WASTE

Waste (also known as rubbish, trash, refuse, garbage, junk, litter) is unwanted or
useless materials. In biology, waste is any of the many unwanted substances or
toxins that are expelled from living organisms; such as urea, sweat or faeces.
Litter is waste which has been disposed of improperly.

Waste is directly linked to human development, both technologically and

socially. The compositions of different wastes have varied over time and
location, with industrial development and innovation being directly linked to
waste materials.

An Example of this include plastics and nuclear technology. Some components

of waste have economical value and can be recycled once correctly recovered.

Waste is sometimes a subjective concept, because items that some people

discard may have value to others.

It is widely recognized that waste materials are a valuable resource, whilst there
is debate as to how this value is best realized. Such concepts are colloquially
expressed in western culture by such idioms as "One man's trash is another
man's treasure."

There are many waste types defined by modern systems of waste management,
notably including:

• Municipal Waste includes household waste, commercial waste, demolition

waste

• Hazardous Waste includes Industrial waste

• Bio-medical Waste includes clinical waste

• Special Hazardous waste includes radioactive waste, Explosives waste, E-

waste

According to the United Nations Environment Programme (UNEP) According

to the Basel Convention: "Substances or objects which are disposed of/or are
intended to be disposed of or are required to be disposed of by the provisions of
international law" (Basel Convention).

Produced by the United Nations Statistics Division (U.N.S.D.): "Wastes are

materials that are not prime products (that is products produced for the market)
for which the generator has no further use in terms of his/her own purposes of
production, transformation or consumption, and of which he/she wants to
dispose.

Wastes may be generated during the extraction of raw materials, the processing
of raw materials into intermediate and final products, the consumption of final
products, and other human activities. Residuals recycled or reused at the place
of generation are excluded."

Taxonomically, waste can be categorized in terms of state of matter i.e: solid,

liquid and gaseous. Also, it can be toxic, hazardous or volatile.

A typical solid domestic waste will consist of paper, glass, plastic, metals,
textiles, woods, vegetables etc. liquid waste include gey water, kitchen sludges,
oils, grease while gaseous include CH4, CO2, CO, aerosols.

Identification of waste source helps in giving proper nomenclature to waste. It

also helps in identification of the required collection, storage, transportation and
disposal.
Similarly, analysis of waste involves quantification in volumes or mass.

Sources of Waste
Sources of waste can be broadly classified into: Industrial, Commercial,
Domestic, and Agricultural ,Construction and mining.

Industrial Waste
These are the wastes created in factories and industries. Most industries dump
their wastes in rivers and seas which cause a lot of pollution.

Example: plastic, glass, etc.

Commercial Waste
Commercial wastes are produced in schools, colleges, shops, and offices.

Example: plastic, paper, etc.

Domestic Waste
The different household wastes which are collected during household activities
like cooking, cleaning, etc. are known as domestic wastes.

Example: leaves, vegetable peels, excreta, etc.

Agricultural Waste
Various wastes produced in the agricultural field are known as agricultural
wastes.

Example: cattle waste, weed, husk, etc.

Types of Waste
Commonly waste is classified into two types: Biodegradable and Non-
biodegradable waste. These two kinds of wastes are explained below:

Biodegradable waste
These are the wastes that come from our kitchen and it includes food remains,
garden waste, etc. Biodegradable waste is also known as moist waste. This can
be composted to obtain manure. Biodegradable wastes decompose themselves
over a period of time depending on the material.

Non-biodegradable waste
These are the wastes which include old newspapers, broken glass pieces,
plastics, etc. Non-biodegradable waste is known as dry waste. Dry wastes can
be recycled and can be reused. Non-biodegradable wastes do not decompose by
themselves and hence are major pollutants.

Recycling of Waste
Recycling of waste product is very important as this process helps in processing
waste or used products into useful or new products. Recycling helps in
controlling air, water, and land pollution.

It also uses less energy. There are a number of items that can be recycled like
paper, plastic, glass, etc. Recycling helps in conserving natural resources and
also helps in conserving energy.

Recycling helps in protecting the environment as it helps in reducing air, water,

and soil pollution.

Decomposition of Biodegradable Waste

Biodegradable waste can be decomposed and converted into organic matter with
the help of different processes.

Composting
This is the method in which waste can be decomposed and converted into
organic matter by burying them in the compost pits. The wastes are composed
by the action of bacteria and fungi.

Vermicomposting
This method involves decomposition of organic matter into fertile manure with
the help of red worms. This manure is known as vermicompost.

Chemical waste
Chemical wastes are wastes that are made from harmful chemicals which are
mostly produced in large factories. Chemical wastes may or may not be
hazardous. A chemical waste which is hazardous can be solid, liquid or gaseous
and will show hazardous characteristics like toxicity, corrosivity, ignitability,
and reactivity.

WASTE MANAGEMENT

Waste disposal leads to direct and in direct environmental impacts, such as land
occupation, resource depletion, amplification of global warming due to methane
and other greenhouse gas emissions, waters intoxication due landfilling, as well
as acidification and toxic effects from emissions to air in the case of
incineration.

Possible waste disposal methods are recycling, composting, incineration,

landfills, bioremediation, waste to energy, and waste minimization. As for waste
management, it is the measures utilized to manage waste in its entire life cycle,
from waste generation to disposal or recovery.

How do we use waste? Ways to reuse Donate items that are still in a good,
usable condition to charities or charity shops. Repurpose glass, plastic and
cardboard containers to give them another life.

Carry a re-usable shopping bag. Re-use wrapping paper or gift bags. Convert
old clothing, towels or sheets into cleaning rags/cloths.

Waste management is the collection, transport, processing, recycling 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 also carried out to recover resources from it. Waste
management can involve solid, liquid, gaseous or radioactive substances, with
different methods and fields of expertise for each.

Waste management practices differ for developed and developing nations, for
urban and rural areas, and for residential and industrial producers.
Management for non-hazardous waste residential and institutional waste in
metropolitan areas is usually the responsibility of local government authorities,
while management for non-hazardous commercial and industrial waste is
usually the responsibility of the generator.

WASTE STORAGE

Storage of waste takes place at the spot where the waste is generated. Domestic
refuse is normally stored continually in a container or sack until collected.

The daily production is usually stored inside until it is carried outside for
collection. There can be 1 unit/household or per several households, or local
communal collection points where garbage is emptied in a bin or caontainer.

In some developing countries, old oil barrels, concrete tubes and other
improvised enclosures may be used for storage often without any systematized
garbage collection taken place. Industry and business often have their own
systems with relatively large storage units.

Some factories run large refuse heaps on the factory’s premises without any
form of regular collection. Containers used as storage units are common for a
great many industries and outside large market places.

WASTE COLLECTION

Collection of waste generally take place by loading from the storage containers
unto a vehicle e.g. hand-cart (simple), donkey-cart (complex), tractor with
trailer (sophisticated), lorry special garbage truck.

The garbage is usually collected and emptied by the crew of the vehicle
(garbage collectors) but in some cases, collectors make a sound signal in which
members come and empty their garbage into the vehicle.

Collection requires passable routes and the choice of technology must be

adapted to the existing quality of roads, streets and settlement.

A simple cart can often be more useful than a modern garbage truck and labour
intensive method, more efficient than modern mechanized ones.

The choice of technology should also be considered on the basis of available

facilities for maintenanace.
In some places, tractors ordinarily used for agricultural purposes have proved
useful for collection and transportation of waste. Moreover, in agricultural areas
where tractors are sued, there is often a food infrastructure with garages
available spare parts.

Where there is systematic collection, small scale industries and businesses are
usually included. Major manufacturing industries producing large amount of
waste usually run their own system for collection and transport.

Collections of liquid waste (sludge) from waste water treatment plants require
separate collection routes. Also, gaseous wastes are often collected through
emission pipes (stacks) to be emitted into the atmosphere.

WASTE TRANSFER AND TRANSPORT

This is the process of shifting discarded resources from the point of generation
or storage to the point of recovery or pre-disposal point by a pre-determined
medium.

The medium can be man, mechanical or nature. If the place of disposal is far
away or if very small vehicles are used for collection, it can be appropriate to
load the garbage unto a larger transport vehicle.

Transport is thereby rationalized in that it takes fewer vehicles and crews.

Waste transfer can take place by the collection car emptying the garbage into a
container for collection by a larger container car that transports it to a place of
final disposal.

There are certain factors to be considered when designing waste transport

system aspect of waste management.

These include:

i) Location of disposal points

ii) ii) Disposal facilities
iii) iii) Available technology
iv) iv) Prevailing climate
v) Route plans and road network and
vi) Waste quality and quantity
In the transportation of waste resources the following can be used
: i) Tippers
 ii) Side loader
iii) Skip vehicles and
iv) Roll over vehicle
These are useful in the transportation of compressible wastes.
transportation of liquid waste may take place through networking in
which the effluent passes into soil pipes (a channel) or through the
channel to the final storage point and this is regulated through the use of
gauge valve. Methods of disposal

Open Dumps It appears that in most low‐

income countries and many medium income countries,
very little progress has been in upgrading waste disposal methods.
Open dumps are consequently often used.

Solid waste is usually accumulated in the open, where the refuse is piled up wit
hout being covered or otherwise protected.

Dumps are located wherever land is available, without regard to safety, health h
azards and aesthetic degradation. Open dumps where the waste is unloaded in pi
les, make very uneconomical use of the available space, allow free access to wa
ste pickers, animals and flies and often produce unpleasant and hazardous smok
e from slow burning fires.

In industrialized nations, open dumps area is a thing of the past.

In the U.S., thousands of open dumps have been closed and new ones
banned.

Common sites were mines and quarries where gravel and stones had been
removed, natural low areas like swamps or flood plains, and hillside
areas above or below towns.

In some instances, the refuse is

ignited and allowed to burn, in some the refuse is leveled and compacted.

As a general cycle, open dumps create a nuisance by being unsightly,

providing breeding grounds for pests creating health hazards, polluting
the air and sometimes polluting ground water and surface water.

Disposing of waste in a landfill involves burying the waste, and this remains a
common practice in most countries.
Landfills were 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.

Another common byproduct of landfills is gas (mostly composed of methane

and carbon dioxide), which is produced as organic waste breaks down
anaerobically.

This gas can create odour problems, kill surface vegetation, and is a greenhouse
gas.

Deposited waste is normally compacted to increase its density and stability, and
covered to prevent attracting vermin (such as mice or rats).

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 electricity.

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 and other high temperature waste treatment systems are sometimes
described as "thermal treatment".

Incinerators convert waste materials into heat, gas, steam and ash. Besides
reducing a large volume of waste to a much smaller volume of ash, incineration
has another advantage in that the process can be used to supplement other fuels
and generate electrical power.

Incineration is carried out both on a small scale by individuals and on a large

scale by industry.

It is used to dispose of solid, liquid and gaseous waste. 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.

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.

Combustion in an incinerator is not always perfect and clean; there have been
concerns about pollutants in gaseous emissions from incinerator stacks.

Particular concern has focused on some very persistent organics such as dioxins
(a carcinogenic toxin),

furans, PAHs which may be created which may have serious environmental
consequences. Smoke stacks from incinerators may emit oxides of nitrogen and
sulphur that lead to acid rain after series of photochemical reactions in the
atmosphere.

Heavy metals such as Pb, Cd and Hg; and CO2 which hypothetically is related
to global warming.

In modern incinerator facilities, smoke stacks are filled with special devices to
trap pollutants but the process of pollutant abatement is very expensive.

Furthermore, the plant themselves are expensive to establish.

On-site disposal A common on-site disposal method in urban areas in developed

countries is mechanical grinding of kitchen food waste. Garbage disposal
devices are installed in the waste water pipe system at the kitchen sink and the
garbage is ground and flushed into the sewer system.

Final material is transferred to sewage treatment plants, where solids remaining

as sewage sludge still must be disposed off.

Sanitary landfill Sanitary landfill is a site where solid wastes are placed are
placed on or in the ground at a carefully selected location by means of
engineering techniques that minimize pollution of air, water and soil, and other
risks to man and animals.

Aesthetic considerations are also taken into considerations are also taken into
account. A sanitary landfill is designed to concentrate and contain refuse
without creating a nuisance or hazard to public health or safety.

The idea is to confine the waste to the smallest practical area, reduce it to the
smallest practical volume and cover it with a layer of soil at the end of each day
of operation or more frequently if necessary.
Covering the waste is what makes the landfill sanitary. The compacted layer
restricts (but does not eliminate) continued access to the waste by insects,
rodents and animals such as seagulls.

It also isolates the refuse, minimizing the amount of surface water entering into
and gas escaping from the waste.

Most sanitary landfills designs attach considerable importance to prevailing

polluted water (leachate) from escaping from the site.

It has been shown that large quantities of leachates can be produced by landfills
even in semi-arid climates.

Most designs include expensive and carefully constructed impermeable layers

which present leachates moving downward into the ground and drainage
systems to bring the leachates to a treatment plant or a sewage tank.

However, if the plant is not emptied before it overflows, or if the plant is not
working the leachate control system actually makes the pollution worse than
from an open dump, because all the leachates is concentrated in one place,
giving natural purification system very little chance of reducing the pollution
impacts. This example shows that good design and construction alone can
achieve nothing if they not followed by good operation.

Hence, there is training of a site manager, the provision of sufficient financial

and physical resources to allow a reasonable standard of operation.

The most significant hazard from a sanitary landfill is obviously the pollution of
groundwater or surface water. If waste buried in a landfill comes into contact
with water percolating down from the surface or with groundwater moving
laterally through the refuse, leachates are produced.
The nature and strength of such leachates produced at a disposal site depends on
the composition of the waste, and the length of time that the infiltrated water is
in contact with the refuse.

Choosing the site for a sanitary landfill is important. A number of factors must
be taken into consideration including:

i) Topography
ii) ii) Location of the ground water
iii) iii) Amount of precipitation
iv) iv) Type of soil and rocks
v) v) Location of the disposal zone in the surface-water and groundwater
flow system.
A favourable combination of climates, hydrologic and geologic
conditions help to ensure reasonable safety in containing the waste and
its leachates.

The best sites are in arid regions, disposal conditions are relatively safe
because little leachate is produced in a dry environment.
In humid climates, sanitary landfills are best cited where there is
relatively impermeable clay and silt soils well above the water table.
This is so that any leachate produced remains in the vicinity of the site
and degrades by natural filtering action and chemical reactions between
the clay and the leachate.
Monitoring Pollution in Sanitary Landfills Once a site is chosen for a
sanitary landfill and before filling starts, monitoring the movement of
groundwater should begin.
The monitoring is accomplished by periodically taking samples of water
and gas from specially designed monitoring wells.
Monitoring the movement of leachates and gases should be as long as
there is any possibility of pollution.
This procedure is particularly important after the site is completely filled
with a final, permanent cover material is in place. Continued monitoring
is necessary because a certain amount of settlement always occur after a
landfill is completed, and if small depressions form, surface water may
collect, infiltrate and produce leachate.
Monitoring and proper maintenance of an abandoned landfill reduce the
pollution potential. Hazards effect of Pollution from Landfills Landfills,
if not properly managed can become source of hazardous substances into
the environment.
Such pollution may enter the environment by as many as six routes
namely:
i) Methane, ammonia, hydrogen sulphide and nitrogen gases may be
produced from compounds in the soil and the waste, and may
enter into the atmosphere
ii) ii) Soluble materials such as chloride and iron may be retained in
the soil, soluble materials such as chloride, nitrates and sulphates
may readily pass through the waste and soil to the underground
water
iii) iii) Heavy metals such as Lead, chromium and iron may be
retained in the soil
iv) iv) Overland run-off may pick up leachates and transport it into
streams and rivers
v) Some plants (including crops) growing in the disposal area may
selectively take up heavy metals and the toxic materials to be
passed up the food chain as people and animal eat them
vi) vi) If the plant residue from crops left in the field contains toxic
substances, these materials will return to the soil. Ideally, a
thorough monitoring program considers all six possible paths by
which pollutants enter the environment. Hence, adequate
precautions could have been taken.