WASTE DISPOSAL IN ENGLISH
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WASTE DISPOSAL-
} Waste disposal is a big issue and
environmental health concern in each setting. It is absolutely necessary to
dispose waste in proper manner otherwise it ill cause a big public health
concern .
HEALTH HAZARDS OF SOLID WASTE-
} if solid waste is not disposed
properly it may become health hazard. Following are possible health hazards of
collected waste –
} Heap of garbage may provide a
breeding place for flies and insects.
} It allows rodents and vermin to stay
and grow which are health hazard for people living nearby.
} The pathogens which may be present in
the solid waste may transmitted to man's food through flies and dust.
} there is a possibility of air, water
and soil pollution due to collected waste.
} heaps of refuse present an unsightly
appearanceand nuisance from bad odours.
SOURCE OF REFUSE-
} DOMESTIC REFUSE- The domestic
refuse consists of ash, rubbish and garbage.
} Ash is the residue from fire used for
cooking and heating.
} Rubbish comprises paper, clothing,
bits of wood, metal, glass, dust and dirt.
} Garbage is waste matter from the preparation, cooking and consumption
of food. It consists of waste food, vegetable peelings and other organic
matter.
} STREET REFUSE- Refuse that is
collected by the street cleansing service or scavenging is called street
refuse. It consists of leaves, straw, paper, animal droppings and litter of
all kinds
} MARKET REFUSE- Refuse that is collected from markets is called market
refuse. It contains a large proportion of putrid vegetable and animal
matter.
} STABLE/ANIMAL SHELTER REFUSE- Refuse
that is collected from stables is called stable litter. It contains
mainly animal droppings and left-over animal feeds.
} INDUSTRIAL REFUSE- Industrial
refuse consists of a wide variety of wastes ranging from completely inert
materials such as calcium carbonate to highly toxic and explosive compounds.
SOLID WASTE MANAGEMENT-
Solid waste management includes three steps-
} Storage
} Collection
} Disposal
STORAGE-
} The first step in solid waste
management is proper storage of refuse, while awaiting collection. The steel or
plastic dust bin with close fitting cover is a suitable receptacle for storing
refuse. The capacity of a bin will depend upon the number of users and
frequency of collection.
} Refuse may be stored in paper sac and
the sack itself is removed with the contents for disposal and a new sack is
substituted. It is biodegradable and there fore a good and clean system.
} Public dust bins cater for a larger
number of people. Small dust bins are fixed while big dustbins are kept on a
concrete platform raised 2 to 3 inches above ground level to prevent flood
water entering the bins.
COLLECTION-
} House-to-house collection is the best
method of collecting refuse. Only at some places in the urban areas this kind
of facility is available. In majority of areas people are expected to dump the
refuse in the nearest public bin.
} The refuse is then transported in
refuse collection vehicles to the place of ultimate disposal. Dead animals are
directly transported to the place of disposal. The open refuse collection cart
should be abandoned and replaced by enclosed vans.
DISPOSAL-
} There are many methods of waste
disposal such as-
} (a) Dumping
} (b) Controlled tipping or sanitary
land-fill
} (c) Incineration
} (d) Composting
} (e) Manure pits
} (f) Burial.
} A) Dumping- Dumping is an easy method
of disposal of dry refuse. As a result of bacterial action, refuse decreases
considerably in volume and is converted gradually into humus. But it is not a
good method. It has some drawbacks such as-
} ( 1) the refuse is exposed to flies
and rodents, insects etc.
} (2) it is a source of nuisance from
the smell and unsightly appearance,
} (3) the loose refuse is dispersed by
the action of the wind results in air pollution
} (4) drainage from dumps contributes
to the pollution of surface and ground
water.
} B) Controlled tipping-Controlled
tipping or sanitary landfill is the most satisfactory method of refuse
disposal. It differs from ordinary
dumping in that the material is placed in a trench, adequately compacted, and
covered with earth at the end of the working day.
} A long trench is dug out - 2 to 3
M deep and 4 to 12 M, wide, depending
upon local conditions and availability of land. The refuse is compacted,
pressed and covered with excavated earth. compacted refuse is placed in the
trench to a depth of 2 M
} Chemical, bacteriological and
physical changes occur in buried refuse. The temperature rises to over 60
degree centigrade within 7 days and kills all the pathogens and hastens the
decomposition process. Then it takes 2 to 3 weeks to cool down. Normally it
takes 4 to 6 months for complete decomposition of organic matter
} C) Incineration- burning of refuse is
known as incineration. Hospital refuse which is particularly dangerous is best
disposed of by incineration. Incineration is used in several of the
industrialized countries, particularly in large cities due to lack of suitable
land
} D) Composting- Composting is a method
of combined disposal of refuse and human excreta. Composting is a process of
nature whereby organic matter breaks down under bacterial action resulting in
the formation of compost which has considerable manurial value for the soil.
} The following methods of composting
are used in India -
} (1) Bangalore method (Anaerobic
method)
} (2) Mechanical composting (Aerobic
method)
} Bangalore method- It has been
recommended as a satisfactory method of disposal of town wastes and nightsoil.Trenches
are dug 3 feet deep, 5-8 feet broad and 15-30 feet long, depending upon the
amount of refuse and nightsoil to be disposed off. The pits should be located
not less than 800 M from city limits
} First a layer of refuse about 15 cm
thick is spread at the bottom of the trench. Over this, nightsoil is added
corresponding to a thickness of 5 cm. Then alternate layers of refuse and
nightsoil are added in the proportion of 15 cm and 5 cm respectively, till the
heap rises to 30 cm above the ground level.
} The top layer should be of refuse, at
least 25 cm thickness. Then the heap is covered with excavated earth. Within 7
days as a result of bacterial action considerable heat (over 60 deg C) is
generated in the compost mass. This intense heat over 2 or 3 weeks help to
decompose the refuse and nightsoil and to destroy all pathogenic and parasitic
organisms. At the end of 4 to 6 months, decomposition is complete andmanure is
formed.
} Mechanical composting method- In this method compost manufactured on a
large scale by processing of refuse. The refuse is first cleared of salvageable
materials such as rags, bones, metal, glass and items which are likely to interfere
with the grinding operation.
} the refuse is then grinded and mixed
with sewage, sludge or nightsoil in a rotating machine and incubated. The
factors which are controlled in the operation are a certain carbon-nitrogen
ratio, temperature, moisture, pH and aeration. The entire process of composting
is complete in 4 to 6 weeks.
} (E) Manure pit- The problem of refuse disposal in rural areas
can be solved by digging 'manure pits' by the individual householders. The
garbage, cattle dung, straw, and leaves should be dumped into the manure pits
and covered with earth after each day's dumping. Two such pits will be needed,
} when one manure pit is full it is
closed. In 5 to 6 month's time, the refuse is converted into manure which can
be returned to the field. Till this time another pit is used. This method of
refuse disposal is effective and relatively simple in rural communities.
} (F) Burial- This method is suitable
for small camps or small parties or picnics. A trench 1.5 m wide and 2 m deep
is excavated, and at the end of each day the refuse is covered with 20 to 30 cm
of earth. When the level in the trench is 40 cm from ground level, the trench
is filled with earth and compacted, and a new trench is dug out.
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