 Solid waste are non-liquid, non-soluble materials ranging
from municipal garbage to industrial waste which contain
complex and hazardous substances.
 Population growth, Increasing urbanization,
Industrialization, and standard of living have contributed
to rise in both the amount and variety of waste generated
in most countries.
 The technology of recovering energy from solid waste
will play a significant role in mitigating issues relating
to waste and will also result in reduction of overall
quantity of waste.

Solid waste?
 Any material that we discard, that is not liquid or gas, is
solid waste.
 Municipal Solid Waste:
solid waste from home and offices.
 Industrial Solid Waste:
solid waste produced from mines, Agriculture, and
industries.

Sources and Types of Solid Waste
Sources of solid waste in a community are:
 Residential
 Commercial
 Institutional
 Construction
 Municipal services
 Treatment plant sites
 Industrial
 Agricultural

Sources and Types of Solid Waste

Sources and Types of Solid Waste

Sources and Types of Solid Waste

Waste as a renewable source of
Energy
 The enormous increase in the quantity of
waste materials generated by human activity and
their potential harmful effects on the general
environment and public health, have led to an
increasing awareness
about an urgent need to
adopt scientific methods
for safe disposal of
wastes.

Waste Conversion Technology
 Technologies used to convert solid waste into useful
products, chemicals and fuels are referred as conversion
technology.

 Various technologies are available for realizing the
potential of waste as an energy source, ranging from
very simple systems for disposing of dry waste to more
complex technologies capable of dealing with large
amounts of industrial waste.
 There are three main pathways for conversion of
organic waste material to energy – thermo chemical,
biochemical and physicochemical

Thermo chemical Conversion
 It is characterized by higher temperatures and faster
conversion rates.
 Best suited for lower moisture feedstock.
 Thermochemical routes can convert the entire organic
(carbon) portion of suitable feedstock to energy.
 Inorganic fraction (ash) of a feedstock does not contribute
to the energy products but may increase nutrient loading
in wastewater treatment and disposal facilities.

Thermo chemical Conversion
It includes the following;
 Incineration
 Gasification
 Pyrolysis

Waste Incineration
The incineration technology is the controlled combustion
of waste with the recovery of heat to produce steam
which in turn produces power through steam turbines.
• Volume and weight reduced.
• Incineration can be done at generation site .
• Air discharges can be controlled and small disposal
area required.

Gasification
 Partial oxidation process, pure oxygen, oxygen enriched
air, hydrogen, or steam.
 Produces electricity, fuels (methane, hydrogen, ethanol,
synthetic diesel), and chemical products.
 Temperature > 700oC.
 More flexible than incineration, more technologically
complex than incineration or pyrolysis, more public
acceptance.

Pyrolysis
 Thermal degradation of carbonaceous materials.
 Lower temperature than gasification (400 – 700oC)
 Absence or limited amount of oxygen.
 Products are pyrolitic oils and gas, solid char.
 Distribution of products depends on temperature
 Pyrolysis oil is used for (after appropriate posttreatment) liquid
fuels, chemicals, adhesives, and other products.
 A number of processes directly combust pyrolysis
gases, oils, and char.

Biochemical Conversion
It includes the following;
 Anaerobic digestion (occurs in controlled reactors or
digesters and also in a less controlled environment in
landfills)
 Anaerobic fermentation (for example, the conversion of
sugars from cellulose to ethanol).
Biochemical conversion proceeds at lower temperatures
and lower reaction rates than other conversion processes.

Physicochemical Conversion
It includes the following;
 Transesterification (biodiesel production)
 Physical and chemical synthesis of products from feedstock
 The combustible fraction of the waste is converted into high-
energy fuel pellets which may be used in steam generation.
 Fuel pellets have several distinct advantages over coal and
wood because it is cleaner, free from incombustibles, has
lower ash and moisture contents, is of uniform size, cost-
effective, and ecofriendly.

Advantages
 Majority of waste that goes into landfills can be reused.
 Always a reliable source of fuel as people will always have
waste.
 The fuel is obtained cheaply.

Disadvantages
 Public is not convinced that Waste to Energy facilities are
clean and free of harmful chemicals.
 Waste to Energy facilities are expensive to construct.
 Air Pollution from combustion process.
 Possibility of toxic ash as a byproduct and it may leach
into groundwater and make it impure.

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