In this ppt, a whole idea related to the management of solid waste is discussed like from management of waste from household level to its collection ,separation ,recovery ,recycling etc. This ppt can be used for civil engg subject Titled "SOLID WASTE MANAGEMENT" or it can be used by other students who are mainly concerned with the management of solid waste.

1. SOLID WASTE MANAGEMENT
WASTE TO ENERGY
PREPARED BY:-
CHARANJIV SINGH
B.Tech Civil Engineering

2. What is Solid Waste
Solid waste comprises of all the
wastes arising from human and
animal activities that are typically solid
and that are discarded as useless or
unwanted. It is all-inclusive of the
heterogeneous mass from the urban
community as well as more
homogeneous accumulation of
agriculture and industrial wastes.

3. Why solid waste: A consequence of life
 The relationship between public health and improper storage, collection and disposal of solid waste is quite clear.
 The consequences of improper disposal of solid waste can be very well highlighted with the following examples.

5. Functional Elements of SWM
The activities associated
with the management of
solid waste from the point
of generation to final
disposal have been grouped
into six functional elements.

6. TYPES OF SOLID WASTES
Solid waste can be broadly classified as:
a) Municipal wastes which include garbage or food wastes, ashes and residues, construction and demolition
wastes, treatment plant wastes, special wastes.
b) Industrial wastes which include all types of liquid or solid waste generated from different types of
industries.
c) Hazardous wastes are waste (liquid, solid, gaseous or sludge) that is dangerous or potentially harmful to
our health or environment. They can be discarded commercial products, byproducts from industries, or
from households.

7. CLASSIFICATION OF MUNICIPAL SOLID WASTE: BASED ON SOURCE

9. WASTE AS A FUEL
 The primary difference between waste
incineration and other combustion systems is
that the waste incineration process treats
incoming waste with great variation.
 Practical design limits allowable variations of
waste composition.
 Basic considerations before design-
 Best available data on the amount and composition of
each waste type.
 Effect of future changes in waste management.
 Waste led to incineration plant consists of domestic,
commercial, institutional and industrial waste (great
variation). Inert wastes from sweeping Recent waste
generation data shows the presence of huge quantity
of packaging material
 Street sweepings, and construction and demolition
wastes are not suitable for incineration as they
contain a large fraction of incombustible matter.

10. WASTE CHARACTERISTICS
 For waste characterization as a fuel, it is required to determine:
 Moisture content (W) [15-35% when drying at 105°C]
 Ash content (A) or inorganic content [10-25% after ignition at
550°C]
 Combustible solids (C) or organic solids [typically 40-65%]

12. INCINERATION/COMBUSTION
• Incineration is a waste treatment process that involves combustion of waste at very high temperatures in the
presence of oxygen and results in the production of ash, flue gas, and heat.
• Incineration is a feasible technology for combustion of unprocessed or minimum processed refuse and for
the segregated fraction of high calorific value waste.
• The potential for energy generation depends on the composition, density, moisture content, and presence of
inert in the waste (about 65% – 80% of the energy content of the organic matter can be recovered as heat
energy, which can be utilized either for direct thermal applications or for producing power via steam turbine
generators) .
• Incineration of MSW helps to reduce landfill volumes. Incineration is feasible when there are no better
options of processing of waste, shortage of land for landfilling.(e.g., Japan, having land shortage).
• On the downside, incineration is expensive and ash remaining after the process completion can be harmful
for the environment if not treated properly.

13. INCINERATION PROCESS
• In a furnace, the combustible components
react with oxygen of the combustion air,
releasing a significant amount of hot
combustion gas.
• The moisture content of the waste is
evaporated in the initial stage of the
incineration process and incombustible
parts of the waste form solid residues
(bottom ash, fly ash).
• Through incineration, the solid constituents
of the waste undergo a range of processes
as a result of exposure to heat and contact
with the combustion air.

14. • The combustion gases pass from the furnace to the afterburning chamber.
• As per European Union (EU), a minimum temperature of 850°C for municipal waste and 1100
°C for certain types of hazardous waste have been set for the complete burnout of
combustion gases in the afterburning chamber.
• As per EU, the above temperature should be maintained for a minimum time of 2s as
measured from the last injection of combustion air.
• EU has strict legislation as to no feeding into the incinerator before attainment of required
temperature and if at all there is any interruption such as drop in the temperature, then feeding
should be stopped right away.
• In India, as per CPHEEO manual, 2016, minimum gas phase combustion temperature of
850°C for MSW and a minimum residence time of the flue gases, above this temperature, of
2s after the last incineration air supply should be followed.

15. PROBLEMS ASSOCIATED WITH MSW INCINERATION RESIDUES
• Due to the volatilization and subsequent condensation as well as concentration phenomena acting
during combustion,MSWI residues have high concentrations of heavy metals, salts as well as organic
micro-pollutants.
• The fly ash is problematic for incinerator operation and can cause slagging and fouling in addition to
environmental issues.
• Fly ash contains heavy metals, a high content of easily soluble salts, and, in some cases,
polychlorinated dioxins and furans.
• The quantity, quality, and characteristics of MSWI residues depend on many factors, such as the
composition of feed, type of incinerator, operating parameters, and pollution control techniques.
• In some European countries great efforts are devoted to utilization of such residues through various
treatment processes.
• If utilization is not possible due to regulatory constraints or any other reasons, these residues have to
be disposed in an environmentally acceptable and economically sustainable way.

16. TREATMENT OF BOTTOM ASH
 Separation Processes
• Separation is the simplest treatment principle and may include both physical and chemical processes or
a combination of both.
• Particle size separation (sieving) and magnetic separation is universally used where MSWI bottom ash
is processed for utilization.
• The bottom ash typically contains 7–10% of scrap iron and 1–2% of nonmagnetic metal.
• It is commonly subjected to coarse sieving, sometimes in combination with crushing, to remove
oversize material, magnetic separation to remove and recover ferromagnetic material and eddy current
separation to remove and recover nonmagnetic metal, including aluminium and copper.
• A substantial amount of the soluble chlorides may be removed by washing of the bottom ash.

17.  Stabilization and Solidification
• Solidification is a physical or mechanical stabilization resulting in a harder or more coherent waste form,
which increases the strength and tortuosity of the material and reduces the exposed surface area, thus
reducing the rate of release of contaminants.
• Chemical stabilization is aimed at chemical fixation of various contaminants by transforming them into
compounds with low solubility.
• Solidification and chemical stabilization may be applied separately or in combination at bottom ash.
• Addition of hydraulic binders such as cement with or without additives to bottom ash will often result in
both solidification and chemical stabilization.
 Thermal Treatment
• Bottom ash may be treated thermally at different temperatures.
• Sintering occurs at temperatures of approximately 400–850ºC, may cause fusion and reorganization of
solid phases, thereby reducing the availability of various components for leaching.
• Melting/vitrification occurs at temperatures of 1100–1500ºC or higher. By simple melting, crystalline or
heterogeneous products are formed, whereas vitrification, which may require additives, produces a single
amorphous glass phase.
• The rate of leaching of contaminants from these products is generally slow.

18. TREATMENT OF AIR POLLUTION CONTROL (APC) RESIDUES
 Separation Processes
• The application of the separation processes to these residues generally requires the residues or the
mass streams to be dissolved or suspended in or saturated with water.
• For residues from the dry and semidry APC process, and fly ash, the initial treatment step often consists
of or include an aqueous extraction operation, regardless of the nature of any subsequent treatment
steps involved.
• Metals and trace elements may be removed from the wastewater by pH adjustment and chemical
precipitation prior to discharge or salt recovery.
• HCl from acid scrubber effluents could be separated by distillation and chlorine could be produced by
electrolysis.
 Solidification/Stabilization
• Stabilization of APC residues with puzzolanic or hydraulic binders, such as cement, has both a
mechanical and chemical effect, but is generally deemed both mechanically and chemically insufficient
due to the high salt content.

19.  Thermal Treatment
• Due to the high energy requirement and problems associated with the reformation of HCl and
vaporization of metals, APC residues are generally not treated by melting processes.
• Sintering processes may be performed on fly ash and acid gas cleaning residues, which have
been subjected to aqueous or acid extraction.
 SOME ENGINEERING APPLICATIONS OF BOTTOM ASH
• Road Construction
• Aggregate Replacement in Concrete
 SOME ENGINEERING APPLICATIONS OF FLY ASH
• Soil Stabilization
• Water Treatment

20. PROLYSIS
• Pyrolysis is thermal degradation (300-
800°C) of organic material in the absence of
oxidizing agents such as oxygen, steam and
CO2
• Pyrolysis, unlike incineration, is an
endothermic reaction and heat must be applied
to waste to distil volatile components.
• Composition and energy contents of the
pyrolysis products are highly dependent of the
waste input and may vary significantly:
• Gas (H2, CH4, CO and CO2): 20–50% by
weight of the input.
• Liquid (tar, oil, water, organic acids, phenols,
PAHs and alcohols): 30–50% by weight.
• Solid (char like material): 20–50% by weight.

21. GASIFICATION
• Gasification is thermal and chemical conversion (800-1500°C) of carbon based material
into a mainly gaseous output by partial oxidation with a gasification agent typically air, steam
or oxygen.
• Products of gasification are in general:
• Gas (similar to pyrolysis gas but higher CO2): 30–60% by weight of the input.
• Liquid (tar and oil): 10–20% by weight of theinput.
• Solid (ashes): 30–50% by weight of the input.

22. BENEFITS OF PYROLYSIS AND GASIFICATION WITH RESPECT TO INCINERATION
• The possibility and flexibility to recover chemical energy in the waste as hydrogen and/or other chemical
feedstocks rather than converting this energy into hot flue gases.
• Potentially better overall energy efficiency.
• Less trouble with corrosion.
• Less need for flue gas cleaning: smaller volumes of flue gas with a better quality.
• Potentially better options for CO2 capture.
• Potentially lower emissions of dioxins.
• Improved qualities of solid residues, particular for high-temperature processes.
• Gasification units operating with a low fuel load, potentially facilitating small plants producing less than 1
MW.
• Potentially lower costs.

23. COMPOSTING
• Composting is the biological decomposition and stabilization of organic substrate under
conditions that allow development of thermophilic temperatures as a result of biologically
produced heat, to produce a final product that is stable, free of pathogens, plant seeds and
can be beneficially applied to land.

24. Functional group of organisms in compost

25. PHASES OF COMPOSTING
 Composting proceeds in three stages-
 An initial lag period (lag phase).
 A period of exponential growth and accompanying intensification of activity (active phase).
 Eventually tapers into one of final decline, which continues until ambient levels are reached
(curing phase or maturation phase).
 Lag Phase
• The lag phase begins as soon as composting conditions are established.
• Microbes begin to proliferate, by using sugars, starches, simple celluloses, and amino acids
present in the raw waste.
• Pseudomonads are in abundant in this phase while, protozoa and fungi are not discernible.
• This phase is very brief when putrescible and/or herbaceous wastes are involved, somewhat
longer when woody and/or MSW wastes are involved and very protracted with dry leaves and
resistant waste such as, dry hay, straw, rice hulls, and saw dust.

26.  Active Phase
• Exponential increase in microbial numbers and activity manifested by precipitous and uninterrupted rise
in temperature of the composting mass can be observed.
• The temperature may peak at 70 °C or higher followed by flattening of the temperature curve called
the plateau phase.
• Duration of the entire active stage (exponential plus plateau) varies with substrate and with
environmental and operational conditions.
 Maturation or curing Phase
• When the easily decomposable material is depleted, maturation stage begins.
• The proportion of resistant materials steadily rises and microbial proliferation correspondingly declines.
• Temperature begins an inexorable decline, which persists until ambient temperature is reached.
• The time involved in maturation is a function of substrate and environmental and operational
conditions.

27. FACTORS AFFECTING COMPOSTING PROCESS
 Temperature
• As an environmental factor, temperature effects the well-being and activities of the microbial population.
• The curve of composting process efficiency and speed flatten between 35-55 °C, and are negligible at
temperatures above 70 °C.
• At temperatures higher than 65 °C, most non-spore formers die off and spore formers enter the spore
stage and, as such, are dormant.
 Moisture Content
• Almost all biological activity ceases at moisture contents lower than about 12%.
• A moisture content of 50-60% is generally considered optimum for composting.
• Microbial induced decomposition occurs most rapidly in the thin liquid films found on the surfaces of the
organic particles.
• Whereas too little moisture (<40%) inhibits bacterial activity, too much moisture (>65%) results in slow
decomposition, odor production in anaerobic pockets, and nutrient leaching.
• Often the same materials that are high in nitrogen are very wet, and those that are high in carbon are dry.

28.  Particle size
• Microbial activity generally occurs on the surface of the organic particles.
• Therefore, decreasing particle size, through its effect of increasing surface area, will encourage microbial
activity and increase the rate of decomposition.
• On the other hand, when particles are too small and compact, air circulation through the pile is inhibited.
This decreases O2 available to microorganisms within the pile and ultimately decreases the rate of
microbial activity.
• Recommended size of particle: < 1 cm
 AERATION
• Oxygen is a key element in the respiratory and metabolic activities of microbes.
• The amount of oxygen required by the microbes is termed “oxygen demand”.
• Temperature, moisture content, size of bacterial population, and availability of nutrients are some of the
key factors that influence oxygen demand.

29. Nutrients: Carbon to Nitrogen (C/N) ratio
• The ideal ratio is about ~30 parts of
available carbon to 1 part of available
nitrogen.
Carbon = Source of energy
Nitrogen = Building cell structures.
• If C/N ratio of compost is more, the excess
carbon tends to utilize nitrogen in soil to
build cell protoplasm (Robbing of soil).
• If C/N ratio is too low the resultant product
does not help improve the structure of soil.

30. COMPOST SYSTEMS

31.  Agitated/windrow composting
• Large volumes of diverse wastes such as
yard trimmings, grease, liquids, and animal
byproducts (such as fish and poultry
wastes) can be composted through this
method.

32. Reactor configurations in in-vessel systems
• Horizontal drum
• Vertical silo
• Open tank

34. Rotating drums
• This system uses a horizontal rotary drum to
mix, aerate and move the material through the
system.
• A drum about 3.35 m in diameter and 36.58 m
long has a daily capacity of approximately 50
tonnes with a residence time of 3 days.
• In the drum, the composting process starts
quickly and the highly degradable, O-
demanding materials are decomposed.
• Further decomposition is accomplished
through a second stage of composting, usually
in windrows or aerated static piles.
• Air is supplied through the discharge end and is
incorporated into the material as it tumbles. (Air
moves in the opposite direction to the material)

35. • The drum can be open or partitioned.
• An open drum moves all the material through
continuously in the same sequence as it enters.
• The speed of rotation of the drum and the
inclination of the axis of rotation determine the
residence time.
• In some commercial systems, the composting
materials spend less than one day in the drum.

36. SPECIFIC ADVANTAGES OF ROTARY DRUM COMPOSTER
 Limitations
• Capital Cost
• Power Requirement

38. VERMICOMPOSTING
• Vermicompost is the product of the
decomposition process using various species of
worms, usually red wigglers (Eisenia fetida),
white worms (Enchytraeus buchholzi), and
other earthworms, to create a mixture of
decomposing vegetable or food waste, bedding
materials, and vermicast.
• Vermicast (also called worm castings, worm
humus, worm manure, or worm faeces) is the
end-product of the breakdown of organic matter
by earthworms.
• Vermicompost contains water-soluble nutrients
and is an excellent, nutrient-rich organic
fertilizer and soil conditioner

39. Mechanisms of vermicomposting

40. Salient Features
 Bedding
• Bedding is any material that provides a relatively stable habitat to worms.
• High absorbency: As worms breathe through skin, the bedding must be able to absorb and retain adequate
water.
• Good bulking potential: The bulking potential of the material should be such that worms get oxygen
properly.
• Low nitrogen content (high Carbon: Nitrogen ratio): High protein/nitrogen levels can result in rapid
degradation and associated heating may be fatal to worms.
 Food Source
• Regular input of feed materials for the earthworms is most essential step in the vermicomposting
process.
• Earthworms can use a wide variety of organic materials as food but do exhibit food preferences.
• Under ideal conditions, worms can consume amount of food higher than their body weights, the general
rule-of_x0002_thumb is consumption of food weighing half of their body weight per day.
• In adverse conditions, earthworms can extract sufficient nourishment from soil to survive.

41.  Moisture
• The most important requirement of earthworms is adequate moisture.
• They require moisture in the range of 60-70%.
• The feed stock should not be too wet otherwise it may create anaerobic conditions which may be fatal
to earthworms.
 Aeration
• Factors such as high levels of fatty/oily substances in the feedstock or excessive moisture combined
with poor aeration may render anaerobic conditions in vermicomposting system.
• Worms suffer severe mortality partly because they are deprived of oxygen and partly because of toxic
substances (e.g. ammonia) produced under such conditions.
 Temperature
• The activity, metabolism, growth, respiration and reproduction of earthworms are greatly influenced by
temperature.
• Worms have an optimal temperature range of 16 to 25°C.
• Temperature above 40°C can kill worms

42.  pH
• Worms can survive in a pH range of 5 to 9, but a range of 7.5 to 8.0 is considered to be the optimum.
• In general, the pH of worm beds tends to drop over time due to the fragmentation of organic matter
under series of chemical reactions.
 How to build a worm home ??
• Worms need air to survive. They can live in a plasticbin or a wooden box, with several air holes
punched or drilled all around.
• It is more convenient to have several smaller, more portable units rather than one large one.
• Do not use a bin that was once used to store chemicals, such as pesticides, or you may end up with a
pile of dead worms.
• Vermicomposting container box should be shallow, and wider than it is tall.
• An average size vermicomposting bin for a household of two people should be 30 cm high x 40 cm
deep x 60cm long.

43.  ADVANTAGES
• Labour and equipment cost minimal.
• One of the promising decentralized composting technology.
• Excellent composting concept for smaller communities that require a rapid and enclosed pathogen kill
process.
• It can be very useful in peri-urban areas of large cities, institutional areas, vegetable markets, large
dairies along with nurseries and demand driven places (garden/park areas and official areas).
• Worm Castings improve plant growth.
• Earthworms double their population every four months.
 DISADVANTAGES
• Initial cost high.
• Care for Survival very sensitive.

44. THANK YOU