Solid waste management

Solid waste management

Solid wastes are the total wastes arising
from human and animal activities that
are normally solid and hence are
useless or unwanted.

 It comprises  of the heterogeneous mass
of throw away from houses of
commercial centers as well as the
nearby homogeneous accumulation of a
single industrial activity.

Watch videoTypes of waste
 Refuse represents the dry wastes or
solid wastes of the society.

 The term ‘refuse’ is often used
interchangeability with term solid
wastes.

 The density of Indian refuse is generally
higher than of the developed countries
and hence the Indian refuse can be
carried efficiency and economically by
mechanical transport (carrying more
wt. for the same volume).


Watch video Landfilling

 The calorific value of Indian refuse is
much smaller, and its moisture content
is high.

TYPES OF SOLID WASTES 

Major categories of solid waste generation
are :
i) Municipal wastes
ii) Industrial wastes
iii) Hazardous wastes.

Municipal waste

Solids wastes generated from different
zones of the city differs in
characteristics. There solid waste
comprise refuse, ordinary refuse
(includes garbage & rubbish) and trash.

Refuse refers to non-hazardous solid
waste from the community requiring
collection and transporting to
processing/disposal site.

Garbage comprises items that are highly
decomposable (putrescible) food, waste
vegetables and meat scraps.

 Rubbish contains mostly dry, no
decomposable (nonputrescribe)
material – glass, rubber, tin cans, also,
or combustible material – paper,
textiles, wooden articles, etc.

Hence, community refuse can be
referred to as municipal solid waste
(MSW).

 Watch video Composing

INDUSTRIAL WASTES 

Industrial wastes are generated from
the industrial activities or
manufacturing processes.

All the three types of wastes, solid,
liquid and gaseous are generated.

 Industrial wastes can be categorized as
non-hazardous and hazardous. It is well
known hazardous wastes have a
potential for every deleterious impact
on environment and life in general.

Some of the common industries which
generate solid waste along other wastes
on a large scale are :
i) Paper and pulp
ii) Metallurgical industries
iii) Pesticides/Insecticides
iv) Fertilizers
v) Plastics
vi) Refineries

HAZARDOUS WASTES 

Hazardous substance can be defined as
anything which because of its quantity,
concentration or characteristics may
contribute to increased mortality,
illness or hazard to human health and
environment if not properly stored and
transported or disposed off.

As per the Resource Conservation and
Recovery Act (RCRA), USA, the
hazardous waste is one which
possesses any one of the four
characteristics, such as, ignitability,
corresibility, reactivity or toxicity.

 Hazardous differ in form as well as
behavior from ordinary solid wastes.
They generally are produced in liquid
form; however, they can also occur as
solids, sludge, or gases. They are
infectious and radioactive.

 Some of the common industries which
generate hazardous waste are:
i) Ferrous, non-ferrous industries
ii) Cement industries
iii) Petroleum industries
vi) Chemical industries

BASED ON THE TYPE OF WASTES 

a) Garbages

It includes all sort of putrescribe
organic wastes, obtained from kitchens,
hotels, restaurants like waste food
articles, vegetable peelings, fruit
peelings, etc. these wastes are organic
in nature, and hence, likely to
decompose quickly, producing foul
odours and health hazards. They may
also result in breeding of files,
mosquitoes, insects, etc. Hence, garbage
must be disposed off, properly and
quickly. When it is scientifically
processed and composted then we may
obtain some valuable products like
grease, fertilizer, etc. from garbage. The
density of garbage usually varies
between 450 to 900 kg/m3.

b) Ashes :-

Ashes are the incombustible waste
products from hearths and furnace, and
houses or industries. The density of ashes generally vary between 700 to 850 kg/m3.

c) Rubbish

Rubbish includes all non-putrecible
wastes expect ashes. All combustible
wastes, such as rags, paper pieces,
broken pieces of glass and furniture,
card-boards, broken crockery comes
under. Rubbish is lighter, and normally
has a density varying between 50 to
400 kg/m3.

ON SITE HANDLING, STORAGE, AND PROCESSING 

The handling, storage, and processing of
solid wastes at the source before they are
collected are the functional elements in a
solid-waste management system.
On-site handling refers to the activities
associated with the handling of solid
wastes until they are placed in the
containers used for their storage before
collection. Depending on the type of
collection service, handling may also be
required to move loaded containers to the
collection point and to return the empty
containers to the point where they are
stored between collections.
Factors considered in the on-site storage
of solid wastes include:
i) the type of container to be used,
ii) the container location,
iii) public health and aesthetics
iv) the collection methods to be used.

On-site processing methods are used to 

recover usable materials from solid wastes, 

to reduce the volume, or to alter the 

physical form. The most common on-site 

processing operations include manual 

sorting, compaction, and incineration.

Processing techniques

Processing techniques are used in solid 

waste management systems to 

i) improve the efficiency of solid-waste 

disposal systems

ii) to recover resources (usable materials)

iii) to prepare materials for the recovery of 

conversion products and energy.

Important processing techniques used 

routinely in municipal solid-waste systems 

include; compaction, thermal volume 

reduction (incineration), and manual 

separation of waste components.

i) Mechanical volume reduction 

It is the most important factor in the 

development and operation of solid-

waste management systems. Vehicles 

equipped with compaction mechanisms 

are used for the collection of most 

municipal solid wastes. Wastes are 

compacted to increase the useful life of 

landfills.

ii) Thermal volume reduction 

The volume of municipal wastes can be 

reduced by more than 90 percent by 

incineration. Incineration was quite 

common in the past, however, with 

more restrictive air-pollution control 

requirements, only a limited number of 

municipal incinerators are currently in 

operation.

iii) Manual component separation 

The manual separation of solids waste 

components can be accomplished at the 

source where solid wastes are 

generated, at a transfer station, at a 

centralized processing station, or at the 

disposal site. Manual sorting at the 

source of generation is the most 

positive way to achieve the recovery 

and reuse of materials. The number and 

types of components salvaged or sorted 

(e.g., cardboard and high quality paper, 

metals, and wood) depend on the 

location, the opportunities for recycling, 

and the resale market.

METHODS OF SOLID WASTE COLLECTION

COLLECTION, REMOVAL AND 

CARRIAGE OF REFUSE

Regular collection and transport of solid 

waste are most important operations in 

any efficient solid waste management 

which costs about 80% of the total cost 

of solid waste management.

 In India, refuse is generally collected in 

individual houses in small containers 

and from there it is collected by 

sweepers in small hand driven 

lorries/carts and then dumped into the 

layout of street and density of 

population.

 The capacity of the bins may vary from 

100 to 500 liters depending on the 

quantity of zone wise waste generation. 

 In case of large quantity of putrescible 

garbage from residential area, it will be 

appropriate to follow on-site storage.

The waste from the community storage 

bins is collected by transport vehicles 

daily for final disposal or treatment. 

Combined collection of garbage and 

rubbish is more economical. If materials 

are to be recycled, home owners can 

practice source separation i.e. into 

paper, glass etc.