Lecture notes on solid waste management as per Solapur university syllabus of TE CIVIL. Prepares by Prof S S Jahagirdar Associate Professor, N K Orchid College of Engg and Technology

1. L-48
SOLID WASTE
MANAGEMENT
PART-II
ENVIRONMENTAL
ENGINEERING-II

2. HAZARDOUS WASTE :
INTRODUCTION

3. Definition
 Solid wastes are considered a
hazardous waste if it exhibits one of the
four characteristics
 IGNITABILITY
CORROSIVITY
REACTIVITY
TOXICITY

4. Ignitability
Ignitable wastes can create fires
under certain conditions, are
spontaneously combustible, or
have a flash point less than 60 °C
(140 °F).
 Examples: waste oils and used
solvents.

5. Corrosivity
Corrosive wastes are acids or
bases (pH less than or equal to 2,
or greater than or equal to 12.5)
that are capable of corroding metal
containers, such as storage tanks,
drums, and barrels.
Example: Battery acid

6. Reactivity
Reactive wastes are unstable under
"normal" conditions.
 They can cause explosions, toxic
fumes, gases, or vapors when heated,
compressed, or mixed with water.
 Examples : lithium-sulfur batteries
and explosives.

7. Toxicity
 Toxicity - Toxic wastes are harmful or fatal when
ingested or absorbed (e.g., containing mercury,
lead, etc.).
 When toxic wastes are land disposed,
contaminated liquid may leach from the waste and
pollute ground water.
 Toxicity is defined through a laboratory procedure
called the
Toxicity Characteristic Leaching Procedure (TCLP
)
 Examples: wastes containing heavy metals Pb, hg

9. STORAGE AND
TRANSPORTATION

10. Indian scenario
 MSWM is a major problem in Indian cities
 Average waste generated in India is 500
gram /person /day according to pollution
control board(PCB 2000)
 Typical rate of waste generation increase in
India is 1.3% annually
 Studies reveal that 90% of municipal wastes is
disposed of unscientifically in open dumps.

11. Onsite storage
Storage of wastes before final
disposal is done at three levels:
1) At source
Solid wastes are often stored at the
source in containers until they are
picked up by waste collectors
(collection crew) or taken out to be
thrown into an open space or a
community bin.

12. 2) At community level
Community bins are used in
crowded and narrow market areas,
which is a common feature of most
developing countries.
Because of the high cost of door to
door collection many waste
management authorities have
introduced community bins.

13. 3) At transfer stations
Transfer stations are established, for
economic reasons in cities, which have
long haulage distances to final disposal
sites.
Smaller collection vehicles bring in the
wastes collected at their source of
generation or from the community bins and
larger vehicles transport them away to final
disposal sites.
Transfer stations are also used as collection
and sorting points for recycling materials

14. Most of the collection systems followed
in India are:
1) Door to door collection
This system is used in narrow streets
where a collection truck cannot reach
individual houses.
The house places the filled containers
outside their doors when the waste
collectors arrive.

15. 2) Curbside collection
This method is used in wider streets,
where the collection trucks can pass
through conveniently.
The house owners leave the waste
containers at the edge of the pavement.
The waste collectors collect the waste
from the curbside or empty the
containers into the vehicle as it passes
through the street at a set time and day
and return the containers.

16. 3) Block collection
The collection vehicles arrive at a
particular place or a set day and time to
collect waste from the households.
Households bring their waste containers
and empty directly into the vehicle.
4) Community bins
Community storage bins are placed at
convenient locations, where the
community members carry their waste
and throw it.

17. Community bins

19. Transport of solid waste
1. Autorikshaws :- these are
3 or 4 wheelers have covered
bodies. Capacities are limited to
½ to ¾ tonnes are used for
narrow localities where large
vehicles can not go.

20. Small - collecting vehicles

21. 2. Trailors
Capacity – 2 to 3 tonnes
Used for localities where trucks can not
go
Loading is done manually
They are of tilting tipping type, hence
unloading can be done automatically.

22. 3. Trucks
Capacity- 5 to 10 tonnes
They are of tilting tipping type so
unloading is automatic

27. Disposal of refuse
Refuse or solid waste can be finally
disposed of by the following methods
1.Controlled tipping
2.Filling of low lying area (Land-filling)
3.Dumping into the sea
4.Pulverization
5.Incineration
6.Composting

28. 1. Controlled tipping
This method is adopted where there is
adequate Land is available.
Refuse is tipped in hollows of depth 1 to 2
m.
Coarse material is tipped at the bottom while
fine material is tipped on the top surface.
Tips are covered with soil so as to seal the
top surface.
After 12 months decomposition is complete.
Area of 0.3 to 0.5 m2
/cap/yr is required

29. 2. Filling of low lying area
(LANDFILL)
A landfill is the place where we dispose our
waste by burying them inside the earth.
It is the most common and oldest method to
dispose our waste.
It is used to dispose hazardous as well as
non –hazardous waste and solid municipal
waste.
This kind of waste disposal is eco- friendly.

30. Garbage is dumped into low lying
areas.
Dumping is done in the layers of 1-2
m and each layer is covered by
thickness of good earth (0.2 m thick)
A rest of 2-3 weeks is given before
dumping the second layer
Each layer is compacted

31. Land filling

33. Advantages
i. Simplest and economical
ii. No plant/ equipment are required
iii. Separation of solid waste is not
required
iv. No byproducts are generated
v. Low lying area can be reclaimed

34. Disadvantages
i. Proper sites may not be available
nearby
ii. Large land area are required
iii. Leachate problems in rainy season
iv. Leachate may pollute the ground
water

35. 3. INCINERATION:
Incineration is the process of removal
of waste through thermal combustion.
Wastes are collected and burnt them
in incinerators (boilers) at
temperatures greater than 6000
C
During burning, the heat is converted
into energy.

36. Only thing we have to consider is during
this process is there is a chance of
release of some toxic substances
during burning.
This method destroys the waste instead
of disposing or storing it, and offers
better solution.
Volume of waste reduces
considerably.

37. Advantages
i. Most hygienic method
ii. No odour trouble or dust nuisance
iii. Heat generated can be used to generate
power
iv. Lesser space required for disposal of
residues
v. No effect of weather conditions.
vi. Can burn variety of refuses
vii. Clinker can be used in road construction

38. Disadvantages
1. Large initial cost
2. Problem of air pollution
3. Special attention shall be
given to dispose residues
4. High stacks are needed to
dispose flue gases.

39. 4. Trenching
 This method is adopted when low lying aera is
not available.
 Trench size – length= 4 to 10 m, width =2 to
3 m and depth = 1 to 2 m
 Trenches are filled with refuse/garbage in the
layers of 15 cm.
 On the top of each layer 5 cm thick layer of
night soil or animal dung is placed in semi
liquid form
 On the top local soil is placed
 After 6 months compost is available for use.

40. 5. Dumping into the sea
Solid waste can also be disposed into the
sea.
Waste has to be carried 15 to 20 km into
the sea.
The depth at disposal point should not be
less than 30 m
Solid waste may float on the top surface of
water.
During stormy weather disposal is not
possible.

41. 6. Pulverization
Dry refuse is pulverized to powdered
form without changing its chemical form.
Powdered refuse can be used as
manure.
Not commonly practiced in India.

42. 7. COMPOSTING

43. COMPOSTING:
Composting is the oldest form of solid
waste treatment method. The municipal
waste consists of 50 – 60 % of organic
matters.
These organic wastes are converted into
usable forms by using micro organisms
such as fungi, bacteria. The fungi or
bacteria convert the organic waste into
humus.

44. The humus is rich in carbon and nitrogen
content, can be used as natural fertilizing
medium for growing plants.
 This method is cheap as well as safe.

46. performed by aerobic
microorganisms;
decomposition of organic matter;
(organic acids, amino acids, sacharides)
occurs;
consuming of O2 and release of CO2
and energy;
high rate of composting process;
temperature - up to 55-60° С.
I. First stage: active (thermophilic)

47. Decomposing of more complicated organic
molecules;
Most of the microorganisms die from lаck of “food”;
Lower rate of the process;
Temperature - up to 40 - 45° С;
Duration – few weeks
humification!
Waste appearance before and after composting process
II. Second stage: cooling

48. III. Third stage: maturation
Temperature is equal to the ambient;
A completely disinfected high quality compost
is formed as a result

49. 1. Temperature
 Thermophilic (45 –750
C) and Mesophillic (10-
450
C).
 Above this temperature Microorganisms
inactivated or die off.
 Affected by its climatic surroundings and
method of aeration.
 In a windrow highest temperature reached in
centre, lower at edges.
Environmental Factors Affecting
Composting

50. 2. pH
Anaerobic digestion the pH level covers a
narrow range (pH 6.5 to 7.5)
Aerobic- pH so broad difficulties rarely
encountered with too high or too low pH
in composting.
During the early stages the pH usually
drops (down to about pH 5.0) because of
organic acid formation.

51. 3. Aeration (Anaerobic & Aerobic)
Anaerobic:
Advantages
a) minimisation of the loss of nitrogen
b) less costly
Disadvantages include:
a) Slowness of decomposition
b) Absence of high temperatures
c) The presence of un-decomposed
intermediates
d) The un-pre-processed appearance of
the product

52. Aerobic
Aerobic composting benefits from:
a) A rapid rate of degradation
b) Elevated temperature levels
c) Absence of putrefactive matter
Oxygen uptake reflects intensity of
microbial activity.

53. 4. Moisture Content
Moisture content and oxygen availability
are closely related
If the moisture content of the mass is so
high as to displace the air from the
interstices (voids between particles)
anaerobic conditions will develop within
the mass .
Woodchips, straw and hay can be as high
as 75 to 80% whereas paper (upon
becoming wet, collapses and forms mats)
has a permissible moisture content of 55
to 60%.

54. 5. Substrate
The waste (referred to as the substrate) should
contain all necessary nutrients.
Macronutrients Micronutrients
 Carbon (C) Cobalt (Co)
 Nitrogen (N) Manganese (Mn)
 Phosphorous (P) Manganese (Mg)
 Potassium (K) Copper (Cu)
Only available if they are in a form that
can be assimilated by the microbes.

55. Certain groups of microbes have an
enzymatic complex that permits them to
attack, degrade and utilize the organic
matter found in freshly generated waste.
Others can only utilize decomposition
products (intermediates) as a source of
nutrients.

56. Carbon: Nitrogen Ratio (C: N)
The C: N ratio of the waste to be
composted is the most important factor
that requires attention.
A large percentage of the carbon is
oxidized to carbon dioxide by the
microbes in their metabolic activities .
The C: N of the substrate should fall
within the range of 20-25:1.
Mmicroorganisms such as bacteria and
fungi grow best with the proper level of
Carbon and Nitrogen.

57. METHODS OF COMPOSTING

58. 1. Composting by trenching
Trench is 4 to 10 m long, 2 to 3 m wide,
0.7 to 1 m deep.
Trenches are filled with garbage/refuse
layers of 15 cm thick.
On the top of each layer night soil/ animal
dung is spread in semi liquid form.
On the top layer 10 cm thick local soil is
laid

59. Within 2 to 3 days decomposition
process starts.
Because of decomposition
temperature raises up to 750
C
Refuse gets stabilized after 4 to 5
months and turns brown in colour
Manure is sieved through 12.5 mm
sieve to separate out stones, bricks
etc
Sieved manure is applied to farms

60. 2. Open windrow composting
In India, 50-60% of municipal solid waste is
organic waste.
Considering the climatic conditions and other
factors, composting of organic waste is
excellently suited for India and Windrow
composting is the best option to deal with the
huge volume of bio-degradable waste.
 Windrow composting is the available best
model for stabilization of the biodegradable
portion of the MSW.

61. Refuse is dumped on ground in the
form of 0.6m to 1 m high, 6 m long
and 1 to 2 m wide piles at about 60%
moisture content.
Pile is covered with night soil, cow
dung, cattle urine etc.
Temperature during process is 750
C
After this pile is reversed (turned up)
Within 4-6 weeks compost/manure is
ready

63. Windrow turner

64. Static pile composting

65. 3. Indore method
Refuse, night soil, animal dung etc are
placed in small brick lined pit 3m x 3 m x 1
m deep in alternate layers of 7.5 cm to 10
cm height so as to take total height of 1.5 m
DDT or any other insecticide can be added
to prevent flies breeding
The material is turned regularly for period
of 8-12 weeks. Water is sprayed on dried
material during overturning
Manure/compost is ready after 4 months

66. 3 m
3 m

67. The advantages of this method are:
1. the process can be kept under control
and runs smoothly, because the heap
is turned regularly;
2.compost is produced in a short time.
Disadvantages of this method are:
1. it requires much water;
2. it is very labour intensive.

68. 4. Bangalore method
In Bangalore method refuse is stabilized
anaerobically.
Earthen trenches of size 10m x 1.5m x
1.5m deep are filled up in alternate layers
of refuse and night soil or animal dung.
The material is covered up with 15 cm layer
of good earth and left for decomposition for
4-5 months.
The compost is ready after 4-5 months

69. 10 m
1.5 m
1.5 m
1.5 m

70. The major advantages of the Bangalore
Method are:
1.a saving of water;
2. it requires less labour, because the heap
is not turned over during the
decomposition process.

71. Disadvantages of the Bangalore
Method are:
1. more disease germs and weed seeds
survive due to the temperature during
decomposition;
2. the decomposition process is more
difficult to control because the heap has to
be kept continually covered;
3. it is a less suitable method for those with
little or no experience in composting.

72. 5. Mechanical composting
Indore and Bangalore methods are suitable
for small cities and towns to decompose the
garbage.
Mechanical compost plants of 200
tonnes/day and above capacity have been
made for converting the city waste into
compost.
Before that, the non compostable material
such as bricks, stones, iron pieces, broken
glass pieces, rubber, plastics etc. are
removed.

73. Advantages of composting
Reduces mass and volume
- lower hauling costs
• Reduces odour
• Pathogens are destroyed
• Kills weed seeds
• Improves transportability as volume gets
reduced
• Good Soil conditioner

74. • Improves nutrient qualities
- the nutrients from compost are
released slowly and steadily
• Decreases pollutants
- stabilizes the volatile nitrogen into
large protein particles, reducing losses
• Land application when convenient
Saleable product
• Increases water retention of soil

75. Disadvantages
• Loss of ammonia (N)
• Time and labour involved
• More Cost of equipment (initial and
operating)
• Land required for composting
• Marketing required for sale

76. Theory Questions
Q1. Explain theory of composting.
Q2. Enlist different methods of composting and explain
any one method in detail.
Q3. Discuss factors affecting composting process.
Q4. What are advantages and disadvantages of
composting?
Q5. Draw a neat sketch of ‘Landfill’.
Q6. Write short notes on
1. Landfill
2. Effects of solid waste on human and environment
3. Bangalore method of composting
4. Indore method of composting 5. Incineration of MSW