration is common in countries such as Japan where land is more scarce, as these
facilities generally do not require as much area as landfills. Waste-to-energy (WtE) or energy-
from-waste (EfW) are broad terms for facilities that burn waste in a furnace or boiler to
generate heat, steam or electricity.
ENERGY RECOVERY :
The energy content of waste products can be harnessed
directly by using them as a direct combustion fuel, or indirectly by
processing them into another type of fuel. Thermal treatment
ranges from using waste as a fuel source for cooking or heating
and the use of the gas fuel, to fuel for boilers to generate steam
and electricity in a turbine. The process usually occurs in a sealed
vessel under high pressure.
Two related forms of thermal treatment :
Pyrolysis : Pyrolysis of solid waste converts the material
into solid, liquid and gas products. The liquid and
gas can be burnt to produce energy or refined
into other chemical products (chemical refinery).
The solid residue (char) can further refined into
products such as activated carbon.
Gasification : Gasification is used to convert organic materials
directly into a synthetic gas (syngas) composed
of carbon monoxide and hydrogen. The gas is
then burnt to produce electricity and steam.
AVOIDANCE & REDUCTION METHODS :
An important method of waste management is the prevention of waste material being
created, also known as waste reduction.
Methods of avoidance include :
- Reuse of second-hand products
- Repairing broken items instead of buying new
- Designing products to be refillable or reusable (such as cotton instead of plastic
- Encouraging consumers to avoid using disposable products (such as disposable cutlery)
- Removing any food/liquid remains from cans
- Designing products that use less material to achieve the same purpose (for example,
light weighting of beverage cans)
noun [grēn ′kem·ə·strē]
The use of chemical products and processes
that reduce or eliminate substances hazardous
to human health or the environment
Green chemistry, also called sustainable chemistry, is a philosophy of chemical
research and engineering that encourages the design of products and processes that
minimize the use and generation of hazardous substances. While environmental
chemistry is the chemistry of the natural environment, and of pollutant chemicals in
nature, green chemistry seeks to reduce and prevent pollution at its source.
As a chemical philosophy, green chemistry applies to organic chemistry, inorganic
chemistry, biochemistry, analytical chemistry, and even physical chemistry. Click
chemistry is often cited as a style of chemical synthesis that is consistent with the
goals of green chemistry. The focus is on minimizing the hazard and maximizing the
efficiency of any chemical choice.
The year 2005 witnessed three key developments in the field of green chemistry:
- use of supercritical carbon dioxide as green solvent
- aqueous hydrogen peroxide for clean oxidations
- use of hydrogen in asymmetric synthesis
Examples of applied green chemistry are : Supercritical water oxidation
On water reactions
Dry media reactions
The term "Green Chemistry" was coined by Paul Anastas in 1991, who is renowned
worldwide as “The Father of Chemistry”.
GREEN CHEMISTRY IN DAY-TO-DAY LIFE :
Dry Cleaning Of Clothes:
Tetra chloroethene (Cl2C=CCl2) was earlier used as solvent for dry
cleaning. The compound contaminates the ground water and is also a
suspected carcinogen. The process using this compound is now being
replaced by a process, where liquefied carbon dioxide, with a suitable
detergent is used. Replacement of halogenated solvent by liquid CO2 will
result in less harm to ground water.
These days hydrogen peroxide(H2O2) is used for the purpose of bleaching
clothes in the process of laundry, which gives better results and makes use
of lesser amount of water.
Bleaching of Paper:
Chlorine gas was used earlier for bleaching paper. These days,
hydrogen peroxide (H2O2) with suitable catalyst, which promotes the
bleaching action of hydrogen peroxide, is used.
Synthesis Of Chemicals:
Ethanal(CH3CHO) is now commercially prepared by one step
oxidation of ethene in the presence of ionic catalyst in aqueous
medium with a yield of 90%.
CH2=CH2 O2 CH3CHO (90%)